D2065 3 13 172 SERIES (1977 THRU 1986) Cessna_172_1977 1986_MM_D2065 Cessna 1977 1986 MM

User Manual: Cessna_172_1977-1986_MM_D2065-3-13

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Cessna
ATextron

Company

Service Manual

1977
Thru
1986
MODEL 172
SERIES

Member of GAMA

FAA APPROVAL HAS BEEN OBTAINED ON TECHNICAL DATA IN THIS PUBLICATION THAT AFFECTS AIRPLANE TYPE DESIGN.

THIS REPRINT
CONSISTS OF THE BASIC MANUAL, DATED 20 MARCH 1985,
AND INCORPORATES REVISION 2, DATED 1 MAY 1992.
AND REVISION 3, DATED 1 JULY 1995.

20 MARCH 1985

D2065-3-13
(RGI-200-10/00)

REVISION 3

1 JULY 1995

TEMPORARY REVISION NUMBER 5
DATED 7 January 2000
MANUAL TITLE

MODEL 172 SERIES 1977 THRU 1986 SERVICE MANUAL

MANUAL NUMBER - PAPER COPY D2065-3-13

AEROFICHE

D2065-3-13AF

TEMPORARY REVISION NUMBER PAPER COPY D2065-3TR5

AEROFICHE N/A

MANUAL DATE

DATE 1 JULY 1995

20 MARCH 1985 REVISION NUMBER

This Temporary Revision consists of the following pages, which affect existing pages in the
paper copy manual and supersede aerofiche information.
SECTION
18
18

PAGE
6A
6B

AEROFICHE
FICHE/FRAME

SECTION

PAGE

AEROFICHE
FICHE/FRAME

Added
Added

REASON FOR TEMPORARY REVISION
To provide additional information for the stop drilling of cracks that originate at the trailing edge
of control surfaces with corrugated skins.
FILING INSTRUCTIONS FOR THIS TEMPORARY REVISION
For Paper Publications:
File this cover sheet behind the publication's title page to identify the inclusion of the
Temporary Revision into the manual. Insert the new pages into the publication at the
appropriate locations. Draw a line, with a permanent red ink marker, through any
superceded information.
For Aerofiche Publications:
Draw a line through any aerofiche frame (page) affected by the Temporary Revision with a
permanent red ink marker. This will be a visual identifier that the information on the frame
(page) is no longer valid and the Temporary Revision should be referenced. For "added"
pages in a Temporary Revision, draw a vertical line between the applicable frames which is
wide enough to show on the edges of the pages. Temporary Revisions should be collected
and maintained in a notebook or binder near the aerofiche library for quick reference.

TEMPORARY REVISION NUMBER 4
DATED

MANUAL TITLE

MODEL 172 SERIES 1977 THRU 1986 SERVICE MANUAL

MANUAL NUMBER - PAPER COPY

20 MARCH 1985

AEROFICHE

D2065-3-13

TEMPORARY REVISION NUMBER - PAPER COPY
MANUAL DATE

16 FEBUARY 1996

D2065-3TR4-13

REVISION NUMBER

D2065-3-13AF
AEROFICHE
DATE

N/A

1 JULY 1995

This Temporary Revision consists of the following pages, which affect and replace existing pages in the paper ccmanual and supersede aerofiche information.
CHAPTER/
SECTION/
SUBJECT

PAGE

AEROFICHE
FICHE/FRAME

11-11
11-15

CHAPTER/
SECTION/
SUBJECT

PAGE

AEROFICHE
FICHE/FRAME

2B19
2B23

REASON FOR TEMPORARY REVISION
To change torque values for engine mount-to-fuselage bolts.
FILING INSTRUCTIONS FOR THIS TEMPORARY REVISION
For Paper Publications:
File this cover sheet behind the publication's title page to identify inclusion of the temporary revision in the
manual. Insert the new pages in the publication at the appropriate locations and remove and discard the
superseded pages.
For Aerofiche Publications:
Draw a line, with a permanent red ink marker, through any aerofiche frame (page) affected by the temporary
revision. This will be a visual identifier that the information on the frame (page) is no longer valid and the
temporary revision should be referenced. For "added" pages in a temporary revision, draw a vertical line
between the applicable frames. Line should be wide enough to show on the edges of the pages. Temporary
revisions should be collected and maintained in a notebook or binder near the aerofiche library for quick
reference.

1.996
COPYRIGHT
CESSNA AIRCRAFT COMPANY
WICHITA, KANSAS, USA

MODEL 172 SERIES SERVICE MANUAL

LIST OF EFFECTIVE PAGES
INSERT LATEST REVISED PAGES. DESTROY SUPERSEDED PAGES.
NOTE
The portion of the text affected by the revision is indicated by
a vertical line in the outer margins of the page. Changes to
illustrations are indicated by miniature pointing hands.
0
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Original
Revision
Revision
Revision

20 March 1985
20 October 1985
1 May 1992
1 July 1995

TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS 652.
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MODEL 172 SERIES SERVICE MANUAL

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Upon receipt of a revision to this book, personnel responsible for maintaining this
publication in current status should ascertain that all previous revisions havebeen
received and incorporated.
C Revision 3

Revision
No.
1
0
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MODEL 172 SERIES SERVICE MANUAL

TABLE OF CONTENTS
PAGE NO.
AEROFICHE/MANUAL

SECTION
1.
2.
3.
4.
5.
5.
7.
8.
9.
10.
11.
11A.
12.
13.
14.
15.
16.
17.
18.
19.
20.

.........
GENERAL DESCRIPTION .....................
GROUND HANDLING, SERVICING, CLEANING,
LUBRICATION AND INSPECTION ......................
FUSELAGE ............................................
WINGS AND EMPENNAGE .............................
LANDING GEAR AND BRAKES .........................
AILERON CONTROL SYSTEM ..........................
WING FLAP CONTROL SYSTEM ........................
ELEVATOR CONTROL SYSTEM ........................
ELEVATOR TRIM TAB CONTROL SYSTEM .............
RUDDER CONTROL SYSTEM ..........................
ENGINE (MODEL O-320-H2AD) .........................
ENGINE (MODEL O-320-D2J AND
MODEL O-360-A4N) ....................................
FUEL SYSTEM .........................................
PROPELLERS AND PROPELLER GOVERNORS ..........
SYSTEMS ..............................................
INSTRUMENTS AND INSTRUMENT SYSTEMS ..........
.........
ELECTRICAL SYSTEMS ......................
ELECTRICAL SYSTEMS (DELETED)
STRUCTURAL REPAIR .................................
PAINTING .............................................
WIRING DIAGRAMS ...................................

1A9/1-1
1B11/2-1
1F9/3-1
1H5/4-1
111/5-1
1K5/6-1
1K21/7-1
1L13/8-1
2A3/9-1
2A17/10-1
2B7/11-1
2D3/11A-1
2E3/12-1
2F19/13-1
2G3/14-1
2G13/15-1
217/16-1
3A3/18-1
3C3/19-1
3C171/20-1

WARNING
When performing any inspection or maintenance that requires
turning on the master switch, installing a battery, or pulling the
propeller through by hand, treat the propeller as if the ignition
switch were ON. Do not stand, nor allow anyone else to stand,
within the arc of the propeller, since a loose or broken wire, or a
component malfunction, could cause the propeller to rotate.

Revision3

MODEL 172 SERIES SERVICE MANUAL

CROSS REFERENCE LISTING
OF POPULAR NAME VS. MODEL NUMBERS AND SERIALS
All aircraft, regardless of manufacturer, are certified under model number designations. However, popular
names are often used for marketing purposes. To provide a consistent method of referring to these aircraft, the
model number will be used in this publication unless the popular name is necessary to differentiate between
versions of the same basic model. The following table provides a listing of popular name, model number and
serial number.
POPULAR NAME

MODEL
YEAR

MODEL

BEGINNING

SERIAL
ENDING

SKYHAWK,SKYHAWK II

1977

172N

17261445,17267585

17069309

1978

172N

17261578,17269310

17271034

(except 17270050)

1979
1980
1981
1982
1983
1984
1985
1986

172N
172N
172P
172P
172P
172P
172P
172P

17271035
17270050,17272885
17274010
17275035
17275760
17276080
17276260
17276517

17272884
17274009
17275034
17275759
17276079
17276259
17276516
17276654

REIMS/CESSNA F172
SKYHAWK, SKYHAWK II

1977
1978
1979
1980
1981
1982
1983
1984
1985
1986

F172N
F172N
F172N
F172N
F172P
F172P
F172P
F172P
F172P
F172P

F17201515
F17201640
F17201750
F17201910
F17202040
F17202135
F17202195
F17202217
F17202234
F17202239

F17201639
F17201749
F17201909
F17202039
F17202134
F17202194
F17202216
F17202233
F17202238
F17202254

CUTLASS, CUTLASS II

1983
1984
1985

172Q
172Q
172Q

17275869
17276101
NONE

17276054
17276211

Revision 3

MODEL 172 SERIES SERVICE MANUAL

INTRODUCTION
This manual contains factory-recommended procedures and instructions for ground handling, servicing, and
maintaining Cessna 172 Series airplanes. Besides serving as a reference for the experienced mechanic, this
manual also covers step-by-step procedures for the less experienced. If properly used, it will better enable the
mechanic to maintain Cessna 172 Series airplanes and thereby establish a reputation for reliable service.
This service manual is designed for aerofiche presentation. To facilitate the use of the aerofiche, refer to the
aerofiche header for basic information.
KEEPING CESSNA PUBLICATIONS CURRENT
The information in this publication is based on data available at the time of publication and is updated, supplemented, and automatically amended by all information issued in Service News Letters, Service Bulletins, Supplier Service Notices, Publication Changes, Revisions, Reissues and Temporary Revisions. All such amendments
become part of and are specifically incorporated within this publication. Users are urged to keep abreast of the
latest amendments to this publication through information available at Cessna Authorized Service Stations or
through the Cessna Product Support subscription services. Cessna Service Stations have also been supplied with
a group of supplier publications which provide disassembly, overhaul, and parts breakdowns for some of the various supplier equipment items. Suppliers publications are updated, supplemented, and specifically amended by
supplier issued revisions and service information which may be reissued by Cessna; thereby automatically
amending this publication and is communicated to the field through Cessna's Authorized Service Stations
and/or through Cessna's subscription services.
WARNING:

ALL INSPECTION INTERVALS, REPLACEMENT TIME LIMITS, OVERHAUL TIME
LIMITS, THE METHOD OF INSPECTION, LIFE LIMITS, CYCLE LIMITS, ETC., RECOMMENDED BY CESSNA ARE SOLELY BASED ON THE USE OF NEW, REMANUFACTURED, OR OVERHAULED CESSNA APPROVED PARTS. IF PARTS ARE DESIGNED, MANUFACTURED, REMANUFACTURED, OVERHAULED, PURCHASED,
AND/OR APPROVED BY ENTITIES OTHER THAN CESSNA, THEN THE DATA IN
CESSNA'S MAINTENANCE/SERVICE MANUALS AND PARTS CATALOGS ARE NO
LONGER APPLICABLE AND THE PURCHASER IS WARNED NOT TO RELY ON
SUCH DATA FOR NON-CESSNA PARTS. ALL INSPECTION INTERVALS, REPLACEMENT TIME LIMITS, OVERHAUL TIME LIMITS, THE METHOD OF INSPECTION, LIFE LIMITS, CYCLE LIMITS, ETC., FOR SUCH NON-CESSNA PARTS MUST
BE OBTAINED FROM THE MANUFACTURER AND/OR SELLER OF SUCH NONCESSNA PARTS.

REVISIONS/CHANGES. These are issued to the dealers by Cessna Aircraft Company for this publication as required, and include only pages that require updating.

REISSUE. Manual is reissued to dealers as required, and is a complete manual incorporating all the
latest information and outstanding revisions/changes. It supersedes and replaces previous issue(s).

REVISIONS/CHANGES and REISSUES can be purchased from your Cessna Dealer or directly from the Cessna
Parts Distribution, (CPD 2) Dept. 701, Cessna Aircraft Company, 5800 East Pawnee, Wichita, Kansas 67201.
All supplemental service information concerning this manual is supplied to all appropriate Cessna Dealers so
that they have the latest authoritative recommendations for servicing these Cessna aircraft. Therefore, it is recommended that Cessna owners utilize the knowledge and experience of the factory-trained Dealer Service Organization.

Revision 3 iii

MODEL 172 SERIES SERVICE MANUAL

CUSTOMER CARE SUPPLIES AND PUBLICATIONS CATALOG
A Customer Care Supplies and Publications Catalog is available from your Cessna Dealer or directly from the
Cessna Parts Distribution, (CPD 2), Dept. 701, Cessna Aircraft Company, 5800 East Pawnee, Wichita, Kansas
67201. The Supplies and Publications catalog lists all publications and Customer Care Supplies available from
Cessna for prior year models as well as new products.
SUPPLEMENTAL TYPE CERTIFICATE INSTALLATIONS
Inspection, maintenance and parts requirements for supplemental type certificate (STC) installations are not included in this manual. When an STC installation is incorporated on the airplane, those portions of the airplane
affected by the installation must be inspected in accordance with the inspection program published by the owner
of the STC. Since STC installations may change systems interface, operating characteristics and component
loads or stresses on adjacent structures, Cessna provided inspection criteria may not be valid for airplanes with
STC installations.
CUSTOMER COMMENTS ON MANUAL
Cessna Aircraft Company has endeavored to furnish you with an accurate, useful, up-to-date manual. This manual can be improved with your help. Please use the return card, provided with your manual, to report any errors,
discrepancies, and omissions in this manual as well as any comments you wish to make.

Revision 3

MODEL 172 SERIES SERVICE MANUAL

SECTION 1
GENERAL DESCRIPTION

TABLE OF CONTENTS

Page No
Aerofiche/Manual

GENERAL DESCRIPTION .....
Model 172 Series ...............
Description .................
Aircraft Specifications .......
Stations ....................
General Airframe Practices .....
Torqueing Procedures ...........
Calculating Torque ..........
Torque Values - Bolts ........
Torque Values - Fittings .....

1A9/1-1
1A9/1-1
1A9/1-1
1A9/1-1
1A9/1-1
1A14/1-6
1A14/1-6
1A14/1-6
1A14/1-6
1A17/1-9

Page No
Aerofiche/Manual
Safetying Procedures ........ 1A18/1-10
LA19/1-11
Safety Wire Procedures ......
Use of Cotter Pins ........... 1A23/1-15
Use of Locking Cips .......... 1B1/1-17
Use of Lockwashers .......... 1B3/1-19
1B3/1-19
Use of Self-Locking Nuts .....
Control Cable Wire Breakage
and Corrosion Limitations .. 1B411-20
Adhesives Cements and Sealants1B6/1-22
Shelf Life and Storage ......

1-1.

GENERAL DESCRIPTION.

1-2.

MODEL 172 SERIES.

1-3.

DESCRIPTION. Cessna Model 172 aircraft, described in this manual, are high-wing monoplanes of all-metal, semimonocoque construction. These aircraft are equipped with a fixed
tricycle landing gear with tubular spring-steel main gear struts. The steerable nose gear is
equipped with an air/hydraulic fluid shock strut. Four-place seating is standard, and a
double-width, fold-up auxiliary rear seat may be installed as optional equipment. All are
powered by four-cylinder, horizontally-opposed, air-cooled Lycoming "Blue Streak" engines. The engines drive an all-metal, fixed-pitch propeller. Model 172 Series aircraft feature rear side windows, a "wrap-around" rear window and a swept-back fin and rudder.

1-4.

AIRCRAFT SPECIFICATIONS. Leading particulars of these aircraft, with dimensions
based an gross weight, are given in figure 1-1. If these dimensions are used for constructing
a hangar or computing clearances, remember that such factors as nose gear strut inflation,
tire pressure, tire sizes and load distribution may result in some dimensions that are considerably different from those listed.

1-5.

STATIONS. Station diagrams are shown in figure 1-2 to assist in locating equipment when
a written description is inadequate or impractical.

Revision 3

1-1

MODEL 172 SERIES SERVICE MANUAL
NOTE
These specifications are applicable to Model 172 and F172
Series airplanes and Model 172Q airplanes, except as indicated.
GROSS WEIGHT (Takeoff and Landing)
172 and F172 Landplane (1977 thru 1980) ....................
172 and F172 Landplane (1981 & On) ......................
172 and F172 Floatplane ................................
172Q Model Only ......................................
FUEL CAPACITY
Standard Wing (Total) ...................................
Standard Wing (Usable) .................................

Long-Range Wing (Total)

...............................

Long-Range Wing (Usable) ...............................
Wet Wing (Total) BEGINNING 1981 MODEL YEAR .............
Wet Wing (Usable) BEGINNING 1981 MODEL YEAR ............
OIL CAPACITY
(Without External Filter) THRU 1980 MODEL YEAR ............
(With External Filter) THRU 1980 MODEL YEAR .............
(Without External Filter) BEGINNING 1981 MODEL YEAR .......
(With External Filter) BEGINNING 1981 MODEL YEAR ..........
ENGINE MODEL
172 and F172 Series (Refer to Section 11 for Engine Data) ........
172Q Model Only (Refer to Section 11A for Engine Data) .........
PROPELLER (Fixed Pitch) (172 and F172 Series) ................
PROPELLER (Fixed Pitch) (Model 172Q Only) ..................
MAIN WHEEL TIRES (172 and F172 Series) ....................
Pressure THRU 1980 MODEL YEAR ........................
Pressure BEGINNING 1981 MODEL YEAR ...................
MAIN WHEEL TIRES (Model 172Q Only) ......................
Pressure .............................................
NOSE WHEEL TIRE (172 and F172 Series)
TIRE THRU 1980 MODEL YEAR ...........................
Pressure ............................................
BEGINNING 1981 MODEL YEAR ..........................
Pressure ...........................................
NOSE WHEEL TIRE (Model 172Q Only) .......................

Pressure

...........................................

2300
2400
2200
2550

Lbs.
Lbs.
Lbs.
Lbs.

43 Gal.
40 Gal.

. 54 Gal.
50 Gal.
68 Gal.
62 Gal.
6
7
7
8

Quarts
Quarts
Quarts
Quarts

LYCOMING 0-320 Series
LYCOMING 0-360 Series
75" McCAULEY
76" McCAULEY
6.00 x 6, 4-Ply
29 Psi
28 Psi
6.00 x 6,6-Ply
38 Psi
5.00 x 5, 4-Ply
31 Psi
5.00 x 5, 6-Ply
34 Psi
5.00 x 5, 6-Ply

45 Psi

NOSE GEAR STRUT PRESSURE (Strut Extended) ................
45 Psi
WHEEL ALIGNMENT (Tubular Spring Struts)
Camber ..............................................
2° to 4 °
Toe-in ............................................... 0" to .18"
(Tubular Gear is non-adjustable)
AILERON TRAVEL
Up ..
..............................................
20 °± 1°
Down ......................................
......
15 ° ±1°
No provisions are made for aligning wheels on tubular gear aircraft.
The tolerances provided are to be used only for checking existing wheel
alignment.

Figure 1-1. Aircraft Specifications (Sheet 1 of 2)
1-2

Revision 1

MODEL 172 SERIES SERVICE MANUAL
WING FLAP TRAVEL (172 and F172 Series)
Landplane THRU 1980 MODEL YEAR .......................
BEGINNING 1981 MODEL YEAR ..........................
WING FLAP TRAVEL (Model 172Q Only) ......................
RUDDER TRAVEL (Measured Parallel to Water Line)
Right ...............................................
Left .................................................
RUDDER TRAVEL (Measured Perpendicular to Hinge Line)
Right ...............................................
Left .................................................
ELEVATOR TRAVEL
Up .........
.
.................................
Down ...............................................
ELEVATOR TRIM TAB TRAVEL
Up THRU 1980 MODEL YEAR ..............................
Down THRU 1980 MODEL YEAR ...........................
Up BEGINNING 1981 MODEL YEAR (Landplane) ..............
Down BEGINNING 1981 MODEL YEAR (Landplane) ............
Up BEGINNING 1981 MODEL YEAR (Floatplane) ..............
Down BEGNNING 1981 MODEL YEAR (Floatplane) ............
PRINCIPAL DIMENSIONS
Wing Span (Conical-Camber With Strobe Lights)
(172 and F172 Series) ..................................
Wing Span (With Strobe Lights) (Model 172Q Only) .............
Tail Span (172 andF172 Series) ............................
Length THRU 1980 MODEL YEAR .........................
Length BEGINNING 1981 MODEL YEAR .....................
Tail Span (Model 172Q Only) ..............................
Fin Height (Maximum With Nose Gear Depressed and
Flashing Beacon Installed on Fin) (172 and F172 Series) .........
Fin Height (Maximum With Nose Gear Depressed and
Flashing Beacon Installed on Fin) (Model 172Q Only) ...........
Track Width (172 and F172 Series) .........................
Track Width (Model 172Q Only) ...........................
BATTERY LOCATION ....................................

0° to 40 ° , +0 °- 2 °
0 ° to 30 °, + 0 ° - 2 °
0 ° to 30 ° , +0°- 2 °
16 ° 10'
16 ° 10'

1°
1°

17° 44' °±1
17 ° 44' ± 1°
28 ° + 1°- 0°
23° +1 °- 0 °
28 °
13 °
22 °
19 °
28 °
13 °

1°- 0°
1°- 0 °
1°- 0 °
1°- 0°
+
1°- 0°
+ 1°- 0°
+
+
+
+

433.00"
432.00"
135.14"
323.00"
323.04"
136.00".
104.00"
107.00"
100.36"
100.50"
Firewall

* Neutral position measured with the bottom of the balance area flush
with the bottom of the stabilizer.

Figure 1-1. Aircraft Specifications (Sheet 2 of 2)
Revision 1

1-3

MODEL 172 SERIES SERVICE MANUAL

23. 62

NOTE

172. 00
190. 00
208. 00

56.70

Figure 1-2. Reference Stations (Sheet 1of 2)
1-4

Revision 1

MODEL 172 SERIES SERVICE MANUAL

NOTE
Wet wing option beginning
with 1981 model year
22. 875
39.00

85.875
100.50

23.65

Figure 1-2.

Reference Stations (Sheet 2 of 2)

Revision 11

1-5 5
1-

MODEL 172 SERIES SERVICE MANUAL
1-6.

GENERAL AIRFRAME PRACTICES. the following paragraphs deal with general torque and
safetying practices used to ensure security of installation and prevent overstressing of components. Special torque values, when required, are specified with the specific component
maintenance and installation instructions.

1-7.

TORQUEING PROCEDURES. The importance of correct application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts as well as parts
they are holding together. When insufficient pressures are applied, uneven loads will be
transmitted throughout assembly, which may result in excessive wear or premature failure
due to fatigue. Overtorque can be equally damaging because of failure of a bolt or nut from
overstressing threaded areas.
a. Calculating Torque. There are a few simple, but very important, procedures that
should be followed to assure that correct torque-is applied:
1. Calibrate torque wrench periodically to assure accuracy; and recheck frequently.
2. When using a torque wrench adapter which changes distance from torque
wrench drive to adapter drive, the indicated reading must be adjusted for desired
torque reading. (See Figure 20-1.)
3. Be sure that bolt and nut threads are clean and dry unless otherwise specified.
4. Determine friction drag torque and add to specified dry torque value to ensure
proper bolt utilization.
(a) Hand-turn nut onto bolt until it stops.
(b) Using a torque wrench, measure running torque (torque required to turn nut
on bolt).
(c) This running torque must be added to specified dry torque value to ensure
proper bolt utilization.

EXAMPLE
Average running torque for a nut
Dry torque required
Final torque wrench reading
(d)
(e)

= 15 in.-lbs.
= 125 ±5 in.-lbs.
= 140 ±5 in.-lbs.

Since running torque will become less due to nut/bolt re-use (in accepted applications), this procedure must be repeated each time.
When necessary to tighten from bolt head, increase torque value by an
amount equal to shank torque (torque required to turn bolt when installed).
Measure with a torque wrench.

EXAMPLE
Average running torque for a nut
= 15 in.-lbs.
Average running shank torque for installed bolt = 10 in.-lbs.
Dry torque required
= 125 ±5 in.-lbs.
Final torque wrench reading
= 150 ±5 in.-lbs.
b.

Torque Values - Bolts and Nuts. (See Table 1-1.)
1.
Tables included in this section do not apply to the following exceptions:
(a) Sheet metal screws should be tightened firmly, but with no specific torque
value.
(b) Screws attached to nutplates should be tightened firmly, but with no specific
torque value.
(c) Bolts, nuts, and screws used in control systems and installations where required torque would cause binding or interfere with proper operation of

parts.
(d)
(e)
1-6

Revision 1

Screws used with dimpled washers should not be drawn tight enough to eliminate washer crown.
Fasteners that have a specified torque in a specific installation.

MODEL 172 SERIES SERVICE MANUAL
NOTE
When using a torque wrench adapter which changes
the distance from torque wrench drive to adapter
drive, apply following formula to obtain corrected
torque reading.
SHORT OPEN END
ADAPTER

LEGEND

FORMULA
T
Y
L
E

Tx L = Y
L + E

=
=
=
=

Desired Torque
Indicated Torque
Effective Length Lever
Effective Length of Extension

WRENCH
DRIVE
CENTERLINE

SETSCREW
ADAPTER

HANDGRIP
CENTERLINE
(PREDETERMINED)

ADAPTER
DRIVE
CENTERLINE

TORQUE
WRENCH

HOSE CLAMP
ADAPTER
EXAMPLE
T
Y
L
L
E

=
=
=
=
=

OPEN-END WRENCH
ADAPTER

y = 135 x 10 = 1350 = 117.39

135 In.-Lbs
Unknown
10.0 In.-Lbs
10.0 In.-Lbs
1.5 In.

10 + 1.5

11.5

Y = 117 In.-Lbs

ADAPTER
DRIVE
CENTERLINE
WRENCH
DRIVE
CENTERLINE

HANDGRIP
CENTERLINE
(PREDETERMINED)
TORQUE
WRENCH

FLARE NUT WRENCH
ADAPTER

EXAMPLE
SPANNER WRENCH
ADAPTER

T
Y
L
E

=
=
=
=

135 In.-Lbs
Unknown
10.0 In.-Lbs
-1.5 In.

135 x 10

1350

158.82

10 - 1.5
8.5
Y = 159 In.-Lbs

Figure 1-3. Torque Wrench Adapter Adjustment
Revision 1

1-7

MODEL 172 SERIES SERVICE MANUAL

BOLT TORQUE VALUES
Tension

Shear

Tension

I
Shear
BOLTS
MS20004 thru MS20024 NAS464
NAS144 thru NAS148
NAS172
NAS174
NAS333 thru NAS340
NAS585 thru NAS590
NAS624 thru NAS644
NAS1303 thru NAS1320
NAS517

BOLTS
AN3 thru AN20
AN42 thru AN49
AN73 thru AN81
AN173 thru AN186
AN509NK9
AN525NK525
MS20033 thru MS20046
MS20073
MS20074
MS24694
MS27039
AN310
AN315
AN363
AN365
MS20365
MS20500
MS21045
NAS679

Nut-bolt
size
size
8-36
10 32
14-28
5 16-24
38-24
716-20
1 2-20
916-18
58-18
34-16
78-14
1-14
1-1 8-12
1-1 4-12
Nut-bolt

8-32
10-24
14-20
5 16-18
38-16
716-14
12-13
9 16-12
58-11
3.4-10
78-9
1-8
1-1 8-8
1-1 4-8

NOTE: Bolts in tension
column may be used
with shear nuts. Bolts
in shear
column
should not be used unless a minimum of two
threads extend beyond
nut after installation.

NUTS
AN320
AN364
MS20364
NAS1022

NUTS
AN320
AN364
NAS1022
MS20364

AN310
AN315
NA363
AN365
MS20365
MS21045
NAS679
NAS1021
NAS1021
291

FINE THREAD SERIES
Torque Limits
Torque Limits
in.-lbs.
in.-lbs.

MIN.

MAX.

MIN.

MAX.

12
20
50
100
160
450
480
800
1100
2300
2500
3700
5000
9000

15
25
70
140
190
500
690
1000
1300
2500
3000
4500
7000
11000

7
12
30
60
95
270
290
480
660
1300
1500
2200
3000
5400

9
15
40
85
110
300
410
600
780
1500
1800
3300
4200
6600

COURSE THREAD SERIES
Torque Limits
Torque Limits
in.-lbs.
in.-lbs.
MIN.
MAMINM . I MAX.
12
15
7
9
20
25
12
15
40
50
25
30
80
90
48
55
160
185
95
110
235
255
140
155
400
480
240
290
500
700
300
420
700
900
420
540
1150
1600
700
950
2200
3000
1300
1800
3700
5000
2200
3000
5500
6500
3300
4000
6500
8000
4000
5000

Nut-bolt

10-32
14-28
5 16-24
38-24
716-20
1 2-20
916-18
58-18
34-16
78-14
1-14
1-1 8-12
1-1 4-12
Nut-bolt

10-32
14-28
5 16-24
3,8-24
716-20
12-20
9.16-18
5.8-18
3/4-16
78-14
1-14
1-1 8-12
1-1 4-12

FINE THREAD SERIES
Torqu Limits
Torque Limits
in.-bs.
in.-lbs.

MIN.

I MAX.

MIN.

I MAX.

25
80
120
200
520
770
1100
1250
2650
3550
4500
6000
11000

30
00
145
250
630
950
1300
1550
3200
4350
5500
7300
13400

15
50
70
120
300
450
650
750
1600
2100
2700
3600
6600

20
60
90
150
400
550
800
950
1900
2600
3300
4400
8000

MS17825
Torque Limits
in.-bs.
MIN. I MAX.
28
35
65
80
180
225
260
325
460
575
720
900
880
1100
1300
1600
2200
2800
3700
4600
5400
6800
8000
10000
11000
14000

Table 1-1. Torque Values - Bolts and Nuts
1-8

Revision 1

MS17826
Torque Limits
in.-lbs.
MIN.
MAX.
16
20
35
45
70
90
100
125
180
225
240
300
320
400
480
600
880
1100
1500
1900
2400
3000
4000
5000
5600
7000

MODEL 172 SERIES SERVICE MANUAL
2.
3.

The values shown in Table 1-1 are based on parts being clean and dry with no lubricants added.
Castellated nuts requiring cotter pins should be tightened to low torque value.
Torque can be increased to install cotter pin, but should never exceed maximum

torque value.
NOTE

Self-locking castellated nuts, MS17825 and MS17826, require a separate torque range. These values are shown
separately in torque value tables.
Torque Value - Threaded Straight Fittings.
NOTE
Tables in this section are for general applications. Refer
to specific installations for special torque values and procedures.
Connectors installed in bosses with no required orientation should be installed
using torque values given in Table 1-2.
2. Connectors installed in bosses requiring a specific orientation do not use a torque
value, but use the following steps:
(a) Place jam-nut on fitting along with retainer and packing.
(b) Turn nut down until packing is firmly against lower threaded section of fitting.
(c) Install fitting into boss and tighten until there is a sudden increase in torque.
(d) Tighten fitting 1-1/2 turns.
(e) Orientation is accomplished by tightening fitting, but not exceeding one turn.
(f) Tighten jam-nut to torque values in Table 1-2.
1.

TORQUE VALUE - HOSE ASSEMBLIES

THREADED CONNECTOR
TUBE
OUTSIDE
DIAMETER
(Inches)

1/8
3'16
1/4
5'16
38
12
58
34
1
1-14
1-12
2

JAM-NUT
THREAD
Torque-Limits
(in.-lbs.)
516-24
3/8-24
7/16-20
1/2-20
916-18
34-16
77-14
116-12
1-516-12
1-5 8-12
1-7 8-12
2-1 2-12

MIN.
35
65
85
105
120
240
320
500
720
960
1200
1400

MAX.
50
80
105
125
150
280
380
600
880
1200
1440
1500

CONNECTOR
HOSE
w/ PACKING
INSIDE
DIAMETER
w/o JAM-NUT
Torque-Limits
(in.-lbs.) (in.-lbs.)
MIN.
50
65
95
125
155
280
380
550
800
900
900
900

Table 1-2. Torque Values
Jam-Nuts and Threaded Connector

MAX.
55
75
105
135
165
305
405
600
900
1000
1000
1000

18
3.16
14
516
38
12
58
34
1
1-14
1-1 2
1-3 4
2

Nipple or Nut
STEEL
ALUMINUM
Torque-Limits
Torque-Limits
in.-lbs
in.-lbs.
MAX.
MAX.
MIN.
20
25
50
70
110
230
330
460
500
800
800
1800

30
35
65
90
130
260
360
500
700
900
900
2000

75
95
135
170
270
450
650
900
1200
1520
1900
2660

85
105
150
200
300
500
700
1000
1400
1680
2100
2940

Table 1-3. Torque Values
Hose Assemblies
Revision 1

1-9

MODEL 172 SERIES SERVICE MANUAL

THREADED STRAIGHT FITTING TORQUE VALUE (RIGID TUBE)
TUBE
OUTSIDE
DIAMETER

FLARED END
ALUMINUM
On Oxygen Lines
Torque-Limits
in-lbs.

ALUMINUM
Torque-Limits
in-lbs.
MIN.

MAX.

MIN.

MAX.

18
316

STEEL
Torque-Limits
in-lbs.
MIN.

MAX.

6061-0 ALUMINUM
5052-0 ALUMINUM
Torque-Limits
in-lbs.

STRAIGHT END
STEEL
6061-T(X) ALUMINUM
w/ steel sleeve
Torque-Limits
Torque-Limits
in-lbs.
in-lbs.

100

MIN.
20
30

MAX.
30
40

MIN.
45
90

135

150

135

150-

180

200

180

I MAX. TUBE WALL
55
100
0.028

MIN.

MAX.

0.022
0.028
0.035
0.049

-80
80
80
90

105
105
105
115

200

0.028
0.035
0.042

80
80
125

105
105
175

516

125

270

300

125

270

300

0.028
0.035
0.049

125
125
125

175
175
175

150

250

450

500

150

250

450

500

0.028
0.035
0.049
0.058
0.065

135
200
400
400
400

180
300
500
500
500

200

350

700

800

200

350

700

800

All

500

600

300

500

1100

1150

300

500

1100

1150

All

600

700

1
1-1 4

500
600

700
900

1200
1300

1400
1450

500
600

700
900

1200
1300

1400
1450

All
All

1000
1300

1300
1500

1-1 2

600

900

1350

1500

600

900

1350

1500

All

1400

1700

600

900

1500

1700

100

125

Table 1-4. Torque Values - Straight Threaded Fittings (Line)
3.
4.
5.

1-8.

1-10

Bulkhead fittings are installed with jam-nuts and should be torqued to values in
Table 1-2.
Torque values for hose end fittings (nipple or nut) are given in Table 1-3.
Torque values for straight threaded fittings used with rigid lines are given in
Table 1-4.

SAFETYING PROCEDURES. The use of safety wire, cotter pins, lockwashers, and self-locking nuts is to prevent relative movement of critical components subject to vibration, torque,
tension, etc., which could cause attaching parts to be broken, loosened, and/or detached.

Revision 1

MODEL 172 SERIES SERVICE MANUAL
1-9.

SAFETY WIRE PROCEDURES.
a. Identification. Lockwire comes in three types which are identified by size and color.
The three types are classified by use.
1. Inconel and Monel wire is used for general lockwiring and is identified by a natural wire color.
(a) Inconel can withstand temperatures up to 1500°F.
(b) Monel can withstand temperatures up to 800°F.
2. Copper that is cadium-plated and dyed yellow is used for shear and seal wiring

applications.
(a)

Shear applications are those where it is necessary to break or shear wire to
permit operation or actuation of emergency devices.
(b) Seal applications are where wire is used with a lead seal to prevent tampering
or use of a device without indication.
3. Aluminum Alloy (Alclad 5056) is dyed blue and is used exclusively for safety-wiring magnesium parts.
4. Size of wire is dependent on material and purpose of installation.
(a) 0.020-inch diameter copper wire should be used for shear and seal application.
(b) 0.020-inch diameter wire may be used to lockwire parts with tie holes smaller
than 0.045 inches; or, on parts with tie hole diameters between 0.045 and
0.062 when spacing between ports is less than two inches; or, when bolts and
screws of 0.25-inch diameter or less are closely spaced.
(c) 0.032-inch minimum diameter wire is used for general purpose lockwiring.
NOTE
When using single-wire method of locking, the largest
wire that will fit tie holes should be used.
b. Lockwire Installation. There are two basic forms of lockwiring. The single-wire
method has limited application; the double-twist method is the common method of
lockwiring.
1.
Use new wire for each application; do not try to re-use old wire.
2. Single-wire method is accomplished by passing a single wire through tie holes
and back with ends then twisted together. (See Figure 1-4.)
(a) Single-wire method is used for shear and seal wiring applications.
(b) Single-wire method can be used in closely spaced, closed geometric patterns.
Closely spaced is defined as spacing two inches or less between centers of

parts.
CAUTION
Screws in closely spaced geometric patterns which secure
hydraulic or air seals, hold hydraulic pressure, or are
used in critical areas should use double-twist method of

lockwiring.
3.

Lockwiring by the double-twist method is really one wire twisted on itself several
times and is accomplished by the following steps (see Figure 1-4).
(a) Insert one end of wire through tie holes of bolt head and firmly loop around
bolt head.
NOTE
This does not necessarily apply to castellated nuts when
slot is close to top of nut. The wire will be more secure if
it is made to pass along side of stud.
Revision 1

1-11

MODEL 172 SERIES SERVICE MANUAL

FOR LEFT-HAND THREADS.

SINGLE FASTENER APPLICATION

CASTELLATED NUTS ON DRILLED STUDS

DOUBLE-TWIST METHOD

Figure 1-4. Lockwire Safetying (Sheet 1 of 2)
1-12

Revision 1

MODEL 172 SERIES SERVICE MANUAL

DOUBLE-TWIST METHOD
STEP 1. Insert wire through bolt A and bend
around bolt (if necessary, bend wire
across bolt head). Twist wires clockwise

BOLT A

until they reach bolt B.

STEP 2. Insert one end of wire through bolt B.
Bend other end around bolt (if necessary,
bend wire across head of bolt). Twist
wires counterclockwise 1/2 inch or six
twists. Clip ends. Bend pigtail back againt
part.

BOLT B
CLOCKWISE

DOUBLE-TWIST METHOD

COUNTERCLOCKWISE

CLOCKWISE

COUNTERCLOCKWISE

CLOCKWISE

MULTIPLE FASTENER APPLICATION
DOUBLE-TWIST METHOD

ELECTRICAL CONNECTION

Figure 1-4. Lockwire Safetying (Sheet 2 of 2)
Revision 1

1-13

MODEL 172 SERIES SERVICE MANUAL
(b)

While taut, twist strands to within 1/8 inch of next part. The twisting keeps
wire taut without overstressing and prevents wire from becoming nicked,
kinked, or mutilated.
(c) Lockwiring multiple groups by double-twist method is accomplished in a
similar manner except twists between parts are alternated between clockwise
and counterclockwise.
(d) After last tie hole, wire is twisted three to five times to form a pigtail.
(e) Cut off any excess wire and bend pigtail towards part.
4. When lockwiring widely spaced multiple groups by double-twist method, three
units shall be the maximum number in a series.
NOTE
Widely spaced multiple groups shall mean those in which
fasteners are from four to six inches apart. Lockwiring
shall not be used to secure fasteners or fittings which are
spaced more than six inches apart, unless tie points are
provided on adjacent parts to shorten span of lockwire to
less than six inches.
5.

When lockwiring closely spaced multiple groups, the number of units that can be
lockwired by a 24-inch length of wire shall be the maximum number in a series.
6. Parts should be lockwired so that wire is placed in tension (pulled on) if a part attempts to loosen.
c. Required Lockwire Installation Applications.
1. Bolts and other fasteners securing critical parts that affect airplane safety and
operation.
(a) In blind-tapped hole applications or bolts or castellated nuts on studs.
lockwiring is installed in same manner as described for bolt heads.
(b) Hollow head bolts are safetied in manner prescribed for regular bolts.
(c) Drain plugs and cocks may be safetied to a bolt, nut, or other part having a
free tie hole in accordance with instructions described.
(d) External snap rings may be locked if necessary using general locking principles as described and illustrated. Internal snap rings should not be lockwired.
(e) When locking is required on electrical connectors which use threaded coupling rings, or on plugs which employ screws or rings to fasten individual
parts of plug together, they shall be lockwired with 0.020-inch diameter wire
in accordance with locking principles as described and illustrated. It is preferable to lockwire all electrical connectors individually. Do not lockwire one
connector to another unless it is necessary to do so.
(f) Drilled head bolts and screws need not be lockwired if installed into self-locking nuts or installed with lockwashers. Castellated nuts with cotter pins or
lockwire are preferred on bolts or studs with drilled shanks, but self-locking
nuts are permissible within limitations described in Paragraph 1-13.
2. For new design, lockwire shall not be used to secure nor shall lockwire be dependent upon fracture as basis for operation of emergency devices such as handles,
switches, and guard-covering handles that operate emergency mechanisms such
as emergency exits, fire extingushers, emergency cabin pressure release,
emergency landing gear release, and the like. However, where existing structural
equipment or safety of flight emergency devices requires shear wire to secure
equipment while not in use, but which are dependent upon shearing or breaking
of lockwire for successful emergency operation of equipment, particular care
exercised to assure that wiring under these circumstances shall not prevent
emergency operations of these devices.

1-14

Revision 1

MODEL 172 SERIES SERVICE MANUAL
1-10.

USE OF COTTER PINS.
a. Cotter Pin Installation. Castellated nuts and pins may be safetied with cotter pins or
lockwire. The preferred method is to use cotter pins.
1. Select cotter pin material in accordance with
temperature, atmosphere, and service limitations (see Table 1-5).
2. Cotter pins shall be new upon each application.
3. When nuts are to be secured to fastener with cotter pins, tighten nut to low side
(minimum) of applicable specified or selected torque range, unless otherwise
specified, and if necessary, continue tightening until slot aligns with hole. In no
case shall you exceed high side (maximum) torque range.
4. If more than 50 percent of cotter pin diameter is above nut castellation, a washer
should be used under nut or a shorter fastener should be used. A maximum of
two washers may be permitted under a nut.
5. The largest diameter cotter pin which hole and slots will accommodate should be
used, but in no application to a nut, bolt, or screw shall pin size be less than sizes
described in Table 1-6.
6. Install cotter pin with head firmly in slot of nut with axis of eye at right angles
to bolt shank. Bend prongs so that head and upper prong are firmly seated
against bolt (see figure 1-5).
7. In pin applications, install cotter pin with axis of eye parallel to shank of clevis
pin or rod end. Bend prongs around shank of pin or rod end (see Figure 1-5).
CAUTION
Cadium-plated cotter pins should not be used in applications bringing them in contact with fuel, hydraulic fluid,
or synthetic lubricants.

COTTER PIN - MINIMUM SIZE

THREAD SIZE
COTTER PINS (MS24665)
MATERIAL
Carbon Steel

TEMPERATURE
Up to 450°F

USE
Pins that contact cadmiumplated surfaces.
General Applications
Normal Atmospheres

Corrosion-Resistant

Up to 800°F

Pins that contact corrosion-resistant steel.
Corrosive atmospheres

Table 1-5. Cotter Pin
Temperature and Use

14
3

MINIMUM PIN SIZE
0.028

8
10

0.044

516

0.044

0.044
0.044

0.072

712
16
12
9 16
58
34
78
1

0.072
0.072
0.086
0.086
0.086
0.086
0.086
0.086

1-18
1-1 4
1-38
1-12

0.116
0.116
0.116
0.116

Table 1-6. Cotter Pin
Minimum Size
Revision 1

1-15

MODEL 172 SERIES SERVICE MANUAL

TO PROVIDE CLEARANCE
PRONG MAY BE CUT HERE

ALTERNATE METHOD

PREFERRED METHOD

CASTELLATED NUT ON BOLT

TANGENT TO PIN

MAXIMUM
COTTER PIN
LENGTH

PIN APPLICATION

Figure 1-5. Installation of Cotter Pins
1-16

Revision 1

MINIMUM
COTTER PIN
LENGTH

MODEL 172 SERIES SERVICE MANUAL
1-11.

USE OF LOCKING CLIPS.
a.
afetying Turnbuckles. (ee Figure 1-6.)
1.

Prior to safetying, both threaded terminals shall be screwed an equal distance
into turnbuckle body and shall be screwed in at least so far that not more than
three threads of any terminal are exposed outside body.
2. After turnbuckle has been adjusted to its locking position, with slot indicator
groove on terminals and slot indicator notch on body aligned, insert end of locking clip into terminal and body (refer to Figure 1-6) until U-curved end of locking
clip is over hole in center of body.
(a) Press locking clip into hold to its full extent.
(b) Curved end of locking clip will expand and latch in body slot.
(c) To check proper seating of locking clip, attempt to remove pressed "U" end
from body hole with fingers only.
NOTE
Do not use tool as locking clip could be distorted.
3.
4.

Locking clips are for one time use only and shall not be re-used.
Both locking clips may be inserted in same hole of turnbuckle body or in opposite
holes of turnbuckle body.

Revision 1

1-17

MODEL 172 SERIES SERVICE MANUAL

LOCKING CLIP

BARREL

Detail A

Figure 1-6. Safetying Turnbuckle Assemblies
Revision 1

1-12.

USE OF LOCKWASHERS.
a.
Lockwashers can be used only under the following conditions.
1. When self-locking feature cannot be provided in externally or internally threaded
part.
2. When a cotter pin cannot be used to prevent rotation of internal threads with respect to external threads.
3. When lookwire cannot be used to prevent loosening of threaded parts.
4. When fastening is not used for fabrication of primary structure.
5. When loosening of threaded parts would not endanger safety of airplane or

people.
6.

1-13.

When corrosion encouraged by gouging aluminum or magnesium alloys by edges
of teeth on tooth-locked washers would not cause malfunctioning of parts being
fastened together.

USE OF SELF-LOCKING NUTS.
a. Restrictions.
1. Self-locking nuts cannot be used under certain conditions.
(a) Used. reworked, or reprocessed nuts should not be installed for any application.
(b) Do not use if at joints in control systems for singular attach points.
(c) Do not use on externally threaded parts that serve as an axle of rotation for
another part where tensional (torque) loads can cause nut to loosen and/or become separated. Examples are pulleys, levers, linkages, and cam followers.

NOTE
Self-locking nuts can be used when threaded parts are
held by a positive locking device that requires shearing
or rupture before torsional loads can act on threaded

parts.
(d)
(e)
(f)

Do not use where a loose nut, bolt, or screw could fall or be drawn into an
area that would impede or damage or otherwise distort operation.
Do not use to attach access panels and doors or to assemble components that
are routinely disassembled or removed for access and servicing.
In general, do not use self-locking nuts where loss of bolt affects safety of

flight.
2.

Bolts, studs, or screws, excluding Hi-Locks, must extend through self-locking
nut for a length equivalent of two threaded pitches. This length includes
chamfer.
Self-locking nuts which are attached to structure shall be attached in a positive
manner to eliminate possibility of their rotation or misalignment when tightening is to be accomplished by rotating bolts to structure, and permit replacement
of nuts.

Revision 2

1-19

MODEL 172 SERIES SERVICE MANUAL
1-14.

1-20

CONTROL CABLE WIRE BREAKAGE AND CORROSION LIMITATIONS.
a. Inspection of Control Cables.
1.
Control cable assemblies are subject to a variety of environmental conditions and forms of
deterioration that ultimately may be easy to recognize such as wire/strand breakage, or the
not so readily visible types ofdeterioration including corrosion and/or distortion.
Thefollowing information will aid in detecting these cable conditions.
2.
Broken Wire.
(a)
Examine cables for broken wires by passing a cloth along length of cable. This will
detect broken wires, if cloth snags on cable. Critical areas for wire breakage are those
sections of cable which pass through fairleads, across rob blocks, and around pulleys.If
no snags are found, then no further inspection is required. If snags are found or broken
wires are suspected, then a more detailed inspection is necessary which requires that
the cables be bent in a loop to confirm broken wires (refer to figure 1-7). Loosen or
remove cable to allow it to be bent in a loop as shown. While rotating cable, inspect
bent area for broken wires.
(b)
Wire breakage criteria for cables in flap, aileron, rudder, and elevator systems are as
follows:
(1) Individual broken wires are acceptable in primary and secondary control cables
at random locations when there are no more than six broken wires in any given
ten-inch cable length.
3.
Corrosion.
(a)
Carefully examine any cable for corrosion that has a broken wire in a section not in
contact with wear-producing airframe components such as pulleys, fairleads, rub
blocks, etc. It may be necessary to remove and bend cable to properly inspect it for
internal strand corrosion as this condition is usually not evident on outer surface of
cable. Replace cable if internal corrosion is found. If a cable has been wiped clean of its
corrosion-preventive lubricant and metal-brightened, the cable shall be examined
closely for corrosion. For description of control cable corrosion, refer to Chapter 18,
Corrosion and Corrosion Control.

Revision 2

MODEL 172 SERIES SERVICE MANUAL

BROKEN WIRE UNDETECTED BY WIPING CLOTH ALONG CABLE

BROKEN WIRE DETECTED VISUALLY
WHEN CABLE WAS REMOVED AND BENT

NORMAL TECHNIQUE FOR
BENDING CABLE AND
CHECKING FOR BROKEN WIRES

00 NOT BEND INTO LOOP SMALLER
THAN 50 CABLE DIAMETERS

55611119

Figure 1-7.

Cable Broken Wire Inspection

Revision 2

1-21

MODEL 172 SERIES SERVICE MANUAL
1-15.

1-22

ADHESIVES, CEMENTS AND SEALANTS - SHELF LIFE AND STORAGE.
a. General.
1.
This section provides information which defines the proper storage and usable life (shelf life)
of adhesives, cements and sealents which are used for maintenance and/or repair of the
airplane. Also included in this section is the criteria used for testing these materials after the
normal shelf life has expired, to determine if an extension to the shelf life is possible.
2.
Shelf life refers to a specified period of time usually from the date of manufacture (normally
stamped or printed on the product container ) to the expiration date (which should be
determined using limits specified in Table 1-7 or if applicable, the manufacturer's expiration
date printed or stamped on the product container). The specified shelf life is dependent on
proper storage in accordance with the limits specified in this section and/or the
manufacturer's instructions.
b. Storage Criteria.
1.
Storage of Adhesives and Cements. All adhesives and cements shall be stored under
controlled temperature conditions. . If open shop storage becomes necessary, these products
shall in no case be stored in an area which will subject them to temperatures in excess of
95°F. Containers shall be tightly closed prior to being placing them into the proper storage
environment. For proper storage environment, refer to Table 1-7 and the-following
paragraphs.
(a)
Class I - These adhesives are epoxy base materials and have one year storage at room
temperature. 0°F storage will extend the storage life. Refer to the product container
instructions for storage temperature and life.
(b)
Class II, III and IV - These adhesives are rubber and resin base and are good for six
months at room temperature storage. 40°F storage will extend the storage life. Refer to
the product container instructions for limits of each adhesive.
(c)
Class V - These are silicone rubber adhesives. If stored in their original containers at a
temperature below 80°F, have a shelf life of one year or as indicated on the storage
container.
(d)
Class VI - These are solvent bonding solvents. They should be stored in their original
containers and tightly closed, and stored at 40°F temperature.
(e)
ClassVII - Cyanoacrylate base materials must be stored in the original containers at
40°F or as specified on the container instructions.
(f)
Class VIII - These are pressure sensitive materials. The shelf life is two years when
stored at 75°F and 50 percent relative humidity.
(g)
Class IX - These are polyurethane products. Store in original container, between 70
and 100°F. Urethanes are moisture sensitive and precautions should be taken to
ensure complete protection from moisture contamination. Container must be tightly
closed at all times.
(h)
Class X - These are acrylic base materials. They require storage at 40°F or per
instructions on product container.
c Storage of Sealants.
1.
All sealants shall be stored under controlled temperature conditions. If open shop storage
becomes necessary, these products shall in no case be stored in an area which will subject
them to temperatures in excess of 95°F or below 40°F. Containers shall be tightly closed prior
to placing them in the proper storage environment. For proper storage environment, refer to
Table 1-7 and the following paragraphs.
(a)
Premixed and frozen sealants shall bestored at -40°F or colder and shall not be used
more than six weeks after the date of mixing even if all storage is at -40°F or colder. If
storage temperatures rise above 40°F, but not warmer than -30°F, the material may be
stored for a maximum of two weeks warmer than -40°F plus time at -40°F or colder for
a combined total not to exceed five weeks beyond the date of mixing. If storage
temperatures rise above -40°F but are not warmer than -20°F, the materials may be
stored for a maximum of one week above -30°F plus time at -40°F or colder for a
combined total not to exceed four weeks beyond the date of mixing.
(b)
Unmixed sealants shall be stored at a controlled temperature of between 40 and 80°F
and have a shelf life of approximately six months when stored within this temperature
range. Unmixed sealants stored at temperatures exceeding 80°F shall be used within
five weeks.
2.
All materials should be used on a "first in-first out" basis. The adhesives, cements and
sealants should be rotated so this requirement can be accomplished. All material containers
should be clearly marked with a "use by" date, consisting of the year and month. All
materials not used by this date must be tested prior to use. Refer to Testing criteria and Table
1-7.
d. Testing Criteria.
1.
Any material (adhesive, cement or sealant)not used within its shelf life will be tested and the
results reviewed to determine if the material is usable. If there is doubt about the material
being usable, it must be properly disposed of. Material that has exceeded its original shelf life
may be retested to determine if the material meets its requirements. Materials meeting their
requirements will have their shelf life extended as specified in Table 1-7. Materials with
shelf life extensions must be retested after a specified period of time. Refer to Table 1-7.
Revision 2

MODEL 172 SERIES SERVICE MANUAL
2.

Testing of Overaged Adhesives and Cements.
NOTE
Overaged adhesives and cements are those
that have exceeded their original shelf life
and must be tested prior to use and/or given
extended shelf life.
(a)

Class I Epoxy Adhesive - Examine bothcomponents to ensure that they are still
workable. Check for gelling and/or contamination. Stir components and mix a small
amount of adhesive. Verify that adhesive sets up and hardens.
(b)
Class II, III and IV Rubber and Resin Base Adhesives - Open containers and check for
gelling and/or contamination. Check for spreading and drying.
(c)
Class V Silicone Rubber Adhesives - Examine adhesive for hardness. If adhesive is
still soft and can be spread, it is acceptable. Verify that adhesive will harden.
(d)
Class VI Solvent Bonding Solvents - Check for signs of apparent contamination.
Solvents should be clean and clear with no signs of cloudiness.
(e)
Class VII Cyanoacrylic Base Adhesives - Verify that product is still liquid with no
visible signs of contamination.
(f)
Class VII Pressure Sensitive Materials - Open containers and inspect for hardening,
gelling and contamination. Stir components and mix a small amount of adhesive.
Verify that adhesive sets up properly.
(g)
Class X Acrylic Adhesives - Inspect base material to ensure that it is still liquid. Mix a
small amount of the components and verify that it sets up properly.
3.
In general, if these materials exhibit normal physical properties, with no signs of hardening,
gelling or contamination and set up and/or harden properly as applicable, the shelf life may
be extended as specified in Table 1-7.
Testing of Overaged Sealants.
NOTE
Overaged sealants are those that have
exceeded their original shelf life and
must be tested prior to use and/or given
extended shelf life.
1.
2.
3.

5.
6.
7.

For identification of sealants Classification, refer to Fuel, Weather, Pressure and HighTemperature Sealing - Maintenance Practices.
Overaged sealants to be tested for possible shelf life extension shall be properly mixed using
the correct materials, procedures and equipment.
Overaged premixed frozen sealants, along with unmixed sealants should be visually
inspected. Sealants whic show conclusive evidence of separation, discoloration and/or gelling
prior to the addition of a thinner or curing agent shall be discarded. When in doubt of the
sealant quality, the overaged sealant should be compared with the same type of sealant,
under six months old, which is known to be satisfactory.
The mixed sealants may be tested by placing a small amount of sealant (smaple buttons) on a
sheet of paper. After the sample buttons have cured, they should be cut in half and examined.
The sealant should show no signs of spots or streaks of unmixed base compound or curing
agent. However, sample buttons containing spots, streaks, discoloration and/or variations in
uniformity of color are acceptable if these spots, streaks, etc., are tack free upon inspection.
All mixed sealant should be as void free as possible.
Contaminated sealant, premixed sealant that have been thawed and refrozen shall be
discarded.
Type I, Class A sealants should be checked for appearance, application time, tack-free time,
cure time and adhesion.
Type I, Class B sealants should be checked for appearance, applicatiion time, cure time, tackfree time and adhesion. In addition, Class B-2 and B-4 sealants should be checked for initial
flow.

8.
9.
10.

Type I, Class C sealants should be checked for appearance, application time, cure time and
adhesion. In addition, Class C sealants should be tested to determine that they ARE NOT at
a tackfree condition at the end of their rated work life (squeeze out life).
Type II sealants should be checked for appearance, application time, tack-free time and cure
time.
Type III sealants should be easily thinned with MEK, when difficulty is encountered in
thinning the sealant, it should be discarded.

Revision 2

1-23

MODEL 172 SERIES SERVICE MANUAL
11.
12.
13.
14.

1-24

Revision 2

Type IV sealants should be checked for appearance, application time, tack-free time
and cure time.
Type V and VI sealants should be checked for appearance, tack-free time and cure
time.
Type VII sealants should be checked for appearance, application time, tack-free time
and cure time.
Type VIII sealants should be checked for appearance, application time, tack-free time,
cure time and adhesion. Adhesion to aluminum should be (peel) less than two-pounds,
per inch of width.

MODEL 172 SERIES SERVICE MANUAL

PRODUCT

STORAGE
CONDITION

EXTEND

(TEMPERATURE

SHELF LIFE

IN DEGREES

IN MONTHS

MONTHS

FAHENHEIT)
ADHESIVES AND
CEMENTS

EA9309.3NA
EA9339
EA9314
EA9330
EA907
Devcon F
EA934NA
380/6
A1186B
EC2216
#10 Fastset
608 Quickset
EC880
EC847
EC1300L
5452
56431
1636
RTV - 157
RTV - 158
RTV - 159
RTV732
RTV102
RTV103
RTV106
RTV108
RTV109
RTV94034
Loctite 222
Loctite 242
Loctite 271
Loctite 277
Loctite 290
Loctite 416
Loctite 495
Loctite 515
Loctite 569
Loctite 592
Loctite 595

40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80° F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F

12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
8 Months
8 Months
*6 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months

6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
3 Months
3 Months
*3 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months

not use after three months of storage in the 81 ° F to 90°F range
Do not use after five days of storage above 90°F.
* Do

Table 1-7. (Sheet 1 of 2)
Revision 2

1-25

MODEL 172 SERIES SERVICE MANUAL

PRODUCT

ADHESIVES AND
CEMENTS (CONTINUED)
Loctite 601
Loctite 620
Loctite 680
Loctite 1282
Loctite 1283
DA-5521
PS- 18
PS-30
XA-3678
XF-3585
LR-100-226
EC776
SB and P2

STORAGE
CONDITION
(TEMPERATURE
IN DEGREES
FAHENHEIT)

SHELF LIFE
IN MONTHS

EXTEND
SHELF LIFE
IN MONTHS

RETEST IN
MONTHS

40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40 TO 80°F
40TO 80°F
40 TO 80°F
40 TO 80°F

12 Months
12 Months
12 Months
12 Months
12-Months
12 Months
12 Months
12 Months
12 Months
12 Months
12 Months
* 8 Months
12 Months

6 Months
6 Months
6 Months
6 Months
6Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
* 3 Months
6 Months

6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
*3 Months
6 Months

6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
6 Months
*8 Months
*8 Months
*8 Months

2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
*3 Months
*3 Months
*3Months

2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
2 Months
*3 Months
*3 Months
*3 Months

SEALANTS
Pro-Seal 890
GC-408
PR1422
PR1440
GC435
Pro-Seal 567
PR810
Pro-Seal 700
GC 1900
PR366
Pro-Seal 735
Pro-Seal 895
Pro-Seal 706B
PR1321
GC200
RTV-730
Pro-Seal 815
GC402
PR-1005L
GC-3001
444R

Do not use after three months of storage in the 81°F to 90°F range
Do not use after five days of storage above 90°F.
*

Table 1-7. (Sheet 2 of 2)
1-26

Revision 2

MODEL 172 SERIES SERVICE MANUAL
SECTION 2
GROUND HANDLING, SERVICING, CLEANING,
LUBRICATION AND INSPECTION
WARNING
When performing any inspection or maintenance that requires turning on the master switch, installing a battery,
or pulling the propeller through by hand, treat the propeller as if the ignition switch were ON. Do not stand, nor
allow anyone else to stand, within the arc of the propeller, since a loose or broken wire, or a component malfunction, could cause the propeller to rotate.

TABLE OF CONTENTS

GROUND HANDLING .........
Towing ..................
Hoisting .................
Jacking ...............
Leveling .................
Weighing ................
Parking .................
Tie-Down ...............
Flyable Storage ............
Returning Aircraft to Service ..
Temporary Storage .........
Inspection During Storage ..
Returning Aircraft to
Service ................
Indefinite Storage ..........
Inspection During Storage ....
Returning Aircraft to Service ..
SERVICING ................
Fuel ....................
Use of Fuel Additives for
Cold Weather Operation .....
Fuel Drains ...............
Carburetor Drain Plug
Inspection ...............
Engine Oil ...............
Engine Oil Additive .........

Page No.
Aerofiche/
Manual
1B14/2-4
1B14/2-4
1B14/2-4
1B14/2-4
1B14/2-4
B14/2-4
1B14/2-4
1B14/2-4
1B15/2-5
1B16.2-6
1B16/2-6
1B18/2-8
1B18/2-8
1B18/2-8
1B20/2-10
1B20/2-10
1B21/2-11
1B21/2-11
1B21/2-11
1B22/2-12
1B22/2-13
B23/2-13
1C1/2-15

Engine Induction Air Filter
(172 & F172 Series Only) ....
1C1 2-15
Engine Induction Air Filter
(172Q Only) .............
1C2 2-16
Vacuum System Filter .......
1C2 2-16
Battery ..................
C2 2-16
Tires .................
1C3 2-17
Nose Gear Shock Strut .......
1C3 2-17
1C3 2-17
Nose Gear Shimmy Damper ..
Hydraulic Brake System . . . 1C4 2-18
CLEANING .........
....
.C4
2-18
Cleaning and Care
of Windshield and Windows
. 1C4 2-18
Plastic Trim
....
1C6 2-20
Painted Surfaces ......
. .
1C6 2-20
Aluminum Surfaces .........
1C7 2-21
Engine Engine Compartment .. 1C7 2-21
Upholstery and Interior ......
1C9 2-23
Propeller .........
....
. 1C10 2-24
Wheels .........
.......
1C10 2-24
LUBRICATION ............
C10 2-24
Wheel Bearings ............
1C10 2-24
Nose Gear Torque Links .....
1C10 2-24
Wing Flap Acuator .........
1C11 2-24
Fuel Selector Valve .........
1C11 2-25
Rod End Bearings ..........
1C11 2-25
INSPECTION ...............
1C21 2-35

Revision 1

2-1

MODEL 172 SERIES SERVICE MANUAL

NOTE
Use tow bar carefully to
avoid scarring finish on
speed fairing.
Figure 2-1. Tow Bar

REFER TO SHEET 2
FOR JACKING

INFOR MATION

NOTE
Corresponding points on both upper door sills may be used to level the aircraft laterally.
Reference points for longitudinal leveling of aircraft are two screws on left side of
tailcone at zero waterline. These are indicated in illustration by A
(Also refer to paragraph 2-5)

Figure 2-2.
2-2

Jacking and Leveling (Sheet 1 of 2)

MODEL 172 SERIES SERVICE MANUAL
JACKING INFORMATION

ITEM NUMBER
1

TYPE AND NUMBER
Block

REMARKS
1x4x4 padded with 1/4" rubber

#2-170

Basic jack (includes #2-71
Slide tube: Liftstroke 22-1/2")
#2-70 Slide tube: Liftstroke
22-1/2"
#2-64 Extension cap
#2-109 Leg extension

Min.
Max.
Min.
Max.
Adds
Adds

Built-in jack pad

Part of step bracket (SEE CAUTION)

Cessna #SE2-168

Tail tie-down stand

closed height: 34"
extension height: 56-1/2"
closed height: 57-1/2"
extension height: 80"
4"
12"

Wing jacks are placed under front spar of wing just outboard of wing strut, and
must extend far enough to raise wheels off ground, and must be adequate strength.

Attach a Cessna #SE2-168 stand to the tie-down ring. Beure tail stand weighs
enough to keep tail down and under all conditions that it is stong engough to support any weight that might be placed on it (place shot bags or sand bags on tail
stand). In addition, the base of adjustable tail stand is to be filled with concrete for
additional weight as a safety factor.

Operate jacks evenly until desired height is reached.
CAUTION
When using built-in jack pad, flexibility of the gear strut
will cause the main wheel to slide inboard as the wheel is
raised, tilting the jack. The jack must be lowered for a
second operation jacking both wheels simultaneously at
built-in jack pads is not recommended. jack pad may be
used to raise only one main wheel. Do not USE brake

casting as a jack point.
4.

Items 2 and 4 areavailable from the Cessna Supply Division.

Figure 2-2. Jacking and Leveling (Sheet 2 of 2)
2-3

MODEL 172 SERIES SERVICE MANUAL
2- .

GROUND HANDLING.

2-2.

TOWING. Moving the aircraft by hand is accomplished by using the wing struts and landing
gear struts as push points. A tow bar attached to the nose gear should be used for steering
and maneuvering the aircraft on the ground. When no tow bar is available, press down at the
horizontal stabilizer front spar adjacent to the fuselage to raise the nose wheel off the
ground. With the nose wheel clear of the ground, the aircraft can be turned by pivoting it
about the main wheels. Beginning with serials 17275035 and F1722135 tow bar stowage
provisions are provided. In the baggage area a strap located at FS 110.75 and a bracket
located at FS 140.10 are used to secure and store the tow bar assembly when not in use.
CAUTION
When towing the aircraft, never turn the nose wheel more
than 30 degrees either side of center or the nose gear will
be damaged. Do not push on control surfaces or outboard
empennage surfaces. When pushing on the tailcone.
always apply pressure at a bulkhead to avoid buckling
the skin.

2-3.

HOISTING. The aircraft may be lifted with a hoist of two-ton capacity by using hoisting
rings, which are optional equipment, or by means of suitable slings. The front sling should
be hooked to each upper engine mount at the firewall, and the aft sling should be positioned
around the fuselage at the first bulkhead forward of the leading edge of the stabilizer. If the
optional hoisting rings are used, a minimum cable length of 60 inches for each cable is
required to prevent bending of the eyebolt-type hoisting rings. If desired, a spreader jigmay
be fabricated to apply vertical force to the eyebolts.

2-4.

JACKING. See figure 2-2 for jacking procedures.

2-5.

LEVELING. Corresponding points on both upper door sills may be used to level the aircraft
laterally. The reference points for longitudinally leveling the aircraft are the two screws
located on the left side of the tailcone. See figure 2-2 for screw locations.

2-5A.

WEIGHING AIRCRAFT. Refer to Pilot's Operating Handbook.

2-6.

PARKING. Parking precautions depend principally on local conditions. As a general
precaution, set parking brake or chock the wheels and install the controls lock. In severe
weather and high wind conditions, tie down the aircraft as outlined in paragraph 2-7 if a
hangar is not available.

2-7.

TIE-DOWN. When mooring the aircraft in the open, head into the wind if possible. Secure
control surfaces with the internal control lock and set brakes.

CAUTION
Do not set parking brakes when they are overheated or
during cold weather when accumulated moisture may
freeze them.

2-4

MODEL 172 SERIES SERVICE MANUAL
After completing the preceding, proceed to moor the aircraft as follows:
a. Tie ropes, cables, or chains to the wing tie-down fittings located at the upper end of
each wing strut. Secure the opposite ends of ropes, cables, or chains to ground
anchors.
b. Secure rope (no chains or cables) to forward mooring ring and secure opposite end to
ground anchor.
c. Secure the middle of a rope to the tail tie-down ring. Pull each end of rope away at a 45
degree angle and secure to ground anchors at each side of tail.
d. Secure control lock on pilot control column. If control lock is not available, tie pilot
control wheel back with front seat belt.
e. These aircraft are equipped with a spring-loaded steering system which affords
protection against normal wind gusts. However, if extremely high wind gusts are
anticipated, additional external locks may be installed.
2-8.

FLYABLE STORAGE. Flyable storage is defined as a maximum of 30 days nonoperational
storage and/or the first 25 hours of intermittent engine operation.

NOTE
O-320-H2AD ENGINES
Thru aircraft serial 17274009, these engines are delivered from the factory with SAE 20W-50 Ashless Dispersant Oil conforming to MIL-L-22851. This oil must be
used in these engines for all operations. (See figure 2-4,
sheet 2 of 6.)
MODEL 172Q ONLY - 0-360-A4N ENGINES
172 AND F172 SERIES -320-D2J ENGINES
Beginning with aircraft serial 17274010, these engines
are delivered from the factory with MIL-L-6082 Aviation
Grade Mineral Oil. This oil is to be used to replenish the
oil supply during the first 25 hours of operation, at the
first 25-hour oil change, and until a total of 50 hours
have accumulated or oil consumption has stabiized. Then
use MIL-L22851 Ashless Dispersant Oil conforming to
AVCO Lycoming Service Instruction No. 1014 and all revisions and supplements thereto. (See figure 2-4, sheet 3
of 6).
During the 30 day nonoperational storage or the first 25 hours of intermittent engine
operation, every seventh day the propeller shall be rotated through five revolutions, without
running the engine. If the aircraft is stored outside, tie-down in accordance with paragraph
2-7. In addition, the pitot tube, static air vents, air vents, openings in the engine cowling, and
other similar openings shall have protective covers installed to prevent entry of foreign
material. After 30 days, aircraft should be flown for 30 minutes or ground run-up until oil has
reached operating temperature (lower green arc range).
CAUTION
Excessive ground operation shall be avoided.

Revision 1

2-5

MODEL 172 SERIES SERVICE MANUAL
2-9.

RETURNING AIRCRAFT TO SERVICE. After flyable storage, returning the aircraft to
service is accomplished by performing a thorough preflight inspection. At the end of the
first 25 hours of engine operation, drain engine oil and clean oil screens (or change external
oil filter). Service engine with correct grade and quantity of engine oil. See figure 2-4 and
paragraph 2-21 for correct grade of engine oil.

2-10.

TEMPORARY STORAGE. Temporary storage is defined as aircraft in a nonoperational
status for a maximum of 90 days. The aircraft is constructed of corrosion resistant alclad
aluminum, which will last indefinitely under normal conditions if kept clean, however,
these alloys are subject to oxidation. The first indication of corrosion on unpainted surfaces
is in the form of white deposits or spots. On painted surfaces, the paint is discolored or
blistered. Storage in a dry hangar is essential to good preservation and should be procured,
if possible. Varying conditions will alter the measures of preservation, but under normal
conditions in a dry hangar, and for storage periods not to exceed 90 days, the following
methods of treatment are suggested:
a.

Fill fuel tanks or bays with the correct grade of gasoline.
WARNING
DURING ALL FUELING PROCEDURES, FIRE FIGHTING
EQUIPMENT MUST BE AVAILABLE. TWO GROUND
WIRES FROM DIFFERENT POINTS ON THE AIRPLANE
TO SEPARATE APPROVED GROUND STAKES SHALL
BE USED TO PREVENT ACCIDENTAL DISCONNECTION
OF ONE GROUND WIRE. ENSURE THAT FUELING
NOZZLE IS GROUNDED TO THE AIRPLANE.
NOTE
Tie-down rings should be used as grounding points for
all grounding wires during refueling procedures.

b.
c.
d.
e.

Clean and wax aircraft thoroughly.
Clean any oil or grease from tires and coat tires with a tire preservative. Cover tires
to protect against grease and oil.
Either block up fuselage to relieve pressure on tires or rotate wheels every 30 days to
change supporting points and prevent flat spotting the tires.
Lubricate all airframe items and seal or cover all openings which could allow moisture and/or dust to enter.
NOTE
The aircraft battery serial number is recorded in the
aircraft equipment list. To assure accurate warranty
records, the battery should be reinstalled in the same
aircraft from which it was removed. If the battery is
returned to service in a different aircraft, appropriate
record changes must be made and notification sent to the
Cessna Claims Department.

2-6

Remove battery and store in a cool, dry place; service battery periodically and charge
as required.

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MODEL 172 SERIES SERVICE MANUAL
NOTE
An engine treated in accordance with the following may
be considered being protected against normal atmospheric corrosion for a period not to exceed 90 days.
g.

Disconnect spark plug leads and remove upper and lower spark plugs from each
cylinder.
NOTE
The preservative oil must be Lubricating Oil-Contact and
Volatile, Corrosion Inhibited, MIL-C-6529. Type I heated
to 200°F-220°F spray nozzle temperature.

h. Using a portable pressure sprayer, atomize spray preservative oil through the upper
spark plug hole of each cylinder with the piston in a down position. Rotate crankshaft
as each pair of cylinders is sprayed.
i. After completing step "h," rotate crankshaft so that no piston is at a top position. If
the aircraft is to be stored outside, stop two-bladed propeller so that blades are as near
horizontal as possible to provide maximum clearance for passing aircraft.
j. Again, spray each cylinder without moving the crankshaft to thoroughly cover all
interior surfaces of the cylinder above the piston.
k. Install spark plugs and connect spark plug leads.
l. Apply preservative oil to the engine interior by spraying approximately two ounces
of the preservative oil through the oil filler tube.
m. Seal all engine openings exposed to the atmosphere, using suitable plugs or nonhygroscopic tape. Attach a red streamer at each point that a plug or tape is installed.
n. If the aircraft is to be stored outside, perform the procedures in paragraph 2-7. In
addition, the pitot tube, static source vents. air vents, openings in the engine cowling.
and other similar openings should have protective covers installed to prevent entry
of foreign material.
o. Attach a warning placard to the propeller to the effect that the propeller shall not be
moved while the engine is in storage.

2-7

MODEL 172 SERIES SERVICE MANUAL
2-11.

INSPECTION DURING STORAGE.
a. Inspect airframe for corrosion at least once a month and remove dust collections as
frequently as possible. Clean and wax aircraft as required.
b. Inspect the interior of at least one cylinder through the spark plug hole for corrosion
at least once a month.
NOTE
Do not move crankshaft when inspecting interior of
cylinder for corrosion.
c.

If at the end of the 90 day period. the aircraft is to be continued in nonopertional
storage, repeat the procedural steps "g" thru "o" of paragraph 2-10.

2-12.

RETURNING AIRCRAFT TO SERVICE. After temporary storage. use the following
procedures to return the aircraft to service.
a. Remove aircraft from blocks and check tires for proper inflation Check for proper
nose gear strut inflation. (See figure 1-1.)
b. Check battery and install.
c. Check that oil sump has proper grade and quantity of engine oil.
d. Service induction air filter and remove warning placard from propeller.
e. Remove materials used to cover openings.
f. Remove spark plugs from engine.
g. While spark plugs are removed, rotate propeller several revolutions to clear excess
rust preventive oil from cylinders.
h. Clean. gap and install spark plugs. Torque plugs to the value specified in Section 11
or 11A and connect spark plug leads.
i. Check fuel strainer. Remove and clean filter screen if necessary. Check fuel tanks or
bays and fuel lines for moisture and sediment, drain enough fuel to eliminate
moisture and sediment.
j. Perform a thorough pre-flight inspection, then start and warm-up engine.

2-13.

INDEFINITE STORAGE. Indefinite storage is defined as aircraft in a nonoperational status
for an indefinite period of time. Engines treated in accordance with the following may be
considered protected against normal atmosphere corrosion, provided the procedures
outlined in paragraph 2-14 are performed at the intervals specified.
a. Operate engine until oil temperature reaches normal operating range. Drain engine
oil sump and reinstall drain plug and safety.
b. Fill oil sump to normal operating capacity with corrosion preventive mixture which
has been thoroughly mixed.
NOTE
Corrosion-preventive mixture consists of one part compound MIL-C-529. Type I. mixed with three parts by
volume of MIL-L-6082 mineral aircraft engine oil.
c.

2-8

Immediately after filling the oil sump with corrosion-preventive mixture. fly the
aircraft for a period of time not to exceed a maximum of 30 minutes.

MODEL 172 SERIES SERVICE MANUAL
d.

With engine operating at 1200 to 1500 rpm and induction air filter removed, spray
corrosion-preventive mixture into induction airbox, at the rate of one-hall gallon per
minute, until heavy smoke comes from exhaust stack, then increase the spray until
the engine is stopped.
CAUTION
Injecting corrosion-preventive
cause a hydrostatic lock.

mixture too fast can

e.
f.

Do not rotate propeller after completing step "d".
Remove all spark plugs and spray corrosion-preventive mixture. which has been
preheated to 200°F to 220°F, into all spark plug holes to thoroughly cover interior
surfaces of cylinders.
g. Install lower spark plugs or install solid plugs, and install dehydrator plugs in upper
spark plug holes. Be sure that dehydrator plugs are blue in color when installed.
h. Cover spark plug lead terminals with shipping plugs (AN4060-1) or other suitable
covers.
i. With throttle in full open position, place a bag of desiccant in the carburetor intake
and seal opening with moisture resistant paper and tape.
j. Place a bag of desiccant in the exhaust tailpipe(s) and seal openings with moisture
resistant tape.
k. Seal cold air inlet to the heater muff with moisture resistant tape.
L Seal engine breather by inserting a protex plug in the breather hose and clamping in
place.
m. Seal all other engine openings exposed to atmosphere using suitable plugs or nonhygroscopic tape.
NOTE
Attach a red streamer to each place plugs or tape is
installed. Either attach red streamers outside of the
sealed area with tape or to the inside of the sealed area
with safety wire to prevent wicking of moisture into the
sealed area.
n.

Drain corrosion-preventive mixture from engine sump and reinstall drain plug.
NOTE
The corrosion-preventive, mixture is harmful to paint
and should be wiped from painted surfaces immediately.

Attach a warning placard on the throttle control knob, to the effect that the engine
contains no lubricating oil. Placard the propeller to the effect that it should not be
moved while the engine is in storage.
Prepare airframe for storage as outlined in paragraph 2-10 thru step "f".

2-9

MODEL 172 SERIES SERVICE MANUAL
NOTE
As an alternate method of indefinite storage. the aircraft
may be serviced in accordance with paragraph 2-10
providing the aircraft is run up at maximum intervals of
90 days and then reserviced per paragraph 2-10.
2-14.

INSPECTION DURING STORAGE. Aircraft in indefinite storage shall be inspected as
follows:
a. Inspect cylinder protex plugs each 7 days.
b. Change protex plugs if their color indicates an unsafe condition.
c. If the dehydrator plugs have changed color in one half of the cylinders. all desiccant
material in the engine shall be replaced with new material.
d. Every 6 months respray the cylinder interiors with corrosion-preventive mixture.
NOTE
Before spraying, inspect the interior of one cylinder for
corrosion through the spark plug hole and remove at
least one rocker box cover and inspect the valve mechanism.

2-15.

RETURNING AIRCRAFT TO SERVICE. After indefinite storage. use the following procedure to return the aircraft to service.
a. Remove aircraft from blocks and check tires for correct inflation. Check for correct
nose gear strut inflation.
b. Check battery and install.
c. Remove all materials used to seal and cover openings.
d. Remove warning placards posted at throttle and propeller.
e. Remove and clean engine oil screen, then reinstall and safety. On aircraft that are
equipped with an oil filter, install new filter.
f. Remove oil sump drain plug (or open quick-drain valve) and drain sump. Install and
safety drain plug (or close quick-drain valve) and service engine with correct
quantity and grade of engine oil in accordance with figure 2-4.
NOTE
The corrosion-preventive mixture will mix with the
engine lubricating oil. so flushing the oil system is not
necessary. Draining the oil sump will remove enough of
the corrosion-preventive mixture.
g. Service and install the induction air filter.
h. Remove dehydrator plugs and spark plugs or plugs installed in spark plug holes and
rotate propeller by hand several revolutions to clear corrosion-preventive mixture
from cylinders.
i. Clean, gap, and install spark plugs. Torque plugs to the value listed in Section 11 or
11A.
j. Check fuel strainer. Remove and clean filter screen. Check fuel tanks or bays and fuel
lines for moisture and sediment, and drain enough fuel to eliminate.
k. Perform a thorough preflight inspection, then start and warm-up engine.
l. Thoroughly clean aircraft and flight test aircraft.

2-10

MODEL 172 SERIES SERVICE MANUAL
2-16.

SERVICING.

2-17.

Servicing requirements are shown in figure 2-4. The following paragraphs supplement this
figure by adding details not included in the figure.

2-18.

FUEL. Fuel tanks or bays should be filled immediately after flight to lessen moisture condensation. Tank or bay capacities are listed in Section 1. The recommended fuel grade to be
used is given in figure 2-4.
WARNING
DURING ALL FUELING PROCEDURES, FIRE FIGHTING
EQUIPMENT MUST BE AVAILABLE. TWO GROUND
WIRES FROM DIFFERENT POINTS ON THE AIRPLANE
TO SEPARATE APPROVED GROUND STAKES SHALL
BE USED TO PREVENT ACCIDENTAL DISCONNECTION
OF ONE GROUND WIRE. ENSURE THAT FUELING
NOZZLE IS GROUNDED TO THE AIRPLANE.
NOTE
Tie-down rings should be used as grounding points for
all grounding wires during refueling procedures.

2-18A.

USE OF FUEL ADDITIVES FOR COLD WEATHER OPERATION. Strict adherence to
recommended preflight draining instructions will eliminate any free water accumulations
from the tank sumps. While small amounts of water may still remain in solution in the
gasoline, it will normally be consumed and go unnoticed in the operation of the engine.
One exception to this can be encountered when operating under the combined effect of: (1)
use of certain fuels, with (2) high humidity conditions on the ground (3) followed by flight at
high altitude and low temperature. Under these unusual conditions small amounts of water
in solution can precipitate from the fuel stream and freeze in sufficient quantities to induce
partial icing of the engine fuel system.
While these conditions are quite rare and will not normally pose a problem to owners and
operators, they do exist in certain areas of the world and consequently must be dealt with.
when encountered.
Therefore, to alleviate the possibility of fuel icing occuring under these unusual conditions
it is permissible to add isopropyl alcohol or ethylene glycol monomethyl ether (EGME)
compound to the fuel supply. See Figure 2-2A for fuel additive mixing ratio.
The introduction of alcohol or EGME compound into the fuel provides two distinct effects: (1)
it absorbs the dissolved water from the gasoline and (2) alcohol has a freezing temperature
depressant effect.
Alcohol, if used, is to be blended with the fuel in a concentration of 1% by volume.
Concentrations greater than 1% are not recommended since they can be detrimental to fuel
tank materials.

Revision 1

2-11

MODEL 172 SERIES SERVICE MANUAL
The manner in which the alcohol is added to the fuel is significant because alcohol is most
effective when it is completely dissolved in the fuel. To insure proper mixing the following
is recommended:
1. For best results the alcohol should be added during the fueling operation by pouring
the alcohol directly on the fuel stream issuing from the fueling nozzle.
2. An alternate method that may be used is to premix the complete alcohol dosage with
some fuel in a separate clean container (approximately 2-3 gallon capacity) and then
transfer this mixture to the tank or bay prior to the fuel operation.
Any high quality isopropyl alcohol may be used, such as:
Anti-icing fluid (MIL-F-5566) or
Isopropyl alcohol (Federal Specification TT-I-735a).
Ethylene glycol monomethyl ether (EGME) compound in compliance with MIL-I-27686 or
Phillips PFA-55MB, if used, must be carefully mixed with the fuel in concentrations not to
exceed 0.15% by volume.
CAUTION
Mixing of the EGME compound with the fuel is extremely
important because concentration in excess of that recommended (0.15 percent by volume maximum) will result in
detrimental affects to the fuel tanks, such as deterioration
of protective primer and sealants and damage to O-rings
and seals in the fuel system and engine components. Use
only blending equipment that is recommended by the
manufacturer to obtain proper proportioning.
Do not allow the concentrated EGME compound to come
in contact with the airplane finish or fuel cell as damage
can result.
Prolonged storage of the airplane will result in a water build-up in the fuel which "leeches
out" the additive. An indication of this is when an excessive amount of water accumulates in
the fuel tank sumps. The concentration can be checked using a differential refractometer. It
is imperative that the technical manual for the differential refractometer be followed
explicitly when checking the additive concentration.
2-19.

FUEL DRAINS. On aircraft serials 17267585 thru 17275034 and F17201515 thru F17202134, the
fuel drains are located in the fuel tanks or bays, fuel strainer, and carburetor. Drain plugs are
installed in the fuel selector valve and carburetor; drain valves are located in the fuel tanks
or bays and fuel strainer. Beginning with 17275035 and F17202135, a drain valve is located in
the bottom of the fuel selector valve for sampling and draining of fuel. To activate the drain
valves for fuel sampling, place cup up to valve and depress valve with rod protruding from
cup. Refer to Section 12 for illustration of fuel tank and bay drain valve. The strainer valve is
an integral part of the fuel strainer assembly. The strainer drain is equipped with a control
which is located adjacent to the oil dipstick. Access to the control is through the oil dipstick
access door. Open drains and remove drain plugs at intervals specified in figure 2-4. Also,
during daily inspection of the fuel strainer, fuel selector, and tanks or bays, if water is found
in the system, all fuel drain plugs should be opened and all water drained from the system.

2-12

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MODEL 172 SERIES SERVICE MANUAL

140
-

4.5

16 -

4.0

120-

GALLONS OF GASOLINE
Figure 2-2A. Fuel Additive Mixing Ratio Chart.
2-20.

CARBURETOR DRAIN PLUG INSPECTION. In order to prevent the possibility of thread
sealant contamination in the carburetor float chamber, cleaning and inspection of the
carburetor should be accomplished at each 100-hour inspection and anytime water in the
fuel is suspected.
a. With the fuel selector valve OFF, remove carburetor drain plug and clean off any
sealant present on the end of the plug or in the threads on the plug.
b. Inspect drain plug hole in the carburetor and remove any sealant remaining in the
hole.
c. Turn fuel selector valve to BOTH to flush float chamber and drain plug chamber
while probing drain plug hole to ascertain that all residue of sealant material is
dislodged and washed out of the chamber. Flushing operation should last 15 to 30
seconds.
d. A second flushing should then be accomplished and the drained fuel retained for
inspection to ensure that no sealant particles are present.
e. Install drain plug as follows:
1. Install drain plug in carburetor 1-1/2 to 2 turns.
2. Apply sealant to drain plug threads (use NS-40 [RAS-4] or equivalent).
3. Tighten and safety drain plug.
f. Turn fuel selector valve to BOTH and inspect for evidence of fuel leakage.

2-21.

ENGINE OIL. Check engine lubricating oil with the dipstick five to ten minutes after the engine has been stopped. The aircraft should be in as near a level position as possible when
checking the engine oil, so that a true reading is obtained. Engine oil should be drained
while the engine is still hot, and the nose of the aircraft should be raised slightly for more

Revision 1

2-13

MODEL 172 SERIES SERVICE MANUAL
positive draining of any sludge which may have collected in the engine oil sump. Engine oil
should be changed as specified in servicing intervals figure 2-4. Reduce these intervals for
prolonged operations in dusty areas, in cold climates where sludging conditions exist, or
where short flights and long idle periods are encountered, which cause sludging conditions.
Always change oil and oil filter whenever oil on the dipstick appears dirty. Aviation grade
oil conforming to AVCO Lycoming Service Instruction No. 1392 for the 0-320-H2AD engine,
and AVCO Lycoming Service Instruction No. 1014 for the O-320-D2J engine (Model 172 and
F172 Series) and 0-360-A4N engine (Model 171Q only) and any revisions or supplements
thereto, shall be used.
NOTE
O-320-H2AD ENGINES
Service with 20W-50 Ashless Dispersant Oil conforming
to MIL-L-22851. (See figure 2-4, sheet 2 of 6.)
O-320-D2J AND 0-360-A4N ENGINES
Service with SAE 20W-50 (MIL-L-6082) Aviation Grade
Mineral Oil when new or newly overhauled, during the
first 25 hours of operation, at the first 25 hour oil
change, and until 50 hours have accumulated or oil consumption has stabilized. (See figure 2-4, sheet 3 of 6.)
WARNING
The U.S. Environmental Protection Agency advises that
mechanics and other workers who handle engine oil are
advised to minimize skin contact with used oil and
promptly remove used oil from the skin. In a laboratory
study, mice developed skin cancer after skin was exposed
to used engine oil twice a week without being washed off,
for most of their life span. Substances found to cause
cancer in laboratory animals may also cause cancer in
humans.

Valve shown open. To close, twist
screwdriver until valve unlocks
and snaps down to closed position.

Figure 2-3. Quick-Drain Valve
2-14

Revision 1

MODEL 172 SERIES SERVICE MANUAL
An oil quick-drain valve may be installed. This valve provides a quicker and cleaner method
of draining the engine oil. This valve is installed in the oil drain port of the oil sump and
allows oil to be drained by attaching a hose over the fitting end and pushing up, causing the
oil to drain through the hose into a container. To drain the engine oil, proceed as follows:
a. Operate engine until oil temperature is at normal operating temperature.
b. (With Quick-Drain Valve.) Attach a hose to the quick-drain valve in the oil sump.
Push up on quick-drain valve until it locks open, and allow oil to drain through the
hose into the container, and remove oil filter (if installed).
c. (Without Quick-Drain Valve.) Remove oil drain plug from engine sump and allow oil
to drain into a container, and remove oil filter (if installed).
d. After engine oil has drained, close quick-drain valve as shown in figure 2-3 and
remove hose. Install and safety drain plug and oil filter. Torque oil filter to 18-20 lb-ft.
e. Service engine with correct quantity and grade of engine oil in accordance with
figure 2-4.
2-21A.

ENGINE OIL ADDITIVE. Refer to AVCO Lycoming Service Bulletin No. 446.

2-22.

ENGINE INDUCTION AIR FILTER (MODEL 172 AND F172 SERIES ONLY). The induction
air filter keeps dust and dirt from entering the induction system. The value of maintaining
the air filter in a good clean condition can never be overstressed. More engine wear is
caused through the use of a dirty or damaged air filter than is generally believed. The frequency with which the filter should be removed, inspected, and cleaned will be determined
primarily by aircraft operating conditions. A good general rule, however, is to remove, inspect and clean the filter at least every 100 hours of engine operating time and more frequently if warranted by operating conditions. Some operators prefer to hold spare induction
air filters at their home base of operation so that a clean filter is always readily available for
use. Under extremely dusty conditions, daily servicing of the filter is recommended. To service the filter, proceed as follows:
a.

Remove filter from aircraft.
NOTE
Use care to prevent damage to filter element when
cleaning filter with compressed air.

b. Clean filter by blowing with compressed air (not over 100 psi) from direction
opposite of normal air flow. Arrows on filter case indicate direction of normal air
flow.
CAUTION
Do not use solvent or cleaning fluids to wash filter. Use
only water and a household detergent solution when
washing the filter.
c.

After cleaning as outlined in step "b", the filter may be washed, if necessary, in a
solution of warm water and a mild household detergent. A cold water solution may be
used.
NOTE
The filter assembly may be cleaned with compressed air a
maximum of 30 times or it may be washed a maximum of
20 times. A new filter should be installed after using 500
hours of engine operating time or one year, whichever

Revision 1

2-15

MODEL 172 SERIES SERVICE MANUAL
should occur first. However, a new filter should be
installed at anytime the existing filter is damaged. A
damaged filter may have sharp or broken edges in the
filtering panels which would allow unfiltered air to enter
the induction system. Any filter that appears doubtful,
shall have a new filter installed in its place.
d.

After washing, rinse filter with clear water until rinse water draining from filter is
clear. Allow water to drain from filter and dry with compressed air (not over 100 psi).
NOTE
The filtering panels of the filter may become distorted
when wet, but they will return to their original shape
when dry.

e.
f.
2-22A.

Be sure air box is clean, inspect filter. If filter is damaged, install a new filter.
Install filter at entrance to air box with gasket on aft face of filter frame and with air
flow arrows on filter frame pointed in the correct direction.

ENGINE INDUCTION AIR FILTER (MODEL 172Q ONLY). The induction air filter keeps
dust and dirt from entering the induction system. More engine wear is caused through the
use of a dirty or damaged air filter than is generally believed. The polyurethane foam filter
element should be changed every 200 hours. Under extremely dusty conditions, the filter
should be replaced on condition.
CAUTION
This filter cannot be washed or cleaned by compressed
air; it is a remove and replace item.
Prior to installation of a new filter, squeeze out excess
wettant. It is possible that the runoff of excess wettant
could damage the paint.

2-23.

VACUUM SYSTEM CENTRAL AIR FILTER. The vacuum system central air filter keeps dirt
and dust from entering the vacuum operated instruments. Inspect vacuum system central
air filter every 200 hours of operating time for damage. Change central air filter element
every 500 hours of operating time and whenever it becomes sufficiently clogged to cause
suction gage readings to drop below 4.5 inches of mercury. Also, do not operate the vacuum
system without a filter, or with the filter removed, or a vacuum line disconnected as particles of dust or other foreign matter may enter the system and damage the vacuum operated
instruments.
CAUTION
Smoking will cause premature filter clogging.

2-24.

BATTERY. Battery servicing involves adding distilled water to maintain the electrolyte 18"
below the horizontal baffle plate at the bottom of the filler holes, checking the battery cable
connections, and neutralizing and cleaning spilled electrolyte or corrosion. Use bicarbonate
of soda (baking soda) and water to neutralize electrolyte or corrosion. Follow with a thorough flushing with water. Brighten cables and terminals with a wire brush, then coat with
petroleum jelly before connecting. The battery box also should be checked and cleaned if any
corrosion is noted. Distilled water, not acid or "rejuvenators", should be used to maintain
electrolyte level. Check the battery every 100 hours (or at least every 90 days), more often in
hot weather. Refer to Section 16 for detailed battery removal, installation and testing.

2-16

Revision 1

MODEL 172 SERIES SERVICE MANUAL
2-25.

TIRES. Maintain tire pressure at the pressure specified in figure 1-1. When checking tire
pressure, examine tires for wear, cuts, bruises, and slippage. Remove oil, grease, and mud
from tires with soap and water.
NOTE
Recommended tire pressures should be maintained.
Especially in cold weather, remember that any drop in
temperature of the air inside a tire causes a corresponding drop in air pressure.

2-26.

NOSE GEAR SHOCK STRUT. The nose gear shock strut requires periodic checking to
ensure that the strut is filled with hydraulic fluid and is inflated to the correct air pressure.
To service the nose gear shock strut, proceed as follows:
a. Remove valve cap and release all air.
b. Remove valve housing assembly.
c. Compress strut completely (stops in contact with outer barrel hub).
d. Oil Level.
1. Fluid used should comply with specification MIL-H-5606
2. Fill strut to bottom of valve installation hole.
3. Maintain oil level at bottom of valve installation hole.
e. Fully extend strut.
f. Replace valve housing assembly.
g. With strut fully extended and nose wheel clear of ground, inflate strut to 45 psi.
NOTE
The nose landing gear shock strut will normally require
only a minimum amount of service. Maintain the strut
extension air pressure, as shown in figure 1-1. Lubricate
landing gear as shown in figure 2-5. Check the landing
gear daily for general cleanliness, security of mounting,
and for hydraulic fluid leakage. Keep machined surfaces
wiped free of dirt and dust, using a clean, lint-free cloth
saturated with MIL-H-5606 hydraulic fluid or kerosene.
All surfaces should be wiped free of excessive hydraulic
fluid.

2-27.

NOSE GEAR SHIMMY DAMPER. The nose gear shimmy damper should be serviced at least
every 100 hours. The shimmy damper must be filled completely with fluid, free of entrapped
air, to serve its purpose. To service the shimmy damper, proceed as follows:
a.
Remove shimmy damper from aircraft.
b. While holding the damper in a vertical position with fitting end pointed downward,
pull fitting end of the damper shaft to its limit of travel.
c. While holding damper in this position, fill damper through open end of cylinder with
hydraulic fluid.
d. Push the shaft upward slowly to seal off the filler hole.
e. Clean dampener with solvent. Be sure to keep the shaft protruding through the filler
hole until damper is installed on the aircraft.
f. Install dampener on aircraft.
NOTE
Keep the shimmy damper, especially the exposed portions of the damper piston shaft, clean to prevent collec-

Revision 1

2-17

MODEL 172 SERIES SERVICE MANUAL
tion of dust and grit which could cut the seals in the
damper barrel. Keep machined surfaces wiped free of dirt
and dust, using a clean lint-free cloth saturated with
MIL-H-5606 hydraulic fluid or kerosene. All surfaces
should be wiped free of excessive hydraulic fluid.
2-28.

HYDRAULIC BRAKE SYSTEMS. Check brake master cylinders and refill with hydraulic
fluid as specified in the inspection charts. Bleed the brake system of entrapped air whenever
there is a spongy response to the brake pedals. Refer to Section 5 for filling and bleeding of
the brakes.

2-29.

CLEANING.

2-30.

Keeping the aircraft clean is important. Besides maintaining the trim appearance of the
aircraft, cleaning lessens the possibility of corrosion and makes inspection and maintenance easier.

2-31.

CLEANING AND CARE OF THE WINDSHIELD AND WINDOW.
a. General Maintenance Procedures. The following procedures provide information regarding cleaning and servicing windshields and windows. Improper cleaning, or use
of unapproved cleaning agents can cause damage to windshield and windows.
b. Materials Required:

NAME

MANUFACTURER

USE

Mild soap or detergent
(hand dishwashing type)

Commercially available

Cleaning windshields and
windows.

Aliphatic Naphtha Type II
conforming to Federal
Specification TT-N-95

Commercially available

Removing deposits which
cannot be removed with
mild soap solution.

Polishing wax:
(Refer to Note 1)

S.C. Johnson and Son, Inc.

Waxing acrylic windshields and windows.

Turtle Wax (paste)

Turtle Wax, Inc.
Chicago, IL 60638

Great Reflections
Paste Wax

E.I. duPont deNemours
and Co. (Inc)
Wilmington, DE 19898

Slip-stream Wax
(paste)

Classic Chemical
Grand Prairie, TX 75050

Acrylic polish conforming
to Federal Specification
P-P-560 such as:
Permatex plastic cleaner
Number 403D

Permatex Company, Inc.
Kansas City, KS 66115

Cleaning and polishing
acrylic windshields and
windows.

Soft cloth, such as:
Cotton flannel or old
tee shirt material

Commercially available

Applying and removing wax
and polish.

2-18

Revision 1

MODEL 172 SERIES SERVICE MANUAL
c.

Cleaning Instructions.
CAUTION

Windshields and windows (Acrylic Faced) are easily damaged by improper handling and cleaning techniques.
1.
2.
3.

Place airplane inside hangar or in shaded area and allow to cool from heat of
sun's direct rays.
Using clean (preferably running) water, flood the surface. Use bare hands with
no jewelry to feel and dislodge any dirt or abrasive materials.
Using a mild soap or detergent (such as a dishwashing liquid) in water, wash the
surface. Again use only the bare hand to provide rubbing force. (A clean cloth
may be used to transfer the soap solution to the surface, but extreme care must
be exercised to prevent scratching the surface.)
On acrylic windshields and windows only, if soils which cannot be removed by a
mild detergent remain, Type II aliphatic naphtha applied with a soft clean cloth
may be used as a cleaning solvent. Be sure to frequently refold cloth to avoid redepositing soil and/or scratching windshield with any abrasive particles.
Rinse surface thoroughly with clean fresh water and dry with a clean cloth.
CAUTION

Do not use any of the following on or for cleaning
windshields and windows: methanol, denatured alcohol,
gasoline, benzene, xylene, MEK, acetone, carbon tetrachloride, lacquer thinners, commercial or household
window cleaning sprays.
6.
7.

Hard polishing wax should be applied to acrylic surfaces. (The wax has an index
of refraction nearly the same as transparent acrylic and will tend to mask any
shallow scratches on the windshield surface).
Acrylic surfaces may be polished using a polish meeting Federal Specification PP-560 applied per the manufacturer's instructions.
NOTE
When applying and removing wax and polish, use a
clean soft cloth such as well worn tee shirt material or
cotton flannel.

DO NOT USE rain repellent on acrylic surfaces.

Revision 1

2-19

MODEL 172 SERIES SERVICE MANUAL
d.

Windshield and Window Preventive Maintenance.
NOTE
Utilization of the following techniques will help minimize
windshield and window crazing.
Keep all surfaces of windshields and windows clean.
If desired, wax acrylic surfaces.
Carefully cover all surfaces during any painting, powerplant cleaning or other
procedure that calls for use of any type of solvents or chemicals. The following
coatings are approved for use in protecting surfaces from solvent attack.
(a) White Spary Lab, MIL-C-6799, Type I, Class II.
(b) WPL-3 Masking Paper - St. Regis, Newton, MA.
(c) 5 X N - Poly-Spotstick - St. Regis, Newton, MA.
(d) Protex 40 - Mask Off Company, Monrovia, CA, and Southwest Paper Co.,
Wichita, KS.
(e) Protex 10VS - Mask Off Company, Monrovia, CA, and Southwest Paper Co.,
Wichita, KS.
(f) Scotch 344 Black Tape - 3M Company.
4. Do not park or store airplane where it might be subjected to direct contact with
or vapors from: methanol, denatured alcohol, gasoline, benzene, xylene, MEK,
acetone, carbon tetrachloride, lacquer thinners, commercial or household window
cleaning sprays, paint strippers, or other types of solvents.
5. Do not use solar screens or shields installed on inside of airplane or leave sun visors up against windshield. The reflected heat from these items causes elevated
temperatures which accelerate crazing and may cause formation of bubbles in the
inner ply of multiple ply windshields.
6. Do not use a power drill motor or other powered device to clean, polish, or wax
surfaces.

1.
2.
3.

2-32.

PLASTIC TRIM. The instrument panel, plastic trim, and control knobs need only be wiped
with a damp cloth. Oil and grease on the control wheel and control knobs can be removed
with a cloth moistened with Stoddard solvent. Volatile solvents, such as mentioned in
paragraph 2-31. must never be used since they soften and craze the plastic.

2-33.

PAINTED SURFACES. The painted exterior surfaces of your new Cessna have a durable,
long lasting finish. Approximately 10 days are required for the paint to cure completely; in
most cases, the curing period will have been completed prior to delivery of the airplane. In
the event that polishing or buffing is required within the curing period, it is recommended
that the work be done by someone experienced in handling uncured paint. Any Cessna Dealer can accomplish this work.

2-20

Revision 1

MODEL 172 SERIES SERVICE MANUAL
Generally, the painted surfaces can be kept bright by washing with water and mild soap, followed by a rinse with water and drying with cloths or chamois. Harsh or abrasive soaps or
detergents which could cause corrosion or scratches should never be used. Remove stubborn
oil and grease with a cloth moistened with Stoddard solvent.
To seal any minor surface chips or scratches and protect against corrosion, the airplane
should be waxed regularly with a good automotive wax applied in accordance with the manufacturer's instructions. If the airplane is operated in a seacoast or other salt water environment, it must be washed and waxed more frequently to assure adequate protection. Special
care should be taken to seal around rivet heads and skin laps, which are the areas most susceptible to corrosion. A heavier coating of wax on the leading edges of the wings and tail
and on the cowl nose cap and propeller spinner will help reduce the abrasion encountered in
these areas. Reapplication of wax will generally be necessary after cleaning with soap solutions or after chemical de-icing operations.
2-34.

ALUMINUM SURFACES. The aluminum surfaces require a minimum of care, but should
never be neglected. The aircraft may be washed with clean water to remove dirt and may be
washed with nonalkaline grease solvents to remove oil and/or grease. Household type detergent soap powders are effective cleaners, but should be used cautiously since some of them
are strongly alkaline. Many good aluminum cleaners, polishes and waxes are available from

commercial suppliers of aircraft products.

2-35.

ENGINE AND ENGINE COMPARTMENT. An engine and accessories wash-down should be
accomplished during each 100-hour inspection to remove oil, grease, salt corrosion or other
residue that might conceal component defects during inspection. Also, periodic cleaning can
be very effective preventive maintenance.
Precautions should be taken when working with cleaning agents such as wearing of rubber
gloves, an apron or coveralls and a face shield or goggles. Use the least toxic of available
cleaning agents that will satisfactorily accomplish the work. These cleaning agents include:
(1) Stoddard Solvent (Specification P-D-680 type II), (2) A water alkaline detergent cleaner
(MIL-C-25769J) mixed, 1 part cleaner, 2 to 3 parts water and 8 to 12 parts Stoddard solvent
or (3) A solvent base emulsion cleaner (MIL-C-4361B) mixed 1 part cleaner and 3 parts Stoddard sovlent.
CAUTION
Do not use gasoline or other highly flammable substances for wash down.

Revision 1

2-21

MODEL 172 SERIES SERVICE MANUAL
Perform all cleaning operations in well ventilated work areas and ensure that adequate firefighting and safety equipment is available. Do not smoke or expose a flame, with 100 feet of
the cleaning area. Compressed air, used for cleaning agent, application or drying, should be
regulated to the lower practical pressure. Use of a stiff bristle brush rather than a steel
brush is recommended if cleaning agents do not remove excess grease and grime during
spraying.
A recommended procedure for cleaning an engine and accessories is as follows:
CAUTION
Do not attempt to wash an engine which is still hot or
running. Allow the engine to cool down before cleaning.
a.
b.
c.
d.
e.

Remove engine cowling.
Carefully cover the coupling area between the vacuum pump and the engine drive
shaft so that no cleaning solvent can reach the coupling or seal.
Cover the open end of the vacuum discharge tube.
Cover the vacuum relief valve filter, if installed in the engine compartment.
Use fresh water for wash-down when the engine is contaminated with salt or corrosive chemicals. A cleaning agent such as described previously may then be used to
remove oil and grime.
CAUTION
Care should be exercised to not direct cleaning agents or
water streams at openings on the starter, magnetos, alternator or vacuum pump.

Thoroughly rinse with clean warm water to remove all traces of cleaning agents.
CAUTION
Cleaning agents should never be left on engine components for an extended period of time. Failure to remove
them may cause damage to components such as neoprene
seals and silicone fire sleeves, and could cause additional
corrosion.

2-22

Revision 1

MODEL 172 SERIES SERVICE MANUAL
g.

Completely dry engine and accessories using clean, dry compressed air.

h.
i.

Remove the cover over the coupling area
Remove the cover from the vacuum discharge tube.

j.
k.

Remove the cover from the vacuum relief valve filter, if installed.
If desired, engine cowling may be washed with the same cleaning agents, then rinsed
thoroughly and wiped dry. After cleaning engine, relubricate all control arms and

moving parts as required.
WARNING
For maximum safety, check that the magneto switches
are off, the throttle is closed, the mixture control is in
the idle cut-off position, and the airplane is secured before rotating the propeller by hand. Do not stand within
the arc of the propeller blades while turning the propeller.
m.

2-36.

Before starting engine, rotate the propeller by hand no less than four complete revolutions.

UPHOLSTERY AND INTERIOR. Keeping the upholstery and interior trim clean prolongs
upholstery fabric and interior trim life. To clean the interior, proceed as follows:
a. Empty all ash trays and refuse containers.
b. Brush or vacuum clean the upholstery and carpet to remove dust and dirt.
c. Wipe leather and plastic trim with a damp cloth.
d. Soiled upholstery fabrics and carpet may be cleaned with a foam-type detergent used
according to manufacturer's instructions.
e. Oil spots and stains may be cleaned with household spot removers, used sparingly.
Before using any solvent, read the instructions on the container and test it on an
obscure place in the fabric to be cleaned. Never saturate the fabric with volatile
solvent; it may damage the padding and backing material.
f. Scrape sticky material from fabric with a dull knife, then spot clean the area.

Revision 1

2-23

MODEL 172 SERIES SERVICE MANUAL
2-37.

PROPELLER. Wash hub and blade with a soft cloth and Stoddard cleaning solvent or
equivalent, then dry thoroughly with compressed air. The propeller should be wiped
occasionally with an oily cloth, then wiped with a dry cloth. In salt water areas this will
assist in corrosion proofing the propeller.

2-38.

WHEELS. The wheels should be washed periodically and examined for corrosion, chipped
paint, and cracks or dents in the wheel halves or in the flanges or hubs. If defects are found,
remove and repair in accordance with Section 5. Discard cracked wheel halves, flanges or
hubs and install new parts.

2-39.

LUBRICATION.

2-40.

Lubrication requirements are shown in figure 2-5. Before adding grease to grease fittings,
wipe dirt from fitting. Lubricate until grease appears around parts being lubricated, and
wipe excess grease from parts. The following paragraphs supplement figure 2-5 by adding
details.

2-41.

WHEEL BEARINGS. Clean and repack the wheel bearings at first 100-hour inspection and at
each 500-hour inspection thereafter. If more than the usual number of takeoffs and landings
are made, extensive taxiing is required, or the aircraft is operated in dusty areas or under
seacoast conditions, cleaning and lubrication of the wheel bearings shall be accomplished at
each 100-hour inspection.

2-42.

NOSE GEAR TORQUE LINKS. Lubricate nose gear torque links every 50 hours. When
operating in dusty conditions, more frequent lubrication is required.

2-43.

WING FLAP ACTUATOR. Clean and lubricate wing flap actuator jack screw each 100 hours
as follows:
a. Expose jack screw by operating flaps to full down position.
b. Clean jack screw threads with solvent rag and dry with compressed air.
NOTE
It is not necessary to remove actuator from aircraft to
clean or lubricate threads.
c.

2-24

With oil can, apply light coat of No. 10 weight, non-detergent oil to threads of jack
screw.

Revision 1

MODEL 172 SERIES SERVICE MANUAL
2-44.

FUEL SELECTOR VALVE. At each 100 hour inspection, check the fuel selector valve and
drive shaft for the following:
a. Valve control detent plate for cleanliness and excessive wear. Dirt accumulation on
this plate can cause binding, poor detent feel and rapid wear of the plate.
b. All drive shaft attach points for security, binding, excessive wear and lubrication, if
required.
c. Operate valve handle through all positions and check for proper operation, detent
feel and freedom of movement.

2-45.

ROD END BEARINGS. Periodic inspection and lubrication is required to prevent corrosion
of the bearing in the rod end. At each 100-hour inspection, disconnect the control rods at
the aileron, flap and nose gear steering rods, and inspect each rod end for corrosion. If no
corrosion is found, wipe the surface of the rod end balls with general purpose oil and rotate
ball freely to distribute the oil over its entire surface and connect the control rods to their respective units. If corrosion is detected during the inspection, install new rod ends.

Revision 1

2-25

MODEL 172 SERIES SERVICE MANUAL

Refer to Sheets 2 & 3 for Fuel and Oil Specifications.

Figure 2-4. Servicing (Sheet 1 of 6)
2-26

Revision 1

MODEL 172 SERIES SERVICE MANUAL
SPECIFIED AVIATION GRADE FUELS:

WARNING
ONLY AVIATION GRADE FUELS ARE APPROVED FOR USE.

ENGINE MODEL

APPROVED FUEL GRADES

NOTE

100LL (blue)

LYCOMING 0-320-H2AD
O-320-100

LYCOMING
(green) (formerly

100/130)

NOTE
1. Compliance with Avco Lycoming Service Instruction No. 1070, and all revisions
thereto, must be accomplished.

SPECIFIED AVIATION GRADE OIL:
AVERAGE AMBIENT TEMPERATURE (°F)/OIL GRADE
0°

10°

20°

40°

60°

80°

MAXIMUM OIL
TEMPERATURE
F°
245

SAE 60

SAE 40 or SAE 50
SAE 40

245°

SAE 30. SAE 40 or SAE 20W-40
SAE 30 or
SAE 20W-30

210°
SAE 15W-50 or SAE 20W-50

245°

The overlap of oil grades is based on a mid-range of ambient ground temperature vs
maximum oil inlet temperature. Aviation grade ashless dispersant oil conforming to
Avco Lycoming Service Instruction No. 1392, and all revisions and supplements
thereto MUST BE USED.
Oil capacities for the aircraft are given in the following chart For extended flight, fill
to FULL mark on dipstick. Do not operate with less than MINIMUM FOR FLIGHT
quantities listed. If an external oil filter is installed, one additional quart of oil is required when filter is changed.

CAPACITY
(TOTAL)
667

CAPACITY (TOTAL
WITH FILTER)

NORMAL
OPERATION

MINIMUM
FOR FLIGHT

Figure 2-4. Servicing (Sheet 2 of 6)
Revision 1

2-27

MODEL 172 SERIES SERVICE MANUAL
SPECIFIED AVIATION GRADE FUELS:

WARNING
ONLY AVIATION GRADE FUELS ARE APPROVED FOR USE.

NOTE

APPROVED FUEL GRADES

ENGINE MODEL

LYCOMING 0-320-D2J & 0-360-A4N

100LL

(blue)
100 (green) (formerly 100/130)

NOTE
1. Compliance with Avco Lycoming Service Instruction No. 1070, and all revisions
thereto, must be accomplished.

SPECIFIED AVIATION GRADE OIL:
AVERAGE AMBIENT TEMPERATURE (°F)/OIL GRADE
0°

30°

50°

60°

70°

80°

90°

MAXIMUM OIL
TEMPERATURE
F°

SAE 60

245°

SAE 40 or SAE 50
245 °
SAE 30, SAE 40 or SAE 20W-40

245 °

SAE 30 or
SAE 20W-30

210°
SAE 15W-50 or SAE 20W-50

245 °

Aviation grade oils conforming to Avco Lycoming Service Instruction No. 1014, and all
revisions and supplements thereto, MUST BE USED, except as noted in paragraph 2-21.

Oil capacities for the aircraft- are given in the following chart. For extended flight, fill
to FULL mark on dipstick. Do not operate with less than MINIMUM FOR FLIGHT
quantities listed. If an external oil filter is installed, one additional quart of oil is required when filter is changed.

CAPACITY
(TOTAL)

CAPACITY (TOTAL
WITH FILTER)

NORMAL
OPERATION

Figure 2-4.
2-28

Revision 1

Servicing (Sheet 3 of 6)

MINIMUM
FOR FIGHT
5

MODEL 172 SERIES SERVICE MANUAL

DAILY

FUEL TANK OR BAY FILLER
Service after each flight. Keep full to retard condensation. Refer to paragraph 2-18 for
details.

FUEL TANK OR BAY SUMP DRAINS:
Drain off any water and sediment before first flight of the day.

FUEL STRAINER
Drain off any water and sediment before first flight of the day. Refer to paragraph 2-19 for
details.
PITOT AND STATIC PORTS
Check for obstructions before first flight of the day.

INDUCTION AIR FILTER
Inspect and service under dusty conditions. Refer to paragraphs 2-22 and 2-22A for
details.

OIL DIPSTICK
Check oil on preflight. Add oil as necessary. Refer to paragraph 2-21 for details.
Gouges or deep marks on the lower end of the dipstick would be evidence of prior interference with the crankshaft and is cause for further investigation of the engine.

OIL FILLER CAP
Whenever oil is checked or added, check that filler cap is tight and oil filler door is
secure.

FIRST 25 HOURS

Figure 2-4. Servicing (Sheet 4 of 6)
Revision 1

2-29

MODEL 172 SERIES SERVICE MANUAL

50 HOURS

ENGINE OIL SYSTEM (WHEN NOT EQUIPPED WITH EXTERNAL OIL FILTER)
Drain engine oil sump, clean oil pressure screen, and refill with ashless dispersant oil.
NOTE
Refer to 100 hour servicing interval when equipped with
long external oil filter.

100 HOURS
12

NOSE GEAR SHIMMY DAMPER

Check fluid level and refill as required with hydraulic fluid. Refer to paragraph 2-27 for
details.
11

NOSE GEAR SHOCK STRUT
Keep strut filled and inflate to correct pressure. Refer to paragraph 2-26 for details.

INDUCTION AIR FILTER
Clean filter per paragraph 2-22 (172 & F172 Series) and paragraph 2-22A (Model 172Q
Only). Replace as required.

BATTERY

Check electrolyte level each 100 hours or each 90 days, which ever comes first.
7

TIRES
Maintain correct tire inflation as listed in figure 1-1. Also refer to paragraph 2-25 for
details.

FUEL SELECTOR VALVE DRAIN
Drain off any water or sediment. Refer to paragraph 2-19.

FUEL STRAINER
Disassemble and clean strainer bowl and screen.

ENGINE OIL SYSTEM
On O-320-H2AD engines, drain oil sump and clean pressure screen or replace oil filter, if
installed. Refill with MIL-L-22851 Ashless Dispersant Oil. (See figure 2-4.) On 0-320D2J and 0-360-A4N engines, drain oil sump, replace oil filter, and service with MIL-L22851 Ashless Dispersant oil in accordance with oil chart in figure 2-4.
NOTE
Refer to 50 hour servicing interval when not equipped
with long external oil filter.
Change engine oil at least every 6 months, even though the recommended hours have not
accumulated.

Figure 2-4. Servicing (Sheet 5 of 6)
2-30

Revision 1

MODEL 172 SERIES SERVICE MANUAL
1

VACUUM RELIEF VALVE URETHANE FILTER
Replace filter.

VACUUM SYSTEM CENTRAL AIR FILTER
Inspect for damage. See paragraph 2-23 for details.
BRAKE MASTER CYLINDERS
Check fluid level and refill as required with hydraulic fluid. Refer to paragraph 2-28 for
details.

200 HOURS

GROUND SERVICE RECEPTACLE
Connect to 24-volt DC. negative-ground power unit. Refer to Section 11 for details.

500 HOURS

VACUUM SYSTEM CENTRAL AIR FILTER
Replace every 500 hours.

Figure 2-4. Servicing (Sheet 6 of 6)
Revision 1

2-31

MODEL 172 SERIES SERVICE MANUAL
FREQUENCY (HOURS)

METHOD OF APPLICATION

HAND

GREASE
GUN

OIL
CAN

SYRINGE
(FOR POWDERED
GRAPHITE)

WHERE NO INTERVAL IS SPECIFIED,
LUBRICATE AS REQUIRED AND
WHEN ASSEMBLED OR INSTALLED.
NOTE
The military specifications listed are not mandatory, but are intended as
guides in choosing satisfactory materials. Products of most reputable
manufacturers meet or exceed these specifications.
LUBRICANTS
PG GRGHGLOG PL-

SS-G-659
............
MIL-G-81322A ..........
MIL-G-23827A ...........
MIL-G-21164C ...........
MIL-L-7870A ..........
VV-P-236 .............

OL-

VV-L-800A

GP-.....

SYSTEM

............

POWDERED GRAPHITE
GENERAL PURPOSE GREASE
AIRCRAFT AND INSTRUMENT GREASE
MOLYBDENUM DISLULFIDE GREASE
GENERAL PURPOSE OIL
PETROLATUM
NO. 10-WEIGHT, NON-DETERGENT OIL
LIGHT OIL

ALSO REFER TO

OG
SHIMMY
DAMPENER
PIVOTS
ALSO REFER TO

BEARING

2-32

Revision 1

MODEL 172 SERIES SERVICE MANUAL
CONTROL

WHEEL SHAFT
UNIVERSALS

BUSHINGS AND
BUSHINGB AND

BATTERY
ELEVATOR

TRIM TAB
ACTUATOR

ALSO REFER TO INSPECTION

CHART IN THIS SECTION AND
TO SECTION 9 OF THIS MANUAL

NEEDLE BEARNGS
CONTROL "U"

ALL

PLANO

HINGES

*ENGINE

CONTROLS

USE NO LUBRICANT UNDER
EXTREME DUSTY CONDITIONS

AILERON BELLCRANK

NEEDLE BEARINGS

ROD END
BEARINGS
SPRING STOP

TYPICAL

CABIN DOOR WINDOW
INSERT GROOVES
Figure 2-5.

Lubrication. (Sheet 2 of 3)

Revision 1

2-33

MODEL 172 SERIES SERVICE MANUAL

OILITE BEARINGS
(RUDDER BAR ENDS)

NEEDLE
BEARINGS

ALL LINKAGE
POINT PIVOTS

RUDDER BARS AND PEDALS

WING SPAR AND
STRUT-ATTACH

BOLTS

ELECTRIC FLAP
DRIVE MECHANISM
SCREW JACK
THREADS

REFER
TO
PARAGRAPH
2-43

NOTES
Sealed bearings require no lubrication.
Do not lubricate roller chains or cables except under seacoast conditions.
dry cloth.

Wipe with a clean,

Lubricate unsealed pulley bearings, rod ends, Oilite bearings, pivot and hinge points, and any
other friction point obviously needing lubrication, with general purpose oil every 1000 hours or
oftener if required.
Paraffin wax rubbed on seat rails will ease sliding the seats fore and aft.
Lubricate door latching mechanism with MIL-G-81322A general purpose grease, applied sparingly
to friction points, every 1000 hours or oftener, if binding occurs. No lubrication is recommended
on the rotary clutch.

Figure 2-5.
2-34

Revision 1

Lubrication (Sheet 3 of 3)

MODEL 172 SERIES SERVICE MANUAL
2-46.

GENERAL INSPECTION (MODEL 172 AIRPLANES).
NOTE
Cessna Aircraft Company recommends PROGRESSIVE
CARE for airplanes flown 200 hours or more per year, and
100-HOUR INSPECTION for airplanes flown less than 200
hours per year.
A.

Inspection Requirements.
(1)Two basic types of inspections are available as defined below:
(a) As required by Federal Aviation Regulation Part 91.409(a), all civil airplanes of U.S.
registry must undergo an annual inspection each 12 calendar months. In addition
airplanes operated commercially (for hire) must also have an annual 100 hour inspection
each 100 hours of operation as required by Federal Aviation Regulation Part 91.409(b).
(b) In lieu of the above requirements, an airplane may be inspected in accordance with a
progressive inspection program in accordance with Federal Aviation Regulation Part
91.409(d), which allows the work load to be divided into smaller operations that can be
accomplished in a shorter time period. The CESSNA PROGRESSIVE CARE PROGRAM
has been developed to satisfy the requirements of Part 91 409 (d).
Inspection Program Selection.
(1)
As a guide for selecting the inspection program that best suits the operation of the airplane,
the following is provided:
(a) If the airplane is flown less than 200 hours annually, the following conditions apply:
1. If flown for hire.
a.
An airplane operating in this category must be inspected each 100 hours of
operation (100-HOUR) and each 12 calendar months of operation (ANNUAL).
2.
If not flown for hire.
a.
An airplane operating in this category must be inspected each 12 calendar
months of operation (ANNUAL). It is recommended that between annual
inspections, all items be inspected at the intervals specified in the Inspection
Time Limits Charts and Component Time Limits Charts.
(b) If the airplane is flown more than 200 hours annually, the following condition applies:
1. Whether flown for hire or not, it is recommended that airplanes operating in this
category be placed on the CESSNA PROGRESSIVE CARE PROGRAM. However.
if not placed on the CESSNA PROGRESSIVE CARE PROGRAM, the inspection
requirements for airplanes in this category are the same as those defined under
Paragraph B. (1)(a)1.a. or 2.a. CESSNA PROGRESSIVE CARE PROGRAM may
be utilized as a total concept program which ensures that the inspection intervals in
the inspection charts are not exceeded. Manuals and forms which are required for
conducting the CESSNA PROGRESSIVE CARE PROGRAM inspections are
available from the Cessna Supply Division.

Revision 2

2 35

MODEL 172 SERIES SERVICE MANUAL
C.

Inspection Charts.
NOTE
Cessna has prepared these Inspection Charts to assist the owner or operator in
meeting the foregoing responsibilities and to meet the intent of Federal Aviation
Regulation Part 91.409(d). The Inspection Charts are not intended to be allinclusive, for no such charts can replace the good judgment of a certified airframe
and powerplant mechanic in performance of his duties.
As the one primarily
responsible for this airworthiness of the airplane, the owner or operator should
select only qualified personnel to maintain the airplane.
(1)

(2)

2-36

The following Inspection Charts (Inspection Time Limits, Component Time Limits, Progressive
Care Inspection, and Expanded Inspection) show the recommended intervals at which items
are to be inspected based on normal usage under average environmental conditions. Airplanes operated in extremely humid tropics, or in exceptionally cold, damp climates, etc., may
need more frequent inspections for wear, corrosion, and lubrication. Under these adverse conditions, perform periodic inspections in compliance with this chart at more frequent intervals
until the operator can set his own inspection periods based on field experience. The operator's inspection intervals shall not deviate from the inspection time limits shown in this manual
except as provided below:
(a) Each inspection interval can be exceeded by 10 hours or can be performed early at any
time prior to the regular interval as provided below:
1. In the event of late compliance of any operation scheduled, the next operation in
sequence retains a due point from the time the late operation was originally scheduled.
2.
In the event of early compliance of any operation scheduled, that occurs 10 hours
or less ahead of schedule, the next phase due point may remain where originally
set.
3.
In the event of early compliance of any operation scheduled, that occurs more than
10 hours ahead of schedule, the next phase due point must be rescheduled to establish a new due point from the time of early accomplishment.
As shown in the charts, there are items to be checked at 50 hours, 100 hours, 200 hours, or
at Special of Yearly inspection. Special or Yearly inspection items require servicing or inspection at intervals other than 50. 100, or 200 hours. If two inspection time requirements are listed for one inspection item, one hourly and the yearly, both apply and whichever requirement
occurs first determines the time limit.
(a) When conducting a 50-hour inspection. check all items listed under EACH 50 HOURS. A
100-hour inspection includes all items listed under EACH 50 HOURS and EACH 100
HOURS. The 200-hour inspection includes all items listed under EACH 50 HOURS,
EACH 100 HOURS, and EACH 200 HOURS. All of the items listed would be inspected,
serviced, or otherwise performed as necessary to ensure compliance with the inspection
requirements.
(b) A COMPLETE AIRPLANE INSPECTION includes all 50-, 100-, and 200-hour items plus
those Special and Yearly Inspection Items which are due at the specified time.
(c) Component Time Limits Charts should be checked at each inspection interval to ensure
proper overhaul and replacement requirements are accomplished at the specified times.

Revision 2

MODEL 172 SERIES SERVICE MANUAL
D.

Inspection Guidelines.
(1) The Inspection Charts are to be used as a recommended inspection outline. Detailed information of systems and components in the airplane will be found in various chapters of this Maintenance Manual and the pertinent vendor publications. It is recommended that reference be
made to the applicable portion of this manual for service instructions, installation instructions,
and to the vendor's data or publications specifications for torque values, clearances, settings,
tolerances, and other requirements.
(2) For the purpose of this inspection, the term on condition is defined as follows: The necessary inspections and/or checks to determine that a malfunction or failure will not occur prior to
the next scheduled inspection.
(3) MOVABLE PARTS:
Inspect for lubrication, servicing, security of attachment, binding, excessive wear, safetying, proper operation, proper adjustment, correct travel, cracked fittings, security of hinges, defective bearings, cleanliness, corrosion, deformation, sealing, and tension.
(4) FLUID LINES AND HOSES: Inspect for leaks, cracks, bulging, collapsed, twisted, dents,
kinks, chafing, proper radius, security, discoloration, bleaching, deterioration, and proper routing; rubber hoses for stiffness and metal lines for corrosion.
(5) METAL PARTS: Inspect for security of attachment, cracks, metal distortion, broken spotwelds,
condition of paint (especially chips at seams and around fasteners for onset of corrosion) and
any other apparent damage.
(6) WIRING: Inspect for security, chafing, burning, arcing, defective insulation, loose or broken
terminals, heat deterioration, and corroded terminals.
(7) STRUCTURAL FASTENERS: Inspect for correct torque in accordance with applicable torque
values. Refer to Bolt Torque Data during installation or when visual inspection indicates the
need for a torque check.
NOTE
Torque values listed are not to be used for checking tightness of installed parts
during service.
(8)
(9)

FILTERS, SCREENS, AND FLUIDS: Inspect for cleanliness and the need for replacement at
specified intervals.
System check (operation or function) requiring electrical power must be performed using 28.5
±0.25 volts bus voltage. This will ensure all components are operating at their designed requirements.
(a) Airplane file.
1. Miscellaneous data, information, and licenses are a part of the airplane file. Check
that the following documents are up-to-date and in accordance with current Federal
Aviation Regulations. Most of the items listed are required by the Federal Aviation
Regulations. Since the regulations of other nations may require other documents
and data, owners of exported airplanes should check with their own aviation officials to determine their individual requirements.
a.
To be displayed in the airplane at all times:
1) Standard Airworthiness Certificate (FAA Form 8100-2).
2) Aircraft Registration Certificate (FAA Form 8050-3).
3) Aircraft Radio Station License (Federal Communication Commission Form
556 if transmitter is installed).
4) Radio Telephone Station License (Federal Communication Commission
Form 409 it Flitetone Radio Telephone is installed).
b.
To be carried in the airplane at all times:
1) Weight and Balance Data Sheets and associated papers (all copies of the
Repair and Alteration Form, FAA Form 337, are applicable).
2) Equipment List.
3) Pilot's Operating Handbook and FAA-Approved Airplane Flight Manual.
c.
To be made available upon request:
1) Airframe, Engine, Propeller, and Avionics Maintenance Records.

Revision 2

2 37

MODEL 172 SERIES SERVICE MANUAL
2-47.

PRE-INSPECTION CHECKS. (MODEL 172 AIRPLANES.)
A.

Pre-inspection Operational Checks.
(1) Before beginning the step-by-step inspection, start and run up the engine and upon completion, shut down the engine in accordance with instructions in the Pilot's Operating Handbook
and FAA-Approved Airplane Flight Manual. During the run-up, observe the following, making
note of any discrepancies or abnormalities:
(a) Engine temperatures and pressures.
(b) Static RPM. (Also refer to Section 11 and 11A of this manual.)
(c) Magneto drop. (Also refer to Section 11 and 11A of this manual.)
(d) Engine response to changes in power.
(e) Any unusual engine noises.
(f) Fuel selector and/or shutoff valve; operate engine on each tank (or cell) position and
OFF position long enough to ensure shutoff and/or selector valve functions properly.
(g) Idling speed and mixture; proper idle cut-off.
(h) Alternator and ammeter.
(i) Suction gage.
(j) Fuel flow indicator.
(2) After the inspection has been completed, an engine run-up should again be performed to determine that any discrepancies or abnormalities have been corrected.
(3) Some of the items in the Inspection Time Limits paragraph are optional, therefore not applicable to all airplanes.
Mechanic's Pre-nspection Discrepancies or Abnormalities to be Checked:

Mechanic's Post-inspection Corrective Action Taken:

2-38

Revision 2

MODEL 172 SERIES SERVICE MANUAL
EACH

2-48

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

50
HOURS

EACH

100
HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

A
Placards (Refer to Pilot's Operating Handbook).
A

1 Placards and Decals - Inspect presence, legibility, and
security. Consult Pilot's Operating Handbook and FAAApproved Airplane Flight Manual for required placards.

B
Fuselage (Section 3).
B

B
B
B
B

B
B

1 Fuselage Surface - Inspect for skin damage, loose rivets,
condition of paint, and check pitot-static ports and drain
holes for obstruction. Inspect covers and fairings for
security.
2 Internal Fuselage Structure - Inspect bulkheads, doorposts,
stringers, doublers, and skins for corrosion, cracks,
buckles, and loose rivets, bolts and nuts.
3 Control Wheel Lock - Check general condition and
operation.
4 Fuselage Mounted Equipment - Check for general
condition and security of attachment.
5 Antennas and Cables - Inspect for security of attachment,
connection, and condition.
6 Emergency Locator Transmitter - Inspect for security of
attachment and check operation by verifying transmitter
output. Check cumulative time and useful life of batteries
in accordance with FAR Part 91.207. Refer to Section 16 Emergency Locator Transmitter - Checkout Interval.
7 Instrument Panel Shock Mounts, Ground Straps, and
Covers - Inspect for deterioration, cracks, and security of
attachment.
8 Pilot's and Copilot's Inertia Reels - Inspect for security of
installation, proper operation, and evidence of damage.
9 Seats. Seat Belts, and Shoulder Harnesses - Check
general condition and security. Check operation of seat
stops and adjustment mechanism. Inspect belts for
condition and security of fasteners.
10 Windows, Windshield, Doors, and Seals - Inspect general
condition. Check latches, hinges, and seals for condition,
operation, and security of attachment.
11 Upholstery, Headliner, Trim, and Carpeting - Check
condition and clean as required.
12 Flight Controls - Check freedom of movement and proper
operation through full travel with and without flaps
extended. Check electric trim controls for operation (as
applicable).
13 Aileron, Elevator, and Rudder Stops - Check for damage
and security.
14 Portable Hand Fire Extinguisher - Inspect for proper
operating pressure, condition, security of installation, and
servicing date.
15 Seat Tracks and Stops . Inspect seat tracks for condition
and security of installation. Check seat track stops for
damage and correct location. Ensure inspection of seat
rails for cracks EACH 50 HOURS. Refer to Section 3.

EACH
400

Revision 3

EACH
1

2-39

MODEL 172 SERIES SERVICE MANUAL
SPECIAL

2-48
B

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

EACH
50
HOURS

EACH

100
HOURS

EACH

INSPECTIONS

200
HOURS HOURS YEARS

16 Control Column - Inspect pulleys, cables, sprockets,
bearings, chains, bungees, and turnbuckles for condition
and security.
17 Fuel Line and Selector Valve Drain(s) - Remove plug and
drain.

C
Wings and Empennage (Section 4).
C
C
C

C
C
C

1 Wing Surfaces and Tips - Inspect for skin damage, loose
rivets, and condition of paint.
2 Wing Struts and Strut Fairings - Check for dents, cracks,
loose screws and rivets, and condition of paint.
3 Wing Spar and Wing Strut Fittings - Check for evidence of
wear. Check attach bolts for indications of looseness and
retorque as required.
4 Wing Structure - Inspect spars, ribs, skins, and stringers
for cracks, wrinkles, loose rivets, corrosion, or other
damage.
5 Metal Lines, Hoses, Clamps, and Fittings - Check for
leaks, condition, and security. Check for proper routing
and support.
6 Wing Access Plates - Check for damage and security of
installation.
7 Vertical and Horizontal Stabilizers, Tips and Tailcone Inspect externally for skin damage and condition of paint.
8 Vertical and Horizontal Stabilizers and Tailcone Structure Inspect bulkheads, spars, ribs, and skins for cracks,
wrinkles, loose rivets, corrosion, or other damage.
Inspect vertical and horizontal stabilizer attach bolts for
looseness. Retorque as necessary. Check security of
inspection covers, fairings, and tips.

D
Landing Gear and Brakes (Section 5).
D

D
D
D

2-40

1 Brakes, Master Cylinders, and Parking Brake - Check
master cylinders and parking brake mechanism for
condition and security. Check fluid level and test
operation of toe and parking brake.
2 Main Gear Tubular Struts - Inspect for cracks, dents,
corrosion, condition of paint or other damage. Check
axles for condition and security.
3 Brake Lines, Wheel Cylinders, Hoses. Clamps, and Fittings
- Check for leaks, condition, and security and hoses for
bulges and deterioration. Check brake lines and hoses for
proper routing and support.
4 Wheels, Brake Discs. and Linings - Inspect for wear,
cracks, warps, dents, or other damage. Check wheel
through-bolts and nuts for looseness.
5 Tires - Check tread wear and general condition. Check for
proper inflation.
6 Wheel Fairings. Strut Fairings, and Cuffs - Check for
cracks. dents, and condition of paint.
7 Main Landing Gear Attachment Structure - Check for
damage. cracks, loose rivets, bolts and nuts and security
of attachment.

Revision 3

EACH
400

EACH
1

MODEL 172 SERIES SERVICE MANUAL
2-48
D
D

D
D
D

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)
8 Nose Gear Steering Mechanism - Check for wear,
security, and proper rigging.
9 Nose Gear - Inspect torque links, steering rods, and boots
for condition and security of attachment. Check strut for
evidence of leakage and proper extension. Check strut
barrel for corrosion, pitting, and cleanliness. Check
shimmy damper and/or bungees for operation, leakage,
and attach points for wear and security.
10 Nose Gear Fork - Inspect for cracks, general condition,
and security of attachment.
11 Wheel Bearings - Clean, inspect and lube.
12 Nose Gear Attachment Structure - Inspect for cracks,
corrosion, or other damage and security of attachment.

EACH

100

HOURS HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

E
Aileron Control System (Section 6).
E
E

E
E

1 Ailerons and Hinges - Check condition, security and
operation.
2 Aileron Structure, Control Rods. Hinges, Balance Weights,
Bellcranks, Linkage, Bolts, Pulleys, and Pulley Brackets Check condition, operation, and security of attachment.
3 Ailerons and Cables - Check operation and security of
stops. Check cables for tension, routing, fraying,
corrosion, and turnbuckle safety. Check travel if cable
tension requires adjustment or if stops are damaged.
Check fairleads and rub strips for condition.
4 Autopilot Rigging - Check per Avionics Installation Manual.
5 Aileron Controls - Check freedom of movement and proper
operation through full travel with and without flaps
extended.

F
Wing Flap Control System (Section 7).
F
F
F
F
F

1 Flaps - Check tracks, rollers, and control rods for security
of attachment. Check operation.
2 Flap Actuator Threads - Clean and lubricate. Refer to
paragraph 2-43 for detailed instructions.
3 Flap Structure, Linkage, Bellcranks, Pulleys, and Pulley
Brackets - Check for condition, operation and security.
4 Wing Flap Control - Check operation through full travel and
observe Flap Position indicator for proper indication.
5 Flaps and Cables - Check cables for proper tension.
routing, fraying, corrosion, and turnbuckle safety. Check
travel if cable tension requires adjustment.
6 Flap Motor, Actuator, and Limit Switches (electric flaps) Check wiring and terminals for condition and security.
Check actuator for condition and security.

G
Elevator Control System (Section 8).
G

1 Elevator Control - Check freedom of movement and proper
operation through full travel with and without flaps
extended.
2 Elevator, Hinges, and Cable Attachment - Check condition.
security, and operation.
Revision 3

2-41

MODEL 172 SERIES SERVICE MANUAL
2-48
G

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

EACH EACH
50
100
HOURS HOURS

SPECIAL
EACH INSPECTIONS
200
HOURS HOURS YEARS

3 Elevator Control System - Inspect pulleys, cables,
sprockets, bearings, chains, and turnbuckles for condition,
security, and operation.

H
Elevator Trim Tab Control System (Section 9).
H
H

H
H
H

1 Elevator Trim Tab and Hinges - Check condition, security,
and operation.
2 Elevator Trim System - Check cables, push-pull rods,
bellcranks, pulleys, turnbuckles, fairleads, rub strips, etc.
for proper routing, condition, and security.
3 Trim Controls and Indicators - Check freedom of
movement and proper operation through full travel. Check
pulleys, cables, sprockets, bearings, chains, bungees, and
turnbuckles for condition and security. Check electric trim
controls for operation as applicable.
4 Elevator Trim Tab Stop Blocks - Inspect for damage and
security.
5 Elevator Trim Tab Actuator - Clean, lubricate, and check
free-play.
6 Elevator Trim Tab Actuator - Free-Play limits inspection.
Refer to Section 9 for cleaning, inspection, and repair
procedures.

Rudder Control System (Section 10).
I

1 Rudder - Inspect the rudder skins for cracks and loose
rivets, rudder hinges for condition, cracks and security;
hinge bolts, hinge bearings, hinge attach fittings, and
bonding jumper for evidence of damage and wear, failed
fasteners, and security. Inspect the rudder hinge bolts for
proper safetying of nuts with cotter pins. Inspect balance
weight for looseness and the supporting structure for
damage.
2 Rudder Pedals and Linkage - Check for general condition,
proper rigging, and operation. Check for security of
attachment.
3 Rudder, Tips, Hinges. and Cable Attachment - Check
condition, security, and operation.
4 Rudder - Check internal surfaces for corrosion, condition
of fasteners, and balance weight attachment.

J
Engines (Sections 11 and 11 A).
J

J
J

J
2-42

1 Cowling - Inspect for cracks. dents. and other damage,
security of cowl fasteners, and cowl mounted landing lights
for attachment.
2 Engine - Inspect for evidence of oil and fuel leaks. Wash
engine and check for security of accessories.
3 Engine Controls and Linkage - Check general condition.
freedom of movement through full range. Check for
proper travel. security of attachment, and for evidence of
wear. Check friction locks for proper operation.
4 Ignition Switch and Electrical Harness - Inspect for
damage. condition, and security.
Revision 3

MODEL 172 SERIES SERVICE MANUAL
2-48

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

J
J
J

J
J

J
J
J
J
J
J

5 Firewall Structure - Inspect for wrinkles, damage, cracks,
sheared rivets, etc. Check cowl shock mounts for
condition and security.
6 Engine Shock Mounts, Engine Mount Structure, and
Ground Straps - Check condition, security, and alignment.
7 Induction System - Check security of clamps, tubes, and
ducting. Inspect for evidence of leakage.
8 Induction Airbox, Valves, Doors, and Controls - Remove
air filter and inspect hinges, doors, seals, and attaching
parts for wear and security. Check operation. Clean and
inspect.
9 Induction Air Filter - Remove and clean. Inspect for
damage, and service per Paragraph 2-22 and 2-22A.
10 Alternate Induction Air System - Check for obstructions,
operation, and security.
11 Alternator, Mounting Bracket and Electrical Connections Check condition and security. Check alternator belts for
condition and proper adjustment. Check belt tension per
Section 16, Paragraph 16-38.
12 Alternator - Check brushes, leads, commutator or slip ring
for wear.
13 Starter, Starter Solenoid, and Electrical Connections Check for condition of starter brushes, brush leads, and
commutator.
14 Oil Cooler - Check for obstructions, leaks, and security of
attachment.
15 Exhaust System - Inspect for cracks and security. Special
check in area of heat exchanger. Refer to Section 11,
Paragraph 11-73 for inspection procedures.
16 Auxiliary (Electric) Fuel Pump (172Q) - Check pump and
fittings for condition, operation, security. Remove and
clean filter (as applicable).
17 Engine-Driven Fuel Pump - Check for evidence of leakage,
security of attachment, and general condition.
18 Magnetos - Check external condition, security, and
electrical leads for condition. Check timing to engine and
internal timing if engine timing requires adjustment.
19 Magnetos - Check impulse coupling and stop pins for
condition, replace as required.
20 Magnetos - Inspection, lubrication, and overhaul
procedures.
21 Ignition Harness and Insulators - Check for proper routing,
deterioration. and condition of terminals.
22 Spark Plugs - Remove. clean, analyze. test. gap, and
rotate top plugs-to-bottom and bottom plugs-to-top.
23 Cylinder Compression - Perform differential compression
test.
24 Carburetor - Drain and flush carburetor bowl, clean inlet
strainer, and drain plug. Check general condition and
security.
25 Engine Primer - Check for leakage, operation. and
security.

EACH

50
HOURS

HOURS

100

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

G
H

J
K

Revision 3

2-43

MODEL 172 SERIES SERVICE MANUAL
EACH

2-48

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

J
J

26 Hoses. Metal Lines, and Fittings - Inspect for signs of oil
and fuel leaks. Check for abrasions, chafing, security,
proper routing and support and for evidence of
deterioration.
27 Cold and Hot Air Hoses - Check condition, routing, and
security.
28 Engine Cylinders, Rocker Box Covers, and Pushrod
Housings - Check for fin damage, cracks, oil leakage,
security of attachment, and general condition.
29 Engine Baffles and Seals - Check condition and security of
attachment.
30 Crankcase, Oil Sump, and Accessory Section - Inspect for
cracks and evidence of oil leakage. Check bolts and nuts
for looseness and retorque as necessary. Check
crankcase breather lines for obstructions, security, and
general condition.
31 Engine Oil With Oil Filter - Drain oil sump and oil cooler,
replace filter and refill with recommended grade aviation
oil.
32 Engine Oil Without Oil Filter - Drain oil sump and oil
cooler, clean and inspect screens, and refill with
recommended grade aviation oil.

EACH

100

HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

K
Fuel System (Section 12).
K
K
K
K
K
K
K

1 Fuel Tanks or Integral Fuel Bays - Check for evidence of
leakage and condition of fuel caps, adapters, and placards.
2 Fuel Tanks or Integral Fuel Bays - Drain fuel and check
tank interior and outlet screens.
3 Fuel System - Inspect plumbing and components for
mounting and security.
4 Fuel Tank or Bay Drains - Drain water and sediment.
5 Fuel Tank Vent Lines and Vent Valves - Check vents for
obstruction and proper positioning.
6 Fuel Selector Valve - Check controls for detent in each
position, security of attachment, and for proper placarding.
7 Fuel Strainer, Drain Valve, and Controls - Check freedom
of movement, security, and proper operation.
Disassemble. flush, and clean screen and bowl.
8 Fuel Quantity Indicators - Check for damage, security of
installation. and perform accuracy test.

L
Propeller and Propeller Governor (Section 13).
L
L
L
L
L

L
2-44

1 Propeller Mounting - Check for security of installation.
2 Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.
3 Spinner - Check general condition and attachment.
4 Spinner and Spinner Bulkhead - Remove spinner, wash,
and inspect for cracks and fractures.
5 Propeller Mounting Bolts - Inspect mounting bolts and
safety-wire for signs of looseness. Retorque mounting
bolts as required.
6 Propeller Hub - Check general condition.
Revision 3

EACH
1

MODEL 172 SERIES SERVICE MANUAL
EACH

2-48

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

EACH

100

HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

Utility Systems (Section 14).
M
M

1 Ventilation System - Inspect clamps, hoses, and valves for
condition and security.
2 Heater Components, Inlets, and Outlets - Inspect all lines,
connections, ducts, clamps, seals, and gaskets for
condition. restriction, and security.
3 Cabin Heat and Ventilation Controls - Check freedom of
movement through full travel. Check friction locks for
proper operation.
4 Pitot Tube and Stall Warning Vane - Check for condition
and obstructions.

400

EACH
1

N
Instruments and Instrument Systems (Section 15).
N
N
N

N
N
N
N
N
N
N
N

1 Vacuum System - Inspect for condition and security.
2 Vacuum System Hoses - Inspect for hardness,
deterioration, looseness, or collapsed hoses.
3 Vacuum Pump - Check for condition and security. Check
vacuum system breather line for obstructions, condition,
and security.
4 Vacuum System Air Filter - Inspect for damage,
deterioration and contamination. Clean or replace, if
required.
NOTE: Smoking will cause premature filter clogging.
5 Vacuum System Relief Valve - Inspect for condition and
security.
6 Instruments - Check general condition and markings for
legibility.
7 Instrument Lines, Fittings, Ducting, and Instrument Panel
Wiring - Check for proper routing, support, and security of
attachment.
8 Static System - Inspect for security of installation,
cleanliness, and evidence of damage.
9 Navigation Indicators, Controls, and Components - Inspect
for condition and security.
10 Airspeed Indicator, Vertical Speed Indicator. and Magnetic
Compass - Calibrate.
11 Altimeter and Static System - Inspect in accordance with
FAR Part 91.411.
12 Instrument Panel Mounted Avionics Units (Including Audio
Panel, VHF Nav Com(s), ADF, Transponder. DME, and
Compass System) - Inspect for deterioration. cracks. and
security of instrument panel mounts. Inspect for security
of electrical connections, condition, and security of wire
routing.
13 Avionics Operating Controls - Inspect for security and
proper operation of controls and switches and ensure that
all digital segments will illuminate properly.
14 Remote Mounted Avionics - Inspect for security of units
and electrical connectors. condition and security of wire
routing. Also. check for evidence of damage and
cleanliness.

EACH
2
EACH
2

Revision 3

2-45

MODEL 172 SERIES SERVICE MANUAL
EACH

2-48
N
N

INSPECTION TIME LIMITS. (MODEL 172
AIRPLANES.)

EACH

100

HOURS HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

15 Microphones, Headsets, and Jacks - Inspect for
cleanliness, security, and evidence of damage.
16 Magnetic Compass - Inspect for security of installation,
cleanliness, and evidence of damage.

O
Electrical Systems (Section 16).
O

O
O
O

1 General Airplane and System Wiring - Inspect for proper
routing, chafing, broken or loose terminals, general
condition, broken or inadequate clamps, and sharp bends
in wiring.
2 Instrument, Cabin, Navigation, Beacon, Strobe, and
Landing Lights - Check operation, condition of lens, and
security of attachment.
3 Circuit Breakers and Fuses - Check operation and
condition. Check for required number of spare fuses.
4 Battery - Check general condition and security. Check
level of electrolyte.
5 Battery Box and Cables - Clean and remove any
corrosion. Check cables for routing, support, and security
of connections.
6 Switch and Circuit Breaker Panel, Terminal Blocks, and
Junction Boxes - Inspect wiring and terminals for condition
and security.
7 Alternator Control Unit - Inspect wiring, mounting,
condition, and wire routing.
8 Switches - Check operation, terminals, wiring, and
mounting for conditions, security, and interference.
9 Instrument Panel and Control Pedestal - Inspect wiring,
mounting, and terminals for condition and security. Check
resistance between stationary panel and instrument panel
for proper ground.
10 External Power Receptacle and Power Cables - Inspect for
condition and security.

P
Post Inspection.
P

1 Replace all fairings, doors, and access hole covers.
Ground check engine, alternator charging rate, oil
pressure, tachometer, oil temperature and pressure gages.
and general operation of components.

Q
Perform the Following Operational Checks:
Q

1 Brakes - Test toe brakes and parking brake for proper
operation.

R
Service Bulletins/Airworthiness Directives.
R
R

2-46

1 Check that all applicable Cessna Service Bulletins and
Supplier Service Bulletins are complied with.
2 Check that all applicable Airworthiness Directives and
Federal Aviation Regulations are complied with.

Revision 3

MODEL 172 SERIES SERVICE MANUAL
EACH

2-48

INSPECTION TIME LIMITS.

(MODEL 172

AIRPLANES.)

EACH

100

HOURS

EACH

SPECIAL
INSPECTIONS

200
HOURS HOURS YEARS

3 Ensure all Maintenance Record Entries required by
Federal Aviation Regulations are completed before
returning the airplane to service.

Revision 3

2-47

MODEL 172 SERIES SERVICE MANUAL
Special Inspections Legends:
A. If the airplane is flown from surfaces with mud, snow. or ice, the main gear speed fairings should be
checked that there is no accumulation which could prevent normal wheel rotation.
B. First 100 hours and each 500 hours thereafter. More often if operated under prevailing wet or dusty conditions.
C. Each 600 hours or 1 year, whichever comes first.
D. Lubrication of the actuator is required each 1000 hours or 3 years, whichever comes first. See figure 2-5
for grease specification.
E. Lubricate each 50 hours (except in extreme dusty conditions). These controls are not repairable and
should be replaced every 1500 hours or whenever maximum linear movement exceeds .050 inch.
F. Model 172Q: Replace polyurethane foam filter every 200 hours or on condition. Model 172 Series: Filter
may be washed 20 times maximum, cleaned by compressed air 30 times maximum. Replace filter each
500 hours or 1 year, whichever comes first.
G. Inspect each 500 hours.
H. Check solenoid and electrical connections each 100 hours, inspect the commutator and brushes each 500
hours.
I. If timing to engine is within tolerance - plus zero degrees, minus two degrees, internal timing will not require checking. Model 172 with 0-320-H2AD engine (1977 thru 1980): Check magnetos at first 25 hours,
first 50 hours, first 100 hours, and each 100 hours thereafter. Model 172 with 0-320-D2J engine (1981
and ON), Model 172Q with 0-360-A4N engine (1983 and ON): Check magnetos at first 100 hours, and every 100 hours thereafter or each one year, whichever occurs first.
J. Compliance with Lycoming Service Bulletin 425B or latest revision is required. Model 172 with 0-320H2AD engine (1977 thru 1980): Each 500 hours.
K. 1. Inspect contact points for condition and adjust or replace as required.
2. Inspect carbon brush, high-tension lead, and distributor block for condition and clean or replace as required.
3. Inspect impulse coupling and pawls for condition and replace as required. Use light pressure only, do
not force pin (or drill bit) when checking pawls.
4. Inspect bearings and lubricate, replace bearings, if required.
5. Lubricate contact point cam.
6. Completely overhaul, or replace existing magneto with a new or rebuilt exchange magneto, at every
engine overhaul. Refer to Overhaul and Maintenance Manual, Publication No. 1037C1-13, covering
Model 4200/6200 series magnetos. Manual No. 1037C1-13 is available from Cessna Supply Division.
Effectivity, Model 172 with 0-320-0-2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine
(1983 and ON); Each 500 hours and every engine overhaul.
L. Model 172 with 0-320-H2AD engine (1977 thru 1980): First 25 hours. Drain oil sump, clean pressure
screen or replace oil filter, and refill with MIL-L-22851 ashless dispersant oil. If oil must be added during
first 25 hours, use MIL-L-6082 aviation grade straight mineral oil. If engine is not equipped with an oil filter,
change oil and clean pressure screen at 50 hours, and each 50 hours thereafter. If engine is equipped
with an oil filter, change oil and filter at 50 hours. and each 100 hours thereafter. Model 172 with 0-320D2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine (1983 and ON): First 25 hours. Drain
oil sump, clean pressure screen or replace oil filter, and refill with MIL-L-6080 aviation grade straight mineral oil. If engine is not equipped with an oil filter, change oil and clean pressure screen at 50 hours and
each 50 hours there after. If engine is equipped with an oil filter, change oil and filter at 50 hours and each
100 hours there after. Beginning with the 50-hour oil change and thereafter. refill oil sump with MIL-L22851 ashless dispersant oil.
M. Each 1000 hours.
N. Replace every 500 hours.
O. Replace filter each 100 hours.
P. Check electrolyte level and clean battery box each 100 hours or 90 days.

2-48

Revision 3

MODEL 172 SERIES SERVICE MANUAL
2-49.

COMPONENT TIME LIMITS. (MODEL 172 AIRPLANES.)
1.

Component Time Limits.
All components not listed herein should be inspected as detailed elsewhere in this chapter
a.
and repaired. overhauled or replaced as required. Items shown here should be overhauled or
replaced during the regular maintenance periods.

Schedule.
POWERPLANTS (Sections 11
a.
and 11A).
(1) Engines (Avco Lycoming
Engine Overhaul Manual)
(See NOTE 2)
(2) Magnetos (Sections 11
and 11A) (See NOTE 3)
(3) Engine Compartment
Flexible Fluid Carrying
Rubber Hoses (Cessna
Installed) Except Drain
Hoses
(4) Engine Compartment
Drain Hoses
(5) Engine Flexible Hoses
(Avco Lycoming Installed)
(See Lycoming Engine
Maintenance Manual)
FUEL SYSTEM (Section 12).
b.
(1) Auxiliary Electric Fuel
Pump (See NOTE 6)
PROPELLER (Section 13).
c.
(1) Propeller (See McCauley
Maintenance and
Overhaul Manual)
(2) Governor (See
Manufacturer's)
McCauley)

REPLACE *

NAVIGATION (Section 15).
(1) Locator Beacon Battery
Pack

OVERHAUL *
REFER TO LATEST
ISSUE OF
MANUFACTURER'S
MAINTENANCE
MANUAL OR SERVICE
BULLETIN

(NOTE 4)

ON CONDITION
(NOTE 5)

REFER TO LATEST
ISSUE OF
MANUFACTURER'S
MAINTENANCE
MANUAL OR SERVICE
BULLETIN
(NOTE 1)

See Note 7.

Revision 3

2-49

MODEL 172 SERIES SERVICE MANUAL
NOTE 1:
NOTE 2:

NOTE 3:
NOTE 4:

NOTE 5:
NOTE 6:
NOTE 7:

2-50

If battery has been in use for more than one collective hour and or at 50 percent of the useful life of
the battery, date on the battery indicates 50 percent of the useful life.
It is recommended the items listed below be inspected at engine overhaul to establish condition for
their replacement or overhaul. Although no overhaul or replacement interval has been established
for these items, the inspection of these items at engine overhaul could eliminate overhaul or replacement of the items at a later time.
a.
Inspect hoses within the engine compartment in accordance with Engine Compartment Hoses
(Refer to Inspection Time Limits). It is recommended the replacement interval not exceed engine overhaul interval.
b.
Engine components, such as turbocharger, controller, manifold pressure relief valve and
wastegate, magnetos, vacuum pumps, etc., should be inspected for condition, at the time of
engine overhaul, as it may be cost effective to overhaul or replace marginal components at
that time. A determination is to be made during engine overhaul such that if the components
have less hours in service than the engine, or have not accumulated hours sufficiently close
to the engine overhaul time to warrant overhaul as judged by inspection or the economic aspect, these components may not require overhaul or replacement concurrent with engine
overhaul. It is recommended that the overhaul or replacement interval for these components
not exceed the engine overhaul interval.
c.
Inspect the engine compartment for structural damage when engine is removed for overhaul.
and make the necessary repairs.
d.
Inspect the engine exhaust as it may be cost effective to replace marginal components at engine overhaul.
e.
Inspect electrical harnesses for damage which would be cost effective to replace at engine
overhaul.
Overhaul Magneto(s) at engine overhaul or when engine is partially overhauled for severe environmental affects, engine overspeed, engine sudden stoppage or other unusual circumstances.
(This life limit is not intended to allow flexible fluid carrying rubber hoses in a deteriorated or damaged condition to remain in service.) Replace engine compartment flexible fluid carrying hoses
(Cessna installed only) manufactured of rubber material every five years or at engine overhaul,
whichever occurs first. This does not include drain hoses. Hoses which are beyond these limits and
are in a serviceable condition, must be placed on order immediately and then be replaced within
120 days after receiving the new hose from Cessna.
Refer to latest Avco Lycoming Engine Service Bulletins.
Refer to latest Dukes Inc. Service Bulletins.
The terms overhaul and replacement as used within this section dictate action as defined below:
a.
Overhaul - Item may be overhauled as defined in Federal Aviation Regulation 43.2 or can be
replaced as defined below:
b.
Replacement - Item must be replaced with a new item or one that has been rebuilt as defined
in Federal Aviation Regulation 43.2.

Revision 3

MODEL 172 SERIES SERVICE MANUAL
2-50.

SCHEDULED MAINTENANCE CHECKS. (MODEL 172 AIRPLANES)

2-51.

PROGRESSIVE CARE PROGRAM. (MODEL 172 AIRPLANES)
A.

Progressive Inspection Program.
(1) Purpose and Use.
(a) As detailed in Federal Aviation Regulation Part 91.409. paragraph (d), airplanes that desire to use a Progressive Inspection Program must be inspected in accordance with an
authorized progressive inspection program. This chapter presents the current progressive inspection program for the Cessna Model 172, recommended by the Cessna Aircraft Company.
Introduction.
(1) Following is the recommended Progressive Care Program for Model 172 airplanes.
(2) This program is divided into four separate operations which are to be accomplished initially
after 50 hours of operation and each 50 hours of operation thereafter. Additional special requirements indicated as Special Inspection, which are required at other intervals are specified
separately.
(3) Recommended progressive care inspection may be accomplished by one of the following.
NOTE
Some 100 HOUR items are covered in Operation 1 and 3. also
some 200 HOUR items are covered in Operation 1, 2, 3 and 4.
These items are placed here for convience and expediency of the
total inspection. After the first completion of all four Operations,
these items will be at the proper intervals.
(a)

(4)
(5)

(6)

NEW DELIVERED AIRCRAFT - A new delivered aircraft must have less than 50 hours
total time in service and enough calander time remaining since the issuance date of the
original Airworthiness Certificate to allow the owner/operator to complete a cycle of all
four Operations before the first annual inspection becomes due. Operation 1 will be due
at 50 hours time in service. Operation 2 will be due at 100 hours. Operation 3 will be
due at 150 hours and Operation 4 will be due at 200 hours. There are additional inspection requirements for new aircraft at the FIRST 50 HOUR inspection point. In addition to
preforming Operation 1, the FIRST 50 HOUR ITEMS listed in the inspection Time Limits
Charts in 2-59 must also be performed. After these FIRST 50 HOUR items have been
accomplished, they have permanent inspection time limits which are covered in the Operations Schedules.
(b) ALL OTHER AIRCRAFT - To qualify other aircraft which have more than 50 hours time
in service for the Progressive Inspection Program, conduct a COMPLETE AIRPLANE INSPECTION. Operation 1 will become due 50 hours from the time the COMPLETE AIRPLANE INSPECTION was accomplished.
Performance of the inspections as listed herein at the specified points will assure compliance
with the Inspection Time Limits detailed in 2-59. Special inspections shall be complied with at
prescribed intervals and/or intervals coinciding with operations 1 through 4 as outlined in 2-62.
An operator may elect to perform the recommended inspections on a schedule other than that
specified. Any inspection schedule requiring the various inspection items detailed in this chapter to be performed at a frequency equal to that specified herein or more frequently is acceptable. Any inspection item performed at a time period in excess of that specified herein must
be approved by the appropriate regulating agency.
As defined in Federal Aviation Regulations Part 91.409,(d) the frequency and detail of the Progressive Inspection Program shall provide for the complete inspection of the airplane within
each 12-calendar months. If the airplane is approaching the end of a 12-calendar month period, but the complete cycle of 4 operations has not been accomplished, it will be necessary
to complete the remaining operations, regardless of airplane hours before the end of the 12calendar month period. If the Progressive Inspection Program is to be discontinued, an annual
inspection becomes due at the time when any item reaches a maximum of 12 calendar
months from the last time it was inspected under the Progressive Inspection Program. Refer
to Federal Aviation Regulation Part 91.409(d) for detailed information.

Revision 2

2-51

MODEL 172 SERIES SERVICE MANUAL
C.

2-52

Inspection Time Limitations.
(1) Each inspection interval may be exceeded by 10 hours or can be performed early at any time
prior to the regular interval as provided below:
(a) In the event of late compliance of any operation scheduled, the next operation in sequence retains a due point from the time the late operation was originally scheduled.
(b) In the event of early compliance of any operation scheduled, that occurs 10 hours or
less ahead of schedule, the next phase due point may remain where originally set.
(c) In the event of early compliance of any operation scheduled, that occurs more than 10
hours ahead of schedule, the next phase due point must be rescheduled to establish a
new due point from the time of early accomplishment.
Procedures.
(1) The following instructions are provided to aid in implementation of the Model 172 Series Progressive Care Program Schedule.
(a) Use the Progressive Care Program Inspection Chart, provided herein, for each airplane.
The chart is to be placed in the airplane flight log book for use as a quick reference for
pilots and maintenance personnel in determining when inspections are due and that they
are performed within prescribed flight time intervals.
(b) Use the Progressive Care Program Component Overhaul and Replacement Log, provided herein, for each airplane. This log is to be kept with the airplane maintenance
records and serves as a periodic reminder to maintenance personnel when various components are due for overhaul or replacement.
(c) To start the Progressive Care Program, begin conducting the inspections defined herein
and refer to Federal Aviation Regulations Part 91.409(d) for procedures to notify the Federal Aviation Administration of the intent to begin a progressive inspection program.
(d) Accomplish each inspection and maintenance item per the checklists on the operation
sheets of the Progressive Care and Maintenance Schedule.
Spaces have been provided for the mechanic's and inspector's signatures as required, as well as any remarks.
These are to become part of the maintenance records for each airplane. Each inspection
is to be logged in the airplane and/or engine log books. Refer to Federal Aviation Regulation Part 43 for the recommended entry statement.

Revision 2

MODEL 172 SERIES SERVICE MANUAL

PROGRESSIVE CARE PROGRAM
(MODEL 172 AIRPLANES)
COMPONENT OVERHAUL AND REPLACEMENT RECORD

COMPONENT

DATE

REASON FOR REPLACEMENT

REPLACEMENT
PART NUMBER
SERIAL
NUMBER
NUMBER

NEXT OVERHAUL
AIRPLANE
HOURS DATE

x
x
x
x
x
x
x
x
x

Revision 2

2.531

MODEL 172 SERIES SERVICE MANUAL
PROGRESSIVE CARE PROGRAM
INSPECTION CHART
REGISTRATION NUMBER:

AIRPLANE MODEL: 172

TIME

TIME
INSPECTION
POINTS

INSPECTION
DUE

INSPECTION
ACCOMPLISHED

INSPECTION
DUE

INSPECTION
ACCOMPLISHED

OPERATION 1
OPERATION 2
OPERATION 3
OPERATION 4

EXAMPLE:
The airplane in this example was placed on the Progressive Care Program after flying a total of 110
hours. At that point, a complete initial inspection of the airplane was performed. The following steps indicate what will have taken place up through an hourmeter reading of 261 hours.
1. After the initial inspection at 110 hours, the first Inspection Due Column was filled out to show
the total flying time at which each of the four (4) operation inspections would be due.
As each inspection was performed, the total flying time was recorded in the Inspection Ac2.
complished column. The next Inspection Due space for that particular operation is also filled in
at this time. These times will always be 200 hours from the last due point providing the operation was actually accomplished within the ten (10) hours limit.
3.
The sample airplane now has a total flying time of 261 hours and the inspection chart shows
that a Phase 4 will be due at 310 hours.
TIME
INSPECTION
POINTS

2-54

TIME

INSPECTION
DUE

INSPECTION
ACCOMPLISHED

INSPECTION
DUE

OPERATION 1

160

162

360

OPERATION 2

210

209

409

OPERATION 3

260

261

460

OPERATION 4

310

Revision 2

INSPECTION
ACCOMPLISHED

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
Registration No.

B
B

C
C
C
C

E
E
E
F
F
G
G
H

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

and operation.
I

I
J
J

1 Rudder - Inspect the rudder skins for cracks and loose
rivets, rudder hinges for condition, cracks and security;
hinge bolts, hinge bearings, hinge attach fittings, and
bonding jumper for evidence of damage and wear, failed
fasteners, and security. Inspect the rudder hinge bolts for
proper safetying of nuts with cotter pins. Inspect balance
weight for looseness and the supporting structure for
damage.
3 Rudder, Tips, Hinges, and Cable Attachment - Check
condition, security, and operation.
1 Cowling - Inspect for cracks, dents, and other damage,
security of cowl fasteners, and cowl mounted landing lights
for attachment.
2 Engine - Inspect for evidence of oil and fuel leaks. Wash
engine and check for security of accessories.

Revision 3

2-55

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
Registration No.

Airplane Model and SN

Airplane Time

INSPECTION COMPLETED BY
J

J
J
J
J
J

J
J
J

J
J
J
J
J
J
J
J
J
J
J

2-56

3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear.
Check friction locks for proper operation.
4 Ignition Switch and Electrical Harness - Inspect for damage,
condition, and security.
5 Firewall Structure - Inspect for wrinkles, damage, cracks,
sheared rivets, etc. Check cowl shock mounts for condition
and security.
6 Engine Shock Mounts, Engine Mount Structure, and
Ground Straps - Check condition, security, and alignment.
7 Induction System - Check security of clamps, tubes, and
ducting. Inspect for evidence of leakage.
8 Induction Airbox, Valves, Doors, and Controls - Remove air
filter and inspect hinges, doors, seals, and attaching parts
for wear and security. Check operation. Clean and inspect
air filter.
9 Induction Air Filter - Remove and clean. Inspect for
damage, and service per Paragraph 2-22 and 2-22A
10 Alternate Induction Air System - Check for obstructions,
operation, and security.
11 Alternator, Mounting Bracket, and Electrical Connections Check condition and security. Check alternator belts for
condition and proper adjustment. Check belt tension per
Section 16, Paragraph 16-38.
13 Starter, Starter Solenoid, and Electrical Connections Check for condition of starter brushes, brush leads, and
commutator.
14 Oil Cooler - Check for obstructions, leaks, and security of
attachment.
15 Exhaust System - Inspect for cracks and security. Special
check in area of heat exchanger. Refer to Section 11,
Paragraph 11-73 for inspection procedures.
16 Auxiliary (Electric) Fuel Pump (172Q)- Check pump and
fittings for condition, operation, security. Remove and
clean filter (as applicable).
17 Engine-Driven Fuel Pump - Check for evidence of leakage,
security of attachment, and general condition.
18 Magnetos - Check external condition, security, and
electrical leads for condition. Check timing to engine and
internal timing if engine timing requires adjustment.
21 Ignition Harness and Insulators - Check for proper routing,
deterioration, and condition of terminals.
22 Spark Plugs - Remove, clean, analyze, test, gap, and rotate
top plugs-to-bottom and bottom plugs-to-top.
23 Cylinder Compression - Perform differential compression
test.
24 Carburetor - Drain and flush carburetor bowl, clean inlet
strainer, and drain plug. Check general condition and
security.
25 Engine Primer - Check for leakage, operation, and security.

Revision 3

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
Registration No.

J
J
J
J

J
J
K
K
K
K
K
L
L
L
L
L
L
M
M
N
O

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

26 Hoses, Metal Lines, and Fittings - Inspect for signs of oil
and fuel leaks. Check for abrasions, chafing, security,
proper routing and support and for evidence of
deterioration.
27 Cold and Hot Air Hoses - Check condition, routing, and
security.
28 Engine Cylinders, Rocker Box Covers, and Pushrod
Housings - Check for fin damage, cracks, oil leakage,
security of attachment, and general condition.
29 Engine Baffles and Seals - Check condition and security of
attachment.
30 Crankcase, Oil Sump, and Accessory Section - Inspect for
cracks and evidence of oil leakage. Check bolts and nuts
for looseness and retorque as necessary. Check crankcase
breather lines for obstructions, security, and general
condition.
31 Engine Oil With Oil Filter - Drain oil sump and oil cooler,
replace filter, and refill with recommended grade aviation
oil.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended
grade aviation oil.
1 Fuel Tanks or Integral Fuel Bays - Check for evidence of
leakage and condition of fuel caps, adapters, and placards.
3 Fuel System - Inspect plumbing and components for
mounting and security.
4 Fuel Tank or Bay Drains - Drain water and sediment.
5 Fuel Tank Vent Lines and Vent Valves - Check vents for
obstruction and proper positioning.
7 Fuel Strainer, Drain Valve, and Controls - Check freedom of
movement, security, and proper operation. Disassemble,
flush, and clean screen and bowl.
1 Propeller Mounting - Check for security of installation.
2 Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.
3 Spinner - Check general condition and attachment.
4 Spinner and Spinner Bulkhead - Remove spinner, wash,
and inspect for cracks and fractures.
5 Propeller Mounting Bolts - Inspect mounting bolts and
safety-wire for signs of looseness. Retorque mounting
bolts as required.
6 Propeller Hub - Check general condition.
2 Heater Components, Inlets, and Outlets - Inspect all lines,
connections, ducts, clamps, seals, and gaskets for
condition, restriction, and security.
4 Pitot Tube and Stall Warning Vane - Check for condition
and obstructions.
3 Vacuum Pump - Check for condition and security. Check
vacuum system breather line for obstructions, condition,
and security.
4 Battery - Check general condition and security. Check
level of electrolyte.

Revision 3

2-57

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
Registration No.

O
O
O

2-58

Airplane Model and SN

5 Battery Box and Cables - Clean and remove any corrosion.
Check cables for routing, support, and security of
connections.
7 Alternator Control Unit - Inspect wiring, mounting, condition,
and wire routing.
10 External Power Receptacle and Power Cables - Inspect for
condition and security.

Revision 3

Airplane Time
INSPECTION COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
INSPECTION

SPECIAL INSPECTION AND YEARLY ITEMS

HOURS YEARS

COMPLETED BY

Please review each of these items for required compliance

11 Upholstery, Headliner, Trim, and Carpeting - Check condition
and clean as required.

3 Brake Lines, Wheel Cylinders, Hoses, Clamps, and Fittings Check for leaks, condition, and security and hoses for bulges
and deterioration. Check brake lines and hoses for proper

6 Wheel Fairings, Strut Fairings, and Cuffs - Check for cracks,
dents, and condition of paint.

EACH

400

EACH
400

EACH
1

routing and support.

D
E

11 Wheel Bearings - Clean, inspect and lube.
4 Autopilot Rigging - Check per Avionics Installation Manual.

B
C

5 Elevator Trim Tab Actuator - Clean, lubricate, and check free-

play.

3 Engine Controls and Linkage - Check general condition,

freedom of movement through full range. Check for proper

travel, security of attachment, and for evidence of wear. Check
friction locks for proper operation.
J

9 Induction Air Filter - Remove and clean. Inspect for damage,

and service per Paragraph 2-22 and 2-22A.
12 Alternator - Check brushes, leads, commutator or slip ring for

J
J

wear.
13 Starter, Starter Solenoid, and Electrical Connections - Check for
condition of starter brushes, brush leads, and commutator.
18 Magnetos - Check external condition, security, and electrical
leads for condition. Check timing to engine and internal timing if
engine timing requires adjustment.
19 Magnetos - Check impulse coupling and stop pins for condition,

H
I

replace as required.
J

20 Magnetos - Inspection, lubrication and overhaul procedures.

31 Engine Oil With Oil Filter - Drain oil sump and oil cooler, replace

filter, and refill with recommended grade aviation oil.

J
K

32 Engine Oil Without Oil Fitter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended grade
aviation oil.
2 Fuel Tanks or Integral Fuel Bays - Drain fuel and check tank

L
M

interior and outlet screens.

8 Fuel Quantity Indicators - Check for damage, security of

EACH

installation, and perform accuracy test.

1 Ventilation System - Inspect clamps, hoses, and valves for

4 Vacuum System Air Filter - Inspect for damage, deterioration
and contamination. Clean or replace, if required.

400

condition and security.

N
N

NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and security.
10 Airspeed Indicator, Vertical Speed Indicator, and Magnetic
Compass - Calibrate.

11 Altimeter and Static System - Inspect in accordance with FAR

Part 91.411.
4 Battery - Check general condition and security. Check level of
electrolyte.

EACH
1

N
O
EACH
2

EACH
2
P

Revision 3

2-59

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 1
Special Inspections Legends:
A. If the airplane is flown from surfaces with mud, snow, or ice, the main gear speed fairings should be
checked that there is no accumulation which could prevent normal wheel rotation.
B. First 100 hours and each 500 hours thereafter. More often if operated under prevailing wet or dusty
conditions.
C. Each 600 hours or 1 year, whichever comes first.
D. Lubrication of the actuator is required each 1000 hours or 3 years, whichever comes first. See figure 2-5 for grease specification.
E. Lubricate each 50 hours (except in extreme dusty conditions). These controls are not repairable and
should be replaced every 1500 hours or whenever maximum linear movement exceeds .050 inch.
F. Model 172Q: Replace polyurethane foam filter every 200 hours or on condition. Model 172 Series:
Filter may be washed 20 times maximum, cleaned by compressed air 30 times maximum. Replace
filter each 500 hours or 1 year, whichever comes first.
G. Inspect each 500 hours.
H. Check solenoid and electrical connections each 100 hours, inspect the commutator and brushes
each 500 hours.
I. If timing to engine is within tolerance - plus zero degrees, minus two degrees, internal timing will not
require checking. Model 172 with 0-320-H2AD engine (1977 thru 1980): Check magnetos at first 25
hours, first 50 hours, first 100 hours, and each 100 hours thereafter. Model 172 with 0-320-D2J engine (1981 and ON), Model 172Q with 0-360-A4N engine (1983 and ON): Check magnetos at first
100 hours, and every 100 hours thereafter or each one year, whichever occurs first.
J. Compliance with Bendix Service Bulletin 425B is required. Model 172 with 0-320-H2AD engine
(1977 thru 1980): Each 500 hours.
K 1. Inspect contact points for condition and adjust or replace as required.
2. Inspect carbon brush, high-tension lead, and distributor block for condition and clean or replace
as required.
3. Inspect impulse coupling and pawls for condition and replace as required. Use light pressure
only, do not force pin (or drill bit) when checking pawls.
4. Inspect bearings and lubricate, replace bearings, if required.
5. Lubricate contact point cam.
6. Completely overhaul, or replace existing magneto with a new or rebuilt exchange magneto, at
every engine overhaul. Refer to Overhaul and Maintenance Manual, Publication No. 1037C1-13,
covering Model 4200/6200 series magnetos. Manual No. 1037C1-13 is available from Cessna
Supply Division. Effectivity, Model 172 with 0-320-0-2J engine (1981 and ON) and Model 172Q
with 0-360-A4N engine (1983 and ON); Each 500 hours and every engine overhaul.
L. Model 172 with 0-320-H2AD engine (1977 thru 1980): First 25 hours. Drain oil sump, clean pressure
screen or replace oil filter, and refill with MIL-L-22851 ashless dispersant oil. If oil must be added
during first 25 hours, use MIL-L-6082 aviation grade straight mineral oil. If engine is not equipped
with an oil filter, change oil and clean pressure screen at 50 hours, and each 50 hours thereafter. If
engine is equipped with an oil filter, change oil and filter at 50 hours, and each 100 hours thereafter.
Model 172 with 0-320-D2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine (1983
and ON): First 25 hours. Drain oil sump, clean pressure screen or replace oil filter, and refill with
MIL-L-6080 aviation grade straight mineral oil. Ifengine is not equipped with an oil filter, change oil
and clean pressure screen at 50 hours and each 50 hours there after. If engine is equipped with an
oil filter, change oil and filter at 50 hours and each 100 hours there after. Beginning with the 50-hour
oil change and thereafter, refill oil sump with MIL-L-22851 ashless dispersant oil.
M. Each 1000 hours.
N. Replace every 500 hours.
O. Replace filter each 100 hours.
P. Check electrolyte level and clean battery box each 100 hours or 90 days.

2-60

Revision 3

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172

OPERATION NO. 2
Registration No.

B
B

B
D

D
D
D
D
D
D

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

1 Fuselage Surface - Inspect for skin damage, loose rivets,
condition of paint, and check pitot-static ports and drain
holes for obstruction. Inspect covers and fairings for
security.
6 Emergency Locator Transmitter - Inspect for security of
attachment and check operation by verifying transmitter
output Check cumulative time and useful life of batteries
in accordance with FAR Part 91.207. Refer to Section 16 Emergency Locator Transmitter - Checkout Interval.
8 Pilot's and Copilot's Inertia Reels - Inspect for security of
installation, proper operation, and evidence of damage.
9 Seats, Seat Belts, and Shoulder Harnesses - Check general
condition and security. Check operation of seat stops and
adjustment mechanism. Inspect belts for condition and
security of fasteners.
10 Windows, Windshield, Doors, and Seals - Inspect general
condition. Check latches, hinges, and seals for condition,
operation, and security of attachment.
12 Flight Controls - Check freedom of movement and proper
operation through full travel with and without flaps
extended. Check electric trim controls for operation (as
applicable).
14 Portable Hand Fire Extinguisher - Inspect for proper
operating pressure, condition, security of installation, and
servicing date.
15 Seat Tracks and Stops - Inspect seat tracks for condition
and security of installation. Check seat track stops for
damage and correct location. Ensure inspection of seat
rails for cracks EACH 50 HOURS. Refer to Section 3.
17 Fuel Line and Selector Valve Drain(s) - Remove plug and
drain.
1 Brakes, Master Cylinders, and Parking Brake - Check
master cylinders and parking brake mechanism for
condition and security. Check fluid level and test operation
of toe and parking brake.
2 Main Gear Tubular Struts - Inspect for cracks, dents,
corrosion, condition of paint or other damage. Check axles
for condition and security.
4 Wheels, Brake Discs, and Linings - Inspect for wear,
cracks, warps, dents, or other damage. Check wheel
through-bolts and nuts for looseness.
5 Tires - Check tread wear and general condition. Check for
proper inflation.
6 Wheel Fairings, Strut Fairings, and Cuffs - Check for
cracks, dents, and condition of paint.
7 Main landing Gear Attachment Structure - Check for
damage, cracks, loose rivets, bolts and nuts and security of
attachment.
8 Nose Gear Steering Mechanism - Check for wear, security,
and proper rigging.

Revision 3

2-61

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 2
Registation No.

Airplane Model and SN

Airplane Time

INSPECTION COMPLETED BY
D

D
D
H
J
J
J

J
J
J

J
J
K
K
L
L
L
M

2-62

9 Nose Gear - Inspect torque links, steering rods, and boots
for condition and security of attachment. Check strut for
evidence of leakage and proper extension. Check strut
barrel for corrosion, pitting, and cleanliness. Check
shimmy damper and/or bungees for operation, leakage, and
attach points for wear and security.
10 Nose Gear Fork - Inspect for cracks, general condition, and
security of attachment.
12 Nose Gear Attachment Structure - Inspect for cracks,
corrosion, or other damage and security of attachment.
2 Elevator Trim System - Check cables, push-pull rods,
bellcranks, pulleys, turnbuckles, fairleads, rub strips, etc.
for proper routing, condition, and security.
1 Cowling - Inspect for cracks, dents, and other damage,
security of cowl fasteners, and cowl mounted landing lights
for attachment.
2 Engine - Inspect for evidence of oil and fuel leaks. Wash
engine and check for security of accessories.
3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear.
Check friction locks for proper operation.
7 Induction System - Check security of clamps, tubes, and
ducting. Inspect for evidence of leakage.
10 Alternate Induction Air System - Check for obstructions,
operation, and security.
11 Alternator, Mounting Bracket, and Electrical Connections Check condition and security. Check alternator belts for
condition and proper adjustment. Check belt tension per
Section 16, Paragraph 16-38.
14 Oil Cooler - Check for obstructions, leaks, and security of
attachment.
15 Exhaust System - Inspect for cracks and security. Special
check in area of heat exchanger. Refer to Section 11,
Paragraph 11-73 for inspection procedures.
26 Hoses, Metal Lines, and Fittings - Inspect for signs of oil
and fuel leaks. Check for abrasions, chafing, security,
proper routing and support and for evidence of
deterioration.
29 Engine Baffles and Seals - Check condition and security of
attachment.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended
grade aviation oil.
4 Fuel Tank or Bay Drains - Drain water and sediment.
6 Fuel Selector Valve - Check controls for detent in each
position, security of attachment, and for proper placarding.
1 Propeller Mounting - Check for security of installation.
2 Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.
3 Spinner - Check general condition and attachment.
4 Pitot Tube and Stall Warning Vane - Check for condition
and obstructions.

Revision 3

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 2
Registration No.
N
N
N

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

1 Vacuum System - Inspect for condition and security.
2 Vacuum System Hoses - Inspect for hardness,
deterioration, looseness, or collapsed hoses.
4 Vacuum System Air Filter - Inspect for damage,
deterioration and contamination. Clean or replace, if
required.
NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and

security.
N
O
O
Q

6 Instruments - Check general condition and markings for
legibility.
2 Instrument, Cabin, Navigation, Beacon, Strobe, and Landing
Lights - Check operation, condition of lens, and security of
attachment.
3 Circuit Breakers and Fuses - Check operation and
condition. Check for required number of spare fuses.
1 Brakes - Test toe brakes and parking brake for proper

operation.

Revision 3

2-63

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 2
INSPECTION

SPECIAL INSPECTION AND YEARLY ITEMS

HOURS YEARS

Please review each of these items for required compliance -

11 Upholstery, Headliner, Trim, and Carpeting - Check condition
and clean as required.

D
D
E

3 Brake Lines, Wheel Cylinders, Hoses, Clamps, and Fittings Check for leaks, condition, and security and hoses for bulges
and deterioration. Check brake lines and hoses for proper
routing and support.
6 Wheel Fairings, Strut Fairings, and Cuffs - Check for-cracks,
dents, and condition of paint.
11 Wheel Bearings - Clean, inspect and lube.
4 Autopilot Rigging - Check per Avionics Installation Manual.

5 Elevator Trim Tab Actuator - Clean, lubricate, and check free-

EACH

400

EACH
400

EACH
1

A
B
C

play.

-J

J
J

3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear. Check
friction locks for proper operation.
9 Induction Air Filter - Remove and clean. Inspect for damage,
and service per Paragraph 2-22 and 2-22A.
12 Alternator - Check brushes, leads, commutator or slip ring for

F
G

wear.

J
J

13 Starter, Starter Solenoid, and Electrical Connections - Check for
condition of starter brushes, brush leads, and commutator.
18 Magnetos - Check external condition, security, and electrical
leads for condition. Check timing to engine and internal timing if

H
I

engine timing requires adjustment.

19 Magnetos - Check impulse coupling and stop pins for condition,
replace as required.

20 Magnetos - Inspection, lubrication and overhaul procedures.

31 Engine Oil With Oil Filter - Drain oil sump and oil cooler, replace
filter, and refill witn recommended grade aviation oil.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended grade

K
L

aviation oil.

2 Fuel Tanks or Integral Fuel Bays - Drain fuel and check tank

interior and outlet screens.

K
M

8 Fuel Quantity Indicators - Check for damage, security of
installation, and perform accuracy test.
1 Ventilation System - Inspect clamps, hoses, and valves for

400

condition and security.

N
N

4 Vacuum System Air Filter - Inspect for damage, deterioration
and contamination. Clean or replace, if required.
NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and security.

N
0

10 Airspeed Indicator, Vertical Speed Indicator, and Magnetic

EACH

Compass - Calibrate.

N
0

2-64

11 Altimeter and Static System - Inspect in accordance with FAR
Part 91.411.
4 Battery - Check general condition and security. Check level of
electrolyte.

Revision 3

EACH
1
EACH

EACH
2
P

COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 2
Special Inspections Legends:
A. If the airplane is flown from surfaces with mud, snow, or ice, the main gear speed fairings should be
checked that there is no accumulation which could prevent normal wheel rotation.
B. First 100 hours and each 500 hours thereafter. More often if operated under prevailing wet or dusty
conditions.
C. Each 600 hours or 1 year, whichever comes first.
D. Lubrication of the actuator is required each 1000 hours or 3 years, whichever comes first. See figure 2-5 for grease specification.
E. Lubricate each 50 hours (except in extreme dusty conditions). These controls are not repairable and
should be replaced every 1500 hours or whenever maximum linear movement exceeds .050 inch.

F. Model 172Q: Replace polyurethane foam filter every 200 hours or on condition. Model 172 Series:
Filter may be washed 20 times maximum, cleaned by compressed air 30 times maximum. Replace
filter each 500 hours or 1 year, whichever comes first.
G. Inspect each 500 hours.
H. Check solenoid and electrical connections each 100 hours, inspect the commutator and brushes
each 500 hours.
I. If timing to engine is within tolerance - plus zero degrees, minus two degrees, internal timing will not
require checking. Model 172 with 0-320-H2AD engine (1977 thru 1980): Check magnetos at first 25
hours, first 50 hours, first 100 hours, and each 100 hours thereafter. Model 172 with 0-320-D2J engine (1981 and ON), Model 172Q with 0-360-A4N engine (1983 and ON): Check magnetos at first
100 hours, and every 100 hours thereafter or each one year, whichever occurs first.
J. Compliance with Bendix Service Bulletin 425B is required. Model 172 with 0-320-H2AD engine
(1977 thru 1980): Each 500 hours.
K. 1. Inspect contact points for condition and adjust or replace as required.
2. Inspect carbon brush, high-tension lead, and distributor block for condition and clean or replace
as required.
3. Inspect impulse coupling and pawls for condition and replace as required. Use light pressure
only, do not force pin (or drill bit) when checking pawls.
4. Inspect bearings and lubricate, replace bearings, if required.
5. Lubricate contact point cam.
6. Completely overhaul, or replace existing magneto with a new or rebuilt exchange magneto, at
every engine overhaul. Refer to Overhaul and Maintenance Manual, Publication No. 1037C1-13,
covering Model 4200/6200 series magnetos. Manual No. 1037C1-13 is available from Cessna
Supply Division. Effectivity, Model 172 with 0-320-0-2J engine (1981 and ON) and Model 172Q
with 0-360-A4N engine (1983 and ON); Each 500 hours and every engine overhaul.
L. Model 172 with 0-320-H2AD engine (1977 thru 1980): First 25 hours. Drain oil sump, clean pressure
screen or replace oil filter, and refill with MIL-L-22851 ashless dispersant oil. If oil must be added
during first 25 hours, use MIL-L-6082 aviation grade straight mineral oil. If engine is not equipped
with an oil filter, change oil and clean pressure screen at 50 hours, and each 50 hours thereafter. If
engine is equipped with an oil filter, change oil and filter at 50 hours, and each 100 hours thereafter.
Model 172 with 0-320-D2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine (1983
and ON): First 25 hours. Drain oil sump, clean pressure screen or replace oil filter, and refill with
MIL-L-6080 aviation grade straight mineral oil. If engine is not equipped with an oil filter, change oil
and clean pressure screen at 50 hours and each 50 hours there after. If engine is equipped with an
oil filter, change oil and filter at 50 hours and each 100 hours there after. Beginning with the 50-hour
oil change and thereafter, refill oil sump with MIL-L-22851 ashless dispersant oil.
M. Each 1000 hours.
N. Replace every 500 hours.
O. Replace filter each 100 hours.
P. Check electrolyte level and clean battery box each 100 hours or 90 days.

Revision 3

2-65

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
Registration No.

B
B

C
C
C
C
C
C
C
C

E
E
E

E
F
F
F
F
F

2-66

Airplane Model and SN

13 Aileron, Elevator, and Rudder Stops - Check for damage
and security.
15 Seat Tracks and Stops - Inspect seat tracks for condition
and security of installation. Check seat track stops for
damage and correct location. Ensure inspection of seat
rails for cracks EACH 50 HOURS. Refer to Section 3.
1 Wing Surfaces and Tips - Inspect for skin damage, loose
rivets, and condition of paint.
2 Wing Struts and Strut Fairings - Check for dents, cracks,
loose screws and rivets, and condition of paint.
3 Wing Spar and Wing Strut Fittings - Check for evidence of
wear. Check attach bolts for indications of looseness and
retorque as required.
4 Wing Structure - Inspect spars, ribs, skins, and stringers for
cracks, wrinkles, loose rivets, corrosion, or other damage.
5 Metal Lines, Hoses, Clamps, and Fittings - Check for leaks,
condition, and security. Check for proper routing and
support.
6 Wing Access Plates - Check for damage and security of
installation.
7 Vertical and Horizontal Stabilizers, Tips and Tailcone Inspect externally for skin damage and condition of paint.
8 Vertical and Horizontal Stabilizers and Tailcone structure Inspect bulkheads, spars, ribs, and skins for cracks,
wrinkles, loose rivets, corrosion, or other damage. Inspect
vertical and horizontal stabilizer attach bolts for looseness.
Retorque as necessary. Check security of inspection
covers, fairings, and tips.
1 Ailerons and Hinges - Check condition, security and
operation.
2 Aileron Structure, Control Rods, Hinges, Balance Weights,
Bellcranks, Linkage, Bolts, Pulleys, and Pulley Brackets Check condition, operation, and security of attachment.
3 Ailerons and Cables - Check operation and security of
stops. Check cables for tension, routing, fraying, corrosion,
and turnbuckle safety. Check travel if cable tension
requires adjustment or if stops are damaged. Check
fairleads and rub strips for condition.
5 Aileron Controls - Check freedom of movement and proper
operation through full travel with and without flaps
extended.
1 Flaps - Check tracks, rollers, and control rods for security
of attachment. Check operation.
2 Flap Actuator Threads - Clean and lubricate. Refer to
paragraph 2-43 for detailed instructions.
3 Flap Structure, Linkage, Bellcranks, Pulleys, and Pulley
Brackets - Check for condition, operation and security.
4 Wing Flap Control - Check operation through full travel and
observe Flap Position indicator for proper indication.
5 Flaps and Cables - Check cables for proper tension,
routing, fraying, corrosion, and turnbuckle safety. Check
travel if cable tension requires adjustment.

Revision 3

Airplane Time
INSPECTION COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
Registration No.

F
G
G
H
H
H
I

I
I
J
J
J

J
J
J

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

7 Flap Motor, Actuator, and Limit Switches (electric flaps) Check wiring and terminals for condition and security.
Check actuator for condition and security.
1 Elevator Control - Check freedom of movement and proper
operation through full travel with and without flaps
extended.
2 Elevator, Hinges, and Cable Attachment - Check condition,
security, and operation.
1 Elevator Trim Tab and Hinges - Check condition, security,
and operation.
4 Elevator Trim Tab Stop Blocks - Inspect for damage and
security.
6 Elevator Trim Tab Actuator - Free-Play limits inspection.
Refer to Section 9 for cleaning, inspection, and repair
procedures.
1 Rudder - Inspect the rudder skins for cracks and loose
rivets, rudder hinges for condition, cracks and security;
hinge bolts, hinge bearings, hinge attach fittings, and
bonding jumper for evidence of damage and wear, failed
fasteners, and security. Inspect the rudder hinge bolts for
proper safetying of nuts with cotter pins. Inspect balance
weight for looseness and the supporting structure for
damage.
3 Rudder, Tips, Hinges, and Cable Attachment - Check
condition, security, and operation.
4 Rudder - Check internal surfaces for corrosion, condition of
fasteners, and balance weight attachment.
1 Cowling - Inspect for cracks, dents, and other damage,
security of cowl fasteners, and cowl mounted landing lights
for attachment
2 Engine - Inspect for evidence of oil and fuel leaks. Wash
engine and check for security of accessories.
3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear.
Check friction locks for proper operation.
4 Ignition Switch and Electrical Harness - Inspect for damage,
condition, and security.
7 Induction System - Check security of clamps, tubes, and
ducting. Inspect for evidence of leakage.
8 Induction Airbox, Valves, Doors, and Controls - Remove air
filter and inspect hinges, doors, seals, and attaching parts
for wear and security. Check operation. Clean and inspect
air filter.
9 Induction Air Filter - Remove and clean. Inspect for
damage, and service per Paragraph 2-22 and 2-22A.
10 Alternate Induction Air System - Check for obstructions,
operation, and security.
11 Alternator, Mounting Bracket, and Electrical Connections Check condition and security. Check alternator belts for
condition and proper adjustment. Check belt tension per
Section 16, Paragraph 16-38.

Revision 3

2-67

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
Registration No.

J
J
J
J
J
J
J
J
J
J
J

J
J
J
J

J
J
K
K
K
K

2-68

Airplane Model and SN

13 Starter, Starter Solenoid, and Electrical Connections Check for condition of starter brushes, brush leads, and
commutator.
14 Oil Cooler - Check for obstructions, leaks, and security of
attachment.
15 Exhaust System - Inspect for cracks and security. Special
check in area of heat exchanger. Refer to Section 11,
Paragraph 11-73 for inspection procedures.
16 Auxiliary (Electric) Fuel Pump (172Q) - Check pump and
fittings for condition, operation, security. Remove and
clean filter (as applicable).
17 Engine-Driven Fuel Pump - Check for evidence of leakage,
security of attachment, and general condition.
18 Magnetos - Check external condition, security, and
electrical leads for condition. Check timing to engine and
internal timing if engine timing requires adjustment.
21 Ignition Harness and Insulators - Check for proper routing,
deterioration, and condition of terminals.
22 Spark Plugs - Remove, clean, analyze, test, gap, and rotate
top plugs-to-bottom and bottom plugs-to-top.
24 Carburetor - Drain and flush carburetor bowl, clean inlet
strainer, and drain plug. Check general condition and
security.
25 Engine Primer - Check for leakage, operation, and security.
26 Hoses, Metal Lines, and Fittings - Inspect for signs of oil
and fuel leaks. Check for abrasions, chafing, security,
proper routing and support and for evidence of
deterioration.
27 Cold and Hot Air Hoses - Check condition, routing, and
security.
28 Engine Cylinders, Rocker Box Covers, and Pushrod
Housings - Check for fin damage, cracks, oil leakage,
security of attachment, and general condition.
29 Engine Baffles and Seals - Check condition and security of
attachment.
30 Crankcase, Oil Sump, and Accessory Section - Inspect for
cracks and evidence of oil leakage. Check bolts and nuts
for looseness and retorque as necessary. Check crankcase
breather lines for obstructions, security, and general
condition.
31 Engine Oil With Oil Filter - Drain oil sump and oil cooler,
replace filter, and refill with recommended grade aviation
oil.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended
grade aviation oil.
1 Fuel Tanks or Integral Fuel Bays - Check for evidence of
leakage and condition of fuel caps, adapters, and placards.
3 Fuel System - Inspect plumbing and components for
mounting and security.
4 Fuel Tank or Bay Drains - Drain water and sediment.
5 Fuel Tank Vent Lines and Vent Valves - Check vents for
obstruction and proper positioning.

Revision 3

Airplane Time
INSPECTION COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
Registration No.

K
L
L
L
L
M
M
N

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

7 Fuel Strainer, Drain Valve, and Controls - Check freedom of
movement, security, and proper operation. Disassemble,
flush, and clean screen and bowl.
1 Propeller Mounting - Check for security of installation.
2 Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.
3 Spinner - Check general condition and attachment.
4 Spinner and Spinner Bulkhead - Remove spinner, wash,
and inspect for cracks and fractures.
2 Heater Components, Inlets, and Outlets - Inspect all lines,
connections, ducts, clamps, seals, and gaskets for
condition, restriction, and security.
4 Pitot Tube and Stall Warning Vane - Check for condition
and obstructions.
3 Vacuum Pump - Check for condition and security. Check
vacuum system breather line for obstructions, condition,

and security.
O
O

4 Battery - Check general condition and security. Check
level of electrolyte.
5 Battery Box and Cables - Clean and remove any corrosion.
Check cables for routing, support, and security of
connections.

Revision 3

2-69

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
SPECIAL INSPECTION AND YEARLY ITEMS
Please review each of these items for required compliance

HOURS YEARS

Upholstery, Headliner, Trim, and Carpeting - Check condition
and clean as required.
3 Brake Lines, Wheel Cylinders, Hoses, Clamps, and Fittings Check for leaks, condition, and security and hoses for bulges
and deterioration. Check brake lines and hoses for proper
routing and support.

EACH
400
EACH
400

6 Wheel Fairings, Strut Fairings, and Cuffs - Check for cracks,

D
E

dents, and condition of paint.
11 Wheel Bearings - Clean, inspect and lube.
4 Autopilot Rigging - Check per Avionics Installation Manual.

EACH
1
EACH
1

B
C

5 Elevator Trim Tab Actuator - Clean, lubricate, and check free-

play.

-J

3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear. Check

friction locks for proper operation.

9 Induction Air Filter - Remove and clean. Inspect for damage,

and service per Paragraph 2-22 and 2-22A.

12 Alternator - Check brushes, leads, commutator or slip ring for

wear.

13 Starter, Starter Solenoid, and Electrical Connections - Check for

condition of starter brushes, brush leads, and commutator.

18 Magnetos - Check external condition, security, and electrical
leads for condition. Check timing to engine and internal timing if

19 Magnetos - Check impulse coupling and stop pins for condition,
replace as required.

20 Magnetos - Inspection, lubrication and overhaul procedures.

K
L

engine timing requires adjustment.

aviation oil.

2 Fuel Tanks or Integral Fuel Bays - Drain fuel and check tank

interior and outlet screens.

8 Fuel Quantity Indicators - Check for damage, security of

EACH

installation, and perform accuracy test.

1 Ventilation System - Inspect clamps, hoses, and valves for

4 Vacuum System Air Filter - Inspect for damage, deterioration
and contamination. Clean or replace, if required.

400

condition and security.

NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and security.

N
O

10 Airspeed Indicator, Vertical Speed Indicator, and Magnetic

EACH

Compass - Calibrate.

N
O

2-70

11 Altimeter and Static System - Inspect in accordance with FAR
Part 91.411.
4 Battery - Check general condition and security. Check level of
electrolyte.

Revision 3

EACH

EACH
2
P

INSPECTION
COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 3
Special Inspections Legends:
A. If the airplane is flown from surfaces with mud, snow, or ice, the main gear speed fairings should be
checked that there is no accumulation which could prevent normal wheel rotation.
B. First 100 hours and each 500 hours thereafter. More often if operated under prevailing wet or dusty
conditions.
C. Each 600 hours or 1 year, whichever comes first.
D. Lubrication of the actuator is required each 1000 hours or 3 years, whichever comes first. See figure 2-5 for grease specification.
E. Lubricate each 50 hours (except in extreme dusty conditions). These controls are not repairable and
should be replaced every 1500 hours or whenever maximum linear movement exceeds .050 inch.
F. Model 172Q: Replace polyurethane foam filter every 200 hours or on condition. Model 172 Series:
Filter may be washed 20 times maximum, cleaned by compressed air 30 times maximum. Replace
filter each 500 hours or 1 year, whichever comes first.
G. Inspect each 500 hours.
H. Check solenoid and electrical connections each 100 hours, inspect the commutator and brushes
each 500 hours.
I. If timing to engine is within tolerance - plus zero degrees, minus two degrees, internal timing will not
require checking. Model 172 with 0-320-H2AD engine (1977 thru 1980): Check magnetos at first 25
hours, first 50 hours, first 100 hours, and each 100 hours thereafter. Model 172 with 0-320-D2J engine (1981 and ON), Model 172Q with 0-360-A4N engine (1983 and ON): Check magnetos at first
100 hours, and every 100 hours thereafter or each one year, whichever occurs first.
J. Compliance with Bendix Service Bulletin 425B is required. Model 172 with 0-320-H2AD engine

(1977 thru 1980): Each 500 hours.

K 1. Inspect contact points for condition and adjust or replace as required.
2. Inspect carbon brush, high-tension lead, and distributor block for condition and clean or replace
as required.
3. Inspect impulse coupling and pawls for condition and replace as required. Use light pressure
only, do not force pin (or drill bit) when checking pawls.
4. Inspect bearings and lubricate, replace bearings, if required.
5. Lubricate contact point cam.
6. Completely overhaul, or replace existing magneto with a new or rebuilt exchange magneto, at
every engine overhaul. Refer to Overhaul and Maintenance Manual, Publication No. 1037C1-13,
covering Model 4200/6200 series magnetos. Manual No. 1037C1-13 is available from Cessna
Supply Division. Effectivity, Model 172 with 0-320-0-2J engine (1981 and ON) and Model 172Q
with 0-360-A4N engine (1983 and ON); Each 500 hours and every engine overhaul.
L Model 172 with 0-320-H2AD engine (1977 thru 1980): First 25 hours. Drain oil sump, clean pressure
screen or replace oil filter, and refill with MIL-L-22851 ashless dispersant oil. If oil must be added
during first 25 hours, use MIL-L-6082 aviation grade straight mineral oil. If engine is not equipped
with an oil filter, change oil and clean pressure screen at 50 hours, and each 50 hours thereafter. If
engine is equipped with an oil filter, change oil and filter at 50 hours, and each 100 hours thereafter.
Model 172 with 0-320-D2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine (1983
and ON): First 25 hours. Drain oil sump, clean pressure screen or replace oil filter, and refill with
MIL-L-6080 aviation grade straight mineral oil. If engine is not equipped with an oil filter, change oil
and clean pressure screen at 50 hours and each 50 hours there after. If engine is equipped with an
oil filter, change oil and filter at 50 hours and each 100 hours there after. Beginning with the 50-hour
oil change and thereafter, refill oil sump with MIL-L-22851 ashless dispersant oil.
M. Each 1000 hours.
N. Replace every 500 hours.
O. Replace filter each 100 hours.
P. Check electrolyte level and clean battery box each 100 hours or 90 days.

Revision 3

2-71

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
Registration No.

Airplane Model and SN

Airplane Time

INSPECTION COMPLETED BY
A
B

B
B
B
B
B

B
B
B

B
B

B
B
D

2-72

1 Placards and Decals - Inspect presence, legibility, and
security. Consult Pilot's Operating Handbook and FAAApproved Airplane Flight Manual for required placards.
1 Fuselage Surface - Inspect for skin damage, loose rivets,
condition of paint, and check pitot-static ports and drain
holes for obstruction. Inspect covers and fairings for
security.
2 Internal Fuselage Structure - Inspect bulkheads, doorposts,
stringers, doublers, and skins for corrosion, cracks,
buckles, and loose rivets, bolts and nuts.
3 Control Wheel Lock - Check general condition and
operation.
4 Fuselage Mounted Equipment - Check for general condition
and security of attachment.
5 Antennas and Cables - Inspect for security of attachment,
connection, and condition.
6 Emergency Locator Transmitter - Inspect for security of
attachment and check operation by verifying transmitter
output. Check cumulative time and useful life of batteries
in accordance with FAR Part 91.207. Refer to Section 16 Emergency Locator Transmitter - Checkout Interval.
7 Instrument Panel Shock Mounts, Ground Straps, and
Covers - Inspect for deterioration, cracks, and security of
attachment.
8 Pilot's and Copilot's Inertia Reels - Inspect for security of
installation, proper operation, and evidence of damage.
9 Seats, Seat Belts, and Shoulder Harnesses - Check general
condition and security. Check operation of seat stops and
adjustment mechanism. Inspect belts for condition and
security of fasteners.
10 Windows, Windshield, Doors, and Seals - Inspect general
condition. Check latches, hinges, and seals for condition,
operation, and security of attachment.
12 Flight Controls - Check freedom of movement and proper
operation through full travel with and without flaps
extended. Check electric trim controls for operation (as
applicable).
14 Portable Hand Fire Extinguisher - Inspect for proper
operating pressure, condition, security of installation, and
servicing date.
15 Seat Tracks and Stops - Inspect seat tracks for condition
and security of installation. Check seat track stops for
damage and correct location. Ensure inspection of seat
rails for cracks EACH 50 HOURS. Refer to Section 3.
16 Control Column - Inspect pulleys, cables, sprockets,
bearings, chains, bungees, and turnbuckles for condition
and security.
17 Fuel Line and Selector Valve Drain(s) - Remove plug and
drain.
1 Brakes, Master Cylinders, and Parking Brake - Check
master cylinders and parking brake mechanism for
condition and security. Check fluid level and test operation
of toe and parking brake.

Revision 3

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
Registration No.

Airplane Model and SN

Airplane Time

INSPECTION COMPLETED BY
D
D
D
D
D
D

D
G
H
H

J
J
J

2 Main Gear Tubular Struts - Inspect for cracks, dents,
corrosion, condition of paint or other damage. Check axles
for condition and security.
4 Wheels, Brake Discs, and Linings - Inspect for wear,
cracks, warps, dents, or other damage. Check wheel
through-bolts and nuts for looseness.
5 Tires - Check tread wear and general condition. Check for
proper inflation.
6 Wheel Fairings, Strut Fairings, and Cuffs - Check for
cracks, dents, and condition of paint.
7 Main landing Gear Attachment Structure - Check for
damage, cracks, loose rivets, bolts and nuts and security of
attachment.
9 Nose Gear - Inspect torque links, steering rods, and boots
for condition and security of attachment. Check strut for
evidence of leakage and proper extension. Check strut
barrel for corrosion, pitting, and cleanliness. Check
shimmy damper and/or bungees for operation, leakage, and
attach points for wear and security.
12 Nose Gear Attachment Structure - Inspect for cracks,
corrosion, or other damage and security of attachment.
3 Elevator Control System - Inspect pulleys, cables,
sprockets, bearings, chains, and tumbuckles for condition,
security, and operation.
2 Elevator Trim System - Check cables, push-pull rods,
bellcranks, pulleys, tumbuckles. fairleads, rub strips, etc.
for proper routing, condition, and security.
3 Trim Controls and Indicators - Check freedom of movement
and proper operation through full travel. Check pulleys,
cables, sprockets, bearings, chains, bungees, and
tumbuckles for condition and security. Check electric trim
controls for operation as applicable.
2 Rudder Pedals and Linkage - Check for general condition,
proper rigging, and operation. Check for security of
attachment.
1 Cowling - Inspect for cracks, dents, and other damage,
security of cowl fasteners, and cowl mounted landing lights
for attachment.
2 Engine - Inspect for evidence of oil and fuel leaks. Wash
engine and check for security of accessories.
3 Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear.
Check friction locks for proper operation.
7 Induction System - Check security of clamps, tubes, and
ducting. Inspect for evidence of leakage.
10 Alternate Induction Air System - Check for obstructions,
operation, and security.
11 Alternator, Mounting Bracket, and Electrical Connections Check condition and security. Check alternator belts for
condition and proper adjustment. Check belt tension per
Section 16. Paragraph 16-38.
14 Oil Cooler - Check for obstructions, leaks, and security of
attachment.

Revision 3

2-73

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
Registration No.
J
J

J
J
K
K
L
L
L
M
M
N
N
N

Airplane Model and SN

15 Exhaust System - Inspect for cracks and security. Special
check in area of heat exchanger. Refer to Section 11,
Paragraph 11-73 for inspection procedures.
26 Hoses, Metal Lines, and Fittings - Inspect for signs of oil
and fuel leaks. Check for abrasions, chafing, security,
proper routing and support and for evidence of
deterioration.
29 Engine Baffles and Seals - Check condition and security of
attachment.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended
grade aviation oil.
4 Fuel Tank or Bay Drains - Drain water and sediment.
6 Fuel Selector Valve - Check controls for detent in each
position, security of attachment, and for proper placarding.
1 Propeller Mounting - Check for security of installation.
2 Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.
3 Spinner - Check general condition and attachment.
3 Cabin Heat and Ventilation Controls - Check freedom of
movement through full travel. Check friction locks for
proper operation.
4 Pitot Tube and Stall Warning Vane - Check for condition
and obstructions.
1 Vacuum System - Inspect for condition and security.
2 Vacuum System Hoses - Inspect for hardness,
deterioration, looseness, or collapsed hoses.
4 Vacuum System Air Filter - Inspect for damage,
deterioration and contamination. Clean or replace, if
required.
NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and

security.
N

6 Instruments - Check general condition and markings for

legibility.
N
N
N
N

2-74

7 Instrument Lines, Fittings, Ducting, and Instrument Panel
Wiring - Check for proper routing, support, and security of
attachment.
8 Static System - Inspect for security of installation,
cleanliness, and evidence of damage.
9 Navigation Indicators, Controls, and Components - Inspect
for condition and security.
12 Instrument Panel Mounted Avionics Units (Including Audio
Panel, VHF Nav/Com(s), ADF, Transponder, DME, and
Compass System) - Inspect for deterioration, cracks, and
security of instrument panel mounts. Inspect for security of
electrical connections, condition, and security of wire
routing.
13 Avionics Operating Controls - Inspect for security and
proper operation of controls and switches and ensure that
all digital segments will illuminate properly.

Revision 3

Airplane Time
INSPECTION COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
Registration No.
N

N
N
O

O
O
O

Airplane Model and SN

Airplane Time
INSPECTION COMPLETED BY

14 Remote Mounted Avionics - Inspect for security of units
and electrical connectors, condition and security of wire
routing. Also, check for evidence of damage and
cleanliness.
15 Microphones, Headsets, and Jacks - Inspect for
cleanliness, security, and evidence of damage.
16 Magnetic Compass - Inspect for security of installation,
cleanliness, and evidence of damage.
1 General Airplane and System Wiring - Inspect for proper
routing, chafing, broken or loose terminals, general
condition, broken or inadequate clamps, and sharp bends
in wiring.
2 Instrument, Cabin, Navigation, Beacon, Strobe, and Landing
Lights - Check operation, condition of lens, and security of
attachment.
3 Circuit Breakers and Fuses - Check operation and
condition. Check for required number of spare fuses.
6 Switch and Circuit Breaker Panel, Terminal Blocks, and
Junction Boxes - Inspect wiring and terminals for condition

and security.
O
O

8 Switches - Check operation, terminals, wiring, and
mounting for conditions, security, and interference.
9 Instrument Panel and Control Pedestal - Inspect wiring,
mounting, and terminals for condition and security. Check
resistance between stationary panel and instrument panel
for proper ground.
1 Brakes - Test toe brakes and parking brake for proper
operation.

Revision 3

2-75

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
SPECIAL INSPECTION AND YEARLY ITEMS
Please review each of these items for required compliance ·

D
E
H

11
4
5

J
J

Upholstery, Headliner, Trim, and Carpeting - Check condition
and clean as required.
Brake Lines, Wheel Cylinders, Hoses, Clamps, and Fittings Check for leaks, condition, and security and hoses for bulges
and deterioration. Check brake lines and hoses for proper
routing and support.
Wheel-Fairings, Strut Fairings, and Cuffs - Check for cracks,
dents, and condition of paint.
Wheel Bearings - Clean, inspect and lube.
Autopilot Rigging - Check per Avionics Installation Manual.
Elevator Trim Tab Actuator - Clean, lubricate, and check freeplay.
Engine Controls and Linkage - Check general condition,
freedom of movement through full range. Check for proper
travel, security of attachment, and for evidence of wear. Check
friction locks for proper operation.
Induction Air Filter - Remove and clean. Inspect for damage,
and service per Paragraph 2-22 and 2-22A.

HOURS YEARS

EACH
400
EACH
400

EACH
1
EACH
1

A
B
C
D
E

12 Alternator - Check brushes, leads, commutator or slip ring for
wear.
13 Starter, Starter Solenoid, and Electrical Connections - Check for

G
H

condition of starter brushes, brush leads, and commutator.

J
J

18 Magnetos - Check external condition, security, and electrical
leads for condition. Check timing to engine and internal timing if
engine timing requires adjustment.
19 Magnetos - Check impulse coupling and stop pins for condition,

replace as required.
20 Magnetos - Inspection, lubrication and overhaul procedures.

J
J
K
K
M
N
N
N
N
O

2-76

31 Engine Oil With Oil Filter - Drain oil sump and oil cooler, replace
filter, and refill with recommended grade aviation oil.
32 Engine Oil Without Oil Filter - Drain oil sump and oil cooler,
clean and inspect screens, and refill with recommended grade
aviation oil.
2 Fuel Tanks or Integral Fuel Bays - Drain fuel and check tank
interior and outlet screens.
8 Fuel Quantity Indicators - Check for damage, security of
installation, and perform accuracy test.
1 Ventilation System - Inspect clamps, hoses, and valves for
condition and security.
4 Vacuum System Air Filter - Inspect for damage, deterioration
and contamination. Clean or replace, if required.
NOTE: Smoking will cause premature filter clogging.
5 Vacuum System relief Valve - Inspect for condition and security.
10 Airspeed Indicator, Vertical Speed Indicator, and Magnetic
Compass - Calibrate.
11 Altimeter and Static System - Inspect in accordance with FAR
Part 91.411.
4 Battery - Check general condition and security. Check level of
electrolyte.

Revision 3

L
L
M

400

EACH
1
EACH
1

N
O
EACH
2
EACH
2
P

INSPECTION
COMPLETED BY

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
Special Inspections Legends:
A. If the airplane is flown from surfaces with mud, snow, or ice, the main gear speed fairings should be
checked that there is no accumulation which could prevent normal wheel rotation.
B. First 100 hours and each 500 hours thereafter. More often if operated under prevailing wet or dusty
conditions.
C. Each 600 hours or 1 year, whichever comes first.
D. Lubrication of the actuator is required each 1000 hours or 3 years, whichever comes first. See figure 2-5 for grease specification.
E. Lubricate each 50 hours (except in extreme dusty conditions). These controls are not repairable and
should be replaced every 1500 hours or whenever maximum linear movement exceeds .050 inch.
F. Model 172Q: Replace polyurethane foam filter every 200 hours or on condition. Model 172 Series:
Filter may be washed 20 times maximum, cleaned by compressed air 30 times maximum. Replace
filter each 500 hours or 1 year, whichever comes first.
G. Inspect each 500 hours.
H. Check solenoid and electrical connections each 100 hours, inspect the commutator and brushes
each 500 hours.
I. If timing to engine is within tolerance - plus zero degrees, minus two degrees. internal timing will not
require checking. Model 172 with 0-320-H2AD engine (1977 thru 1980): Check magnetos at first 25
hours, first 50 hours, first 100 hours, and each 100 hours thereafter. Model 172 with 0-320-D2J engine (1981 and ON), Model 172Q with 0-360-A4N engine (1983 and ON): Check magnetos at first
100 hours, and every 100 hours thereafter or each one year, whichever occurs first.
J. Compliance with Bendix Service Bulletin 425B is required. Model 172 with 0-320-H2AD engine
(1977 thru 1980): Each 500 hours.
K. 1. Inspect contact points for condition and adjust or replace as required.
2. Inspect carbon brush, high-tension lead, and distributor block for condition and clean or replace
as required.
3. Inspect impulse coupling and pawls for condition and replace as required. Use light pressure
only, do not force pin (or drill bit) when checking pawls.
4. Inspect bearings and lubricate, replace bearings, if required.
5. Lubricate contact point cam.
6. Completely overhaul, or replace existing magneto with a new or rebuilt exchange magneto, at
every engine overhaul. Refer to Overhaul and Maintenance Manual, Publication No. 1037C1-13,
covering Model 4200/6200 series magnetos. Manual No. 1037C1-13 is available from Cessna
Supply Division. Effectivity, Model 172 with 0-320-0-2J engine (1981 and ON) and Model 172Q
with 0-360-A4N engine (1983 and ON); Each 500 hours and every engine overhaul.
L. Model 172 with 0-320-H2AD engine (1977 thru 1980): First 25 hours. Drain oil sump, clean pressure
screen or replace oil filter, and refill with MIL-L-22851 ashless dispersant oil. If oil must be added
during first 25 hours, use MIL-L-6082 aviation grade straight mineral oil. If engine is not equipped
with an oil filter, change oil and clean pressure screen at 50 hours, and each 50 hours thereafter. If
engine is equipped with an oil filter, change oil and filter at 50 hours, and each 100 hours thereafter.
Model 172 with 0-320-D2J engine (1981 and ON) and Model 172Q with 0-360-A4N engine (1983
and ON): First 25 hours. Drain oil sump, clean pressure screen or replace oil filter, and refill with
MIL-L-6080 aviation grade straight mineral oil. If engine is not equipped with an oil filter, change oil
and clean pressure screen at 50 hours and each 50 hours there after. If engine is equipped with an
oil filter, change oil and filter at 50 hours and each 100 hours there after. Beginning with the 50-hour
oil change and thereafter, refill oil sump with MIL-L-22851 ashless dispersant oil.
M. Each 1000 hours.
N. Replace every 500 hours.
O. Replace filter each 100 hours.
P. Check electrolyte level and clean battery box each 100 hours or 90 days.

Revision 3

2-77 (2-78 blank)

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC

INSPECTOR

REMARKS

CABIN
1.

Control Wheel Lock - Check security and operation.

Flight Controls - Check freedom of movement and
proper operation through full travel with and without flaps extended. Check electric trim controls for
operation.

Control Column - Inspect pulleys, cables, sprockets,
bearings, chains, bungees and turnbuckles for condition and security.

Elevator Control - Check freedom of movement and
proper operation through full travel with and without flaps extended.

Trim Control and Indicator - Check freedom of
movement and proper operation through full travel.
Check pulleys, cables, sprockets, bearings, chains,
bungees, and turnbuckles for condition and secu-

rity. Check electric trim controls for operation as applicable.

Wing Flap Control - Check operation through full
travel and observe Flap Position Indicator for proper
indication.

Rudder Pedals and Linkage - Check for general condition, proper rigging, and operation. Check for security of attachment.

Pilot's and Copilot's Inertia Reels - Inspect for security of installation, proper operation, and evidence
of damage.

Seats, Seat Belts, and Shoulder Harnesses - Check
general condition and security. Check operation of
seat stops and adjustment mechanism. Inspect belts
for condition and security of fasteners.

10.

Seat Tracks and Stops - Inspect seat tracks for condition and security of installation. Check seat track
stops for damage and correct location.

11.

Portable Hand Fire Extinguisher - Inspect for proper
operating pressure, condition, security of installation, and servicing date.

Sheet 3 of 12
Revision 1

2-79

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
12.

Fuel Selector Valve - Check controls for detent in
each position, security of attachment, and for proper placarding.

13.

Switches - Check operation, terminals, wiring, and
mounting for condition, security, and interference.

14.

Circuit Breakers and Fuses - check operation and
condition. Check for required number of spare
fuses.

15.

Switch and Circuit Breaker Panel, Terminal Blocks,
and Junction Boxes - Inspect wiring and terminals
for condition and security.

16.

Ignition Switch and Electrical Harness - Inspect for
damage, condition, and security.

17.

Engine Controls, and Linkage - Check general condition, freedom of movement through full range.
Check for proper travel, security of attachment, and
for evidence of wear. Check friction locks for proper
operation.

18.

Heater Components, Inlets, and Outlets - Inspect all
lines, connections, ducts, clamps, seals, and gaskets
for condition, restriction, and security.

19.

Cabin Heat and Ventilation Controls - Check freedom of movement through full travel. Check friction
locks for proper operation.

20.

Instrument, Cabin, Navigation, Beacon, Strobe, and
Landing Lights - Check operation, condition of lens,
and security of attachment.

21.

Microphones, Headsets, and Jacks - Inspect for
cleanliness, security, and evidence of damage.

22.

Instrument Lines, Fittings, Ducting, and Instrument
Panel Wiring - Check for proper routing, support,
and security of attachment.

23.

General Airplane and System Wiring - Inspect for
proper routing, chafing, broken or loose terminals,
general condition, broken or inadequate clamps,
and sharp bends in wiring.

Sheet 4 of 12
12-80

Revision 1

INSPECTOR

REMARKS

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
24.

Instrument Panel and Control Pedestal - Inspect wiring, mounting, and terminals for condition and security. Check resistance between stationary panel
and instrument panel for proper ground.

25.

Navigation Indicators, Controls, and Components Inspect for condition and security.

26.

Instrument Panel Mounted Avionics Units (Including
Audio Panel, VHF Nav/Com(s), ADF, Transponder,
DME, and Compass System - Inspect for deterioration, cracks, and security of instrument panel
mounts. Inspect for security of electrical connections, condition, and security of wire routing.

27.

Avionics Operating Controls - Inspect for security
and proper operation of control and switches and
ensure that all digital segments will illuminate properly.

28.

Vacuum System - Inspect for condition and security.

29.

Vacuum System Hoses - Inspect for hardness, deterioration, looseness, or collasped hoses.

30.

Vacuum System Relief Valve - Inspect for condition
and security.

31.

Vacuum System Air Filter - Inspect for damage, deterioration, and contamination. Clean or replace, if
required.

32.

Instrument Panel Shock Mounts, Ground Straps,
and Covers - Inspect for deterioration, cracks, and
security of attachment.

33.

Instruments - Check general condition and markings
for legibility.

34.

Windows, Windshield, Doors, and Seals - Inspect
general condition. Check latches, hinges, and seals
for condition, operation, and security of attachment.

35.

Placards and Decals - Inspect presence, legibility,
and security. Consult Pilot's Operating Handbook
and FAA-approved Airplane Flight Manual for required placards.

36.

Magnetic Compass - Inspect for security of installation, cleanliness, and evidence of damage.

INSPECTOR

REMARKS

Sheet 5 of 12
Revision 1

2-81

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
ENGINE
1.

Cowling - Inspect for cracks, dents, and other damage, security of cowl fasteners, and cowl mounted
landing lights for attachment.

Engine - Inspect for evidence of oil and fuel leaks.
Wash engine and check for security of accessories.

Induction System - Check security of clamps, tubes,
and ducting. Inspect for evidence of leakage.

Induction Airbox, Valves, Doors, and Controls - Remove air filter and inspect hinges, doors, seals, and
attaching parts for wear and security. Check oeration. Clean and inspect air filter and re-oil if flockcoated.

Induction Air Filter - Remove and clean. Inspect for
damage, and service per paragraphs 2-22 and 222A.

Alternate Induction Air System - Check for obstructions, operation, and security.

Oil Cooler - Check for obstructions, leaks, and security of attachment.

Hoses, Metal Lines, and Fittings - Inspect for signs
of oil and fuel leaks. Check for abrasions, chafing,
security, proper routing and support and for evidence of deterioration.

Firewall Structure - Inspect for wrinkles, damage,
cracks, sheared rivets, etc. Check cowl shock
mounts for condition and security.

10.

Fuel Strainer, Drain Valve, and Control - Check freedom of movement, security, and proper operation.
disassemble, flush, and clean screen and bowl.

11.

Vacuum Pump - Check for condition and security.
Check vacuum system breather line for obstructions, condition, and security.

12.

Engine Shock Mounts, Engine Mount Structure, and
Ground Straps - Check condition, security, and
alignment.

Sheet 6 of 12
2-82

Revision 1

INSPECTOR

REMARKS

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
13.

Alternator, Mounting Bracket, and Electrical Connections - Check condition and security. Check alternator belts for condition and proper adjustment.
Check belt tension per paragraph 16-38.

14.

Alternator Control Unit - Inspect wiring, mounting,
condition, and wire routing.

15.

Auxiliary (Electric) (172Q) Fuel Pump - Check pump
and fittings for condition, operation, security. Remove and clean filter (as applicable).

16.

Engine-Driven Fuel Pump - Check for evidence of
leakage, security of attachment, and general condition.

17.

Engine Baffles and Seals - Check condition and security of attachment.

18.

Exhaust System - Inspect for cracks and security,
special check in area of heat exhanger.

19.

Heater Components - Inspect all components for
condition and security.

20.

Ignition Harness and Insulators - Check for proper
routing, deterioration, and condition of terminals.

21.

Spark Plugs - Remove, clean analyze, test, gap, and
rotate top plugs-to-bottom and bottom plugs-to-top.

22.

Carburetor - Drain and flush carburetor bowl and
clean inlet strainer. Check general condition and security.

23.

Engine Primer - Check for leakage, operation, and
security.

24.

Engine Cylinders, Rocker Box Covers, and Pushrod
Housings - Check for fin damage, cracks, oil leakage, security of attachment, and general condition.

25.

Crankcase, Oil Sump, and Accessory Section - Inspect for cracks and evidence of oil leakage. Check
bolts and nuts for looseness and retorque as necessary. Check crankcase breather lines for obstructions, security, and general condition.

INSPECTOR

REMARKS

Sheet 7 of 12
Revision 1

2-831

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
26.

Cold and Hot Air Hoses - Check condition, routing,
and security.

27.

Cylinder Compression - Perform differential compression test.

PROPELLER
1.

Propeller Blades - Inspect for cracks, dents, nicks,
scratches, erosion, corrosion, or other damage.

Spinner - Check general condition and attachment.

Spinner and Spinner Bulkhead - Remove spinner,
wash, and inspect for cracks and fractures.

Propeller Mounting - Check for security of installation.

Propeller Mounting Bolts - Inspect mounting bolts
and safety-wire for signs of looseness. Retorque
mounting bolts as required.

Propeller Hub - Check general condition.

WINGS
1.

Wing Surfaces and Tips - Inspect for skin damage,
loose rivets, and condition of paint.

Wing Struts and Strut Fairings - Check for dents,
cracks, loose screws and rivets, and condition of
paint.

Wing Spar and Wing Strut Fittings - Check for evidence of wear. Check attach bolts for indications of
looseness and retorque as required.

Wing Access Plates - Check for damage and security
of installation.

Pitot Tube and Stall Warning Vane - Check for condition and obstructions.

General Airplane and System Wiring - Inspect for
proper routing, chafing, broken or loose terminals,
general condition, broken or inadequate clamps,
and sharp bends in wiring.

Sheet 8 of 12
2-84

Revision 1

INSPECTOR

REMARKS

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC

Metal Lines, Hoses, Clamps, and Fittings - Check for
leaks, condition, and security. Check for proper routing and support.

Fuel Tank Vent Lines - Check vent lines for obstruction and proper positioning.

Fuel System - Inspect plumbing and components
for mounting and security.

10.

Fuel Tank or Bay Drains - Drain water and sediment.

11.

Fuel Tanks or Integral Fuel Bays - Check for leakage
and condition of fuel caps, adapters, and placards.

12.

Wing Structure - Inspect spars, ribs, skins, and
stringers for cracks, wrinkles, loose rivets, corrosion, or other damage.

13.

Placards and Decals - Inspect presence, legibility,
and security. Consult Pilot's Operating Handbook
and FAA-Approved Airplane Manual for required
placards.

14.

Aileron Structure, Control Rods, Hinges, Balance
Weights, Bellcranks, Linkage, Bolts, Pulleys, and
Pulley Brackets - Check condition, operation, and security of attachment.

15.

Ailerons and Hinges - Check condition, security, and
operation.

16.

Aileron Controls - Check freedom of movement and
proper operation through full travel with and without flaps extended.

17.

Ailerons and Cables - Check operation and security
of stops. Check cables for tension, routing, fraying,
corrosion, and turnbuckle safety. Check travel if
cable tension requires adjustment or if stops are
damaged. Check fairleads and rub strips for condition.

18.

Flap Structure, Linkage, Bellcranks, Pulleys, and Pulley Brackets - Check for condition, operation, and
security.

19.

Flaps - Check tracks, rollers, and control rods for security of attachment. Check operation.

INSPECTOR

REMARKS

Sheet 9 of 12
Revision 1

2-851

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC
20.

Flaps and Cables - Check cables for proper tension,
routing, fraying, corrosion, and turnbuckle safety.
Check travel if cable tension requires adjustment.

21.

Flap Motor, Actuator, and Limit Switches (electric
flaps) - Check wiring and terminals for condition
and security. Check actuator for condition and security.

22.

Flap Actuator Threads - Clean and lubricate.

LANDING GEAR
1.

Nose Gear Attachment Structure - Inspect for
cracks, corrosion, or other damage. Check for security of attachment.

Nose Gear - Inspect torque links, steering rods, and
boots for condition and security of attachment.
Check strut for evidence of leakage and proper extension. Check strut barrel for corrosion, pitting, and
cleanliness. Check shimmy damper and/or bungees
for operation, leakage, and attach points for wear
and security.

Nose Gear Fork - Inspect for cracks, general condition, and security of attachment.

Nose Gear Steering Mechanism - Check for wear,
security, and proper rigging.

Tires - Check tread wear and general condition.
Check for proper inflation.

Wheels, Brake Discs, and Linings - Inspect for wear,
cracks, warps, dents, or other damage. Check wheel
through-bolts and nuts for evidence of looseness.

Brakes - Test toe brakes and parking brake for proper operation.

Brakes, Master Cylinders, and Parking Brake - Check
master cylinders and parking brake mechanism for
condition and security. Check fluid level and test operation.

Sheet 10 of 12
2-86

Revision 1

INSPECTOR

REMARKS

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC

INSPECTOR

REMARKS

EMPENNAGE
1.

Vertical and Horizontal Stabilizers, Tips and Tailcone
- Inspect externally for skin damage and condition
of paint.

Vertical and Horizontal Stabilizers and Tailcone
Structure - Inspect bulkheads, spars, ribs, and skins
for cracks, wrinkles, loose rivets, corrosion, or other
damage. Inspect vertical and horizontal stabilizer attach bolts for looseness. Retorque as necessary.
Check security of inspection covers, fairings, and
tips.

Elevator, Hinges, and Cable Attachment - Check
condition, security, and operation.

Elevator Trim Tab and Hinges - Check condition, security, and operation.

Elevator Trim Tab Actuator - Free-play limits inspection.

Elevator Trim System - Check cables, push-pull
rods, bellcranks, pulleys, turnbuckles, fairleads, rub
strips, etc. for proper routing, condition, and security.

Elevator Control System - Inspect pulleys, cables,
sprockets, bearings, chains, and turnbuckles for
condition, security, and operation.

Rudder - Inspect the rudder skins for cracks and
loose rivets, rudder hinges for condition, cracks and
security; hinge bolts, hinge bearings, hinge attach
fittings, and bonding jumper for evidence of damage and wear, failed fasteners, and security. Inspect
the rudder hinge bolts for proper safetying of nuts
with cotter pins. Inspect balance weight for looseness and the supporting structure for damage.

Rudder, Tips, Hinges, and Cable Attachment - Check
condition, security, and operation.

10.

Rudder - Check internal surfaces for corrosion, condition of fasteners, and balance weight attachment.

11.

General Airplane and System Wiring - Inspect for
proper routing, chafing, broken or loose terminals,
general condition, broken or inadequate clamps,
and sharp bends in wiring.
Sheet 11 of 12
Revision 1

2-87

MODEL 172 SERIES SERVICE MANUAL
CESSNA PROGRESSIVE CARE
MODEL 172
OPERATION NO. 4
MECHANIC

INSPECTOR

SPECIAL INSPECTION ITEMS
1.

Check and accomplish all Special Inspection items
due.

POST INSPECTION
1.

Replace all fairings, doors, floorboard and wing access covers. Ground check engine, alternator charging rate (28 volts minimum), oil pressure/oil temperature, fuel quantity indicator, rpm indicator, flight
instruments, and general operating components.

SERVICE BULLETINS/AIRWORTHINESS DIRECTIVES
1.

Check that all applicable Cessna Service Bulletins
Service Newsletters, and Supplier Service Notices
are complied with.

Check that all applicable Airworthiness Directives
and Federal Aviation Regulations are complied with.

Ensure all Maintenance Record Entries required by
Federal Aviation Regulations are completed before
returning the airplane to service.

OPERATION NO. 4 COMPLETED
AIRPLANE MODEL/SERIAL

REGISTRATION NO.

AIRPLANE HOURS

DATE

I certify that this operation was performed on the above airplane and that this airplane is approved for return to service.

SUPERVISOR MECHANIC

AIRPLANE INSPECTOR

CERTIFICATE NO.

COMPANY NAME
ADDRESS

CITY

Sheet 12 of 12
2-88

Revision 1

STATE

REMARKS

MODEL 172 SERIES SERVICE MANUAL
SECTION 3
FUSELAGE
TABLE OF CONTENTS
FUSELAGE ................
Windshield/Windows ........
Description .............
Cleaning/Waxing .........
Windshield/Window
Installation Techniques ...
Repair .................
Scratches ...............
Cracks .................
Windshield ...............
Removal ............
Installation
..........
Windows ...............
Movable ................
Removal/Installation .....
Wrap-Around Rear ........
Removal/Installation .....
Overhead ...............
Removal/Installation .....
Fixed ..................
Cabin Doors ..............

Description

.............

Removal/Installation .......
Adjustment .............
Weatherstrip ............
Latches (Thru 17275034 &
F17202134) ............
Description .........
...
Adjustment ............
Lock ..................
Indexing Inside Door Handle.
Latches (Beginning with
17275035 & F17202135) ...
Description .............
Installation, Rigging, and
Adjustment Procedures ....
Installation of Lock on
Latch Assembly .........

Page No.
Aerofiche/
Manual
1F9/3-1
1F9/3-1
1F9/3-1
F12/3-4
1F12/3-4
1F13/3-4A
1F13/3-4A
1F15/3-5
1F15/3-5
1F15/3-5
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F16/3-6
1F17/3-7

1F17/3-7
1F17/3-7
1F17/3-7
1F17/3-7
1F17/3-7
1F17/3-7
1F17/3-7
1F21/3-11
1F21/3-11
1F21/3-11
1F21/3-11
1F24 3-12B
1F24/3-12B

Installation of Lock
Assembly ..............
Installation of Cable
Assembly ..............
Rigging Cable Assembly ....
Rigging Inside Door
Handle ................
Replacing Lock Assembly ...
Indexing Inside Door
Handle ................
Baggage Door .............
Removal/Installation .......
Weatherstrip ............
Seats ....................
Pilot and Copilot ..........
Description ............
Removal/Installation .....
Center .................
Description ............
Removal/Installation .....
Auxiliary/Fold Up .........

Description ............

1F24 3-12B
1F24/3-12B
1G1/3-12C
G13-12C
1G3/3-12E
1G3/3-12E
1G3/3-12E
1G3 3-12E
1G3 3-12E
1G3/3-12E
1G3 3-12E
1G3 3-12E
1G5 3-13
1G5 3-13
1G5 3-13
1G5 3-13
1G5 3-13

1G5 3-13

Removal/Installation .....
Repair ................
Cabin Upholstery ........
Materials and Tools .......
Soundproofing ...........
Cabin Headliner ..........
Removal Installation .....
Upholstery Side Panels ....
Carpeting ...............
Safety Provisions .........
Cargo Tie-Downs ........
Safety Belts ............
Shoulder Harness .......
Glider Tow Hook .........
Rear View Mirror .........
Seat Rail Inspection .......

1G5 3-13
1G5 3-13
1G5 3-13
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G19 3-25
1G20 3-26
1G20 3-26
1G20 3-26
1G20 3-26

3-1.

FUSELAGE.

3-2.

WINDSHIELD AND WINDOWS. (See figure 3-1.)

3-3.

DESCRIPTION. The windshield and windows are single-piece, acrylic panels, set in sealing
strips and held by formed retaining strips, secured to the fuselage with screws and rivets.
FS-4291 sealer (TMK01 Kit, Supply Division Cessna Aircraft Company, P.O. Box 949,
Wichita, KS 67201 316/685-9111, Telex 417-489) is applied to all edges of the windshield
and windows, with exception of the wing root area. The wing root fairing has a heavy strip
that completes the windshield sealing.
Revision 1

3-1

MODEL 172 SERIES SERVICE MANUAL

4
Detail B
NOTE
No. 579. 6 sealer (Inmont Corp., St. Louis, Missouri)
and EC-1202 reinforced tape sealant should be applied

to overhead cabin windows.
2

Detail A

Detail

D
4
Detail

NOTE
Apply H.B. Fuller FS-4291 to all edges
of windshield and windows under
outer retainer (4).
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

Inner Retainer
Windshield
Felt Seal
Outer Retainer
Cabin Top Skin
Overhead Cabin Window
External Centerstrip
Rear Window Sealer
Fuselage Structure
Window
Cover
Figure 3-1.

3-2

Revision 1

TYPICAL METHODS OF RETAINING FIXED WINDOWS

Windshield and Fixed Window Installation

MODEL 172 SERIES SERVICE MANUAL

CORRECT
INCORRECT

STOP DRILLED

REINFORCEMENT

CRACK

RUBBER OR

WOOD
AVOID SHARP CORNERS
,

TRIM DAMAGED AREA
AND ROUND ALL
CORNERS

BEVELED EDGE
SURFACE PATCH FOR
SHAPED DAMAGE
, ,IRREGULAR
SURFACE PATCH-

ROUND HOLE

PATCH SHOULD BE
THICKER

BEVELED EDGE
PATCHES

SURFACE PATCH FOR ROUND HOLES
PATCH TAPERED
ON SHARPER
ANGLE THAN
MATERIALDRILLED
CRACK

PATCH AND HOLE
SHOULD BE TRIMMED
WITH TAPERED EDGES.

DURING CEMENTING. PRESSURE
NEED BE APPLIED ONLY ON TOP
SURFACE. TAPER ASSURES EQUAL
PRESSURE ON ALL SIDES.

SURFACE
PATCH
SURFACE PATCH FOR CRACKS

Figure 3-2.

HEAT EDGES OF
PATCH UNTIL
SOFT AND
FORCE IT INTO HOLE.
HOLD IT IN PLACE UNTIL
COOL AND HARDTO
ASSURE PERFECT FIT.
THEN REMOVE PATCH
FOR CEMENTING BATH.

AFTER CEMENT HAS HARDENED
SAND OR FILE EDGES LEVEL
WITH SURFACE

Repair of Windshield and Windows
3-3

MODEL 172 SERIES SERVICE MANUAL
3-4.

CLEANING and WAXING. (Refer to Section 2.)

3-5.

WINDSHIELD AND WINDOW INSTALLATION TECHNIQUES:
Special drills must be used when drilling holes in acrylic. Standard drill will cause the hole
to be oversized, distorted, or excessively chipped.
Whenever possible, a coolant such as a plastic drilling wax should be used to lubricate the
drill bit. Cessna recommends "Reliance" drill wax or Johnson No. 140 Stick Wax.
Drilled holes should be smooth with a finish of 125 rhr.
The feed and speed of the drill is critical. The following chart indicates drill speed for various thicknesses of acrylic.
Material Thickness
1/16" to 3/16"
1/4" to 3/8"
7/16"
1/2"
3/4"
1"

Drill Speed
1500 to 4500 rpm
1500 to 2000 rpm
1000 to 1500 rpm
500 to 1000 rpm
500 to 800 rpm
500 rpm

Specifications for the twist drill used to drill acrylics is as follows:

NOTES
Shallow holes - when hole depth to hole diameter ratio is
less than 1.5 to 1, the drill shall have an included tip
angle of 55 degrees to 60 degrees and a lip clearance
angle of 15 degrees to 20 degrees.
Medium deep holes - when hole depth to hole diameter
ratio is from 1.5 to 1 up to 3 to 1, the drill shall have an
included tip angle of 60 degrees to 140 degrees and a lip
clearance angle of 15 degrees to 20 degrees.
Deep holes - when hole depth to hole diameter ratio is
greater than 3.0 to 1, the drill shall have an included tip
angle of 140 degrees and a lip clearance of 12 degrees to
15 degrees.
Parts which must have holes drilled shall be backed up with a drill fixture. Holes may be
drilled through the part from one side. However, less chipping around holes will occur if
holes are drilled by drilling the holes from both sides. This is accomplished by using a drill
with an acrylic backup piece on the opposite side. Remove the drill from the hole and switch
the backup plate and finish drilling from the opposite side.

3-4

Revision 1

MODEL 172 SERIES SERVICE MANUAL
3-6.

REPAIR. (See figure 3-2.) Replace extensively damaged transparent plastic rather than
repair whenever possible, since even a carefully patched part is not the equal of a new
section, either optically or structurally. At the first sign of crack development, drill a small
hole at the extreme end of the crack as shown in figure 3-1. This serves to localize the cracks
and to prevent further splitting by distributing the strain over a large area. If the cracks are
small, stopping them with drilled holes will usually suffice until replacement or more
permanent repair can be made. The following repairs are permissible; however, they are not
to be located in the pilot's line of vision during landing or normal flight.
a.

3-7.

SURFACE PATCH. If a surface patch is to be installed, trim away the damaged area
and round all corners. Cut a piece of plastic of sufficient size to cover the damaged
area and extend at least 3/4-inch on each side of the crack or hole. Bevel the edges as
shown in figure 3-1. If the section to be repaired is curved, shape the patch to the same
contour by heating it in an oil bath at a temperature of 248 ° to 302°F., or it may be
heated on a hot plate until soft. Boiling water should not be used for heating. Coat the
patch evenly with plastic solvent adhesive and place immediately over the hole.
Maintain a uniform pressure of from 5 to 10 psi on the patch for a minimum of three
hours. Allow the patch to dry 24 to 36 hours before sanding or polishing is attempted.
PLUG PATCH. In using inserted patches to repair holes in plastic structures, trim
the holes to a perfect circle or oval and bevel the edges slightly. Make the patch
slightly thicker than the material being repaired, and similarly bevel the edges.
Install patches in accordance with procedures illustrated in figure 3-1. Heat the plug
until soft and press into the hole without cement and allow to cool to make a perfect
fit. Remove the plug, coat the edges with adhesive, and then reinsert in the hole.
Maintain a firm light pressure until the cement has set, then sand or file the edges
level with the surface; buff and polish.

SCRATCHES. (See figure 3-2.) Scratches on clear plastic surfaces can be removed by handsanding operations, followed by buffing and polishing, if the steps below are followed
carefully.
a.

Wrap a piece of No. 320 (or finer) sandpaper or abrasive cloth around a rubber pad or
wood block. Rub surface around scratch with a circular motion, keeping abrasive
constantly wet with clean water to prevent scratching surface further. Use minimum
pressure and cover an area large enough to prevent formation of "bull's-eyes" or
other optical distortions.
CAUTION
Do not use a coarse grade of abrasive. No. 320 is of
maximum coarseness.

b.
c.

Continue sanding operation, using progressively finer grade abrasives until
scratches disappear.
When scratches have been removed, wash area thoroughly with clean water to
remove all gritty particles. The entire sanded area will be clouded with minute
scratches which must be removed to restore transparency.
Apply fresh tallow or buffingcompound to amotor-driven buffingwheel. Hold wheel
against plastic surface, moving it constantly over damaged area until cloudy
appearance disappears. A 2000-foot-per-minute surface speed is recommended to

Revision 1

3-4A/(3-4B blank)

MODEL 172 SERIES SERVICE MANUAL
prevent overheating and distortion. (Example: 750 rpm polishing machine with a 10inch buffing bonnet)
NOTE
Polishing can be accomplished by hand, but will require a
considerably longer period of time to attain the same
result as produced by a buffing wheel.
e.

When buffing is finished, wash area thoroughly and dry with a soft flannel cloth.
Allow surface to cool and inspect area to determine if full transparency has been
restored. Apply a thin coat of hard wax and polish surface lightly with a clean flannel
cloth.
NOTE
Rubbing plastic surface with a dry cloth will build up an
electrostatic charge which attracts dirt particles and may
eventually cause scratching of surface. After wax has
hardened, dissipate this charge by rubbing surface with a
slightly damp chamois. This will also remove dust
particles which have collected while wax is hardening.

3-8.

Minute hairline scratches can often be removed by rubbing with commercial
automobile body cleaner or fine-grade rubbing compound. Apply with a soft, clean,
dry cloth or imitation chamois.

CRACKS. (See figure 3-2.)
When a crack appears, drill a hole at end of crack to prevent further spreading. Hole
should be approximately 1/8-inch diameter, depending on length of crack and
thickness of material.
b. Temporary repairs to flat surfaces can be accomplished by placing a thin strip of
wood over each side of the surface and inserting small bolts through the wood and
plastic. A cushion of sheet rubber or aircraft fabric should be placed between wood
and plastic on both sides.
c. A temporary repair can be made by drilling small holes along both sides of crack. 1/ 4
to 1/8-inch apart and lacing edges together with soft wire. Small-stranded antenna
wire makes a good temporary lacing material. This type of repair is used as a
temporary measure ONLY, and as soon as facilities are available, panel should be
replaced.
a.

3-9.

WINDSHIELD. (See figure 3-1.)

3-10.

REMOVAL.
a.
b.

Remove wing fairings.
Remove air vent tubes.
CAUTION
If windshield is to be reinstalled, be sure to protect
windshield during removal.

c.
d.

With two people sitting in the airplane placing their feet against the windshield, just
above the centerline, press upward on windshield forcing it out of lower retainers.
Clean sealer from inner sidewalls and bottom of retainers.

Revision 1

3-5

MODEL 172 SERIES SERVICE MANUAL
3-11.

INSTALLATION.
a.
b.
c.
d.
e.
f.
g.
h.

If windshield is to be reinstalled, clean off old sealer and felt, then install new felt
around edges of windshield.
If new windshield is to be installed, remove protective cover and clean, take care not
to scratch windshield.
Apply new felt to edges of windshield.
Apply a strip of sealer (H.B. Fuller FS-4291) along the sides and bottom of felt.
Position the bottom edge of windshield into lower retainer.
Using a piece of bent sheet metal (8 in. wide x length of top edge of windshield)
placed under top edge of upper retainer, bow windshield and guide top edge of
windshield into upper retainer using bent sheet metal in a shoe horn effect.
Install air vent tube.
Install wing fairings.

3-12.

WINDOWS. (See figures 3-1 and 3-3.)

3-13.

MOVABLE WINDOW. (See figure 3-3.) A movable window, hinged at the top, is installed in
the left cabin door, and optionally installed in the right cabin door.

3-14.

REMOVAL AND INSTALLATION. (See figure 3-3.)
a. Disconnect window stop (5).
b. Remove pins from window hinges (6).
c. Reverse preceding steps for installation. To remove frame from plastic panel, drill
out blind rivets at frame splice. When replacing plastic panel in frame, ensure
sealing strip and an adequate coating of Presstite No. 579.6 sealing compound is used
around all edges of panel.

3-15.

WRAP-AROUND REAR WINDOW. (See figure 3-1.) The rear window is a one-piece, acrylic
plastic panel, set in sealing strips and held in place by retaining strips.

3-16.

REMOVAL AND INSTALLATION. (See figure 3-1.)
a. Removal external centerstrip (7).
b. Remove upholstery as necessary to expose retainer strips inside cabin.
c. Drill out rivets as necessary to remove outer retainer strip along aft edge of window.
d. Remove window by lifting aft edge and pulling window aft. If difficulty is encountered, rivets securing retainer strips inside cabin may also be drilled out and retainer
strips loosened or removed.
e. Reverse preceding steps for installation. Apply felt strip and sealing compound to
all edges of window to prevent leaks. Check fit and carefully file or grind away excess
plastic. Use care not to crack plastic while installing.

3-17.

OVERHEAD WINDOW. (See figure 3-1.) Overhead cabin windows, located in the cabin top,
may be installed. These windows are one-piece, acrylic plastic panels, set in sealing strips
and held in place by retaining strips.

3-18.

REMOVAL AND INSTALLATION. (See figure 3-1.)
a. Remove headliner and trim panels.
b. Drill out rivets as necessary to remove retainer strips.
c. Reverse preceding steps for installation. Apply felt strip and sealing compound to
all edges of window to prevent leaks. Check fit and carefully file or grind away excess
plastic. Use care not to crack plastic when installing.

3-19.

FIXED. (See figure 3-1.) Fixed windows, mounted in sealing strips and sealing compound,
are held in place by various retainer strips. To replace side windows, remove upholstery and
trim panels as necessary, and drill out rivets securing retainers. Apply felt strip and sealing

3-6

Revision 1

MODEL 172 SERIES SERVICE MANUAL
compound to all edges of window to prevent leaks. Check fit and file or grind away excess
plastic. Use care not to crack plaster when installing.
3-20.

CABIN DOORS. (See figure 3-3.)

3-21.

DESCRIPTION. A cabin door is installed on each side of the aircraft consisting of a sheetouter skin chemically bonded to a formed inner pan assembly. To this rigid structure are attached the door latch assembly, a remote inside handle, a pair of external hinges, and an integral doorstop assembly. An openable window is installed on the LH door and may also be
optionally installed on the RH door.

3-22.

REMOVAL AND INSTALLATION. (See figure 3-3.) Removal of cabin doors is accomplished
either by removing screws attaching the door hinges or by removing hinge pins.
NOTE
Ensure clevis pin (index 21, figure 3-3) is removed before
removing door.
During reinstallation permanent-type hinge pins may be replaced with clevis pins secured
with cotter pins.

3-23.

ADJUSTMENT. Cabin doors should be adjusted so that door skin fairs smoothly with
fuselage skin. Slots at door latch plate permit re-positioning of latch assembly and bolt
engagement with rotary clutch on door post. If fitting a new door assembly. some trimming
of door flange may be necessary, but gap between door skin and fuselage skin should be 0.09inch or less.
CAUTION
Reforming of bonded door flange by striking with soft
mallet, etc. is NOT permissible, due to possible damage to
bonded areas.

3-24.

CABIN DOOR WEATHERSTRIP. A hollow, fluted-type, rubber weatherstrip is cemented
around all edges of the cabin door. When replacing weatherstrip, ensure that contact surfaces are clean and dry. Cut new weatherstrip to length, using old weatherstrip as a guide.
Cut small notch in butt ends of new weatherstrip to allow for drainage. Position splice with
notch at door low point and apply a thin, even coat of EC-1300L adhesive (3M Company) or
equivalent to both surfaces. Allow to dry until tacky before pressing into place on door. Do
not stretch weatherstrip around door corners.

3-25.

LATCHES (Thru 17275034 and F17202134). (See figure 3-4.)

3-26.

DESCRIPTION. The cabin door latch is a push-pull bolt type, utilizing a rotary clutch for
positive bolt engagement. As door is closed, teeth on underside of bolt engage gear teeth on
clutch. The clutch gear rotates in one direction only and holds door until handle is moved to
LOCK position, driving bolt into slot.

3-27.

ADJUSTMENT. Adjustment of latch or clutch cover is afforded by oversize and/or slotted
holes. This adjustment ensures sufficient gear-to-bolt engagement and proper alignment.

Revision 1

3-7

MODEL 172 SERIES SERVICE MANUAL

NOTE

Right-hand door installation is shown.
Openable window is optional equipment
on RH door and standard equipment on

LH door.

Refer To Figure 3-4

Lock (12) installed
in LH door only.

23
18

As required for
good seal

23
(Typical entire
perimeter)

Detail
1.
2.
3.
4.
5.
6.

Lower Hinge
Upper Hinge
Upholstery Panel
Spring
Window Stop
Window Hinge

THRU 1979 MODELS
7.
8.
9.
10.
11.
12.

Latch Striker Plate
Door Structure
Window Frame
Window
Cam
Lock Assembly

Figure 3-3.
3-8

Washer
Latch Handle
Hinge Pin
Inside Handle
Armrest
Washer

Cabin Door Installation (Sheet 1 of 2)

E-E

19. Doorstop Bracket
20. Doorstop Spring
21. Clevis Pin
22. Clevis Pin
23. Weatherstrip
24. Latch Bracket

MODEL 172 SERIES SERVICE MANUAL

Section A-A

Section B-B

Section D-D
BEGINNING WITH 1980 MODELS
1.
2.
3.
4.
5.
6.

Trim Panel
Arm Rest
Inside Handle
Escutcheon
Door Pull Assembly
Lock Assembly Mounting
Hole

7.
8.
9.
10.
11.
12.

Latch Assembly
Weatherstrip
Push-Pull Rod
Window Assembly
Hinge Assembly
Spring

Section E-E
13.
14.
15.
16.
17.
18.
19.

Latch Assembly
Channel
Hinge Pin
Upper Hinge
Base Plate
Lower Hinge
Upholstery Clip

Figure 3-3. Cabin Door Installation (Sheet 2 of 2)
3-9

MODEL 172 SERIES SERVICE MANUAL
22
24

BEGINNING WITH 1982 MODELS

on RH door and standard equipment on

(Typical entire

2.
3.
4.
5.
6.

Upper Hinge
Upholstery Panel
Spring
Window Stop
Window Hinge

8.
9.
10.
11.
12.

Door Structure
Window Frame
Window
Cam
Lock Assembly

14.
15.
16.
17.
18.

Latch Handle
Hinge Pin
Inside Handle
Armrest
Washer

Figure 3-3. Cabin Door Installation (Sheet 3 of 3)
3-10

20.
21.
22.
23.
24.

Doorstop Spring
Clevis Pin
Clevis Pin
Weatherstrip
Latch Bracket

MODEL 172 SERIES SERVICE MANUAL
NOTE
Lubricate door latch per Section 2. No lubrication is
recommended for the rotary clutch.
3-28.

LOCK. In addition to interior locks, a cylinder and key-type lock is installed on left door. If
lock is to be replaced, the new lock may be modified to accept the original key. This is
desirable, as the same key is used for ignition switch and cabin door lock. After removing old
lock from door, proceed as follows:
a. Remove lock cylinder from new housing.
b. Insert original key into new cylinder and file off any protruding tumblers flush with
cylinder. Without removing key, check that cylinder rotates freely in housing.
c. Install lock assembly in door and check lock operation with door open.
d. Destroy new key and disregard code number on cylinder.

3-29.

INDEXING INSIDE DOOR HANDLE. (See figure 3-4.) When inside door handle is removed.
reinstall in relation to position of bolt (7), which is spring-loaded to the CLOSE position. The
following procedure may be used.
a. Temporarily install handle (17) on shaft assembly (12). approximately vertical.
b. Move handle (17) back and forth until handle centers in spring-loaded position.
c. Without rotating shaft assembly (12), remove handle (17) and install placard (18) with
CLOSE index at top.
d. Install handle (17) to align with CLOSE index on placard (18), using screw (16).
e. Install arm rest (15) on upholstery panel (14).

3-29A. LATCHES (Beginning with 17275035 and F17202135). (See figure 3-4A).
3-29B.

DESCRIPTION. The cabin door latch consists of a two-piece nylon latch base, exterior handle, spring-loaded latch bolt/pull-bar assembly, and a spring-loaded catch/trigger pin assembly. The interior handle base plate assembly is directly connected to the cabin door latch by
means of an adjustable push rod assembly. This push rod assembly has one clamp on the
main rod. This clamp is used to operate a cable assembly that drives a cable pin from the
upper aft end of the cabin door into the aft upper door sill. When the cabin door is open, the
door latch exterior handle should be extended (out), held in this position by means of the
spring-loaded latch catch engaged with the latch bolt through the beveled hole in the bolt.
The push rod assembly will be moved forward, and the attached cable assembly will be retracted from the upper door sill with the cable pin recessed in the pin guide, located in the
upper aft corner of the door. The interior handle, being directly connected by means of the
push rod, will be moved approximately 15 ° aft of the vertical position. Closing the cabin door
drives the trigger pin over the nylon actuator attached to the cover plate, located on the rear
doorpost. As the trigger pin is driven forward, it disengages the latch catch from the latch
bolt The extended extension springs, attached to the latch handle and bolt/pull bar assembly, compress, pulling the latch handle in, and driving the latch bolt over the latch striker.
located on the rear doorpost. Pushing the exterior handle flush with the fuselage skin. The
push rod assembly, attached to the latch bolt/pull bar assembly, moves aft, which also drives
the cable pin from the pin guide in the door into the upper aft door sill receptacle. The interior door handle has now moved from approximately 15 ° aft of vertical to approximately 45 °
forward of vertical. Pushing the interior handle to the horizontal position, flush with the
arm rest, will overcenter the door latch, securing the door for flight. The cabin door latch
assembly also incorporates a locking arm and locking pin, used with a key lock to secure
the aircraft after use. With the cabin door closed, and the exterior latch handle flush, actuating the key lock drives the locking pin into the exterior latch handle, locking the aircraft. It
is important to note that since the cabin door latch assembly and the interior handle base
plate assembly are directly connected by the push rod assembly, that any amount of force

3-11

MODEL 172 SERIES SERVICE MANUAL

17267585 thru 17275034
F17201515 thru F17202134
Adjust door bolt by changing

length of push-rod. 1. Bearing Assembly
2. Nut
3.

Spacer

4. Push-Pull Rod
5. Base Plate
6. Roll Pin
7.

Bolt

8.
9.
10.
11.
12.
13.

Housing
Outside Handle
Spring
Support
Shaft Assembly
Screw

14.

Upholstery Panel

15. Armrest
16. Screw
17.

Inside Handle

18.
19.

Placard
Pivot Base Plate
19

Rotated 180
Figure 3-4. Door Latch InstallationA

Detail 180°
Rotated

Figure 3-4. Door Latch Installation
3-12

MODEL 172 SERIES SERVICE MANUAL

1. -Bearing Assembly
2. Nut
3. Spacer
4. Push-Pull Rod
5. Pivot Base Plate

6. Bolt
7.

Cable

8. Pin
9. Inside Handle
10.

Screw

11.

Armrest

12.
13.
14.
15.

Base Assembly
Screw
Outside Handle
Spring

17.
18.
19.
20.

Washer
Push Rod
Pin
Pull Bar

21. Catch
22. Pin
23. Cotter Pin

24.

Locking Arm

25.

Pin.

26.

27.
28.
29.
30.
31.

Cam Assembly
Clamp
Clamp Bolt
Cover Assembly
Pin

3-12A
3-12A

MODEL 172 SERIES SERVICE MANUAL
applied to the outside handle is subsequently applied to the inside handle. If the push rod assembly is not properly adjusted. it is possible to lock one's self out of the aircraft by applying too much force to the exterior handle when closing the cabin door. Therefore, it is important to adhere to all of the rigging and adjustment specifications pertaining to the preload forces of the interior door handle. Refer to the rigging and adjusting procedures in the
following paragraphs.
3-29C.

INSTALLATION, RIGGING AND ADJUSTMENT PROCEDURES. (See figure 3-4A.)

3-29D.

INSTALLATION OF LOCK ASSEMBLY ON LATCH ASSEMBLY. (See figure 3-4A.)
a. Assemble locking arm (24) with pin assembly (25) by placing one washer on each
side of locking arm (24). Swage pin (25) so that there is a minimal amount of looseness between parts. Cut excessive material from pin (25).
b. Place pin (25) in 1/8-inch hole of base assembly (12).
c. Align .099-inch hole of locking arm (24) with .094-inch hole in latch base (12), and
install pin.
d. Assemble cam assembly (27) to locking arm (24). Cam should be on latch side of
locking arm. Use 3 washers between cam (27) and locking arm.

3-29E.

INSTALLATION OF LOCK ASSEMBLY. (See figure 3-4A)
NOTE
Install with latch in CLOSED position.
a.
b.
c.
d.
e.
f.
g.

Install latch assembly between door pan and door skin.
Cable assembly (7) should be forward of latch base attach plate, and inboard of latch
base cup.
Extend latch handle through cutout in door skin. This will pull latch bolt back far
enough to allow latch to fall into place.
Push latch assembly aft so that bolt (20) and push rod (18) extend through their respective holes.
Trip push rod (18) so that bolt (20) is fully extended and handle (14) is flush.
Secure latch to door pan with four NAS220-5 screws (13) through base assembly (12)
and two AN525-10R6 screws through aft flange of door pan.
Ensure door skin fits properly around latch assembly, then drill eleven .128-inch
holes to align with latch base.
NOTE
Do not oversize holes in the latch base and do not rivet
base to skin at this time.

3-29F.

3-12B

INSTALLATION OF CABLE ASSEMBLY. (See figure 3-4A.)
a. On pin end of cable assembly (7), attach clamp (28) and nut, oneinch from end of
casing.
b. Insert pin end of cable between door pan and door skin at aft end of door. Push pin
end of cable to top of door.
c. Remove plug button (30, figure 3-1 of this Supplement) and align pin on cable with
pin guide, and insert pin through guide. Access is gained through .875-inch diameter hole after removal of plug button (30).
d. Align clamp on cable casing with hole located one-inch below .875-inch hole and install screw.

MODEL 172 SERIES SERVICE MANUAL
e.

3-29G.

Check operation of cable. If sluggish operation of cable is encountered, add S14502A4-062 washers as required to facilitate smoother cable operation.

RIGGING CABLE ASSEMBLY. (See figure 3-4A.)
a. Pull excess slack out of cable (7). Attach clamp (28) and nut to cable so that it aligns
with .193-inch hole in door pan, and attach.
NOTE
Make sure door latch is in OPEN position before proceeding.
b.
.
d.
e.
f.
g.

Cut casing of cable assembly approximately two inches from clamp bolt (29) on push
rod assembly (4).
Insert core of cable through clamp (29).
Pull core through clamp bolt so that pin (8) extends approximately 1/8-inch from
door pan contour.
Cut core approximately one inch forward of push rod clamp (29).
Secure two nuts to push rod clamp bolt.
Operate latch several times to ensure latch works freely. If latch binds up and will
not work freely, remove cable core from clamp (29) and operate latch. If cable operates easily without cable attachment, check cable for possible adjustments to facilitate

case of operation.
h.

3-29H.

After cable operates freely, install cover assembly (30) and recheck cable for operation.

RIGGING INSIDE DOOR HANDLE. (See figure 3-4A.)
a. With latch secured to door pan, attach push pull rod assembly (4) to catch (21), and

secure with pin (31).
NOTE
Do not install cotter pin (23).
b.
c.

Ensure that latch is in CLOSED position.
By removing pin (31) that connects push pull rod to latch base assembly, rotate rod
in or out (180°) for adjustment. Adjust rod so that it takes a load of 6 pounds to 12
pounds at the end of the inner handle to move it from closed position to overcenter

position.
NOTE
Rod must be attached to latch assembly before rigging

can be accomplished.
d.

For fine adjustment for overcentering latch assembly, proceed as follows:
1. Cabin door must be installed and completely fitted to fuselage.
2. Cabin door latch must be in OPEN position. Latch must operate smoothly and
freely.
3. Adjust striker plate forward by installing shims as required, so that there is a
minimal clearance between pull bar (20) and striker plate.

3-12C

MODEL 172 SERIES SERVICE MANUAL
NOTE
This adjustment will ensure that when the door is opened
from the outside, the push rod will engage the latch
catch, and the exterior handle will stay open until the
door is closed again.
NOTE
If cabin door is located too far forward such that the door
latch will not operate, this will not allow latch asembly
push rod (18) to ride up on actuator and trgger the pull
bar (20). Install shims as required beneath actuator, located on cover assembly.
4.

Close the cabin door from inside the aircraft. When latch is overcentered. the exterior handle should pull flush. If it does not pull flush, the connecting push pull
rod from the door latch to the inside handle assembly should be adjusted "out"
(lengthened).
NOTE
When making this adjustment on the overcentering of
the latch, it may be noticed that there is a sharp, loud
canning noise when the inside handle is pushed down. It
is preferred that the outside door handle be flush, even if
the canning noise is noticeable.

When adjusting push pull rod (4), it may need only be adjusted 1/2 turn. To
accomplish this, base plate should be removed.
6. To make 1/2 turn adjustment, remove smaller end of push pull rod (4) and turn it
over (180°). Then reinstall base plate assembly (5).
7. When closing cabin door from the outside, by using a large, sharp force on the
outside handle, it is possible to overcenter the inside handle, thus locking one's
self out. To prevent this from occurring when adjusting the push pull rod in step
"4", adjust the push pull rod so there is sufficient force (6 to 12 pounds) against
the inside handle to prevent it from overcentering when closing the door from the
outside.
8. Do not file, grind or sand any portion of the pull bar (20).
9. Recheck clamps that secure cable. There must not be any slippage between cable
casing and clamp.
10. After overcenter adjustment has been made, install cotter pin (23) in clevis pin
(22).
e. Rivet latch base (12) to door skin with MS20426A4-3 rivets.
f. Attach lock assembly casing (13, figure 3-3) to door skin with nut provided.
g. Install tumblers and attach cam to tumblers with screw and lockwasher provided.
NOTE
After installing cam, seal over head of screw and washer

3-12D

MODEL 172 SERIES SERVICE MANUAL
washer with RTV-102 (white) or RTV-103 (black) silicone
rubber sealant (General Electric, Waterford, N. Y.).
h.

Operate lock several times to assure that all components function properly.

NOTE
Steps "f","g"and "h" apply to LH door only.
3-29L

REPLACING LOCK ASSEMBLY.
a. Remove look cylinder from new housing.
b. Insert original key into new cylinder and file off any protruding tumblers flush with
cylinder. Without removing key, check that cylinder rotates freely in housing.
c. Install lok assembly in door and check lock operation with door open.
d. Destroy new key and disregard code number on cylinder.

3-29J.

INDEXING INSIDE DOOR HANDLE. When inside door handle is removed, reinstall and
index as noted in paragraph 3-27A.

3-30.

BAGGAGE DOOR. (See figure 3-5).

3-31.

REMOVAL AND INSTALLATION. (See figure 3-5.)
a. Remove door-pull handle.
b. Disconnect door-stop chain (8).
c. Remove buttons securing upholstery panel and remove panel.
d. Remove bolts (9) securing door to hinges.
e. Reverse preceding steps for installation.
CAUTION
Reforming of bonded door flange by striking with soft
mallet etc., is NOT permissible, due to possible damage to
bonded areas.

3-32.

BAGGAGE DOOR WEATHERSTRIP. A rubber weatherstrip is cemented around the edge of
the baggage door and seals the door to the fuselage structure when the door is closed. A new
seal can be installed after carefully cleaning door and weatherstrip contact surfaces. Apply
a thin, even coat of EC-880 adhesive (3M Co.) or equivalent and allow to dry until tacky
before pressing into place.

3-33.

SEATS. (See figure 3-6.)

3-34.

PILOT AND COPILOT.
a. RECLINING BACK/FORE-AND-AFT ADJUST.
b. ARTICULATING RECLINE/VERTICAL ADJUST.

3-35.

DESCRIPTION. These seats are manually operated throughout their full range of operation.
Seat stops are provided to limit fore-and-aft travel.

3-12E

MODEL 172 SERIES SERVICE MANUAL

* 17273535 & On
F17202030 & On

17267585 thru 17273534
F17201515 thru F17202029

Detail

12
4

22
19
21

*18
Detail

1.
2.
3.
4.
5.
6.
7.
8.
9.

Handle
Spacer
Shim
Screws
Hinge
Hinge Bracket
Scuff Plate
Chain
Bolt

10.
11.
12.
13.
14.
15.
16.
17.

Washer
Nut
Baggage Door
Cam
Screw
Washer
Nut
Washer

18.
19.
20.
21.
22.
23.
24.
25.
26.

Figure 3-5.
3-12F

A
Cam
Latch
Screw
Lock Assembly
Washer
Nut
Lock Assembly
Mounting Pad
Latch Assembly

Baggage Door Installation

MODEL 172 SERIES SERVICE MANUAL
3-36.

REMOVAL AND INSTALLATION. (See figure 3-6.)
a.
b.
c.
d.
e.
f.
g.

Remove seat stops from rails.
Disengage seat belts by slipping buckle ends through seat belt retainer.
Crank vertical adjust seats to their maximum height.
Slide seat forward to disengage front rollers from seat rails.
Slide seat aft to disengage rear rollers from seat rails.
Lift seat out.
Reverse preceding steps to install seat. Ensure that all seat stops are installed.
WARNING

It is extremely important that pilot's seat stops are
installed, since acceleration and deceleration could possibly permit seat to become disengaged from seat rails
and create a hazardous situation, especially during
takeoff and landing.
3-37.

CENTER. (See figure 3-6.)
a. DOUBLE-WIDTH BOTTOM AND BACK/SINGLE RECLINING BACK.
b. DOUBLE-WIDTH BOTTOM/INDIVIDUAL RECLINING BACKS.

3-38.

DESCRIPTION. These seats are permanently bolted to the cabin structure and incorporate
no adjustment provisions other than manually-adjustable three position backs.

3-39.

REMOVAL AND INSTALLATION. (See figure 3-6.)
a. Remove bolts securing seat to cabin structure.
b. Lift seat out.
c. Reverse preceding steps for installation.

3-40.

AUXILIARY/FOLD UP. (See figure 3-6.)

3-41.

DESCRIPTION. These seats are permanently bolted to the cabin structure and have no
adjustment provisions. The seat structure is mounted on hinge brackets with pivot bolts,
thus allowing seat to be pivoted upward to acquire more baggage area.

3-42.

REMOVAL AND INSTALLATION. (See figure 3-6.)
a. Remove bolts securing seat structure to hinge brackets.
b. Lift seat out.
c. Reverse preceding steps for installation.

3-43.

REPAIR. Replacement of defective parts is recommended in repair of seats.

3-44.

CABIN UPHOLSTERY. Due to the wide selection of fabrics, styles and colors, it is impossible
to depict each particular type of upholstery. The following paragraphs describe general procedures which will serve as guides in removal and replacement of upholstery. Major work, if
possible, should be done by an experienced mechanic. If the work must be done by a
mechanic unfamiliar with upholstery practices, the mechanic should make careful notes
during removal of each item to facilitate replacement later.
NOTE

Repair kits are available for the repair of cracks in ABS,
PBC, PVCP, graphite and fiberglass material. (Cessna
Supply Division, P.O. Box 949, Wichita, KS 67201, 316/
685-9111, Telex 417-489.)
Revision 1

3-13

MODEL 172 SERIES SERVICE MANUAL
PILOT AND COPILOT
(STANDARD)
(THRU 1979 MODELS)
1.
2.
3.
4.
5.
6.
7.
8.
9.

Seat Back Adjust Link
Torque Tube
Seat Back Adjustment Cam
Bushing
Spacer
Spring
Seat Adjustment Pawl
Roller
Bracket

RECLINING BACK/

NOTE

See figure 3-7 for
seat back cam replacement.
12
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Washer
Pin
Adjustment Pin
Seat Stop
Seat Rail
Fore/Aft Adjustment Handle
Recline Handle
Roll Pin
Seat Belt Retainer
Trim

11 10

NOTE
Refer to sheets 9 and 10
for seat stop installation.

Figure 3-6. Seat Installtion (Sheet 1 of 11)
3-14

Revision 2

MODEL 172 SERIES SERVICE MANUAL
1. Vertical Adjustable
Handle
2. Pin
3. Bearing Block
4. Bearing
5. Collar
6.

7.
8.
9.
10.
11.
12.
13.
14.
15.
16.

21.
22.

24.

Fwd Torque Tube
Fwd Torque Tube
Bellcrank
Aft Torque Tube
Bellcrank
Aft Torque Tube

Vertical Adjust

25.

Seat Pivot Bracket

Screw
Vertical adjust
Nut
Seat Adjust Handle
Seat Adjust Pin
Spring (LH Side Only)
Seat Back Adjust
Handle
Jack Screw
Assembly
RH Crank Assembly
LH Crank Assembly
Seat Adjust Bellcrank
Cover

26. Seat Skirt Trim
27. Seat Back Trim
28. Pocket
29. Seat Back Retainer
30. Clip
31. Former Bracket.
32. Former Assembly
33. Bracket
34. Head Rest

23.

PILOT AND COPILOT SEATS
(OPTIONAL)

THRU 1979
MODELS

32
16
31
30
17

29
INFINITELY

ADJUSTABLE

17. Cushion
18.

Seat Stop

19. Torque Tube Intercon20.

NOTE

nect Channel
Pedestal

Install seat stop

in first and thirteenth holes from
front of outboard

seat rail.

26
8

Detail A

Detail

Figure

Beginning with 17268914 & F17201640, seat belt
retainer (*) is separate from trim (26), and is
attached directly to
attached
to seat frame with four screws.
screws.

3-6. Seat Installation

3-15

(Sheet 2 of 11)
3-15

MODEL 172 SERIES SERVICE MANUAL

CENTER SEAT
(STANDARD)

9
8

Detail A

DOUBLE WIDTH BOTTOM/
SINGLE RECLINING BACK

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Recline Shaft
Seat Bottom
Seat Back
Trim
Headrest
Recline Pawl
Lnk
Bushing
Bellcrank
Knob

Figure 3-6. Seat Installation (Sheet 3 of 11)
3-16

MODEL 172 SERIES SERVICE MANUAL
CENTER SEAT THRU 1979
(OPTIONAL)
1.
2.
3.
4.
5.
6.

Set Bottom
Spring
Spacer
Seat Back
Headrest
Bushing

Recline Handle

Pawl

Control Shaft

DOUBLE WIDTH BOTTOM/
INDIVIDUAL RECLINING
BACKS

Detail A

9
Figure 3-6. Seat Installation (Sheet 4 of 11)
3-17

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.
6.

Attach Bracket
Seat Bottom Structure
Seat Bottom
Seat Back
Floorboard
Mounting Bracket

Detail A

Figure 3-6. Seat Installation (Sheet 5 of 11)
3-18

Revision 1

MODEL 172 SERIES SERVICE MANUAL

SEAT PEDESTAL ASSEMBLY
BEGINNING WITH 1980 MODELS

Seat Back Adjust
Bellcrank
2. Pivot Bracket
3. Bellcrank
4. Spring
5. Seat Adjust Pin
6. Vertical Adjust Handle
7. Seat Adjust Handle
1.

8. Torque Tube Bellcrank
9. Forward Torque Tube
10. Aft torque Tube
11. LH Crank Assemble
12. Splice
13. Jack Screw
14. Seat Back Adjust
15. RH Crank Assembly

Figure 3-6. Seat Installation (Sheet 6 of 11)
3-19

MODEL 172 SERIES SERVICE MANUAL

PILOT AND COPILOT SEAT ASSEMBLY
BEGINNING WITH 1980 MODELS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Seat Handle Pin
Spring
Sea t Adjust Handle
Cushion
Cover
Grommet
Head Rest
Former Bracket
Former Assembly
Bracket

11.

Clip

12.
13.
14.
15
16.
17.
18.
19.
20.
21.
22.

Pocket
Bolt and Spacer
Lock Cylinder
Frame
Bracket
Pin
Roller
Spring
Link
Clevis Pin
Lock Cylinder Control

Figureof
11)
7(Sheet
Installation
Seat
3-6.
3-20

MODEL 172 SERIES SERVICE MANUAL

INFINITELY-ADJUSTABLE SEAT ASSEMBLY

BEGINNING WITH 1980 MODELS

31
0 BEGINNING WITH
1983 MODELS

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.

Cushion
Seat Bottom Cover
Cushion
Seat Back Cover
Head Rest
Head Rest Cover
Former Bracket
Former Assembly
Bracket
Clip
Seat Back Retainer
Seat Back Trim
Pocket Assembly
Seat Belt Retainer
Trim
RH Crank Assembly
Splice
LH Crank Assembly
Aft Torque Tube
Pivot Bracket
Seat Back Adjust Bellcrank
LH Pedestal
Bellcrank
Vertical Adjust Handle
Forward Torque Tube
Seat Handle Adjust
Seat Back Adjust Handle
RH Pedestal
Seat Adjust Pin
Jack Screw
Spring
Link
Clevis Pin

20
15
16
17
20

Figure 3-6. Seat Installation (Sheet 8 of 11)
3-21

MODEL 172 SERIES SERVICE MANUAL

SEAT STOP INSTALLATION - STANDARD SEAT
1
ELEVENTH SEAT STOP
HOLE FROM FWD EDGE
OF OUTBD PILOTS &
COPILOTS SEAT RAILS

1.
2.
3.
4.

Screw
Seat Stop
Seat Rail-Outboard
Seat top

Cotter Pin

17267585 thru 17272884
F17201515 thru F17201909

FIRST SEAT STOP HOLE
PILOT'S & COPILOTS OUTBD
SEAT RAILS

17272885 thru 17276517
F17201910 thru F17202238

EXTREME AFT OUTBD
PILOT'S & COPILOT'S
SEAT RAILS.

17276518 & ON
F17202239 & ON

14.75"X

WARNING
It is extremely important that pilot's seat stops are installed, since acceleration and deceleration could possibly
permit seat to become disengaged from seat rails and
create a hazardous situation, especially during takeoff
and landing.
Figure 3-6. Seat Installation (Sheet 9 of 11)
3-22

Revision 1

MODEL 172 SERIES SERVICE MANUAL

SEAT STOPS INSTALLATION - OPTIONAL INFINITE-ADJUST SEAT
SECOND SEAT STOP HOLE
PILOTS & COPILOTrS OUTBD
SEAT RAILS

17267585 thru 17272384
F17201515 thru F17201909
EXTREME AFT OUTBD

.
PILOTS & COPILOTS
SEAT RAILS.

2
1

3
FIRST SEAT STOP HOLE
PILOTS & COPILOT'S OUTBD
SEAT RAILS

17272885 thru 17276517
F17201910 thru F17202238

EXTREME AFT OUTBD
& COPILOTS

PILOTS

SEAT RAILS.

4
6
1.
2.
3.
4.
5.
6.

Screw
Seat Stop
Seat Rail-Outboard
Seat Stop
Pin
Cotter Pin

5
17276518 & ON
F17202239 & ON

5.13
WARNING
It is extremely important that pilot's seat stops are installed, since acceleration and deceleration could possibly
permit seat to become disengaged from seat rails and
create a hazardous situation, especially during takeoff
and landing.

Figure 3-6. Seat Installation (Sheet 10 of 11)
Revision 1

3-22A

MODEL 172 SERIES SERVICE MANUAL
5

SPLIT BACK REAR SEAT
2

BEGINNING WITH 1980 MODELS
6

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.

4
Cover
Cushion
Skirt
Lock
Grommet
Back Panel
Head Rest
Seat Bottom
Seat Back Legs
Seat Belt Stirrup
Bracket
Link
Spacer
Spacer
Hex Nut
Lock Cylinder
Spacer
Spacer

Detail A
-

Detail

Figure 3-6. Seat Installation (Sheet 11 of 11)
3-22B

MODEL 172 SERIES SERVICE MANUAL

THRU 1979 MODELS
CLEVIS BOLT (REF) SEAT

BACK (REF)

2. 50" R. (CONSTANT AT EACH NOTCH)

REPLACEMENT CAM

PAWL (REF)
INDENT PROFILE
.120"
(TYP)

NOTE
Ensure replacement cam conforms
to dimensions shown in Detail A
before installation.

.170" MINIMUM-(TYP)

172 & F172 SERIES ONLY

060"R (TYP)

Detail

REPLACEMENT PROCEDURE:
a. Remove seat from aircraft.
b. Remove plastic upholstery panels from aft side of seat back, then loosen upholstery retaining
rings and upholstery material as required to expose rivets retaining old cam assembly.
c. Drill out existing rivets and insert new cam assembly (2).
gages first cam slot as illustrated.

Position seat back so pawl (3) en-

d. Position cam so each slot bottom aligns with the 2. 50" radius as illustrated.
e. Clamp securely in this position and check travel of cam. Pawl must contact bottom of each cam
slot. Using existing holes in seat frame. drill through new cam and secure with MS20470AD6
rivets.
f. Reinstall upholstery. upholstery panels and seat.

Figure 3-7. Seat Back Cam Replacement
Revision 1

3-23

MODEL 172 SERIES SERVICE MANUAL

4
3

PROVISIONS FOR OPTIONAL
INERTIA REEL INSTALLATION

2
3.

4. Tiara

5.
6.
7.

Cover
Retainer
Cover

Skylight Retainer

9.
10.

PROVISIONS FOR
INERTIA REEL
INSTALLATION

Wire
Zipper

Figure 3-8. Cabin Headliner Installation

3-24

Spar Shield
Headliner Assembly

MODEL 172 SERIES SERVICE MANUAL
3-45.

MATERIALS AND TOOLS. Materials and tools will vary with the job. Scissors for
trimming upholstery to size, and a dull-bladed putty knife for wedging material beneath
retainer strips are the only tools required for most trim work. Use industrial rubber cement
to hold soundproofing mats and fabric edges in place. Refer to Section 18 for repair of glassfiber constructed components.

3-46.

SOUNDPROOFING. The aircraft is insulated with spun glass mat-type insulation and a
sound-deadener compound applied to inner surfaces of skin in most areas of cabin and
baggage compartment. All soundproofing material should be replaced in its original
position anytime it is removed. A soundproofing panel is placed in gap between wing and
fuselage and held in place by wing root fairings.

3-47.

CABIN HEADLINER. (See figure 3-8.)

3-48.

REMOVAL AND INSTALLATION. (See figure 3-8.)
a. Remove sun visors, all inside finish strips and plates, overhead console, upper
doorpost shields and any other visible retainers securing headliner.
b. Remove molding from fixed windows.
c. Remove screws securing headliner and carefully take down headliner.
d. Remove spun glass soundproofing panels above headliner.
NOTE
The lightweight soundproofing panels are held in place
with industrial rubber cement.
e.

Reverse preceding steps for installation. Before installation, check all items concealed by headliner for security. Use wide cloth tape to secure loose wires to fuselage
and to seal openings in wing roots.

3-49.

UPHOLSTERY SIDE PANELS. Removal of upholstery side panels is accomplished by
removing seats for access, then removing parts attaching panels. Remove screws, retaining
strips, arm rests and ash trays as required to free panels. Automotive-type spring clips
attach most door panels. A dull putty knife makes an excellent tool for prying clips loose.
When installing side panels, do not over-tighten screws. Larger screws may be used in
enlarged holes as long as the area behind the hole is checked for electrical wiring, fuel lines
and other components which might be damaged by using a longer screw. Ensure that, after
all seats are reinstalled, seat stops are properly and securely installed.

3-50.

CARPETING. Cabin area and baggage compartment carpeting is held in place by rubber
cement, small sheet metal screws and retaining strips. When fitting a new carpet, use old
carpet as a pattern for trimming and for marking screw holes.

3-51.

SAFETY PROVISIONS.

3-52.

CARGO TIE-DOWNS. (See figure 3-9.) Cargo tie-downs are used to ensure baggage cannot
enter seating area during flight. Methods of attaching tie-downs are illustrated in the figure.
The eyebolt and nutplate can be located at various points. The sliding tie-down lugs also
utilize eyebolts and attach to seat rails.

3-53.

SAFETY BELTS. (See figure 3-11.) Safety belts should be replaced if frayed or cut, latches
are defective or stitching is broken. Attaching parts should be replaced if excessively worn
or defective. A seat belt shortening kit is available for aircraft serials 17266047 thru
17274009. Refer to SK172-76.

Revision 1

3-25

MODEL 172 SERIES SERVICE MANUAL
3-54.

SHOULDER HARNESS. (See figure 3-11.) Individual shoulder harnesses may be installed
for each seat. Each harness is connected to the upper fuselage structure and to the seat
safety belt buckle. Component parts should be replaced as outlined in the preceding paragraph.

3-55.

GLIDER TOW-HOOK. A glider tow-hook, which is mounted in place of the tail tie-down
ring, is available for all models.

3-56.

REAR VIEW MIRROR. (172 AND F172 SERIES ONLY.) (See figure 3-10.) A rear view mirror may be installed on the cowl deck above the instrument panel. The figure illustrates details for removal and installation of rear view mirror.

3-57.

SEAT RAIL INSPECTION. A special inspection of seat rails should be conducted each 50
hours. See figure 3-12 for inspection procedures.

CARGO TIE-DOWN RING
CARGO TIE-DOWN LUG SLIDE ASSEMBLY

SEAT RAIL
Figure 3-9. Cargo Tie-Down Rings

OPTIONAL (THRU
17271034 & F17201749)
1.
2.

Cover
Mirror

Grommet

4.
5.
6.

Nut
Washer
Deck Skin

172 & F172 SERIES ONLY

6
Figure 3-10. Rear View Mirror Installation

3-26

Revision 1

MODEL 172 SERIES SERVICE MANUAL

2
4

Detail B

172Q Models

1.
2.
3.
4.

Shoulder Harness
Spacer
Washer
Cover

5. Bolt
6.
7.
8.
9.
10.
11.
12.
13.

Inertia Reel Assembly
Spar
Mounting Plate
Latch Assembly

Detail

Belt
Bracket
Link
Cover

Left-Hand Only
Beginning with
17265685 and
F17201385

Split Back Seat
Beginning with
1980 Models

Detail Eand F

DetailG
Beginning with 1982 Models
on aircraft equipped with

air conditioning
Figure 3-11.

Seat Belt and Shoulder Harness Installation

Revision 1

3-27

MODEL 172 SERIES SERVICE MANUAL

Counts as one crack. Usable if
not closer than one inch.

REPLACE SEAT RAIL WHEN:
a.
b.
c.

Any portion of web or lower flange is cracked (index 2).
Any crack in crown of rail is in any direction other than right angle to length of
rail.
Number of cracks on any one rail exceeds four, or any two cracks (index 1) are
closer than one inch.

NOTE
Use of seat rail cargo tie-downs is not permissible on seat
rails with cracks.

Figure 3-12. Seat Rail Inspection

3-28

MODEL 172 SERIES SERVICE MANUAL
SECTION 4
WINGS AND EMPENNAGE
TABLE OF CONTENTS
WINGS AND EMPENNAGE ....
Wings ...................
Description .............
Removal ................
Repair
.
................
Installation .............
Adjustment .............
Wing Struts ..............
Description
.............
Removal/Installation .......
Repair
.
................
Fin .....................

Page No.
Aerofiche/
Manual
1H5/4-1
1H5/4-1
1H5/4-1
1H5/4-1
H8/4-4
1H8/4-4
1H12/4-8
1H13/4-9
113/4-9
1H13/4-9
1H13/4-9
1H13/4-9

Description .............
Removal ................
Repair .................
Installation .............
Horizontal Stabilizer ........
Description .............
Removal/Installation .......
Repair .................
Stabilizer Abrasion Boots .....
Description .............
Removal ................
Installation .............

1H13 4-9
1H13 4-9
1H144-10
1H14 4-10
1H14 4-10
1H14 4-10
H14 4-10
1H17/4-11
1H17/4-11
1H17 4-11
1H17 4-11
1H17 4-11

4-1.

WINGS AND EMPENNAGE.

4-2.

WINGS. (See figure 4-1.)

4-3.

DESCRIPTION. Each all-metal wing is a semicantilever, semimonocoque type, with two
main spars and suitable ribs for the attachment of the skin. Skin panels are riveted to ribs.
spars and stringers to complete the structure. An all-metal, piano-hinged aileron, flap and a
detachable wing tip are mounted on each wing assembly. A single metal fuel tank is
mounted between the wing spars at the inboard end of each wing. Beginning with 1981
Models, an optional installation, consisting of an integral fuel bay, formed between the wing
spars at the inboard end of each wing, is available. Colored navigation lights are mounted at
each wing tip. Beginning with 1982 Models, the aircraft landing lights are located in the left
hand wing leading edge.

4-4.

REMOVAL. Wing panel removal is most easily accomplished if four men are available to
handle the wing. Otherwise, the wing should be supported with a sling or maintenance stand
when the fastenings are loosened.
a. Remove wing root fairings and fairing plates.
b. Remove all wing inspection plates.
c. Drain fuel from tank or bay of wing being removed.
d. Disconnect:
1. Electrical wires at wing root disconnects.
2. Fuel lines at wing root. (Refer to precautions outlined in Section 12.)
3. Pitot line (left wing only) at wing root.
4. Cabin ventilator hose at wing root.
e. Reduce aileron cable tension by loosening turnbuckles and disconnect cables at
aileron bellcranks. Disconnect flap cables at turnbuckles above headliner, and pull
cables into wing root area.

Revision 1

4-1

MODEL 172 SERIES SERVICE MANUAL

300INLB

690 LB IN (MAX)

Beginning with 17275035
and F1722135 & On

Detail

1.
2.
3.
4.
5.
6.
7.

4-2

Fairing
Fuel Tank
Lower Rear Fairing
Inspection Plate
Fuel Tank Cover
Fuel Gage Access Cover
Bolt

8. Eccentric Bushings
9. Washer
10. Nut
11. Wing Flap
12. Aileron
13. Wing Tip
14. Navigation and Strobe Lights

15. Wing Mounted Landing Light
16. Wing Assembly
17. Cover Plate
18. Stall Warning Unit
19. Washers
20. Nut

Figure 4-1. Wing Installation (Sheet 1 of 2)

MODEL 172 SERIES SERVICE MANUAL
TORQUE:
300 LB IN (MIN)

500 LB IN (MAX)

690 LB IN (MAX)

1. Fairing
3.
4.

Wing Flap
Aileron

BEGINNING WITH 17275035

5. Wing Tip
7.
8.

Courtesy Light
Fuel Filler Cap

9. Bolt
11.
12.
13.

Washers
Nut
Wing Mounted Landing
Light

Figure 4-1. Wing Installation (Sheet 2 of 2)
4-3

MODEL 172 SERIES SERVICE MANUAL
NOTE
To ease rerouting the cables. a guide wire may be attached to each cable before it is pulled free from the wing.
Cable may then be disconnected from the wire. Leave the
guide wire routed through the wing; it may be attached
again to the cable during installation. and used to pull the
cable into place.
f. Remove screws from strut fairings and slide fairings toward center of strut.
g. Support wing at outboard end and remove strut-to-wing attach bolt.
h. Lower strut carefully to avoid damage to lower strut-to-fuselage fitting.
NOTE
Tape flaps in the streamlined position during wing
removal. This will prevent flap damage due to the unsecured free-swinging action when handling the wing.
i.
j.

Mark position of wing-attachment eccentric bushings (See figure 4-1.) These
bushings are used to rig out "wing heaviness".
Remove nuts. washers, bushings and bolts attaching wing spars to fuselage.
NOTE
It may be necessary to rock the wings slightly and/or to
use a long drift punch to remove attaching bolts.

Remove wing and lay on padded stand.
NOTE
Plans for fabrication of padded wing support stands are
illustrated in Section 18 of this manual.

4-5.

REPAIR. A damaged wing panel may be repaired in accordance with instructions outlined
in Section 18, which supplements Federal Aviation Regulation. Part43. Extensiverepairs of
wing skin and structure are best accomplished by using the wing alignment repair jig.
which may be obtained from Cessna. The wing jig serves not only as a holding fixture.
making work on the wing easier, but also assures absolute alignment of the repaired wing.

4-6.

INSTALLATION. (See figure 4-1.)
NOTE
The forward wing spar fittings are attached to the fuselage fittings with AN8-23 bolts. and the aft wing spar
fittings are attached to the fuselage fittings with AN7-24
bolts. Minimum torque on the AN8-23 bolts is 300 lb-in
and the maximum torque is 690 lb-in. Minimum torque on
the AN7-24 bolts is 300 lb-in, and the maximum torque is
500 lb-in.

4-4

MODEL 172 SERIES SERVICE MANUAL

* NOTE
Lubricate bolt and
hole per Section 2.

NOTE
Seal across top of lower strut fitting

at skin cutout with 576. 1 Permagum.

1.
2.
3.
4.
5.
6.
7.

Wing Strut
Tie-Down Ring
Wing Attachment Fitting
Spacer
Screw
Upper Fairing
Lower Fairing

8. Fuselage Attachment Fitting

Figure 4-2.

Wing Strut
4-5

MODEL 172 SERIES SERVICE MANUAL

NOTE
Fairing (1) and Dorsal (2)
are riveted to Fuselage (13).

Detail A

NOTE
Tighten forward stabilizer attach
bolts first, install required thickness of washers to allow a maximum
.010 gap between washer and stabilizer rear spar (washer required

Detail

2 places),

Detail C

.
Fairing

2. Dorsal
3. Upper Right Fairing
4. Nutplates
5. Fin Assembly

6.
7.

Fin Tip
Upper Rudder Hinge

Center Rudder Hinge

9. Lower Rudder Hinge
10. Shim
14

11.
12

Figure 4-3.
4-6

Vertical Fin

12.
13.

Tailcone
Upper Left Fairing
Fuselage

14.

Washer

MODEL 172 SERIES SERVICE MANUAL

Detail

NOTE
See figure 4-3 for stabilizer
rear attach bolt installation.

1.
2.
3.

Stabilizer Tip
Outboard Elevator Hinge
Bushing

NOTE
A kit is available from the Cessna
Supply Division for installation of
abrasion boots on aircraft not so
equipped.

4.
5.
6.
7.

Inboard Elevator Hinge
Bracket
Upper Right Fairing
Upper Left Fairing

8. Horizontal Stabilizer
9. Forward Left Fairing
10. Forward Right Fairing
11. Abrasion Boot

Figure 4-4. Horizontal Stabilizer
4-7

MODEL 172 SERIES SERVICE MANUAL
NOTE
Upon installation of bolts, coat holes and bolts lightly
with Electro-Moly No. 11 (MIL-G-121164) grease.
Hold wing in position and install bolts. bushings. washers and nuts attaching wing
spars to fuselage fittings. Ensure eccentric bushings are positioned as marked.
Torque nuts to values stipulated in note preceding this step.
b. Install bolts, spacers. and nuts to secure upper and lower ends of wing strut to wing
and fuselage fittings.
a.

NOTE
Upon installation of bolts, coat holes and bolts lightly
with Electro-Moly No. 11 (MIL-G-121164) grease.
NOTE
Seal opening in fuselage skin around lower wing strut
fitting with 579.6 Sealer (Inmont Corp.. St. Louis. Missouri) or equivalent.
c. Route flap and aileron cables. using guide wires. (See note in paragraph 4-4)
d. Connect:
1. Electrical wires at wing root disconnects.
2. Fuel lines at wing root. (Refer to precautions outlined in Section 12.)
3. Pitot line (if left wing is being installed.)
e. Rig aileron system (Section 6).
f. Rig flap system (Section 7).
g. Refuel wing tank or bay and check for leaks. (Refer to precautions outlined in Section
12.)
h. Check operation of wing tip lights.
i. Check operation of fuel gage.
j. Seal all openings common to fuselage root rib and adjacent to fuel cell with clothbacked waterproof tape. Tapes recommended for usage are: Polyken 224. 230 or 231.
Permacel P-69. P-670 or P-672, or Tuck 92T.
k. Install wing root fairings.
NOTE
Be sure to insert soundproofing panel in wing gap, if such
a panel was installed originally, before replacing wing
root fairings.
1.
4-7.

4-8

Install all wing inspection plates. interior panels and upholstery.

ADJUSTMENT (Correcting "Wing-Heavy" Condition). (See figure 4-1.) If considerable
control wheel pressure is required to keep the wings level in normal flight, a "wing-heavy"
condition exists.
a. Remove wing fairing strip on the "wing-heavy" side of the aircraft
b. Loosen nut (10) and rotate bushings (8) simultaneously until the bushings are
positioned with the thick side of the eccentrics up. This will lower the trailing edge of
the wing, and decrease "wing-heaviness" by increasing angle-of-incidence of the
wing.

MODEL 172 SERIES SERVICE MANUAL
CAUTION
Be sure to rotate the eccentric bushings simultaneously.
Rotating them separately will destroy the alignment
between the off-center bolt holes in the bushings, thus
exerting a shearing force on the bolt, with possible
damage to the hole in the wing spar.
c.
d.

Torque nut (10) and reinstall fairing strip.
Test-fly the aircraft. If the "wing-heavy" condition still exists, remove fairing strip
on the "lighter" wing. loosen nut, and rotate bushings simultaneously until the
bushings are positioned with the thick side of the eccentrics down. This will raise the
trailing edge of the wing, thus increasing "wing-heaviness" to balance heaviness in
the opposite wing.
Torque nut (10), install fairing strip, and repeat flight test.

4-8.

WING STRUTS. (See figure 4-2.)

4-9.

DESCRIPTION. Each wing has a single lift strut which transmits a part of the wing load to
the lower portion of the fuselage. The strut consists of a streamlined tube riveted to two end
fittings for attachment at the fuselage and wing.

4-10.

REMOVAL AND INSTALLATION.
a. Remove screws from strut fairings and slide fairings along strut.
b. Remove fuselage and wing inspection plates at strut junction points.
c. Support wing securely, then remove nut and bolt securing strut to fuselage.
d. Remove nut, bolt and spacer used to attach strut to wing. then remove strut from
aircraft.
e. Reverse preceding steps to install strut.
NOTE
Seal opening in fuselage skin around lower wing strut
fitting with 579.6 Sealant (Inmont Corp.. St. Louis, Missouri) or equivalent.

4-11.

REPAIR.
a.

For grooves in wing strut caused by strut fairings, the following applies.
1.
2.
3.

If groove exceeds .010 inch in depth and is less than .75 inch from a rivet center.
the strut should be replaced.
If groove is more than .75 inch from a rivet center and groove depth exceeds .030
inch, strut should be replaced.
If groove depth is less than .030 inch and is more than .75 inch from a rivet center, strut should be repaired by tapering gradually to the original surface and
burnishing out to a smooth finish. The local area should be checked with dye
penetrant to insure that no crack has developed.

4-9

MODEL 172 SERIES SERVICE MANUAL
b.

The following applies to wing struts with grooves worn in the lower trailing edge.
This type damage can occur after extensive cabin door usage with a missing or improperly adjusted door stop which allows the door to bang against the aft edge of the
strut at the lower end.
NOTE
Struts with a groove deeper than 50% of the original ma-

terial thickness should be replaced. Lesser damage may
be repaired as follows:
1.

Without making the damage deeper, remove strut material on each side of groove
to reduce notch effect of damage. Smooth and blend the surface to provide a
gradual transition of strut tube material thickness in damaged area. The local
area should be checked with dye penetrant to insure that no crack has developed.

Apply brush alodine or zink chromate primer and repaint area.

Re-rig the door stop and/or re-form the lower portion of the door pan and skin inboard to prevent the door from rubbing the strut tube. If these actions prove to be
ineffective, install some form of protective bumper, either on strut or lower por-

tion of door, to prevent further damage. A short, hard rubber strip bonded to the
trailing edge of the strut where the door comes close to strut is a possibilty.
NOTE
It should be noted that the above disposition applies only
to the damage caused by strikes from cabin door. The
criteria set forth for strut fairing damage still applies as
a general criteria for the remainer of the strut.
c.

Tie-downs and attaching parts may be replaced. If the strut is severly dented,
cracked or deformed, it should be replaced.

4-12.

FIN. (See figure 4-3.)

4-13.

DESCRIPTION. The fin is primarily of metal construction, consisting of ribs and spars
covered with skin. Fin tips are of ABS construction. Hinge brackets at the fin rear spar
attach the rudder.

4-14.

REMOVAL. The fin may be removed without first removingthe rudder. However, for access
and ease of handling, the rudder may be removed in accordance with procedures outlined in
Section 10 of this manual. Remove fin as follows:
a. Remove fairings on either side of fin.
b. Disconnect flashing beacon lead, tail navigation light lead. antennas and antenna
leads, and rudder cables, if rudder has not been removed.

4-10

MODEL 172 SERIES SERVICE MANUAL
NOTE
The flashing beacon electric lead that routes into the
fuselage may be cut, then spliced (or quick-disconnects
used) at installation.
c.
d.
e.

Remove screws attaching dorsal to fin.
Disconnect elevator cable from elevator bellcrank.
Remove bolts attaching fin rear spar to fuselage fitting. Remove upper elevator stop
bolts.
f. Remove bolts attaching fin front spar to fuselage bulkhead, and remove fin.
g. Retain any shims installed between the rear spar of the fin and the fuselage fitting.
4-15.

REPAIR. Fin repair should be accomplished in accordance with applicable instructions
outlined in Section 18.

4-16.

INSTALLATION. Reverse the procedures outlined in paragraph 4-14 to install the vertical
fin. Be sure to check and reset rudder and elevator travel.
a. Reinstall any shims removed from between the fin rear spar and the fuselage fitting.
If a new fin is being installed, measure any gap existing between the fin rear spar and
the fuselage fitting and use shims as follows:
.000" to .030" gap ..............................
No Shim
.030" to .050" gap .............................
0531115-1 Shim(.020")
.050" to .070" gap .............................
0531115-2 Shim (.040")
A maximum of one shim per bolt is permissible.

4-17.

HORIZONTAL STABILIZER. (See figure 4-4.)

4-18.

DESCRIPTION. The horizontal stabilizer is primarily of all-metal construction, consisting
of ribs and spars covered with skin. Stabilizer tips are of ABS construction. A formed metal
leading edge is riveted to the assembly to complete the structure. The elevator trim tab
actuator is contained within the horizontal stabilizer. The underside of the stabilizer
contains a covered opening which provides access to the actuator. Hinges are located on the
rear spar assembly to support the elevators.

4-19.

REMOVAL AND INSTALLATION.
a. Remove elevators and rudder in accordance with procedures outlined in Sections 8
and 10.
b. Remove vertical fin in accordance with procedures outlined in paragraph 4-14.
c. Disconnect elevator trim control cables at clevis and turnbuckle inside tailcone.
remove pulleys which route the aft cables into horizontal stabilizer. and pull cables
out of tailcone.
d. Remove bolts securing horizontal stabilizer to fuselage.
e. Remove horizontal stabilizer.
f. Reverse preceding steps to install horizontal stabilizer.

4-10A/(4-10B blank)

MODEL 172 SERIES SERVICE MANUAL
NOTE
Tighten forward stabilizer-attach bolts first. Install required thickness of washers to allow a maximum .010-

inch gap between washer and stabilizer rear spar.
Washers are required in 2 places. The following washers
are available from the Cessna Supply Division.
S1450-5A20-100
S1450-5A20-080
S1450-5A20-063

g. Check operation of tail navigation light and flashing beacon.
h. Rig control systems as necessary.
4-20.

REPAIR. Horizontal stabilizer repair should be accomplished in accordance with applicable instructions outlined in Section 18.

4-21.

STABILIZER ABRASION BOOTS. (See figure 4-4.)
NOTE

An Accessory Kit (AK182-217) is available from the
Cessna Supply Division for installation of abrasion boots
onaircraft not so equipped.
4-22.

DESCRIPTION. The aircraft may be equipped with two extruded rubber abrasion boots. one
on the leading edge of each horizontal stabilizer. These boots are installed to protect the
stabilizer leading edge from damage caused by rocks thrown back by the propeller.

4-23.

REMOVAL The abrasion boots can be removed by loosening one end of the boot and pulling
it off the stabilizer with an even pressure. Excess adhesive or rubber can be removed with
Methyl-Ethyl-Ketone.

4-24.

INSTALLATION. Install abrasion boots as outlined in the following procedures.
. Trim boots to desired length.
b. Mask off boot area on leading edge of stabilizer with 1-inch masking tape. allowing
1/4-inch margin.
c. Clean metal surfaces of stabilizer, where boot is to be installed with Methyl-EthylKetone.
d. Clean inside surface of abrasion boot with Methyl-Ethyl-Ketone and a Scotch brite
pad to ensure complete removal of paraffin/talc. Then a normal wipe down with ME K
on a cloth will leave surface suitable for bonding to the aluminum.
NOTE
Boots may be applied over epoxy primer, but if the
surface has been painted, the paint shall be removed from
the bond area. This shall be done by wiping the surfaces
with a clean, lint-free rag, soaked with solvent, and then
wiping the surfaces dry, before the solvent has time to
evaporate, with a clean, dry lint-free rag.
e.
f.

Stir cement (EC-1300 Minnesota Mining and Manufacturing Co.) thoroughly
Apply one even brush coat to the metal and the inner surface of the boot. Allow

4-11

MODEL 172 SERIES SERVICE MANUAL
cement to air-dry for a minimum of 30 minutes. and then apply a second coat to each
surface. Allow at least 30 minutes (preferably one-hour) for drying.
g. After the cement has thoroughly dried. reactivate the surface of the cement on the
stabilizer and boot. using a clean, lint-free cloth. heavily moistened with toluol.
Avoid excess rubbing which would remove the cement from the surfaces.
h. Position boot against leading edge. exercising care not to trap air between boot and
stabilizer.
NOTE
Should boot be attached "off-course". pull it up immediately with a quick motion. and reposition properly.
i.

Press or roll entire surface of boot to assure positive contact between the two
surfaces.
j. Apply a coat of GACO N700A sealer, or equivalent. conforming to MIL-C-21067.
along the trailing edges of the boots to the surface of the skin to form a neat, straight
fillet.
k. Remove masking tape and clean stabilizer of excess material.
1. Mask to the edge of boot for painting stabilizer.

4-12

MODEL 172 SERIES SERVICE MANUAL
SECTION 5
LANDING GEAR, WHEELS AND BRAKES
TABLE OF CONTENTS
LANDING GEAR ............
Description ...............
Trouble Shooting ...........
Main Landing Gear .........
Description .............
Removal ................
Installation .............
Step Bracket Installation ....
Fairings ................
Description ............
Removal/Installation .....
Speed Fairing Removal ...
Speed Fairing Installation .
Wheel Removal ...........
Disassembly (McCauley)
Two-Piece) .............
Inspection/Repair (McCauley
Two-Piece) .............
Reassembly (McCauley
Two-Piece) ...........
Disassembly (Cleveland
Wheel) ................
Inspection/Repair
(Cleveland Wheel) ........
Reassembly (Cleveland
Wheel) ................
Disassembly (McCauley with
Hub and Capscrews) ......
Inspection/Repair (McCauley
with Hub and Capscrews) ..
Reassembly (McCauley with
Hub and Capscrews) ......
Wheel Installation ........
Wheel Axle Removal .......
Wheel Axle Installation.....
Bonded Axle Removal ......
Bonded Axle Installation ....
Wheel Alignment Check ....
Wheel Balancing .........
Nose Gear ................
Description .............
Trouble Shooting .........
Removal ................
Installation .............
Speed Fairing Removal .....

Page No.
Aerofiche/
Manual
1I2/5-2
1I2/5-2
1I2/5-2
1I3/5-3
1I3/5-3
1I5/5-5
1I5/5-5
1I6/5-6
1I6/5-6
1I6/5-6
1I6/5-6
1I11/5-11
1I11/5-11
1I11/5-11
1I12/5-12
1112/5-12
1I12/5-12
1I13/5-13
1I13/5-13
1I14/5-14
1I14/5-14
1I14/5-14
1I15/5-15
1I15/5-15
1I16/5-16
1I16/5-16
1I16/5-16
1I18/5-18
1I19/5-19
1I19/5-19
1I19/5-19
1I19/5-19
1I23/5-21
1I23/5-21
1I23/5-21
1J1/5-23

Speed Fairing Installation ...
/5-23
Wheel Removal
...........
1J3/5-25.
Disassembly (McCauley) ....
1J3/5-25
Inspection/Repair
(McCauley) ............
1J3/5-25
Reassembly (McCauley) ....
1J4/5-26
Disassembly (Cleveland) ....
1J5/5-27
Inspection/Repair
(Cleveland) .............
1J6/5-28
Reassembly (Cleveland) ..... 1J6/5-28
Wheel Installation ........
1J6/5-28
Wheel Balancing
.........
1J7/5-29
Strut Disassembly .......
1J7/5-29
Strut Inspection/Repair ..... 1J9/5-31
Strut Reassembly .........
1J9/5-31
1J10/5-32
Torque Link ............
1J10/5-32
Description ............
J10/5-32
Removal ..............
1J10/5-32
Inspection/Repair .......
1J11/5-33
Installation .........
1J12/5-34
Shimmy Damper .........
1J12/5-34
Description ............
1J12/5-34
...........
Removal
Disassembly/Reassembly . . 1J12/5-34
Installation ............
1J12/5-34
1J13/5-35
Steering System ..........
1J13/5-35
Description ...........
Steering Rod Assemblies . . 1J13/5-35
1J13/5-35
Description ..........
1J13/5-35
Adjustment ............
1J13/5-35
Brake System .............
1J13/5-35
Description .............
1J13/5-35
Trouble Shooting .........
1J14/5-36
Brake Lines .............
Description ............
1J14/5-36
1J14/5-36
Brake Assemblies .........
1J14/5-36
Description ............
1J14/5-36
Removal ..............
1J14/5-36
Disassembly ...........
1J14/5-36
Inspection/Repair .......
Reassembly ............
1J17/5-39
Installtion ............
1J17/5-39
1J17/5-39
Checking Lining Wear ....
Installation ......
1J17/5-39
Lining
System Bleeding ........
1G14/5-40

Revision 1

5-1

MODEL 172 SERIES SERVICE MANUAL
Brake Master Cylinder ........ 1J18/5-40
................
1J185-40
Description .
1J18/5-40
Removal ...................
1J18/5-40
Disassembly (Thru 1978) ....
Inspection/Repair ...........
1J19/5-41
(Thru 1978) ...............
1J19/5-41
Reassembly (Thru 1978) .....
Disassembly (Beginning .....
with 1979) ................ 1J19/5-41

Inspection/Repair
(Beginning with 1979) .. 1J19/5-41
Reassembly (Beginning
with 1979) ............. 1J19/5-41
Installation ............. 1J20/5-42
1J20/5-42
Brake Lining Burn-In ......
1J20/5-42
Parking Brake System ......
Description .............. 1J20/5-42
1J20/5-42
Removal/Installation .....

5-1.

LANDING GEAR.

5-2.

DESCRIPTION. The aircraft is equipped with a fixed tricycle landing gear, consisting of tubular
spring-steel main gear struts, and an air/oil steerable nose gear shock strut. Wheels with disc-type
brakes and tube-type tires are installed on the main landing gear struts, and a two-piece, die-cast aluminum wheel is mounted on the nose gear strut. The nose wheel is steerable with the rudder pedals
up to a maximum pedal deflection, after which it becomes free-swiveling, up to a maximum of 30 degrees, each side of center. Nose and main wheel speed fairings are available for installation.

5-3.

TROUBLE SHOOTING.
TROUBLE
AIRCRAFT LEANS TO ONE
SIDE.

TIRES WEAR EXCESSIVELY.

5-2

Revision 3

PROBABLE CAUSE

REMEDY

Incorrect tire inflation.

Inflate to pressure specified
in figure 1-1.

Landing gear attaching
parts not tight.

Tighten loose parts; replace
defective parts with new
parts.

Landing gear spring
excessively sprung.

Remove and install new
part(s).

Bent axle(s).

Install new part(s).

Incorrect tire inflation.

Inflate to pressure specified
in figure 1-1.

Main wheels out of
alignment.

Remove and install new
part(s).

Landing gear spring
excessively sprung.

Remove and install new
part(s).

Bent axle(s).

Install new part(s).

Dragging brakes.

Refer to paragraph 5-67.

Wheel bearings excessively
tight.

Adjust properly.

MODEL 172 SERIES SERVICE MANUAL
5-3.

TROUBLE SHOOTING. (Cont.)
TROUBLE

Add shims or install new
parts as required.

TIRES WEAR EXCESSIVELY Loose torque links.
(Cont.)
WHEEL BOUNCE EVIDENT
ON SMOOTH SURFACE.

REMEDY

PROBABLE CAUSE

Out of balance condition.

Refer to paragraph 5-30.

5-4.

MAIN LANDING GEAR. (See figure 5-1.)

5-5.

DESCRIPTION. The tubular, spring-steel main landing gear struts are attached to the

AFT LANDING GEAR BULKHEAD

STA. 65.33

FUSELAGE
STA. 56.70

FWD LANDING GEAR BULKHEAD

1.
2.

Inboard Forging
Bolt

3. Outboard Forging
4. Bushing

5.
6.

Bushing Retainer Ring
Tubular Strut

Figure 5-1. Main Landing Gear Installation (Sheet 1 of 2)
5-3

MODEL 172 SERIES SERVICE MANUAL

Apply Y-8560 (3M Corporation) polyurethane tape
(1" wide) to upper and lower surface of spring
and above and below step bracket to prevent chaf-

1. Inboard Forging

ing of spring faring.

Bolt

3.
4.
5.
6.
7.
8.

Outboard Forging
Bushing
Bushing Retainer Ring
Tubular Strut
Brake Line
Clamp

9.
10.
11.
12.
13.
14.
15.
16.

Step
Step Bracket
Axle
Brake Torque Plate
Nut
Hub Cap
Wheel Assembly
Wheel Brake Assembly

17.
18.

Fuselage Fairing
Tubular Strut Fairing

19.
20.
21.
22.

Cap Fairing
Brake Fairing
Elbow
Nut

23. O-Ring

SECTION A-A

Torque bolt (2) to 1100-1300 lb, in.
13

Torque elbow to a maximum of 60 lb. in.
Lube/seal with Liquid-O-Ring #404
(Oil Center Research, P.O. Box 51971,
Lafayette, Louisiana 70501).
(Elbow (*) installed thru 1981 Models).

USED ONLY WITH WHEEL FAIRINGS

Fuselage fairings (17) are split thru aircraft
serials 17271034 and F17201749. Beginning
with aircraft serials 17271035 and F17201750,
one-piece fairings areinstalled. However, service replacement fairings, ordered through the
Cessna Supply Division, will be split, and can
be installed without disassembling the main
landing gear.

Figure 5-1.
5-4

22
15
23
Beginning with 1982 Models.

Main Landing Gear Installation (Sheet 2 of 2)

MODEL 172 SERIES SERVICE MANUAL
aircraft at inboard and outboard forgings, located in the belly of the aircraft. A bracket is
bonded to each strut for attachment of a step. Hydraulic brake lines are routed down and
clamped to each main gear strut. The axles, main wheels and brake assemblies are installed
at the lower end of each strut.
5-6.

MAIN LANDING GEAR REMOVAL. (See figure 5-1.)

NOTE
The following procedure removes the landing gear as a
complete assembly. Refer to applicable paragraph for
removal of individual components.
a.

Remove floorboard access covers over inboard and outboard landing gear forgings

(1) and (3).
b. Hoist or jack aircraft in accordance with procedures outlined in Section 2.
c. Remove screws attaching fairing (17) to fuselage. Remove screws at splice in fairing
and work fairing off strut fairing.
d. Drain hydraulic fluid from brake line (7) on strut being removed.
e. Disconnect hydraulic brake line (7) at fitting where brake line emerges from fuselage
skin Cap or plug disconnected fittings.
f. Remove nut, washer and bolt attaching inboard end of tubular strut to the inboard
landing gear bulkhead fitting.
g. Pull tubular strut from fitting and bushing. Use care when removing strut to prevent
damage to hydraulic brake line.
NOTE
The tubular strut is a compression fit in the bushing in
the outboard landing gear forging (3).
5-7.

MAIN LANDING GEAR INSTALLATION. (See figure 5-1.)
NOTE
The following procedure installs the landing gear as a
complete assembly. Refer to applicable paragraphs for
installation of individual components.

a. Install all parts removed from strut.
b. Apply Dow Corning Compound DC-7 to approximately 11 inches on
upper end of tubular strut.
NOTE

Avoid use of Dow Corning DC-7 on surfaces to be
painted. DC-7 contains silicone which is harmful
to painted areas.
c.

Slide tubular strut into place through bushing in outboard strut fitting and into
inboard strut fitting.
d. Align tubular strut in inboard fitting and install bolt through fitting and strut. Install
washer and nut on bolt and tighten to torque value of 1100-1300 lb.in.
e. Connect hydraulic brake line to fitting. Fill and bleed brake system in accordance
with paragraph 5-79.

5-5

MODEL 172 SERIES SERVICE MANUAL
f. Install fuselage fairing.
g. Lower aircraft and install floorboard access covers.
5-8.

STEP BRACKET INSTALLATION. (See figure 5-1.)
NOTE
The step bracket is secured to the tubular gear strut with
EA9309. EC2216, EC2214, EC3445, or a similar epoxy base
adhesive.
a.
b.
c.
d.

e.
f.
g.
h.
i.
j.

Mark position of the bracket so that the new step bracket will be installed in
approximately the same position on the strut.
Remove all traces of the original bracket and adhesive as well as any rust, paint or
scale with a wire brush and coarse sandpaper.
Leave surfaces slightly roughened or abraded, but deep scratches or nicks should be
avoided.
Clean surfaces to be bonded together thoroughly. If a solvent is used. remove all
traces of the solvent with a clean, dry cloth. It is important that the bonding surfaces
be clean and dry.
Check fit of step bracket on the tubular strut. A small gap is permissible between
bracket and tubular strut.
Mix adhesive (any of those listed in note preceding step "a") in accordance with
manufacturer's directions.
Spread a coat of adhesive on bonding surfaces, and place step bracket in position on
the tubular strut. Clamp bracket to strut to ensure a good, tight fit.
Form a small fillet of the adhesive at all edges of the bonded surfaces. Remove excess
adhesive with lacquer thinner.
Allow adhesive to cure thoroughly according to manufacturer's recommendations
before flexing the tubular gear strut or applying loads to the strut.
Paint tubular strut and step bracket after curing is complete.

5-9

MAIN LANDING GEAR FAIRINGS. (See figures 5-1 and 5-2.)

5-10.

DESCRIPTION. Some aircraft are equipped with fuselage fairings. attached to the fuselage
and the tubular strut fairings with screws. The tubular strut fairings cover the tubular
landing gear struts, and attach to the fuselage fairings atthe upper end and to fairingcaps at
the lower end. The fairing caps attach to the tubular strut fairings at the upper end and are
clamped to the tubular struts at the lower end. Brake fairings are installed at the lower end of
the tubular strut fairings and are attached to the wheel speed fairings by screws around their
outer perimeters. The speed fairings are installed over the wheels and are attached to
mounting plates, attached to the axles. The wheel fairings are equipped with adjustable
scrapers, installed in the lower aft part of the fairings, directly behind the wheels.

5-11.

REMOVAL AND INSTALLATION. (See figure 5-1.)
a. To remove brake fairings, proceed as follows.
1. Remove screws from perimeter of fairing.
2. Remove screws from nutplates holding two halves of fairing together: remove
fairing halves.
3. Reverse preceding steps for installation.
b. To remove cap fairings, proceed as follows:
1. Remove screws attaching fairing to tubular spring strut.
2. Disconnect clamp from tubular strut and spring clamp over strut; remove cap
fairing.

5-6

MODEL 172 SERIES SERVICE MANUAL
17263459 thru 17271569
F17201235 thru F17201794

17273370 thru 17276574
F17202030 And On

17271570 thru 17273369
F17201795 thru F17202029
17276575 & On

1. Stiffener
2.

Mounting Plate

3. Doubler
4.
5.
6.
7.
8.

Fairing
Scraper
Axle Nut
Door, Access
Latch

Plug

-,,

* 7
Figure 5-2. Main Wheel Speed Fairings

3. Reverse preceding steps for installation.
c. To remove fuselage fairings, proceed as follows:
1.
2.

Remove screws attaching fairings to fuselage.
Slide fairings down tubular strut fairings and, thru aircraft serials 17271034 and
F17201749, remove screws from nutplates holding fairings together; spring

fairings over strut fairings. Beginning with aircraft serials 17271035 and
F17201750, fairings are one-piece and cannot be sprung apart.
3.
d. To
1.
2.
3.
4.
5.

Reverse preceding steps for installation.
remove tubular strut fairing, proceed as follows:
Remove brake fairing per step "a".
Remove cap fairing per step "b".
Remove fuselage fairing per step "c".
Remove screws from nutplates on strut fairing.
Spring fairing over tubular gear strut.

Revision 3

5-7

MODEL 172 SERIES SERVICE MANUAL

5
12.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.

Retaining Ring
Grease Seal Retainer
Grease Seal Felt
Grease Seal Retainer
Bearing Cone
Wheel Half
Tire
Tube
Washer
Nut
Brake Disc
Torque Plate
Pressure Plate
Anchor Bolt

MC CAULE WHEEL
(Two-Piece)
Beginning with
1982 Models

16. Brake Cylinder

17. Bolt

18. Bleeder Screw
19. Dust Cover
21.
22.
23.
24.
25.
26.
27.

Piston O-Ring
Brake Piston
Lining
Thru-Bolt
Washer
Back Plate
Bearing Cup
Elbow
28.
29. Nut

Torque to 100-110
Torque to 100-110
in.-lbs. Safety
wire.

30. O-Ring
22
Maximum torque on elbow (15) to be 60 lb, in.
Lube/seal elbow (15) with Liquid-O-Ring # 404
(Oil CenterResearch, P.O. Box 51871,
Lafayette, Louisiana 70501.) Elbow (15) installed
thru 1981 Models.

21
20

Figure 5-3. Main Wheel and Brake (Sheet 1 of 3)
5-8

MODEL 172 SERIES SERVICE MANUAL

CLEVELAND WHEEL

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Snap Ring
Grease Seal Ring
Grease Seal Felt
Bearing Cone
Nut
Washer
Wheel Half
Bearing Cup
Tire
Tube

11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Lining
Brake Disc
Torque Plate
Torque Plate Bushing
Pressure Plate
Anchor Bolt
Brake Cylinder
Bolt
Bleeder screw
Piston O-Ring
Brake Piston
Thru-Bolt
Back Plate

23
11
22
21
20
19

Figure 5-3.

Torque to 80-90 in. -lbs.

Main Wheel and Brake (Sheet 2 of 3)
5-9

MODEL 172 SERIES SERVICE MANUAL

28
10

Snap Ring

2.
3.

Grease Seal Retainer (Outboard)
Grease Seal Felt (Outboard)

Grease Seal Retainer (Outboard)

Bearing Cone

6.
17.
7.
8.

Anchor
PhenolicBolt
Spacer

9.
10.
11.
12.

Tube
Wheel Hub
Bearing Cup(Race)
Grease Seal Retainer (Inboard)

Wheel Flange

Tire

13. Grease Seal Felt (Inboard)
14. Brake Disc
15. Torque Plate
16.

Pressure Plate

17. Anchor Bolt
18. Elbow
19. Brake Cylinder
20. Bolt
21. Bleeder Screw
22. Dust Cup
23. Bleeder Fitting
24. Piston O-Ring
25. Brake Piston
26. Brake Lining
27. Capacrew
28. Washer

torque
Maximum
on elbow (18) to be 60 lb. in.
Lube/seal elbow (18) with Liquid-O-Ring #404
(Oil Center Research, P.O. Box 51871,
Lafayette, Louisiana 70501.) Elbow (18) installed
thru 1981 Models.

Figure 5-3.
5-10

Main Wheel and Brake (Sheet 3 of 3)

MODEL 172 SERIES SERVICE MANUAL
6.
To
1.
2.
3.

Reverse preceding steps for installation.
remove step bracket cover, proceed as follows:
Remove tubular strut fairing per step "d".
Slide step bracket cover from step bracket on tubular gear strut.
Reverse preceding steps for installation.

5-12.

MAIN WHEEL SPEED FAIRING REMOVAL. (See figure 5-2.)
a. Remove wheel brake fairing (item 20, figure 5-1) by removing screws around
perimeter of fairing, then removing screws from nutplates holding two halves of
brake fairing together.
b. Remove screws attaching stiffener (1) and inboard side of wheel speed fairing (4) to
attach plate (2), which is bolted to the axle.
c. Remove bolt securing outboard side of fairing to axle nut.
d. Loosen scraper, if necessary, and work speed fairing from wheel.

5-13.

MAIN
a.
b.
c.

WHEEL SPEED FAIRING INSTALLATION. (See figure 5-2.)
Work speed fairing down over wheel.
Install bolt securing outboard side of fairing to axle nut.
Install screws attaching stiffener (1) and inboard side of wheel speed fairing (4) to
mounting plate (2), which is bolted to the axle.
d. Install wheel brake fairing (item 20, figure 5-1) by installing screws in nutplates
holding two halves of brake fairing together, then install screws around perimeter of
fairing.
e. After installation, check scraper-to-tire clearance for a minimum of 0.25-inch to a

maximum of 0.50-inch. Elongated holes are provided in the scraper for clearance ad-

CAUTION
Always check scraper-to-tire clearance after installing
speed fairings, whenever a tire has been changed, and
whenever scraper adjustment has been disturbed. If the
aircraft is flown from surfaces with mud, snow, or ice, the
speed fairings should be checked to make sure there is no
accumulation which could prevent normal wheel rotation. Wipe fuel and oil from speed fairings to prevent
stains and deterioration.

5-14.

MAIN WHEEL REMOVAL. (See figure 5-1.)
NOTE
It is not necessary to remove the main wheel to reline
brakes or to remove brake parts, other than the brake disc
on the torque plate.
a.
b.
c.
d.

Hoist or jack aircraft in accordance with procedures outlined in Section 2.
Remove speed fairing, if installed, as outlined in paragraph 5-12.
Remove hub caps, if installed, cotter pin and axle nut.
Remove bolts and washers attaching brake back plate to brake cylinder, and remove
back plate.
e. Pull wheel from axle.

5-11

MODEL 172 SERIES SERVICE MANUAL
5-15.

MAIN WHEEL DISASSEMBLY. (McCauley Two-Piece Wheel.)(See figure 5-3. Sheet 1 of 3.)
a. Completely deflate tire and tube and break loose tire beads. Extreme care must be
exercised to prevent tire tool damage when removing tire from wheel halves (6).
WARNING
Serious injury can result from attempting to separate
wheel halves with tire and tube inflated.
b.
c.
d.
e.

Remove nuts (10) and washers (9).
Remove thru-bolts (24) and washers (25).
Separate and remove wheel halves (6) from tire and tube.
Remove retaining rings (1), grease seal retainers (2) grease al felts (3), grease seal
retainers (4) and bearing cones (5) from both wheel halves (6).
NOTE
Bearing cups (races) (27) are a press fit in wheel halves
(6), and should not be removed unless a new part is to be
installed. To remove bearing cups. heat wheel half in
boiling water for 30 minutes. or in an oven. not to exceed
121°C (250°F). Using an arbor press, if available, press
out bearing cup and press in a new bearing cup while
wheel half is still hot.

5- 6.

MAIN WHEEL INSPECTION AND REPAIR. (McCauley Two-Piece WheeL) (See figure 5-3
Sheet 1 of 3.)
a. Clean all metal parts and grease seal felts in Stoddard solvent or equivalent, anddry
thoroughly.
NOTE
A soft bristle brush may be used to remove hardened
grease. dust or dirt.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
L

5-17.

5-12

Inspect wheel halves (6) for cracks or damage.
Inspect bearing cones (5), cups (27), retaining rings (1), grease seal retainers (2),
grease seal felts (3) and grease seal retainers (4) for wear or damage.
Inspect thru-bolts (24) and nuts (10) for cracks in threads or cracks in radius under
bolt head.
Replace cracked or damaged wheel half (6).
Replace damaged retainer rings (1) and seals (2), (3) and (4).
Replace worn or damaged bearing cups (27) and cones (5).
Replace any worn or cracked thru-bolts (24) or nuts (10).
Remove any corrosion or small nicks.
Repair reworked areas of wheel by cleaning thoroughly, then applying one coat of
clear lacquer paint.
Pack bearings with grease specified in Section 2.
Inspect brakes per paragraph 5-81.

MAIN WHEEL REASSEMBLY. (McCauley Two-Piece Wheel.)(See figure 5-3. Sheet 1 of 3.)
a. Assemble bearing cone (5), grease seal retainer (4), grease seal felt (3), grease seal
retainer (2) and retaining ring (1) into each wheel half (6).
b. Insert tube in tire, aligning index marks on tire and tube.

MODEL 172 SERIES SERVICE MANUAL
c.

Place wheel half (6) into tire and tube (side opposite valve stem). With washer (25)

under head of thru-bolt (24), insert bolt through wheel half (6).
d. Place wheel half (6) into other side of tire and tube. aligning valve stem in valve slot.
e. Insert washers (9) and nuts (10) on thru-bolts (24), and pre-torque to 10-15 lb. in.

CAUTION
Uneven or improper torque of the nuts can cause failure
of the bolts with resultant wheel failure.
f.

Prior to torquing nuts (10), inflate tube with approximately 10-15 psi air pressure to
seat tire.

CAUTION
Do not use impact wrenches on thru-bolts or nuts.
g. Dry torque all nuts (10) evenly to a torque value of 140-150 lb. in.
h. Inflate tire to correct pressure specified in figure 1-1.
5-18.

DISASSEMBLY. (Cleveland Wheel.) (See figure 5-3, Sheet 2 of 3.)
a. Remove valve core and deflate tire and tube. Break tire beads loose from wheel rims.
WARNING
Injury can result from attempting to separate wheel
halves with tire inflated. Avoid damaging wheel flanges
when breaking tire beads loose. A scratch, gouge or nick
in the wheel may cause wheel failure.
b. Remove thru-bolts and separate wheel halves, removing tire, tube and brake disc
c. Remove grease seal rings, felts and bearing cones from wheel halves.

NOTE
Bearing cups (races) are press-fit in the wheel halves and
should not be removed unless a new part is to be installed.
To remove bearing cups, heat wheel halves in boiling
water for 30 minutes or in an oven not to exceed 149 C
(300°F). Using an arbor press, if available, press out
bearing cup and press in new bearing cup while wheel
half is still hot.
5-19.

MAIN WHEEL INSPECTION AND REPAIR. (Cleveland Wheel.) (See figure 5-3, Sheet 2 of 3.)
a. Clean all metal parts and grease seal felts in solvent and dry thoroughly.
b. Inspect wheel halves for cracks. Cracked wheel halves should be discarded and new
parts used. Sand out nicks, gouges and corroded areas. When protective coating has
been removed, the area should be cleaned thoroughly, primed with zinc chromate and
painted with aluminum lacquer.
c. Inspect brakes per paragraph 5-81.
d. Carefully inspect bearing cones and cups for damage and discoloration. After
cleaning, pack bearing cones with clean aircraft wheel bearing grease. as outlined in
Section 2, before installing in wheel half.

5-13

MODEL 172 SERIES SERVICE MANUAL
5-20.

MAIN WHEEL REASSEMBLY. (Cleveland Wheel.) (See figure 5-3, Sheet 2 of 3.)
a. Insert thru-bolts through brake disc and position disc in the inner wheel half. using
thru-bolts to guide the disc. Ascertain that the disc is bottomed in the wheel half.
b. Position tire and tube on outboard wheel half with tube inflation valve through hole
in wheel half.
c. Place inner wheel half in position on outboard wheel half. Apply a light force to bring
wheel halves together. While maintaining the light force, assemble a washer and nut
on thru-bolt and tighten to maintain force. Assemble remaining washers and nuts to
thru-bolts. Tighten nuts evenly to the torque value of 90 lb. in.
CAUTION
Uneven or improper torque of thru-bolt nuts can cause
failure of bolts, with resultant wheel failure.
d.
e.
f.

5-21.

Clean and pack bearing cones with clean aircraft wheel bearing grease. as outlined in
Section 2.
Assemble bearing cones, grease seal felts and rings into wheel halves.
Inflate tire to seat tire beads, then adjust to correct tire pressure. Refer to chart in
Section 1 for correct tire pressure.

MAIN WHEEL DISASSEMBLY. (McCauley Wheel with Hub and Capscrews.) (See figure 53, Sheet 3 of 3.)
WARNING
Injury can result from attempting to remove wheel
flanges with tire and tube inflated. Avoid damaging
wheel flanges when breaking tire beads loose. A scratch,
gouge or nick in wheel flange could cause wheel failure.
a.

Remove
flanges.
b. Remove
c. Remove
d. Remove
e. Remove
g. Remove

valve core and deflate tire and tube. Break tire beads loose from wheel
capscrews and washers from outboard wheel flange.
capscrews and washers from inboard wheel flange.
brake disc.
wheel hub from tire.
retainer rings, grease seal retainers, grease seal felts and bearing cones.
NOTE

Bearing cups (races) are a press fit in the wheel hub and
should not be removed unless a new part is to be installed.
To remove the bearing cup, heat wheel hub in boiling
water for 30 minutes. or in an oven not to exceed 121°C
(250°F). Using arbor press, if available, press out the
bearing cup and press in the new bearing cup while the
wheel hub is still hot.
5-22.

5-14

MAIN WHEEL INSPECTION AND REPAIR. (McCauley Wheel With Hub and Capscrews.)
(See figure 5-3, Sheet 3 of 3).
a. Clean all metal parts, grease seal felts and phenolic spacers in cleaning solvent and
dry thoroughly.

MODEL 172 SERIES SERVICE MANUAL
b. Inspect wheel flanges and wheel hub for cracks. Cracked wheel flanges or hub shall
be discarded and new parts installed. Sand out smooth nicks, gouges and corroded
areas. When the protective coating has been removed, the the area should be cleaned
thoroughly, primed with zinc chromate and painted with aluminum lacquer.
c. Inspect brakes per paragraph 5-81.
d. Carefully inspect bearing cones and cups for damage and discoloration. After
cleaning, pack bearing cones with clean aircraft wheel bearing grease. Refer to
Section 2 for grease type.
5-23.

MAIN WHEEL REASSEMBLY. (McCauley Wheel With Hub and Capscrews.) (See figure 5-3,
Sheet 3 of 3.)
a. Place wheel hub in tire and tube with tube inflation stem in hole of wheel hub.
b. Place spacer and wheel flange on inboard side of wheel hub (opposite of tube inflation

stem).
c.

Place washer under head of each capscrew. insert capscrew through brake disc.
wheel flange and spacer, and start capscrews into wheel hub threads.
CAUTION
Be sure that spacers, wheel flanges and brake disc are
seated on flange of wheel hub. Uneven or improper torque
of capscrews can cause failure of capscrews or hub
threads with resultant wheel failure.

d. Tighten capscrews evenly and torque to 190 to 200 lb. in.
e. Place spacer and wheel flange on outboard side of wheel hub and align valve stem
hole in wheel flange.
f. Place washer under head of each capscrew, insert capscrew through wheel flange
and spacer. Start capscrews into wheel hub threads.
g. Tighten capscrews evenly and torque to 190 to 200 lb. in.
h. Clean and pack bearing cones with clean aircraft wheel bearing grease. Refer to
Section 2 for grease type.
i. Assemble bearing cones, grease seal filts and retainer into wheel hub.
j. Inflate tire to seat tire beads, then adjust to correct pressure. Refer to chart in Section
1 for correct tire pressure.
5-24.

MAIN WHEEL INSTALLATION. (See figure 5-1.)
a. Place wheel assembly on axle.
b. Install axle nut and tighten axle nut until a slight bearing drag is obvious when the
wheel is rotated. Back off nut to nearest castellation and install cotter pin.
c. Place brake back plate in position and secure with bolts and washers.
d. Install hub cap. Install speed fairing (if used) as outlined in paragraph 5-13.

CAUTION
Always check scraper-to-tire clearance after installing
speed fairings, whenever a tire has been changed, and
whenever scraper adjustment has been disturbed If the
aircraft is flown from surfaces with mud, snow, or ice, the
fairing should be checked to make sure there is no
accumulation which could prevent normal wheel rotation. Refer to paragraph 5-13 for correct scraper-to-tire
clearance.

5-15

MODEL 172 SERIES SERVICE MANUAL
5-25.

MAIN WHEEL AXLE REMOVAL. (See figure 5-1.)
NOTE
This procedure should be used if the axle is not bonded to
the tubular strut. If the axle is bonded to the strut, refer to
paragraph 5-27.
a.
b.
c.
d.
e.
f.

5-26.

Remove speed fairing, if installed, in accordance with paragraph 5-12.
Remove wheel in accordance with paragraph 5-14.
Disconnect, drain and cap or plug hydraulic brake line at the wheel brake cylinder.
Remove bolts attaching brake torque plate and speed fairing mounting plate to axle.
Remove cotter pin, nut, washer and bolt attaching axle to tubular strut.
Remove axle from spring-strut.

MAIN WHEEL AXLE INSTALLATION. (See figure 5-1.)
NOTE
This procedure should be used if the axle is not to be
bonded to the tubular strut. If the axle is to be bonded to
the strut, refer to paragraph 5-28.

a. Install axle on spring-strut, using wet primer on faying surfaces of
axle and spring-strut. Axle is installed with tapered edges to bottom.
b. Install bolt, washer and nut attaching axle to spring-strut. After
tightening nut, install cotter pin.
c. Install brake components and speed fairing mounting plate to axle.
d. Install wheel on axle in accordance with paragraph 5-24.
e. Connect hydraulic brake line to wheel brake cylinder.
f. Fill and bleed hydraulic brake system in accordance with paragraph
5-79.
g. Install speed fairing, if used, in accordance with paragraph 5-13.
5-27.

BONDED MAIN WHEEL AXLE REMOVAL. (See figure 5-4.)
NOTE
On some aircraft, due to axle looseness, axles have been
bonded to the tubular landing gear strut. The following
procedure should be used to remove a bonded axle.
Remove speed fairings, if installed, accordingto procedures outlined in paragraph 512.
b. Remove wheels in accordance with procedures outlined in paragraph 5-14.
c. Disconnect, drain and cap or plug hydraulic brake line at the wheel brake cylinder.
d. Remove cotter pin, nut and bolt attaching axle to spring strut.
e. Remove brake components and speed fairing plate from axle.
a

5-16

MODEL 172 SERIES SERVICE MANUAL
WARNING
Due to aging of aluminum axle, caused by the heating
tape, a new axle will have to be installed.

CAUTION
Do not place tape in direct contact with tubular gear
spring

1. Axle
2 Tubular Gear Strut
3. Electrical Heating Tape
4. Plug
Figure 5-4 Bonded Main Wheel Axle Removal
NOTE

Axles are bonded to the struts of some tubular gear
aircraft with EA9309-25GR adhesive, which is available from the Cessna Supply Division. The bond is
too strong to allow the axle to be removed without
first weakening the bond strength. The only methods
of weakening the bond are with heat or cryogenic cold;
heat being the most practical. A temperature of
approximately 500°F is sufficient to weaken the bond
so the axle can be removed. This is still a low enough
temperature to prevent damage to the tubular strut.
f. Remove axles as follows:
NOTE

Axles should be removed from strut, using electric
heating tape. Heating tape, P/N 135-459, can be
obtained from the Cessna Supply Division.
g. Wrap heating tape around axle from base head to outer end of axle and
tie it on with string provided with the tape, as shown in figure 5-4.

5-17

MODEL 172 SERIES SERVICE MANUAL

NOTE

Holes in gear strut and

axle must not exceed dia-

meter of mounting bolts by
more than 0.0023/inch.

1. Tire
2. Attaching Bolt
3. Axle
4. Tubular Gear Strut
5. Brake Line
6. Brake

Figure 5-5.

Installation of Main Wheel Strut to Axle Mounting Bolts.
CAUTION

Do not place tape in direct contact with tubular gear
spring.
h. Plug electric tape into 110 volt wall socket and heat for 20 to 30 minutes.
i. Unplug tape and remove from axle. Remove axle by striking axle base head with a
few sharp blows.
j. Clean any old adhesive off landing gear spring with a wire brush. Brush strokes
should run lengthwise along the spring. After old adhesive has been removed, wipe
with clean rag saturated with acetone or alcohol. Immediately wipe drywith a clean.
lint free cloth.
WARNING
Due to aging of the aluminum axle. caused by the heating
tape, a new axle will have to be installed.
5-28.

BONDED MAIN WHEEL AXLE INSTALLATION. (See figure 5-4.)
NOTE

If hole diameters in gear strut and axle exceed
diameter of mounting bolts by more than 0.0023
/inch, it is permissible to bond the axle to the
strut. Do not allow adhesive to enter the holes
in gear strut or axle, or to contact bolt threads.

5-18

MODEL 172 SERIES SERVICE MANUAL
The following procedure outlines the correct
method for bonding axle to strut.
a. Prior to installing new axle, wipe outer surface of tubular gear and
inside of axle with solvent, drying immediately with a clean, lint free
cloth.
b. Mix EA9309-25GR adhesive, available from the Cessna Supply Division,
in accordance with instructions in the package. Spread adhesive thinly
and evenly on outer surface of landing gear spring in area that will be
be covered by axle.
c. Place axle on gear spring and rotate axle to assure even coverage
between inner surface of axle and outer surface of spring.
d. Install retaining bolt, washers, nut and cotter pin. Tighten nut
securely.
e. Allow 24 hours at 75°F for adhesive to cure, or 30 minutes at 250°F,
if heating equipment is available.
f. Install brake components and speed fairing mounting plate to axle.
g. Install wheel on axle in accordance with procedures outlined in paragraph 5-24.
h. Connect hydraulic brake line to wheel brake cylinder.
i. Fill and bleed hydraulic brake system in accordance with paragraph 5-79.

Install speed fairings, if used, in accordance with paragraph 5-13.

5-29. MAIN WHEEL ALIGNMENT CHECK. (See figure 5-6.)
made for aligning the nose wheel. Figure 5-6 contains
ing toe-in and camber. Toe-in limitations are . 00" to
tations are 2° to 4 ° . If wheel alignment is out of these
tubular spring strut will have to be installed.

No provisions are
procedures for check+. 18". Camber limilimitations, a new

5-30. WHEEL BALANCING. Since uneven tire wear is usually the cause of wheel
unbalance, replacing the tire will probably correct this condition. Tire and
tube manufacturing tolerances permit a specified amount of static unbalance.
The light-weight point of this tire is marked with a red dot on the tire sidewall and the heavy-weight point of the tube is marked with a contrasting
color line (usually near the inflation valve stem). When installing a new
tire, place these marks adjacent to each other. If a wheel shows evidence
of unbalance during service, it may be statically balanced. Wheel balancing
equipment is available from the Cessna Supply Division.
5-31. NOSE GEAR.
5-32.

(See figure 5-7.)

DESCRIPTION. A steerable nose wheel, mounted in a fork, attached to an air/oil (oleo)
shock strut, make up the nose gear. The shock strut is attached to the firewall with upper and
lower strut fittings. Nose wheel steering is accomplished by two steering tubes lining the
nose gear steering collar to the rudder pedal bars. A hydraulic fluid-filled shimmy
dampener is provided to minimize nose wheel shimmy. A nose wheel speed fairing may be
installed on some aircraft.

5-19

MODEL 172 SERIES SERVICE MANUAL
NOTE
ENSURE FLOOR IS LEVEL IN WORK AREA. SUSPEND
PLUMB BOB FROM TAIL TIE-DOWN RING (AFT) AND
FROM FORWARD INSPECTION COVER PLATE ATTACH
SCREW OF INSPECTION HOLE LOCATED JUST AFT OF
NOSE GEAR ON BOTTOM OF FUSELAGE.

VALUES.

PERPENDICULAR

GREASED PLATES

Figure 5-6. Main Wheel Alignment Check (Sheet 1 of 2)
5-20
5-20

MODEL 172 SERIES SERVICE MANUAL

TOP VIEW OF TOE-IN CHECK

FRONT VIEW OF CAMBER CHECK

Measure toe-in at edges of wheel flange. Difference in measurements is toe-in for one wheel.
(half of total toe-in.)

Measure camber by reading protractor level
held vertically against outboard flanges of
wheel.
NEGATIVE CAMBER

CARPENTER'S SQUARE

POSITIVE CAMBER

FORWARD

-STRAIGHTEDGE
NOTE
These procedures are specifically for checking main wheel
alignment. No provisions are made for aligning the nose
wheel. Refer to paragraph 5-29 or the chart in figure 1-1
of this manual for camber and toe-in limitations.

Figure 5-6. Main Wheel Alignment Check (Sheet 2 of 2)
5-20A/5-20B blank)

MODEL 172 SERIES SERVICE MANUAL
5-33.

TROUBLE SHOOTING.
PROBABL

TROUBLE
NOSE WHEEL SHIMMY .
(Also refer to Service Letter

CAUSE

REMEDY

Nose strut attaching bolts
loose.

Tighten nose strut attaching
bolts.

Loose or worn nose wheel

Tighten. Replace defective

steering linkage.

parts with new parts.

Nose wheel out of balance.

Refer to paragraph 5-46.

Wheel bearings too loose.

Adjust properly.

Defective himmy
damper.

Repair, or install new
damper.

Shimmy damper fluid
low.

Service in accordance with
Section 2.

Loose torque links.

Add shims, or install new
parts as required.

Defective or loose air
filler valve.

Check gasket and tighten
loose valve. Install new
valve if defective.

Defective strut seals.

Install new seals.

Defective strut seals.

Install new seals.

SE84-21.)

NOSE STRUT DOES NOT
HOLD AIR PRESSURE.

HYDRAULIC FLUID LEAKAGE FROM NOSE STRUT.
5-34.

NOSE GEAR REMOVAL. (See figure 5-7.)

a. Remove cowling for access.
b. Weight or tie down tail of aircraft to raise nose wheel off the floor.
c. Disconnect nose wheel steering tubes from nose gear steering collar.
d. Remove strut clamp cap and shims at lower strut fitting.
WARNING
Be sure strut is deflated completely before removing bolt
or roll pin at top of strut.
e.

Deflate strut completely and telescope strut to its shortest length.

f.
g.

Remove bolt at top of strut.
Pull the strut assembly down out of upper attach forging.

5-35. NOSE GEAR INSTALLATION. (See figure 5-7. )
a. Before inflating nose gear strut, insert top of strut in upper attach
forging and attach with bolt.
b. Telescope strut to mate strut clamp cap with lower strut fitting on
firewall.

5-21

MODEL 172 SERIES SERVICE MANUAL
3

...

nose fitting(4)
rivets If
thatfirewall
attach the
upper
to
work
it gear
is
permissible
to replace
theloose,
AD5 bolts
rivets
with
the 20365appropriate
and MS
1032 length
nuts. AN3
The existing rivet holes should be enlarged to
.193 inch to accomodate the bolts.

CAUTION

When installing cap (14), check gap between cap and strut
fitting before attaching bolts are tightened. Gap tolerance
is .010" minimum and .016" maximum.
If
gap exceeds

maximum tolerance, install shims (16), Part No. 0543042-1
(.016") and Part No. 0543042-2 (. 032"), as required, to
obtain

gap tolerance.

Replace cap if gap is less than mini-

mum, using shims to obtainproper gap.
equally as possible between sides.
1.

Bolt

2. Strut Assembly
3. Bolt
4. Upper Nose Gear Fitting
5. RH Steering Tube
6. LH Steering Tube
7.

Clamp

Lower Strut Fitting

shims as

15.

9.
10.
11.
12.
13.

Bolt
Rod End
Steering Arm Assembly
Wheel Assembly
Shimmy Dampener Arm

14.

16.
17.
18.
19.
20.

Strut Clamp Cap

21.

Figure 5-7.
5-22

Install

Shimmy Dampener

Shim
Rivet
Ball Joint
Nut
Check Nut
Clevis

Nose Gear Installation

Section D-D

MODEL 172 SERIES SERVICE MANUAL
c.

Install shims and strut clamp cap attachig strut to lower strut fitting, observing the

CAUTION in figure 5-7.
d.
e.

5-36.

Inflate and service shock strut in accordance with procedures outlined in Section 2.
Rig nose wheel steering tubes as outlined in appliable paragraph in Section 10.

NOSE WHEEL SPEED FAIRING REMOVAL. (See figure 5-8.)
WARNING
Nose wheel fairing cover plate(3) is secured by the lower
torque link attaching bolt. Maitain weight of airplan
onnose gear while removing this bolt and cover plate.
a.

Remove bolt securing cover plate (3) and fairing (1) to strut and remove cover plate.
Reinstall torque link attach bolt

b.
c.

Weight or tie down tail of airplane to raise nose wheel off the floor.
Remove nose wheel axle stud (6).
WARNING
Bolt (4) securing tow bar spacers (2) also holds strut cylinder base plug retaining spacer in place. Ensure spacer

does not disengage from strut when removing bolt (4).
See figure 5-10.

5-37.

Remove bolt (4) securing speed fairing (1) and tow bar spacers (2) to strut.

e.
f.

Slide speed fairing up and remove nose wheel. Loosen scraper as necessary.
Rotate speed fairing 90 degrees and work fairing down over the fork to remove.

NOSE WHEEL
SPEED FAIRNG INSTALATION. (See figure 5-8.)
a. Rotate speed fairing 90 degrees and work fairing up over nose gear fork to install.

Slide fairing up and install nose wheel; install axle stud (6).

Tighten axle stud nut until a slight bearing drag is obvious when the wheel is rotated. Back off nut to the nearest castellation and install cotter pins.

d.
e.

Install bolt (4), tow bar spacers (2), washers, and nut attaching fairing to strut.
Adjust wheel scraper clearance in accordance with the following caution.
CAUTION
Always check scraper clearance after installing speed
fairing, whenever a tire has been changed, and whenever

scraper adjustment has been disturbed. Set clearane betwen tire and scraper for a minimum
of 0.25-inch to a
maximum of 0.50-inch. Elongated holes are provided in
the scraper for adjustment. If the airplane is flown from
surfaces with mud, snow, or ice, the speed fairing should
be checked to make sure there is no accumulation which
could prevent normal wheel rotation. Wipe fuel and oil

from speed fairing to prevent stains and deterioration.
f.
g.

Lower nose of airplane to floor.
Install cover plate and bolt attaching cover plate to strut.

5-23

MODEL 172 SERIES SERVICE MANUAL
17263459 thru 17271569
F17201235 thru F17201794

17271570 thru 17273369
F17201795 thru F17202029
17276575 & On

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

Speed Fairing
Tow Bar Spacer
Cover Plate
Fork Bolt
Scraper
Axle Stud
Ferrule
S2111-1 Washer
Door, Access
Latch
Plug

Figure 5-8. Nose Wheel Speed Fairing
5-24

Revision 3

17273370 thru 17276574
F17202030 And On

MODEL 172 SERIES SERVICE MANUAL
WHEEL REMOVAL. (See figure 5-7.)
Weight or tie down tail of aircraft to raise the nose wheel off the floor.
Remove nose wheel axle stud.
Pull nose wheel assembly from fork and remove axle tube from nose wheel. Loosen
wheel scraper if necessary, if wheel is equipped with a speed fairing.

5-38.

NOSE
a.
b.
c.

5-39.

DISASSEMBLY (McCauley.) (See figure 5-9, sheet 1.)
WARNING
Serious injury can result from attempting to separate
wheel halves with tire and tube inflated.
a.
b.
c.
d.
e.

Completely deflate tire and tube and break loose tire beads. Extreme care must be
exercised to prevent tire tool damage when removing tire from wheel halves (6).
Remove nuts (4) and washers (5).
Remove thru-bolts (8) and washers (5)
Separate and remove wheel halves (6) from tire and tube.
Remove retaining rings (1), grease seal retainer (2), felt grease seal (3). grease
retainer (2) and bearing cone (9) from each wheel half (6).

NOTE
Bearing cups (races) (7) are a press fit in wheel half (6)
and should not be removed unless a new part is to be
installed. To remove bearing cups, heat wheel half in
boiling water for 30 minutes. or in an oven, not to exceed
121°C (250°F). Using an arbor press, if available, press
out bearing cup and press in new bearing cup while wheel
half is still hot.
5-40.

INSPECTION AND REPAIR. (McCauley.) (See figure 5-9. sheet 1.)
a. Clean all metal parts and felt grease seals in Stoddard solvent or equivalent, and dry
thoroughly.
NOTE
A soft bristle brush may be used to remove hardened
grease, dust or dirt.
b.
c.

Inspect wheel halves (6) for cracks or damage.
Inspect bearing cones (9), cups (7). retaining rings (1) and seals (2) and (3), for wear or

damage.
Inspect thru-bolts (8) and nuts (4) for cracks in threads or cracks in radius of bolt
heads.
e. Replace cracked or damaged wheel half (6).
f. Replace damaged retaining rings (1) and seals (2) and (3).
g. Replace any worn or cracked thru-bolts (8) or nuts (4).
h. Replace worn or damaged bearing cups (7) or cones (9).
i. Remove any corrosion or small nicks.
j. Repair reworked areas of wheel by cleaning thoroughly, then applying one coat of
clear lacquer paint.
d.

5-25

MODEL 172 SERIES SERVICE MANUAL

MC CAULEY WHEEL

1.
2.
3.
4.
5.
6.
7.

8.
9.
10.
11.

Retaining Ring
Grease Seal Retainer
Felt Grease Seal
Nut
Washer
Wheel Half
Bearing Cup

Bolt
Bearing Cone
Tube
Tire

Figure 5-9. Nose Wheel and Tire (Sheet 1 of 2)
k. Pack bearings with grease specified in Section 2.
5-41.

REASSEMBLY. (McCauley.) (See figure 5-9, sheet 1.)
a. Assemble bearing cone (9). grease seal retainer (2), felt grease seal (3), grease seal
retainer (2) and retaining ring (1) into both wheel halves (6).
b. Insert tube in tire, aligning index marks on tire and tube.
c. Place wheel half (6) into tire and tube (side opposite valve stem). With washer (5)
under head of thru-bolt (8), insert bolt through wheel half (6).
d. Place wheel half (6) into other side of tire and tube, aligning valve stem in valve slot.
e. Install washers (5) and nuts (4) on thru-bolts (8) and pre-torque to 10-50 lb. in.
CAUTION
Uneven or improper torque of the nuts can cause failure
of the bolts with resultant wheel failure.

5-26

MODEL 172 SERIES SERVICE MANUAL

1.
Snap Ring
4.
Cone
5. Bearing
Outer Wheel

6.
7.
8.
9.
10.

Half
Tire
Tube
Inner WheelHalf
Bearing Cup
Thru-Bolt

CLEVELAND WHEEL
Figure 5-9. Nose Wheel and Tire (Sheet 2 of 2)

Prior to torquing nuts (4), inflate tube with approximately 10-15 psi
air pressure to
seat tire.
CAUTION
Do not use impact wrenches on thru-bolts or nuts.

g.
h.
5-42.

Dry torque all nuts (4) evenly to a torque value of 140-150 lb. in.
Inflate tire to correct pressure specified in chrt in Section 1.

DISASSEMBLY. (Cleveland.) (See figure 5-9. sheet 2.)

5-27

MODEL 172 SERIES SERVICE MANUAL
WARNING
Injury can result from attempting to separate wheel
halves with tire inflated. Avoid damaging wheel flanges
when breaking tire beads loose.
a.
b.
c.
d.

Deflate tire and break tire beads loose.
Remove thru-bolts and separate wheel halves.
Remove tire and tube.
Remove snap ring. grease seal felt, grease seal rings and bearing cones from both
wheel halves.

NOTE
Bearing are a press-fit in the wheel halves and should not
be removed unless replacement is necessary. To remove
bearing cups. heat wheel half in boiling water for 15
minutes. Using an arbor press, if available, press out
bearing cup and press in new cup while wheel is still hot.
5-43.

INSPECT AND REPAIR. (Cleveland.) (See to figure 5-9, sheet 2.)
a. Clean all metal parts and grease seal felts in solvent and dry thoroughly.
b. Inspect wheel halves for cracks. Cracked wheel halves must be replaced. Sand out
nicks, gouges and corroded areas. Where protective coating has been removed, area
should be cleaned thoroughly. primed with zinc chromate primer and painted with
aluminum lacquer.
c. Bearing cups and cones must be inspected carefully for damage and discoloration.
After cleaning, repack cones with clean aircraft wheel bearing grease (Section 2)
before installation in the wheel. To replace bearing cups. refer to note in paragraph 542.

5-44.

REASSEMBLY. (Cleveland.) (See figure 5-9. sheet 2.)
a. Insert tire in tube. aligning index marks on tire and tube.
b. Place tire and tube on wheel half and position valve stem through hole in wheel half.
c. Insert thru-bolts, position other wheel half. and secure with nuts and washers. Take
care to avoid pinching tube between wheel halves. Torque bolts to 90 lb-in.
CAUTION
Uneven or improper torque on thru-bolt nuts may cause
bolt failure with resultant wheel failure.
d. Clean and repack bearing cones with clean aircraft wheel bearing grease. (Section 2.)
e. Assemble bearing cones, seals and retainers into wheel halves.
f. Inflate tire to seat tire beads, then adjust to correct pressure (Section 1).
g. Install wheel in accordance with paragraph 5-45.

5-45.

5-28

NOSE
a.
b.
c.

WHEEL INSTALLATION. (See figure 5-7.)
Install axle tube in nose wheel.
Install nose wheel assembly in fork and install nose wheel axle stud.
Tighten axle stud until a slight bearing drag is obvious when wheel is rotated. Back
the nut off to the nearest castellation and insert cotter pins.

MODEL 172 SERIES SERVICE MANUAL
CAUTION
On aircraft equipped with speed fairings, always check
scraper-to-tire clearance after installing speed fairing,
whenever a tire has been changed, or whenever scraper
adjustment has been disturbed. Set scraper clearance in
accordance with instructions outlined in paragraph 5-37.

5-46. WHEEL BALANCING. Since uneven tire wear is usually the cause of wheel
unbalance, replacing the tire will probably correct this condition. Tire and
tube manufacturing tolerances permit a specified amount of static unbalance.
The light-weight point of the tire is marked with a red dot on the tire sidewall, and the heavy-weight point of the tube is marked with a contrasting
color line (usually near the inflation valve stem). When installing a new
tire, place these marks adjacent to each other. If a wheel shows evidence
of unbalance during service, it may be statically balanced. Wheel balancing
equipment is available from the Cessna Supply Division.
5-47.

NOSE GEAR SHOCK STRUT DISASSEMBLY. (See figure 5-10.)
NOTE
The following procedures apply to the nose gear shock
strut after it has been removed from the aircraft, and the
speed fairing and nose wheel have been removed. In
many cases, separation of the upper and lower strut will
permit inspection and parts installation without removal
or complete disassembly of the strut.
WARNING
Be sure shock strut is completely deflated before removing lock ring in lower end of upper strut, or disconnecting
torque links.
a.
b.
c.

Remove shimmy dampener.
Remove torque links. Note position of washers, shims and spacers.
Remove lock ring from groove inside lower end of upper strut. A small hole is
provided at the lock ring groove to facilitate removal of the lock ring.
NOTE
Hydraulic fluid will drain from strut halves as lower
strut is pulled from upper strut.

d. Using a straight, sharp pull separate upper and lower struts. Invert lower strut and
drain hydraulic fluid.
e. Remove lock ring and bearing at upper end of lower strut assembly. Note top side of
bearing.
f. Slide packing support ring, scraper ring, retaining ring and lock ring from lower
strut, noting relative position and top side of each ring: wire or tape together. if
desired.
g. Remove O-ring and back-up rings from packing support ring.
h. Remove bolt securing tow bar spacers.

5-29

MODEL 172 SERIES SERVICE MANUAL
NOTE
.

Use shims (2) as required between steering arm assembly (4) and washer (1) to
provide a snug fit with retainer ring (5)
installed. Also. adjust rod ends (3) to
provide dimension shown in detail A-A.

14-

SECTION A-A

NO. 40 (.098) HOLE

1.1.
2.
2.
3.
4.
5.
5.
6.
7.
7.
8.
9.

O-Ring

Pin Shock Strut
Figure 18.
27. Assembly
Tow Bar Spacer
5-10.Metering
Nose Gear

O-Ring
19.
Filler Valve
10.
Washer
Washer
10. Filler
Valve
19. O-Ring
20.
O-Ring
Ring
Lock Ring
11.
Required)
Shim
20. O-Ring
11. Lock
(As Required)
Shim (As
21. Base Plug
Rod End
12. Bearing
Steering
Fork
22. Fork
Strut
(Collar) 13. Lower Strut
Steering Arm Assembly (Collar)
Retaining Spacer
23. Retaining
14. Packing Support Ring 23.
Retaining Ring
24. Back-Up Ring
15. Scraper Ring
Decal
O-Ring
25. O-Ring
16. Retaining Ring
Strut
Upper Strut
O-Ring
26. O-Ring
Orifice Piston Support
17. Lock Ring
27. Tow Bar Spacer
18. Metering Pin
O-Ring

Figure 5-10.
5-30

Nose Gear Shock Strut Assembly

21
21
21

MODEL 172 SERIES SERVICE MANUAL
NOTE
Bolt attaching tow bar spacers also holds bushing and
base plug in place.
i.

Remove bolt attaching fork to strut barrel and remove base plug and metering pin
from lower strut. Remove O-rings and metering pin from base plug.
NOTE
Lower strut barrel and fork are a press fit, drilled on
assembly. Separation of these parts is not recommended,
except for installation of a new part.

Remove retaining ring securing steering arm assembly on upper strut, and remove
steering arm assembly, shims (if installed) and washer. If shims are installed. note
number and position of each shim.
k. Push orifice support from upper strut and remove O-ring.
1. Remove filler valve from orifice support

5-48. NOSE GEAR SHOCK STRUT INSPECTION AND REPAIR. (See figure 5-10.)
a. Thoroughly clean all parts in cleaning solvent and inspect them carefully.
b. All worn or defective parts and all O-rings and back-up rings must be
replaced with new parts.
c. Sharp metal edges should be smoothed with No. 400 emery paper,
then cleaned with solvent.
5-49. NOSE GEAR SHOCK STRUT REASSEMBLY.

(See figure 5-10.)

Assemble these parts, lubricated with a film of
Petrolatum VV-P-236, Hydraulic Fluid MIL-H5606, or Dow-Corning DC-7. Do not use DC-7
on surfaces to be painted.
a. Install washer (1) and shim(s), (2), if installed.
b. Lubricate needle bearings in steering collar (4), as shown in Section 2,
and install collar and retaining ring (5).
c. Check steering collar for snug fit against washer. Shims of variable
thicknesses are available from the Cessna Supply Division to provide
a snug fit for collar against washer.
NOTE

If shims are required, remove retaining ring and
steering collar and add shims as necessary to
provide a snug fit with steering collar retaining
ring installed. Shims are available in the following
part numbers and thicknesses: 1243030-5 (. 006 inch),
1243030-6 (. 012 inch), and 1243030-7 (. 020 inch).

5-31

MODEL 172 SERIES SERVICE MANUAL
d.
e.
f.

Install rod ends (3) in steering collar (4) and adjust rod ends to dimension specified in
Section A-A in figure 5-10.
Install O-ring (9) and filler valve (10) in orifice piston support (8) and install orifice
piston support in upper strut (7).
Install O-ring (20) and metering pin (18) with O-ring (19) in base plug (21); secure with
nut.
NOTE
If base plug (21) is to be replaced, new part will need to be
line-drilled to accept NAS75-5 bushing.

g. Install bushing (23) (if removed) in base plug (21), and install base plug assembly in
lower strut (13).
h. Align holes of bushing, hole in lower strut, and hole in fork. Install tow bar spacer
under head of bolt, and install bolt through fork, lower strut and bushing which is
installed in base plug. Install tow bar spacer on threaded end of bolt. install and
tighten nut.
i. Install lock ring (17). retaining ring (16) and scraper ring (15) on lower strut. making
sure they are installed in same positions as they were removed.
j. Install O-rings (25) and (26) and back-up rings in packing support ring (14); slide
packing support ring over lower strut (13).
k. Install bearing (12) and lock ring (11) at upper end of lower strut assembly. Note top
side of bearing.
1. Install upper strut assembly over lower strut assembly.
m. Install lock ring (17) in groove in lower end of upper strut. Position lock ring so that
one of its ends covers the small access hole in the lock ring groove (Section view CC.)
n. Install torque links, positioning washers. shims and spacers exactly in positions as
removed.
o. Install shimmy dampener.
p. After shock strut assembly is complete. install strut on aircraft as outlined in
paragraph 5-35.
q. After strut is installed on aircraft, fill and inflate shock strut in accordance with
procedures outlined in Section 2.
5-50.

TORQUE LINKS. (See figure 5-11.)

5-51.

DESCRIPTION. Torque links keep the lower strut aligned with the nose gear steering
system, but permit shock strut action.

5-52.

TORQUE LINK REMOVAL. (See figure 5-11.)
WARNING
Completely deflate strut before removing torque links.
a.
b.

5-53.

5-32

Completely deflate shock strut.
Disconnect upper and lower attaching bolts. spacers, shims and nuts: remove torque
links.

TORQUE LINK INSPECTION AND REPAIR. (See figure 5-11.) Torque link bushings should
not be removed except for replacement of parts: replace if excessively worn.

MODEL 172 SERIES SERVICE MANUAL

10
NOTE
Tighten bolts (8) to 20 to 25 pound inches. then safety the
bolts by bending tips of safety lug (10).
7

Tighten nuts (7) snugly, then tighten to align next castellation with cotter pin hole.

Shims (3) are available to use as required to remove any
looseness.

Spacer

Grease Fitting

3. Shim
4.

4
3

Bushing

Stop Lug

Upper Torque Link

Nut

8.
9.

Bolt
Lower Torque Link

10.

Safety Lug

Figure 5-11. Torque Links

5-54.

TORQUE LINK INSTALLATION. (See figure 5-11.)
NOTE
If bolts (8), safety lug (10) and stop lug (5) were removed,
upon installation. tighten bolts (8) to 20-25 pound-inches.
then safety the bolts by bending tips of safety lug (10).
a. With shock strut completely deflated, install upper and lower torque link assemblies.
b. Install bolt attaching upper and lower assemblies.
c. Tighten nuts (7) snugly, then tighten to align next castellation with cotter pin hole in
bolt.
d. Check upper torque link (6) and lower torque link (9) for looseness. If looseness is
apparent, remove nuts (7) and bolts and install shims (3) as necessary to take up any
looseness. This will assist in preventing nose wheel shimmy.
e. Retighten nuts (7) snugly, then tighten to align next castellation with cotter pin hole
in bolt; install cotter pin.
f. Fill and inflate shock strut in accordance with procedures outlined in Section 2.

5-33

MODEL 172 SERIES SERVICE MANUAL

1.
2.

O-Ring
Barrel

3.
4.

Snap Ring
Bearing Head

Piston Rod
Roll Pin
6.
Piston

Figure 5-12. Shimmy Damper

5-55.

SHIMMY DAMPER. (See figure 5-12.)

5-56.

DESCRIPTION. The shimmy damper, provided for the nose gear, offers resistance to
shimmy by forcing hydraulic fluid through small orifices in a piston. The damper piston
shaft is secured to a bracket, welded on the bottom of the upper strut tube. The shimmy
damper housing is secured to the steering arm assembly, which moves as the nose wheel is
turned, causing relative motion between the damper shaft and housing.

5-57.

SHIMMY DAMPER REMOVAL. (See figure 5-7.)
a. Remove cotter pin, nut, washers and bolt attaching piston shaft clevis to bracket
welded on bottom of upper strut tube.
b. Remove cotter pin, nut, spacer and bolt attaching housing to steering arm assembly.

Remove shimmy dampener.

5-58.

DISASSEMBLY AND REASSEMBLY. (See figure 5-12.) Refer to figure for disassembling
and reassembling the shimmy damper. When reassembling damper, install all new O-rings.
Lubricate all parts with clean hydraulic fluid, Petrolatum VV-P-236, or Dow Corning DC-7.
Keep DC-7 away from painted surfaces. When damper is completely assembled, service in accordance with procedures outlined in Section 2.

5-59.

SHIMMY
a.

DAMPER INSTALLATION. (See figure 5-7.)
Attach shimmy damper housing to steering arm assembly with bolt, spacer, nut and
cotter pin.

Attach shimmy damper piston rod clevis to bracket welded on bottom of upper strut

tube with bolt, washers (as required) and nut.

5-34

MODEL 172 SERIES SERVICE MANUAL
5-60.

NOSE WHEEL STEERING SYSTEM. (See figure 5-7.)

5-61.

DESCRIPTION. Nose wheel steering is accomplished through use of the rudder pedals.
Spring-loaded steering rod assemblies connect the nose gear steering arm assembly to arms
on the rudder bars. Steering is afforded up to approximately 10 degrees each side of neutral.
after which brakes may be used to gain a maximum deflection of 30 degrees right or left of
center. A flexible boot seals the fuselage entrance of the steering rod assembly.

5-62.

NOSE WHEEL STEERING ROD ASSEMBLIES. (See figure 5-7.)

5-63.

DESCRIPTION. The steering rods are connected by a clevis to the rod ends extending from
the nose gear steering arm, and to an arm on the rudder pedal crossbars.

5-64.

NOSE WHEEL STEERING ADJUSTMENT. Before attaching nose wheel steering rods to the
rod ends protruding from the steering arm assembly, adjust rod ends to the dimension
specified in section view A-A in figure 5-10. Since the nose wheel steering system and the
rudder system are interconnected, adjustment to one system might affect the other system.
Refer to Section 10 for instructions for rigging the nose wheel steering and the rudder
system.

5-65.

BRAKE SYSTEM. (See figure 5-3.)

5-66.

DESCRIPTION. The hydraulic brake system is comprised of two master cylinders, located
immediately forward of the pilot's rudder pedals, brake lines and hose connecting each
master cylinder to its wheel brake cylinder, and the single-disc, floating cylinder-type brake
assembly. located at each main landing gear wheel.

5-67.

TROUBLE SHOOTING.
TROUBLE

DRAGGING BRAKES.

PROBABLE CAUSE

REMEDY

Brake pedal binding.

Check and adjust properly.

Parking brake linkage holding brake pedal down.

Check and adjust properly.

Worn or broken piston
return spring (in master
cylinder.)

Repair, or install new
cylinder.

Insufficient clearance at
Lock-O-Seal or incorrect
adjustment of cylinder
overall length.
Restriction in hydraulic
lines or restrictions in
compensating port in
brake master cylinder.

Adjust as outlined in paragraph 5-84. (Thru aircraft
serials 17271034 and
F17201749.)
Drain brake line and clean
the inside of the brake line
with filtered compressed air.
If cleaning the lines fails to
give satisfactory results,
the master cylinder may be
faulty and should be repaired.

5-35

MODEL 172 SERIES SERVICE MANUAL
5-67.

TROUBLE SHOOTING (Cont).
TROUBLE

PROBABLE CAUSE

DRAGGING BRAKES.
Cont).

BRAKES FAIL TO
OPERATE.

REMEDY

Worn. scored or warped
brake disc.

Install new disc and brake
linings.

Damaged or accumulated
dirt restricting free movement of wheel brake parts.

Clean and repair or install
new parts as necessary.

Leak in system.

If brake master cylinders or
wheel cylinder assemblies
are leaking, repair, or install new parts.

Air in system.

Bleed system.

Lack of fluid in master
cylinders.

Fill and bleed system.

Defective master cylinder.

Repair, or install new parts.

5-68.

HYDRAULIC BRAKE LINES.

5-69.

DESCRIPTION. The brake lines are rigid tubing, except for flexible hose used at the brake
master cylinders. A separate line is used to connect each brake master cylinder to its
corresponding wheel brake cylinder.

5-70.

WHEEL BRAKE ASSEMBLIES. (See figure 5-3.)

5-71.

DESCRIPTION. (See figure 5-3.) The wheel brake assemblies use a floating brake assembly
and a disc which is attached to the main wheel.

5-72.

WHEEL BRAKE REMOVAL. (See figure 5-3.) Wheel brake assemblies can be removed by disconnecting the brake line (drain hydraulic brake fluid when disconnecting line) and removing the brake back plate. The brake disc is removed after the wheel is removed and disassembled. To remove the torque plate, remove wheel and axle.

5-73.

WHEEL BRAKE DISASSEMBLY. See figure 5-3 for a breakdown of wheel brake parts. This
figure may be used as a guide for disassembling the wheel brakes.

5-74.

WHEEL
a.

BRAKE INSPECTION AND REPAIR. (See figure 5-3.)
Clean all parts except brake linings and O-rings in dry cleaning solvent and dry

thoroughly.
b.

Install all new O-rings. If O-ring reuse is necessary, wipe with a clean cloth saturated in hydraulic fluid and inspect for damage.

NOTE
Thorough cleaning is important. Dirt and chips are the
greatest single cause of malfunctions in the hydraulic

brake system.

5-36

MODEL 172 SERIES SERVICE MANUAL

2
3

VENT HOLE

DO NOTS DAMAGE

9141312

THRU 1978 MODELS

15
ASSEMBLY OF PISTON

1.
2.
3.
4.
5.
6.

Clevis
Jam Nut
Piston Rod
Cover
Setscrew
Cover Boss

7. Body
8. Reservoir
9. O-Ring
10. Cylinder
11. Piston Return Spring
12. Nut
13. Piston Spring

Figure 5-13.

14. Piston
15. Lock-O-Seat
16. Compensating Sleeve
17. Filler Plug
18. Screw
19. Washer

Brake Master Cylinder (Sheet 1 of 2)
5-37

MODEL 172 SERIES SERVICE MANUAL

View
AA
1.
2.
3.
4.
5.
6.
7.
8.
9.

Clevis
Nut
Filler Plug
Cover
Piston
Back-up Ring
Packing
Spring
Cylinder Body

BEGINNING WITH
1979 MODELS
Figure 5-13.
5-38

Brake Master Cylinder (Sheet 2 of 2)

MODEL 172 SERIES SERVICE MANUAL
c.
d.
e.

f.
5-75.

Check brake lining for deterioration and maximum permissible wear. (Refer to
applicable paragraph for maximum wear limit.)
Inspect brake cylinder bore for scoring. A scored cylinder will leak or cause rapid 0ring wear. Install a new brake cylinder if the bore is scored.
If the anchor bolts on the brake assembly are nicked or gouged, they shall be sanded
smooth to prevent binding with the pressure plate or torque plate. When new anchor
bolts are to be installed, press out old bolts and install new bolts with a soft mallet.
Inspect wheel brakes disc for a minimum thickness of 0.190 (McCauley) or 0.205
(Cleveland). If brake disc is below minimum thickness, install a new part.

WHEEL BRAKE REASSEMBLY. (See figure 5-3.)

NOTE
Lubricate parts with clean hydraulic fluid during brake
reassembly.
See figure 5-3 for reassembling wheel brakes.
Thru 1981 Models, torque elbow (18) to a maximum of 60 lb. in. Lube/seal with Liquid O-Ring No. 404 (Oil Research, P.O. Box 51971, Lafayette, La. 7050).
Torque bolt (20) to 120-130 lb. in.
Thru 1981 Models, torque bleeder screw (21) to 30-40 lb. in.

a.
b.
c.
d.
5-76.

WHEEL BRAKE INSTALLATION.
a. Place brake assembly in position with pressure plate in place.
b. Install back plate.
NOTE
If torque plate was removed, install as the axle is
installed, or install on axle. If the brake disc was
removed, install as wheel is assembled.

5-77.

CHECKING BRAKE LINING WEAR. New brake lining should be installed when the
existing lining has worn to a minimum thickness of 3/32-inch. A 3/32-inch thick strip of
material held adjacent to each lining can be used to determine amount of wear. The shank
end of a drill bit of the correct size can also be used to determine wear of brake linings.

5-78.

BRAKE LINING INSTALLATION. (See figure 5-3.)
a.
b.
c.

Remove bolts securing back plate, and remove back plate.
Pull brake cylinder out of torque plate and slide pressure plate off anchor bolts.
Place back plate on a table with lining side down flat. Center a 9/64-inch (or slightly
smaller) punch in the rolled rivet, and hit the punch sharply with a hammer. Punch
out all rivets securing the linings to the back plate and pressure plate in the same
manner.

NOTE

d.
e.

A rivet setting kit, Part No. 199-00100, is available from
the Cessna Supply Division. This kit consists of an anvil
and punch.
Clamp the flat side of the anvil in a vise.
Align new lining on back plate and place brake rivet in hole with rivet head in the

Revision 1

5-39

MODEL 172 SERIES SERVICE MANUAL
lining. Place the head against the anvil.
f. Center rivet setting punch on lips of rivet. While holding back plate down firmly
against lining, hit punch with hammer to set rivet. Repeat blows on punch until lining is firmly against back plate.
g. Realign the lining on the back plate and install and set rivets in the remaining holes.
h. Install a new lining on pressure plate in the same manner.
i. Position pressure plate on anchor bolts and place cylinder in position so that anchor
bolts slide into the torque plate.
j. Install back plate with bolts and washers.
k. Refer to paragraph 5-90 for brake lining burn-in procedure.
5-79.

BRAKE SYSTEM BLEEDING.
NOTE
Bleeding with a clean hydraulic pressure source connected to the
wheel bleeder is recommended.
a. Remove brake master cylinder filler plug and screw flexible hose with appropriate fitting into the filler hole at top of the master cylinder.
b. Immerse opposite end of flexible hose in a container with enough hydraulic fluid to
cover the end of the hose.
c. Connect a clean hydraulic pressure source, such as a hydraulic hand pump or HydroFill unit, to the bleeder valve in the wheel cylinder.
d. As fluid is pumped into the system, observe the immersed end of the hose at the master brake cylinder for evidence of air bubbles being forced from the brake system.
When bubbling has ceased, remove bleeder source from wheel cylinder and tighten
the bleeder valve.

5-40

5-80.

BRAKE MASTER CYLINDER.

5-81.

DESCRIPTION. The brake master cylinders, located immediately forward of the pilot's
rudder pedals, are actuated by applying pressure at the top of the rudder pedals. A small
reservoir is incorporated into each master cylinder for the fluid supply. When dual brakes
are installed, mechanical linkage permits the copilot pedals to operate the master cylinders.

5-82.

BRAKE MASTER CYLINDER REMOVAL.
a. Remove front seats and rudder bar shield for access to the brake master cylinders.
b. Remove bleeder screw at wheel brake assembly and drain hydraulic fluid from brake
cylinders.
c. Disconnect parking brake and disconnect brake master cylinders from rudder pedals.
d. Disconnect hydraulic hose from brake master cylinders and remove cylinders.
e. Plug or cap hydraulic fittings, hose and lines, to prevent entry of foreign material.

5-83.

DISASSEMBLY. (Thru aircraft serials 17271034 and F17201749.) (See figure 5-13, sheet
lof2.)
a. Unscrew clevis (1) andjamnut (2).
h. Remove screw (18) and washer (19).
c. Remove filler plug (17) and setscrew(5).
d. Unscrew cover (4) and remove up over piston rod (3).
e. Remove piston rod (3) and compensating sleeve (16).
f. Slide sleeve (16) up over rod (3).
g. Unscrew nut (12) from threads of piston rod (3).
h. Remove spring (13) and 0-ring (9) from piston (14).

Revision 3

MODEL 172 SERIES SERVICE MANUAL
i.

Remove Lock-O-Seal (15).

5-84.

INSPECTION AND REPAIR. (Thru aircraft serials 17271034 and F17201749.) (See figure 513, sheet 1 of 2). Repair is limited to installation of new parts, cleaning and adjusting. (Refer
to reassembly paragraph for adjustment.) Use clean hydraulic fluid (MIL-H-5606) as a
lubricant during reassembly of the cylinders. Inspect Lock-O-Seal (Parker Seal Co. P/ N 800001-6) and replace if damaged. Replace all O-rings. Filler plug (17) must be vented so
pressure cannot build up in the reservoir during brake operation. Remove plug and drill
1/16-inch hole; 30 ° from vertical if plug is not vented.

5-85.

REASSEMBLY. (Thru aircraft serials 17271034 and F17201749.) (See figure 5-13, sheet 1 of 2.)
a. Install Lock-O-Seal (15) at bottom of piston rod (3).
b. Install O-ring (9) in groove in piston (14); insert piston spring (13) into piston. and
slide assembly up on bottom threaded portion of piston rod (3).
c. Run nut (12) up threads to spring (13). Tighten nut (12) enough to obtain 0.040 0.005inch clearance between top of piston and bottom of Lock-O-Seal as shown in the
figure.
d. Install piston return spring (11) into cylinder (10) portion of body (7).
e. Install piston rod end (3) through spring (11).
f. Slide compensating sleeve (16) over rod (3).
g. Install cover (4), washer (19) and screw (18).
h. Install jamb nut (2) and clevis (1).
i. Install filler plug (17), making sure vent hole is open.
j. Install setscrew (5).

5-86.

DISASSEMBLY. (Beginning with aircraft serials 17271035 and F17201750.) (See figure 5-13.
sheet 2 of 2.)
a.
b.

Unscrew clevis (1) and jamb nut (2).
Remove filler plug (3).
NOTE
A special tool, brake master cylinder wrench No. 34-101
is available from the Cessna Supply Division to accomplish the following step.

c.
d.
e.

Unscrew cover (4) and remove up over piston (5).
Remove piston (5) and spring (8).
Remove packing (7) and back-up ring (6) from piston (5).

5-87.

INSPECTION AND REPAIR. (Beginning with aircraft serials 17271035 and F17201750.) (See
figure 5-13. sheet 2 of 2.) Repair is limited to installation of new parts and cleaning. Use clean
hydraulic fluid (MIL-H-5606) as a lubricant during reassembly of the cylinders. Replace
packing and back-up ring. Filler plug (3) must be vented so pressure cannot build up during
brake operation. Remove plug and drill 1/16-inch hole, 30 ° from vertical. if plug is not
vented Refer to view A-A for location of vent hole.

5-88.

REASSEMBLY. (Beginning with aircraft serials 17271035 and F17201750.) (See figure 5-13.
sheet 2 of 2.)
a. Install spring (8) in cylinder body (9).
b. Install back-up ring (6) and packing (7) in groove of piston (5).
c. Install piston (5) in cylinder body (9).
d. Install cover (4) over piston (5) and screw cover into cylinder body (9).

5-41

MODEL 172 SERIES SERVICE MANUAL

e.
f.
5-89.

Install nut (2) and clevis (1).
Install filler plug (3), making sure vent hole is open.

BRAKE MASTER CYLINDER INSTALLATION.
a. Connect hydraulic hoses to brake master cylinders and install cylinders.
b. Connect brake master cylinders to rudder pedals and connect parking brake linkage.
c. Install bleeder screw at wheel brake assembly and fill and bleed brake system in accordance with paragraph 5-79.
d. Install rudder bar shield and install front seats.

NOTE
Ensure that seat stops are installed properly.
5-90.

BRAKE LINING BURN-IN. The brake pads are equipped with either a non-asbestos organic lining or an iron based metallic lining. These materials must be properly conditioned
(glazed) in order to provide maximum performance and service life. This is accomplished by
a brake burn-in.
a. Non-asbestos organic lining.
1. Taxi airplane for 1500 feet with engine at 1700 RPM applying brake pedal force
as needed to develop a 5 to 9 knots taxi speed.
2. Allow brakes to cool for 10 to 15 minutes.
3. Apply brakes and check to see if a high throttle static run up may be held with
normal pedal force. If so, burn-in is completed.
4. If static run up cannot be held. repeat steps 1 thru 3 as needed to successfully
hold.
b. Iron based metallic lining.
1. Perform two consecutive full stop braking applications from 30 to 35 knots. Do
not allow the brake discs to cool substantially between stops.

NOTE
Light brake usage can cause the glaze to wear off, resulting in
reduced brake performance. In such cases, the lining may be
conditioned again following the instructions set forth in this
burn-in procedure.

5-42

5-91.

PARKING BRAKE SYSTEM. (See figure 5-14.)

5-92.

DESCRIPTION. The parking brake system employs a handle and a ratchet mechanism
connected by a cable to linkge at the brake master cylinders. Pulling out on the handle depresses both master cylinder piston rods, and the handle ratchet locks the handle in this
position until the handle is turned and released.

5-93.

REMOVAL AND INSTALLATION OF COMPONENTS. See figure 5-14 for relative location of system components. The figure may be used for removal and installation of parts of
the system.

Revision 3

MODEL 172 SERIES SERVICE MANUAL

eHos

brake master cy-

Brake

2.
3.

Brake Master Cylinder
Control Assembly

Detail B

7. Catch
8.
10

-r

reB s 1 s

t em5
ak Sy 4.

Handle
Housing

11.
12.

Spring
Tube

14.
15.

Positioning Rack
Rudder Pedals

17.

Pulley

19
20.
21.

Bracket
Spring
Brake Line

gui F

18. Bellcrank

MODEL 172 SERIES SERVICE MANUAL
SECTION 6
AILERON CONTROL SYSTEM
Page No.
Aerofiche/

TABLE OF CONTENTS

Manual
AILERON CONTROL SYSTEM

Description ...............
Trouble Shooting ...........
Control "U" ...............
Description .............
Removal/Installation .......
Repair .................
Aileron Bellcrank ..........
Removal ................

1K11/6-7

Repair .................

.. 1K5/6-1

installatiON .............
Cables and Pulleys ..........
Removal/Installation .......
Ailerons .................
Removal ................
Installation .............
Repair .................
Rigging .................

1K5/6-1
1K5/6-1
1K6/6-2
1K6/6-2
1K7/6-3
1K7/-3
1K7/3
1K11/6-7

1K11/6-7
1K11/6-7
1K11/6-7
1K12/6-8
1K12/6-8
1K12/6-8
1K12/6-8
1K12/6-8

6-1.

AILERON CONTROL SYSTEM. (See figure 6-1.)

6-2.

DESCRIPTION. The aileron control system consists of two control wheels, one for the pilot
and one for the copilot, attached to columns and linked by universal joints to the control "U"
located behind the instrument panel. Lateral rotation of either control wheel is transmitted
to the ailerons, one per wing, via a series of sprockets. chains, pulleys, cables, bellcranks
and push-pull tubes.

6-3.

TROUBLE SHOOTING.
NOTE
Due to remedy procedures in the following trouble shooting chart it may be necessary to rerig system, refer to
paragraph 6-18.
TROUBLE

LOST MOTION IN CONTROL
WHEELS.

PROBABLE CAUSE

REMEDY

Loose control cables.

Adjust cables to proper
tension.

Broken pulley or bracket,
cable off pulley or worn
rod end bearings.

Replace worn or broken
parts. install cables
correctly.

Sprung bellcrank.

Replace bellcrank.

Loose chains.

Adjust chain tension.

Revision 2

6-1

MODEL 172 SERIES SERVICE MANUAL
6-3.

TROUBLE SHOOTING (Cont).
TROUBLE

PROBABLE CAUSE

REMEDY

Cables too tight.

Adjust cables to proper
tension.

Pulleys binding or cable
off.

Replace defective pulleys.
Install cables correctly.

Bellcrank distorted or
damaged.

Replace bellcrank.

Defective U-joints.

Replace defective U-joints.

Clevis bolts in system too
tight.

Loosen. then tighten properly and safety.

Rusty chain or chain binding with sprocket.

Replace chain or defective
parts.

Improper adjustment of
chains or cables. With
control wheel centered.
aileron bellcrank stop bushing should be centered in
slot (both left and right
bellcranks).

Adjust in accordance with
paragraph 6-18.

Improper adjustment of aileron push-pull rods.
If chains and cables are
properly rigged and bellcrank
stop bushings are not
centered in slots. pushpull rods are adjusted
incorrectly.

Adjust in accordance with
paragraph 6-18.

DUAL CONTROL WHEELS
NOT COORDINATED.

Chains improperly
adjusted.

Adjust in accordance with
paragraph 6-18.

INCORRECT AILERON
TRAVEL

Push-pull rods not
adjusted properly.

Adjust in accordance with
paragraph 6-18

Worn bellcrank stop bushings or bellcrank slots.

Replace worn parts.

RESISTANCE TO CONTROL
WHEEL MOVEMENT.

CONTROL WHEELS NOT
LEVEL WITH AILERONS
NEUTRAL.

6-4.

CONTROL "U". (See figure 6-2.)

6-5.

DESCRIPTION. The control "U" transforms rotation of the control wheels into pulling
motion on the aileron cables by means of sprockets and chains. The "U" is pivoted at the
lower end to operate the elevator control system.

6-2

MODEL 172 SERIES SERVICE MANUAL
6-6.

REMOVAL AND INSTALLATION.
a. Disconnect battery cables and insulate terminals as a safety precaution
b. Remove pedestal cover as outlined in paragraph 9-17.
c. Remove rudder bar shields, carpeting and plates as necessary for access to lower end
of control "U".
d. Remove radios, radio cooling plenums, dust covers and associated hardware as
necessary.
e. Remove glove box.
f. Remove cabin air cooling hose directly below right hand side of instrument panel.
g. Remove engine controls and cabin air controls as necessary.
h. Remove right hand forward side upholstery panel.
i. Remove bolt from each end of parking brake assembly and swing assembly away
from working area.
j. Remove bolt attaching bearing (11) to RH side of control "U" and remove bolt attaching roller (32) (beginning with 17265685 and F17201385) to LH side of control "U".

Remove bearing, roller and attaching hardware.
Drill out rivets attaching instrument panel support (after completion of step "j") and
remove support.
1. Drill out rivets attaching right hand side panel to pedestal structure and remove

panel.
Remove safety wire and disconnect direct cable turnbuckles (17).
Remove bolts (12) attaching control wheel tubes to universal joints (13.)
Remove bolt (19) attaching push-pull tube (18) to control "U".
Remove pivot bolt (20) and carefully work control "U" out from under right hand side
of instrument panel.
q. Reverse preceding steps for reinstallation.

m.
n.
o.
p.

NOTE
To prevent loss of strength and to ease reinstallation of
right hand pedestal structure side panel machine screws
and nuts may be installed in the two upper rivet holes.
provided at least No. 6 screws are installed.
Rig aileron control system in accordance with paragraph 6-18 and safety turnbuckles (17).
s. Check and/or rig elevator control system in accordance with paragraph 8-14.
t. Check and/or rig all engine and cabin air controls.
u. Check all radios and electrical components which may have been disconnected or
become inoperative while performing the preceding steps.
v. Reinstall all items removed for access.
r.

6-7.

REPAIR. Repair consists of replacing worn. damaged or defective shafts. bearings.
bushings, sprockets, roller chains, universal joints or other components. Refer to Section 2
for lubrication requirements.

6-8.

AILERON BELLCRANK. (See figure 6-3.)

6-3

MODEL 172 SERIES SERVICE MANUAL

Figure 6-1. Aileron Control System (Sheet 1of 2)
6-4

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.

Spacer
Pulley
Cable Guard

4.
5.

Carry-Thru Cable Turnbuckle
Carry-Thru Cable

6. Bellcrank
7. Aileron
8.
9.

Bushing
LH Direct Cable

10.
11.
12.

RH Direct Cable
Direct Cable
Pulley Bracket

13.
14.

LH
RH Direct
Direct Cable
Cable Turnbuckle
Turnbuckle

2
Detail C

* THRU 17269874 & F17201829
17269875 & ON
F17201830 THRU F17202233

Detail D

CAUTION
Maintain specified cable tension. Direct and followthr cables: 40 ± 10 lbs at average temperature for
the area.

Figure 6-1. Aileron Control System (Sheet 2 of 2)
6-5

MODEL 172 SERIES SERVICE MANUAL
NOTES
Install cable drum (8) with wide groove aft.
Primary cable (7) is wrapped once around aft
groove of cable drum (8) with cable lock (9) on
bottom.
Direct cable (16) is installed in forward groove
of cable drum (8) with lock (14) on top.
26

23
12
1.

Detail A
LH AND RH CONTROLS
*Bushing (10), bearing (11), and washer (30) used thru:
17265684 and F17201384.

Sprocket
2. Bolt
3. Spacer
4. Chain
Secondary Cable
5.
6. Secondary Cable
Turnbuckle
7. Primary Cable
8. Cable Drum
9. Primary Cable Lock
10. Bushing
11.
Bearing
12. Bolt
13. Universal Joint
.14. Direct Cable Lock
15. Primary Cable Turnbuckle
16. Direct Cable
17. Direct Cable Turnbuckle
18. Elevator Push-Pull Tube
19. Bolt
20. Pivot Bolt

NOTE

21.
22.
23.
24.
25.
26.
27.
28.
29.

Hose
Copilot's Control Wheel
Control Tube
Shaft
Retainer
Pilot's Control Wheel
Bearing
Countersunk Washer
Shaft

When dual controls are NOT installed, spacer (3) replaces
copilot's control wheel (22), control tube (23), and universal
joint (13).

30.
31.
32.

Washer
Spacer
Roller

LH CONTROLS
Spacer (31) and roller (32) beginning serials:
17265685 and ON.
F17201385 thru F17202233.

Figure 6-2. Control "U" Installation
6-6

MODEL 172 SERIES SERVICE MANUAL
6-9.

REMOVAL.
a. Remove access plate inboard of each bellcrank on underside of wing.
b. Relieve control cable tension by loosening turnbuckle barrel (17).
c. Disconnect control cables from bellcrank Retain all spacers (12).
d. Disconnect aileron push-pull rod (8) at bellcrank.
e. Remove nuts, washers and bolts securing bellcrank stop bushing (15) and bellcrank

(7) to wing structure.
f.

Remove bellcrank through access opening, using care that bushing (5) is not dropped
from bellcrank.
NOTE
Brass washers (11) may be used as shims between lower
end of bellcrank and wing channel (9). Retain these
shims. Tape open ends of bellcrank to prevent dust and
dirt from entering bellcrank needle bearings (6).

6-10.

REPAIR. Repair of bellcranks consists of replacement of defective parts. If needle bearings
are dirty or in need of lubrication, clean thoroughly and lubricate as outlined in Section 2.

6-11.

INSTALLATION.
a. Place bushing (5) and stop-bushing (15) in bellcrank (7) and position bellcrank in

wing.
b.
c.
d.
e.
f.

Install brass washers (11) between lower end of bellcrank and wing channel (9) to
shim out excess clearance.
Install bellcrank pivot bolt (4). washers and nut.
Position bellcrank stop-bushing and install attaching bolt (16), washers and nut.
Connect aileron cables and push-pull rod to bellcrank.
Rig aileron system in accordance with applicable paragraph in this section, safety
turnbuckle (17) and reinstall all items removed for access.

6-12.

CABLES AND PULLEYS. (See figure 6-1.)

6-13.

REMOVAL AND INSTALLATION.
a. Remove access plates, wing root fairings and upholstery as required
b. Disconnect cables from aileron bellcranks and remove cable guards and pulleys as
necessary to work cables free of aircraft
NOTE
To ease routing of cables, a length of wire may be attached
to end of cable before being withdrawn from aircraft
Leave wire in place. routed through structure:then attach
cable being installed and use to pull cable into position.
c.
d.

After cable is routed install pulleys and cable guards. Ensure cable is positioned in
pulley groove before installing guard.
Rig aileron system in accordance with applicable paragraph in this section. safety
turnbuckles and install access plates, fairings and upholstery removed in step "a"

6-7

MODEL 172 SERIES SERVICE MANUAL
6-14.

AILERONS. (See figure 6-3.)

6-15.

REMOVAL.
a. Disconnect push-pull rod (8) at aileron.
b. Remove screws and nuts attaching aileron hinges (2) to trailing edge of wing.
c. Using care, pull aileron out and down to slide hinges from under wing skin and
auxiliary spar reinforcements.

6-16.

INSTALLATION.
a. Position aileron hinges between skin and auxiliary spar reinforcements and install
screws and nuts attaching hinges to trailing edge of wing.
b. Attach push-pull rod (8) to aileron.
NOTE
If rigging was correct and push-pull rod adjustment was
not disturbed, it should not be necessary to rig system.
c.

Check aileron travel and alignment rig if necessary, in accordance with applicable
paragraph in this section.

6-17.

REPAIR. Aileron repair may be accomplished in accordance with instructions outlined in
Section 18. Before installation, ensure balance weights and hinges are securely attached.

6-18.

RIGGING. (See figure 6-2.)
a.

Check primary cable (7) is in aft groove of cable drum (8) and wrapped once around
drum. The primary cable lock (9) is installed at bottom of drum and direct cable look

(14) is installed at top.
b.

With control wheels neutral, check chain ends (4) are approximately equidistant

from center of sprockets (1).
c.

Keeping control wheels neutral, tighten secondary cable turnbuckles (6) so control
wheels are level in neutral position (synchronized), with enough tension on cables to
remove slack from chains (4), without binding. Results of adjusting turnbuckles are
as follows:
1. Loosening secondary cable turnbuckles (6) and tightening direct cable turnbuckles (17) at center of control "U" will move inboard sides of both control wheels
down.
2. Tightening either primary control cable turnbuckle (15) and loosening secondary
cable turnbuckles (6) at center of control "U"will move outboard side of applicable control wheel down.
d. Tape a bar across both control wheels to hold them in neutral position
e.
Adjust direct cable turnbuckles (17) below control "U" and single carry-thru
turnbuckle (index 17, figure 6-3) at aileron bellcrank (index 7, figure 6-3) so bellcrank
stop bushings (index 15, figure 6-3) are centered in both bellcrank slots with 40 ± 10
pounds tension on aileron carry-thru cable (index 18. figure 6-3). Disregard tension
on direct cables. which will be different than tension on carry-thru cable.
f.
Adjust push-pull rods (index 8. figure 6-3) at each aileron until ailerons are neutral
with reference to trailng edge of wing flaps. Be sure wing flaps are fully up when
making this adjustment.
g. Remove bar from control wheels.

6-8

Revision 2

MODEL 172 SERIES SERVICE MANUAL

NOTE
14
Carry-thru cable turnbuckle (17)
is located at RH aileron bellcrank
thru 17269874 and F17201829.
Carry-thru cable turnbuckle (17)
is located above headliner
beginning 17269875 and F17201830.

16
1.
2.
3.
4.
5.

Aileron
Hinge
Balance Weight
Pivot Bolt
Bushing

7. LH Bellcrank
8. Push-Pull Rod
9. Channel
10. Lower Wing Skin
11. Brss Washer
12. Spacer
13. Direct Cable
14. Bushing

15. Bushing
16. Bolt
17.

Detail A

18.
19.

Carry-Thru Cable
Turnbuckle
Carry-Thru Cable
Washers

Figure 6-3. Aileron Installation(Sheet 1 of 3)

6-9

MODEL 172 SERIES SERVICE MANUAL

2. Hinge
3. Balance Weight
20. Hinge Pin
21.

Hinge

22.
23.

Cotter Pin
Hinge Pin

Detail B

AILERON HINGE (TYP)
Used through Serials 17276254 and F17202233.

AILERON HINGE (TYP)
Beginning Serial: 17276255 and ON.
Detail C

NOTE
Install loop of hinge pin (23) on outboard end of

hinge.

Figure 6-3. Aileron Installation (Sheet 2 of 3)
6-10

MODEL 172 SERIES SERVICE MANUAL

Detail D

2.
20.
24.
25.

Hinge
Hinge Pin
0.89 Diameter Drill Rod
MS24665 Cotter Pin

NOTE
The following method may be utilized to check wear on
aileron hinges used prior to Serial 17276254 and
F17202233. Refer to Service Letter SE83-18 for specific
serials affected.
(1)
(2)
(3)

(4)

Remove cotter pins (22) from both ends of hinge.
Push drill rod (24) or number 43 drill bit into hole past holes from which cotter
pins (25) were removed.
Bend one leg of cotter pin (25) back and attempt to install the other leg into the
cotter pin hole past drill rod (24). If leg of cotter pin (25) GOES, replace hinge
(2). If NO GO condition exits, hinges are not worn sufficiently to require replacement.
Remove drill rods (24) and replace new cotter pins (25) in hinges (2).

Figure 6-3. Aileron Installation (Sheet 3 of 3)

6-11

MODEL 172 SERIES SERVICE MANUAL

AVAILABLE FROM CESSNA SUPPLY DIVISION (TOOL NO. SE716)

Figure 6-4. Inclinometer for Measuring Control Surface Travel

i.
j.

Check ailerons for correct travel (figure 1-1) using an inclinometer (illustrated in
figure 6-4). Make adjustments if necessary and check that the bushing travel stops
are properly centered in the bellcranks.
Safety all turnbuckles by the single-wrap method.
Install all items removed for access.
NOTE
Be sure ailerons move in correct direction when operated
by control wheel.

6-12

MODEL 172 SERIES SERVICE MANUAL
SECTION 7
WING FLAP CONTROL SYSTEM
TABLE OF CONTENTS

WING FLAP CONTROL SYSTEM.
Description ...............
Operation Check ...........
Trouble Shooting ...........
Motor Transmission Assembly .
Removal Installation .......
Repair .................
Drive Pulleys ..............
Removal/Installation .......
Repair .................

Page No.
Aerofiche/
Manual
1K21/7-1
1K21/7-1
1K21/7-1
1K22/7-2
1K24/7-4
1K24/7-4
1L1/7-5
1L1/7-5
1L1/7-5
1L1/7-5

Flaps ...................
Removal/Installation .......
Repair .................
Cable and Pulleys ..........
Removal/Installation .......
Rigging ..............
Follow-Up and Indicating
System ..................
Description .............
Removal/Installation .......
Rigging ................

1L1/7-5
1L1/7-5
1L1/7-5
1L1/7-5
1L1/7-5
1L37-7
1L6/7-10
1L6/7-10
1L8/7-12
1L8/7-12

7-1.

WING FLAP CONTROL SYSTEM. (See figure 7-1.)

7-2.

DESCRIPTION. The wing flap control system is comprised of an electric motor and
transmission assembly, drive pulleys, push-pull rods, cables and a follow-up control. Power
from the motor and transmission assembly is transmitted to the flaps by a system of drive
pulleys, cables and push-pull rods. Electrical power to the motor is controlled by two
microswitches mounted on a floating arm assembly, by a camming lever and a follow-up
control. As the flap control lever is moved to the desired flap setting, the attached cam trips
one of the microswitches. activating the flap motor. As the flaps move to the position
selected, the floating arm is rotated by the follow-up control until the active microswitch
clears the cam breaking the circuit and stopping the motor. To reverse flap direction, the
control lever is moved in the opposite direction causing the cam to trip the second
microswitch which reverses the flap motor. The follow-up control moves the cam until it is
clear of the second switch, shutting off the flap motor. Limit switches at the flap actuator
assembly control flap travel as the flaps reach the full UP or DOWN positions.

7-3.

OPERATIONAL CHECK.

Operate flaps through their full range of travel observing for uneven travel or jumpy
motion, binding or lost motion. Ensure flaps are moving together through their full
range of travel.
b. Check for positive shut-off of motor at flap travel extremes to prevent damage to
actuator assembly.
c. With flaps full UP, mount an inclinometer on one flap and set to 0 ° . Lower flaps to full
DOWN position and check flap angle as specified in figure 1-1. Check approximate
mid-range percentage setting against degrees as indicated on inclinometer. Repeat
the same procedure for the opposite flap.
NOTE
An inclinometer for measuring control surface travel is
available from the Cessna Supply Division. See figure 6-4.

Revision 1

7-1

MODEL 172 SERIES SERVICE MANUAL
d.
e.
7-4.

Remove access plates adjacent to flap drive pulleys and attempt to rock pulleys to
check for bearing wear.
Inspect flap rollers and tracks for evidence of binding or defective parts.

TROUBLE SHOOTING.
NOTE
Due to remedy procedures in the following trouble shooting chart it may be necessary to rerig system, refer to
parapaphs 7-16 and 7-20.
TROUBLE

BOTH FLAPS FAIL TO
MOVE.

BINDING IN SYSTEM AS
FLAPS ARE RAISED AND
LOWERED.

7-2

PROBABLE CAUSE

REMEDY

Open circuit breaker.

Reset and check continuity.
Replace breaker if defective.

Defective switch.

Place jumper across switch.
Replace if defective.

Defective motor.

Remove and bench test motor.
Replace if defective.

Broken or disconnected
wires.

Run a continuity check of
wiring. Connect or repair
wiring.

Defective or disconnected
transmission.

Connect transmission. Remove.
bench best and replace transmission if defective.

Defective limit switch.

Check continuity of switches.
Replace switches found defective.

Cables not riding on
pulleys.

Check visually. Route
cables correctly over
pulleys.

Bind in drive pulleys.

Check drive pulleys in
motion. Replace drive pulleys found defective.

Broken or binding pulleys.

Check pulleys for free
rotation or breaks.
Replace defective pulleys.

Frayed cable.

Check visually. Replace
defective cable.

Flaps binding on tracks.

Observe flap tracks and
rollers. Replace defective
parts.

MODEL 172 SERIES SERVICE MANUAL

Detail

SEE FIGURE 7-2

SEE FIGURE 7-3
SEE FIGURE 7-5

SEE FIGURE 7-5

1. Cable Guard

2. Pulley
3. Washer
4. Direct Cable

5. Retract Cable
6. Turnbuckle
7. Bolt

8. Screw
9. Bracket

BEGINNING 17274125
AND F17202040

10.
11.
12.
13.
14.

Detail

Follow-Up Control
Flap Control Lever
Flap
Drive Pulley
Spacer

CAUTION
MAINTAIN SPECIFIED CONTROL
CABLE TENSION.

CABLE TENSION:
30 LBS ± 10 LBS (AT AVERAGE TEMPERATURE FOR THE AREA.)
REFER TO FIGURE 1-1 FOR TRAVEL.

Figure 7-1. Wing Flap Control System
7-3

MODEL 172 SERIES SERVICE MANUAL

LEFT FLAPS FAILS TO
MOVE.

Disconnected or broken
cable.

Check cable tension. Connect or replace cable.

Disconnected push-pull
rod.

Check visually. Attach
push-pull rod.

Incorrect rigging.

Refer to paragraph 7-16.

Defective operating switch.

Check continuity of switches.
Replace switches found defective.

FLAPS FAIL TO RETRACT.

Defective or disconnected
flaps UP operating switch.

Check continuity of switch.
Connect or replace switch.

FLAPS FAIL TO EXTEND.

Defective or disconnected
flaps DOWN operating
switch.

Check continuity of switch.
Connect or replace switch.

INCORRECT FLAP TRAVEL.

7-5.

FLAP MOTOR AND TRANSMISSION ASSEMBLY.

7-6.

REMOVAL AND INSTALLATION (See figure 7-2.)
a. Run flaps to full DOWN position.
b. Disconnect battery ground cable and insulate terminal as a safety precaution.
c. Remove access plates beneath flap motor and transmission assembly in right wing.
NOTE
Flap motor (9). transmission (7), hinge assembly (10) and
actuating tube (5) are removed from the aircraft as a unit.
On aircraft equipped with long range fuel tank. it may be
easier to detach motor and transmission assembly before
removal from wing.
d.
e.
f.

Remove bolt (20) securing actuating tube (5) to drive pulley (13).
Screw actuating tube (5) in toward transmission (7) as far as possible by hand.
Remove bolt (1) securing flap motor hinge (10) to wing. Retain brass washer between
hinge and wing structure for use on reinstallation.
g. Disconnect motor electrical leads at quick-disconnects.
h. Disconnect wiring at limit switches (23 and 26).
i. Carefully work assembly from wing through access opening.
j. Reverse preceding steps for reinstallation. If hinge assembly (10) was removed from
the transmission (7) for any reason, ensure that short end of hinge is reinstalled
toward the top.
k. Use Loctite grade CV adhesive on threads of setscrew (6) and collar (24) whenever
actuating tube (5) is removed. Torque setscrew to 60 pound-inches.
l. Complete operational check as outlined in paragraph 7-3 and rerig system in
accordance with paragraph 7-16.

7-4

MODEL 172 SERIES SERVICE MANUAL
7-7.

REPAIR. Repair consists of replacement of motor, transmission, actuating tube and
associated hardware. Bearings in hinge assembly may also be replaced. Lubricate as
outlined in Section 2.

7-8.

DRIVE PULLEYS. (See figure 7-2.)

7-9.

REMOVAL AND INSTALLATION.
a. Remove access plate adjacent to drive pulley (13) in right wing.
b. Unzip or remove headliner as necessary for access to turnbuckles (index 4. figure 71), remove safety wire and loosen turnbuckles.
c. Remove bolt (19) securing flap push-pull rod (14) to drive pulley (13) and lower
RIGHT flap gently.
d. Remove bolt (20) securing actuating tube (5) to drive pulley (13) and lower LEFT flap
gently. Retain bushing.

Remove cable locks (12) securing control cables to drive pulley (13). Tag cables for
reference on reinstallation.
f. Remove bolt (11) attaching drive pulley (13) to wing structure.
g. Using care, remove drive pulley through access opening, being careful not to drop
bushing. Retain brass washer between drive pulley and wing structure for use on
reinstallation. Tape open ends of drive pulley after removal to protect bearings.
h. To remove left wing drive pulley, use this same procedure omitting step "d."
i. Reverse the preceding steps for reinstallation. Rig system in accordance with
paragraph 7-16, safety turnbuckles and reinstall all items removed for access.
e.

7-10

REPAIR. Repair is limited to replacement of bearings. Cracked, bent or excessively worn
drive pulleys must be replaced. Lubricate bearings as outlined in Section 2.

7-11.

FLAPS. (See figure 7-3.)

7-12.

REMOVAL AND INSTALLATION.
a. Run flaps to full DOWN position.
b. Remove access plates (1) from top leading edge of flap.
c. Disconnect push-pull rod (6) at flap bracket (7).
d. Remove bolts (5) at each flap track. As flap is removed from wing, all washers, rollers
and bushings will fall free. Retain these for reinstallation.
e. Reverse the preceding steps for reinstallation. If push-pull rod (6) adjustment is not
disturbed, rerigging of system should not be necessary. Check flap travel and rig in
accordance with paragraph 7-16, if necessary.

7-13.

REPAIR. Flap repair may be accomplished in accordance with instructions outlined in
Section 18.

7-14.

CABLES AND PULLEYS. (See figure 7-1.)

7-15.

REMOVAL AND INSTALLATION.
a. Remove access plates, fairings, headliner and upholstery as necessary for access.
b. If direct cable (4) is to be removed, disconnect clamp (index 7, figure 7-5) from
bellcrank (index 2, figure 7-5).
c. Remove safety wire, relieve cable tension, disconnect turnbuckles (6) and carefully
lower LEFT flap.
d. Disconnect cables at drive pulleys, remove cable guards and pulleys as necessary to
work cables free of aircraft.

7-5

MODEL 172 SERIES SERVICE MANUAL

NOTE
Use Loctite grade CV adhesive on
threads of setscrew (6) and collar
(24) whenever actuating tube (5) is
removed. Torquesetscrew to 60
pound-inches.

20. Wing Structure

5.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.

Actuating Tube
Transmission Assembly
Electrical Wiring
Motor Assembly
Hinge Assembly
Bolt
Cable Lock
Drive Pulley
Push-Pull Rod
Attach Bracket
Bolt
Direct Cable
Retract Cable
Bolt
Bolt
Set Screw
Switch Adjustment Block
Up-Limit Switch
Switch Actuating Collar
Support
Down-Limit Switch

VIEW A-A

Figure 7-2.
7-6

Flap Motor and Transmission Installation

MODEL 172 SERIES SERVICE MANUAL

NOTE
To ease routing of cables, a length of wire may be attached
to the end of cable being withdrawn from the aircraft.
Leave wire in place. routed through structure;then attach
the cable being installed and use wire to pull cable into
position.
Reverse the preceding steps for reinstallation.
After cables are routed in position. install pulleys and cable guards. Ensure cables
are positioned in pulley grooves before installing guards
g. Rerig flap system in accordance with paragraph 7-16 and safety turnbuckles.
h. Rerig follow-up system in accordance with paragraph 7-20 and reinstall all items
removed in step "a."

e.
f.

7-16.

RIGGING.
a. (See figure 7-1.) Unzip or remove headliner as necessary for access to turnbuckles (6).
b. With flaps in the full UP position. disconnect follow-up cable (index 4. figure 7-5) by
removing clevis attaching follow-up cable to bellcrank (index 2. figure 7-5).
c. (See figure 7-1.) Remove safety wire, relieve cable tension, disconnect turnbuckles
(6) and carefully lower left flap.
d. (See figure 7-2.) Disconnect push-pull rods (14) at drive pulleys (13) in both wings and
lower RIGHT flap gently.
e. Disconnect actuating tube (5) from drive pulley (13).
NOTE
If control cables are not connected to left and right drive
pulleys, actuating tube (5) and push-pull rods (14) must
be disconnected before installing cables. If drive pulleys
(13) are not installed attach control cables before installing drive pulleys in the wings as illustrated in figure 7-4.
f.

Adjust both push-pullrods (14) to 8.83 ±.12 inches between centers of rod end bearings
and tighten locknuts on both ends. Connect push-pull rods to flaps and drive pulleys.
NOTE
Temporarily connect cables at turnbuckles (index 6.
figure 7-1) and test flaps by hand to ensure both flaps
extend and retract together. If they will not, the cables are
incorrectly attached to the drive pulleys. Ensure that the
right drive pulley rotates clockwise when viewed from
below, as the flaps are extended. Tag cables for reference
and disconnect turnbuckles again.

7-7

MODEL 172 SERIES SERVICE MANUAL

NOTE
Beginning with Serial 17276296, the access plates (1) are attached with recessed
head screws in place of truss head screws.
* Airplanes 17261445,17267585 and On and
F17201515 and On incorporating SK180-44.
When incorporating SK180-44only stainless steel
washers (12) are used.

NOTE
Bushings (4), rollers (3) and spacers (9) are
first positioned through slots in flap tracks,
then are secured to the flap roller supports (2)
with attaching bolts, washers and nuts. Nylon
plug buttons (11) prevent wing flap from chafing
wing trailing edge.
Position spacers (9) and direction of bolts (5) as
required to provide adequate flap clearance at
wing root, flap well skin and aileron. Some lateral movement of flap is inherant due to the width
of rollers. This movement should be considered
when positioning spacers and direction of bolts.

Detail
1.
2.
3.
4.

B
9

Access Plate
Flap Support
Roller Assembly
Bushing

4
9

5. Bolt

6.
7.
8.
9.
10.
11.
12.

Push-Pull Rod
Flap Bracket
Bolt
Spacer
Plug Button
Nylon Plug Button
Stainless Steel Washer

9
Detail C

9
4
Detail C
THRU 1980 MODELS

BEGINNING WITH
1981 MODELS

OUTBOARD HINGE

Figure 7-3.
7-8 Revision 3

Flap Installation

MODEL 172 SERIES SERVICE MANUAL

g. (See figure 7-2.) Screw actuating tube (5) IN toward transmission (7) by hand to .12 .05 inches between switch actuating collar (24) and transmission as illustrated in
View A-A.
h. Loosen setscrew (6) securing actuating tube (5) to switch actuating collar (24) and
hold collar to maintain .12 ± .05 inch while holding RIGHT flap in the full UP position
and adjust actuating tube (5) IN or OUT. as necessary to align with attachment hole in
drive pulley (13).
i. Apply Loctite grade CV sealant (or equivalent) to threads of setscrew (6) and torque
to 60 inch-pounds.
NOTE
If actuating tube (5) is too long to allow attachment to
drive pulley after completion of step "h". proceed to step
j.
k.

Disconnect push-pull rod (14) at drive pulley (13) to allow connecting actuating tube
(5) to drive pulley.
Manually hold RIGHT flap in full UP position and readjust push-pull rod (14) to align
with attachment hole in drive pulley. Connect push-pull rod and tighten locknuts
NOTE
The right flap and actuator must be correctly rigged.
before cables and left flap can be rigged.

With flaps in full UP position, loosen setscrew (21) and slide up limit switch
adjustment block (22) on support (25) to just activate switch and shut off electrical
power to motor at this position. Tighten setscrew.
m. Manually hold LEFT flap. full UP and connect control cables at turnbuckles (index 6.
figure 7-1). Remove reference tags previously installed.
n. With flaps full UP, adjust turnbuckles to obtain 30 ± 10 pounds tension on cables.
Adjust retract cable (18) first.
NOTE
Ensure cables are positioned in pulley grooves and cable
ends are positioned correctly at drive pulleys before
tightening turnbuckles.

Disconnect push-pull rod at left drive pulley. Run motor to extend flaps approximately 20 ° and check tension on each flap cable. If necessary, readjust turnbuckles to
maintain 30 ± 10 pounds tension on each cable and safety turnbuckles.
p. Fully retract right flap. Manually hold left flap in full UP position and readjust pushpull rod to align with attaching hole in drive pulley. Connect push-pull rod and
tighten locknuts.
NOTE
An inclinometer for measuring control surface travel is
available from the Cessna Supply Divison. See figure 6-4.

7-9

MODEL 172 SERIES SERVICE MANUAL
FLAP MOTOR AND
TRANSMISSION
FWD
DRIVE

PULLEY

DRIVE PULLEY
SETSCREW

TO LEFT

TO RIGHT
VIEWED
FROM
ABOVE
Figure
7-4.
Flap System Schematic
TURNBUCKLES

WING FLAP

WING FLAP
VIEWED
FROM7-4.
ABOVE
Figure
Flap System Schematic

q. Mount an inclinometer on RIGHT flap and adjust to 0°.
r. Run flaps to full DOWN position and adj ust DOWN limit switch (32) to stop motor and
flap at the degree of travel specified in figure 1-1. Repeat check on LEFT flap.
Recheck limit switch through several flap cycles.
NOTE
All flap rollers may not bottom in the flap tracks at the
travel extremes.
s.

Reconnect and rerig the flap follow-up system in accordance with paragraph 7-20.
Perform an operational check in accordance with paragraph 7-3. recheck all items for
proper safetying and replace items removed for access.

7-17.

FLAP FOLLOW.UP AND INDICATING SYSTEM. (See figure 7-5.)

7-18.

DESCRIPTION.The flap follow-up and indicating system consists of a sheathed cable
assembly. pointers and microswitches. One end of the cable is attached to the flap
operating switch operating arm. The other end is clamped to the flap direct cable, above
the headliner in the rear cabin area. Motion of the flap cable is transmitted through the
follow-up control to the pointer. attached to the switch mounting arm. Pointer moves
along a scale as the flaps are extended or retracted. When the motion of the switch
mounting arm with the attached operating switches positions the "active" operating
switch to clear the cam on flap lever, flap motor circuit is broken and flaps stop at
selected position.

7-10

MODEL 172 SERIES SERVICE MANUAL

Detail A
NOTE
Lubricate slots of guide (1) and bellcrank (2)
with Lubri-Bond "A" or Lubri-Bond 220
(Electrofilm Inc.) North Hollywood, California
or Perma-Silk (Everlube Corp.,) North Holly-

wood, California
*

Thru 17272169 & F17201909
Beginning 17272170 & F17201910

Detail A

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.

Guide
Bellcrank
Mounting Bracket
Follow-Up Cable
Bushing
Flap Direct Cable
Clamp
Washer
Teflon Washer
Support
Bracket
Knob

13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Flap Lever
Position Indicator
Spacer
Switch Mounting Arm
Clamp Bolt
Flaps DOWN Operating Switch
Cam
Flaps UP Operating Switch
Spring
Clamp Bolt Washer
Insulator

Detail B

* NOTE
Position center cable of flap followup (4) between washers (22)
Figure 7-5.

Flap Follow-Up Control and Position Indicator
7-11

MODEL 172 SERIES SERVICE MANUAL
7-19.

REMOVAL AND INSTALLATION. Figure 7-5 can be used as a guide to removal and installation of the flap follow-up and indicating system.
NOTE
If knob (12) works loose on flap lever (13), remove knob
and clean threads on flap lever with MEK or equivalent.
After threads have thoroughly dried, prime with grade T
primer, and allow primer to flash off or dry from three to
five minutes. Apply grade CU Loctite (M1L-S-22473), Loctite 271. STA-LOK Catalog No. 800. or equivalent to
threads of flap lever (13). Install knob (12) and allow Loctite to cure from five to 20 minutes before service use.

7-20.

RIGGING. (See figure 7-5.)
a. Flap control system must be rigged in accordance with paragraph 7-16 before flap
follow-up system can be rigged.
b. Disconnect spring (21) from switch mounting arm (16).
c. With flaps and flap lever (13) in full UP position and holding flap position indicator
(14) to a clearance of .03 inch maximum with top of instrument panel opening. pull
center cable of flap follow-up (index 4, detail b) to remove slack. Connect cable thru
clamp bolt (17) observing note of figure 7-5.
d. Connect spring (21) to switch mounting arm (16).
e. Adjust switches (18) and (20) in slotted holes in mounting arm (16) until cam (19) is
centered between switch rollers.
f. Mount an inclinometer on one flap and set to 0 ° (flaps full UP). Turn master switch
ON and move flap lever (13) to 10° position.
NOTE
An inclinometer for measuring control surface travel is
available from Cessna Supply Division. See figure 6-4.
. Observe inclinometer reading when flaps stop. Adjust flaps DOWN operating switch
(18) in slotted holes on mounting arm (16) as required to obtain flap travel of 10° -0 ° 2° .
h. Adjust flaps UP operating switch (20) to obtain positive clearance with cam (19) when
flaps DOWN operating switch has just opened in the 10° position.
i. Repeat steps g. and h. for 20 ° flap position (travel 20 ° +0 ° -2°).
j. Run flaps to full DOWN position at the degree of travel specified in figure 1-1. Check
that flaps DOWN operating switch (18) remains closed as flap motor limit switch
(index 26. figure 7-2) stops flaps in full DOWN position.
k. Check flaps through several cycles, recheck all components for security and replace
items removed for access.

7-12

MODEL 172 SERIES SERVICE MANUAL
SECTION 8
ELEVATOR CONTROL SYSTEM
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

ELEVATOR CONTROL SYSTEM . 1L13/8-1
Description ...............
1L13/8-1
Trouble Shooting ...........
1L13/8-1
Elevators .................
1L16/8-4
Removal Installation .......
1L16/8-4
Repair .................
1L16/8-4
Bellcranks ................
1L16/8-4

Forward ................
Removal/Installation .....
Rear ..................
RemovaL/Installation .....
Cables and Pulleys ........
Removal/Installation .....
Rigging ................

1L168-4
1L16/8-4
1L16 8-4
1L16 8-4
1L18 8-6
1L188-6
1L18/8-6

8-1.

ELEVATOR CONTROL SYSTEM.

8-2.

DESCRIPTION. The elevators are operated by power transmitted through forward and aft
movement of the control "U". This power reaches the elevators through a system consisting
of a push-pull tube, cables and bellcranks. The elevator control cables, at their aft ends. are
attached directly to a bellcrank. installed between the elevators. This bellcrank serves as an
interconnect between the elevators and as a bearing point for the travel stop bolts. A trim tab
is installed on the right elevator and is described in Section 9.

8-3

TROUBLE SHOOTING
NOTE
Due to remedy procedures in the following trouble shooting chart it may be necessary to rerig system, refer to
paragraph 8-14.

TROUBLE
NO RESPONSE TO CONTROL WHEEL FORE-ANDAFT MOVEMENT.

PROBABLE CAUSE

REMEDY

Forward or aft end of pushpull tube disconnected.

Attach push-pull tube
correctly.

Cables disconnected.

Attach cables and rig system
in accordance with paragraph 8-14.

Revision 1

8-1

MODEL 172 SERIES SERVICE MANUAL
-3.

TROUBLE SHOOTING (CoNt).
TROUBLE

BINDING OR JUMPY
MOTION FELT IN MOVEMENT OF ELEVATOR
SYSTEM.

ELEVATORS FAIL TO
ATTAIN PRESCRIBED
TRAVEL.

8-2

PROBABLE CAUSE

REMEDY

Defective forward or rear
bellcrank pivot bearing.

Move to check for play or
binding. Replace bellcrank.

Cables slack.

Adjust to tension specified
in figure 8-1.

Cables not riding correctly
on pulleys.

Open access plates and observe pulleys. Route cables
correctly over pulleys.

Nylon bearing on instrument panel binding.

Disconnect universal joint
and check for binding. Replace bearing if binding
is felt.

Defective control "U" pivot
bearing.

Disconnect elevator pushpull tube at lower end of "U"
and check that control moves
freely. Replace bearing if
found defective.

Defective elevator hinges.

Move elevators by hand checking hinges. Replace defective
hinges.

Clevis bolts too tight.

Readjust to eliminate
bolt binding.

Lubrication needed.

Lubricate in accordance
with Section 2.

Defective pulleys or cable
guards.

Replace defective parts and
install guards properly.

Stops incorrectly set.

Check elevator travel with
inclinometer. Rig system in
accordance with paragraph
8-14.

Cables tightened unevenly.

Rig system in accordance
with paragraph 8-14.

Interference at instrument paneL

Rig system in accordance
with paragraph 8-14.

MODEL 172 SERIES SERVICE MANUAL

FIGURE 8-2

SEF FIGURE 6-2

1. Pull

2. Bolt
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.

Rear Up Cable
Bolt
Cable Guard
Rear Down Cable
Rear Bellcrank
Forward Up Cable
Forward Down Cable
Push-Pull Tube
Forward Bellcrank
Bracket
Turnbuckle

Detail F

Detail

and C

TRAVEL

Figure 8-1. Elevator Control System
8-3

MODEL 172 SERIES SERVICE MANUAL
8-4.

8-5.

ELEVATORS. (See figure 8-2.)
REMOVAL AND INSTALLATION.
NOTE
This procedure is written primarily for the right elevator
since the trim tab is attached to this elevator.
a.
b.

Disconnect trim tab push-pull channel (3) at tab actuator.
Remove bolts (6) securing elevators to bellcrank (9).
NOTE
If trim system is not moved and actuator screw is not
turned. rigging of trim system should not be necessary
after installation of elevator.

c.
d.
e.
f.

Remove bolts (16) from elevator hinges.
Using care. remove elevator.
To remove left elevator use same procedure. omitting step "a"
Reverse preceding steps for installation. Rig system in accordance with paragraph
8-14 if necessary.

8-6.

REPAIR. Repair may be accomplished as outlined in Section 18. If repair has affected static
balance. check and rebalance as required.

8-7.

BELLCRANKS.

8-8.

FORWARD. (See figure 8-1.)

8-9.

REMOVAL AND INSTALLATION.
a. Remove seats, upholstery and access plates as necessary.
b. Relieve cable tension at turnbuckles (13) and disconnect cables from bellcrank (11).
c. Disconnect push-pull tube (10) from bellcrank (11).
d. Remove pivot bolt and remove bellcrank.
e. Reverse preceding steps for installation. Rig system in accordance with paragraph
8-14. safety turnbuckles and reinstall all items removed in step "a".

8-10.

REAR. (See figure 8-2.)

8-11.

REMOVAL AND INSTALLATION.
a. Remove rudder. (Refer to Section 10.)
b. Relieve cable tension at turnbuckles (index 13, figure 8-1) and disconnect cables from
rear bellcrank (9).
c. Remove bolts (6) securing elevators to bellcrank.
d. Remove bellcrank pivot bolt (8) and slide bellcrank from between tube assemblies (7).

8-4

MODEL 172 SERIES SERVICE MANUAL

Do not paint cable terminals, bolts, or ends of
elevator bellcrank (9).
NOTE
Install push-pull channel (3) with channel opening up on
all floatplanes and landplanes through Serials 17274009
and F17202039. Beginning with landplanes Serials
17274010 and F17202040, install push-pull channel (3)
with channel opening down.

Detail

NOTE
Install upper bolt with head to the
right and lower bolt with head to
the left. clevises
The cable end
must be free to swivel.
9.
7
1. Elevator Tip

2.
3.
4.
5.
6.
7.
8.
9.
10.

Elevator Trim Tab
Push-Pull Channel
Trim Tab Horn
Balance Weight
Bolt
Tube Assembly
Bolt
Rear Bellcrank
Hinge Bracket

11.
12.
13.
14.
15.

Bonding Strap
Horizontal Stabilizer
Screw
Travel Stop Bolt
Jamnut

15
14

Detail B
C

10
12

Detail D

Detail C

Figure 8-2. Elevator Installation
Revision 3

8-5

MODEL 172 SERIES SERVICE MANUAL

NOTE
It may be necessary to remove one of e stabilizer
attaching bolts for clearance when removing the bellcrank pivot bolt.
e. Reverse preceding steps for installation Rig system in accordance with paragraph
8-14. safety turnbuckles and resinstall all items removed for access

8-12.

CABLES AND PULLEYS. (See figure 8-1.)

8-13.

REMOVAL AND INSTALLATION.
a. Remove seats, upholsteryand access plates as necessary.
b. Relieve cable tension at turnbuckles (13).
c. Disconnect cables at forward bellcrank (11).
d. Disconnect cables at rear bellcrank (7).
e. Remove cable guards and pulleys as necessary to work cables free of aircraft.
NOTE
To ease routing of cables. a length of wire may be attached
to end of cable before being withdrawn from- aircraft.
Leave wire in place. routed through structure. attach
cable being installed and pull cable into position.
f. After cable is routed in position. install pulleys and cable guards. Ensure cable is
positioned in pulley groove before installing guards.
g. Rig system in accordance with paragraph 8-14. safety turnbuckles and reinstall all
items removed in step "a".

8-14.

RIGGING. (See figure 8-1.)
a. Lock control column in neutral position by installing neutral rigging tool (index 2.
figure 8-3).
b. Streamline elevators to neutral with horizontal stabilizer.
NOTE
Neutral position measured with the bottom of the balance
area flush with the bottom of the stabilizer.
c. Holding elevators in neutralposition. adjust turnbuckles (13) equally to obtain 30 ± 10
lbs. cable tension.
d. Mount an inclinometer on elevator and, keeping elevator streamlined with stabilizer.
set inclinometer to 00.

8-6

MODEL 172 SERIES SERVICE MANUAL

17267585, 17261445
17261578 thru 17276079
F17201515 thru F17202216

17276080 & On
F17202217 & On

1.
2.
3.
4.

Support
Neutral Rigging Tool
Instrument Panel
Pilot's Control Column

.46 inch
Press fit

.62 inch

.30 inch
Detail A

Fabricate from . 125 inch steel plate and
.209 inch dia. drill rod according to dimensions shown.

Figure 8-3. Control Column Neutral Rigging Tool
Revision 3

8-7

MODEL 172 SERIES SERVICE MANUAL

NOTE
An inclinometer for measuring control surface travel is
available from Cessna Supply Division. See figure 6-4.
e.

Remove control column neutral rigging tool and adjust travel stop bolts (index 14.

figure 8-2) to range of travel specified in figure 1-1.
f.

Check that control "U" does NOT contact instrument panel in full UP position or
firewall in the full DOWN position.
g. Safety turnbuckles (13) and travel stop bolts: check remainder of elevator control
system for security and reinstall all items removed for access.
WARNING
Be sure elevators move in the correct direction when
operated by controls.

8-8

MODEL 172 SERIES SERVICE MANUAL
SECTION 9
ELEVATOR TRIM CONTROL SYSTEM
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

ELEVATOR TRIM CONTROL
SYSTEM ..................
Description ...............
Trouble Shooting ...........
Trim Tab .................
Removal Installation .......
Tab Actuator ..............
Removal Installation .......
Disassembly .............
Cleaning, Inspection and
Repair ................

Reassembly .............
Tab Free-Play
Inspection ...............
Tab Control Wheel ..........
Removal/Installation .......
Cables and Pulleys ..........
Removal/Installation .......
Pedestal Cover.............
Removal/Installation .......
Rigging .................

2A3/9-1
2A3/9-1
2A3/9-1
2A7/9-5
2A7/9-5
2A7/9-5
2A7/9-5
2A7/9-5

2A8/9-6
2A10/9-8
2A10/9-8
2A11 9-9
2A11/9-9
2A11/9-9
2A11/9-9
2A11/9-9
2A11/9-9

2A8/9-6

9 1.

ELEVATOR TRIM CONTROL SYSTEM. (See figure 9-1.)

9-2.

DESCRIPTION. The elevator trim tab, located on the right elevator, is controlled by a trim
wheel mounted in the pedestal. Power to operate the tab is transmitted from the trim control
wheel by means of chains, cables and an actuator. A mechanical pointer, adjacent to the trim
wheel indicates tab position. A "nose-up" setting results in a tab-down position.

9-3.

TROUBLE SHOOTING.
NOTE
Due to remedy procedure in the following trouble shooting chart it may be necessary to rerig system, refer to
paragraph 9-18.

Revision 1

9-1

MODEL 172 SERIES SERVICE MANUAL
9-3.

TROUBLE SHOOTING (Cont).
TROUBLE

TRIM CONTROL WHEEL
MOVES WITH EXCESSIVE
RESISTANCE.

PROBABLE CAUSE

REMEDY

Cable tension too high.

Adjust tension as specified in figure 9-1.

Pulleys binding or rubbing.

Repair or replace as
necessary.

Cables not in place on
pulleys.

Install cables correctly.

Trim tab hinge binding.

Disconnect actuator and
move tab to check resistance. Lubricate or replace
hinge as necessary.

Defective trim tab actuator.

Remove chain from actuator
sprocket and operate actuator manually. Replace actuator if defective.

Rusty chain.

Replace rusty chain.

Damaged sprocket.

Replace damaged sprocket.

Bent sprocket shaft.

Observe motion of sprockets.
Replace bent sprocket shaft.

Cable tension too low.

Adjust tension as specified
in figure 9-1.

Broken pulley.

Replace defective pulley.

Cables not in place on
pulleys.

Install cables correctly.

Worn trim tab actuator.

Remove and replace worn
actuator.

Actuator attachment loose.

Tighten.

TRIM INDICATOR FAILS
TO INDICATE CORRECT
TRIM POSITION.

Indicator incorrectly engaged
on wheel track.

Reset indicator.

INCORRECT TRIM TAB
TRAVEL.

Stop blocks loose or
incorrectly adjusted.

Adjust stop blocks on
cables. See figure 9-2.

LOST MOTION BETWEEN
CONTROL WHEEL AND
TRIM TAB.

9-2

MODEL 172 SERIES SERVICE MANUAL
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Pulley (Sheet 2)
Chain Guard
Actuator
Aft Chain
Left Aft Cable
Left Forward Cable
Right Aft Cable
Turnbuckle
Right Forward Cable
Stop Block
Bushing
Rear Chain
Forward Chain
Trim Wheel
Sprocket
Pointer
Retainer
Pedestal
Roll Pin

(SEE SHEET 2)

Detail B

FIGURE 8-2

A1(SEE SHEET 2)
Detail A

CABLE
TENSION:
LBS (AT AVERAGE TEMPER15 TO 20
SAFETY WIRE ROLL PIN (19)

Figure 9-1. Elevator Trim Tab Control System (Sheet 1 of 2)
9-3

MODEL 172 SERIES SERVICE MANUAL
Tab Up

Tab Up

Tab Down

Tab Up

DetailA1

Detail B1

Tab Up

Detail D1
Tab Down
Tab Down

Detail H1
Detail J1

Figure 9-1. Elevator Trim Tab Control System (Sheet 2 of 2)

POINT

TRAILING EDGE

HINGE

CHORD LENGTH

Detail A

NEUTRAL POSITION
FREE-PLAY DOWN
TOTAL FREE-PLAY

1. Measure chord length at extreme inboard end of
trim tab as shown in detail A.
2. Mulitiply chord length by 0.025 to obtain maximum
allowable free-play.
3. Measure free-play at same point on trim tab that
chord length was measured.
4. Total free-play must not exceed maximum allowable. Refer to detail B.

Figure 9-1A. Trim Tab Free-Play Inspection
9-4

MODEL 172 SERIES SERVICE MANUAL
9-4.

TRIM TAB. (See figure 8-2.)

9-5.

REMOVAL AND INSTALLATION.
a. Disconnect push-pull channel (3) from horn assembly (4).
b. Drill out rivets attaching hinge to elevator.
NOTE
After tab has been removed and if hinge pin is to be
removed, it is necessary to spread the crimped ends of the
hinge before driving out pin. When a pin has been
installed, crimp ends of hinge to prevent pin from working out.
c.

Reverse preceding steps for installation.

9-6.

TRIM TAB ACTUATOR.

9-7.

REMOVAL AND INSTALLATION. (See figure 9-1.)
CAUTION
Position a support stand under tail tie-down ring to
prevent tailcone from dropping while working inside.
Remove baggage compartment aft wall for access.
Remove safety wire and relieve cable tension at turnbuckle (8).
Disconnect push-pull tube from actuator (3).
Remove access plate from underside of right-hand stabilizer beneath actuator.
Remove chain guard (2) and disengage chain (4) from actuator sprocket.
Remove screws attaching actuator clamps to bracket and carefully work actuator out
through access opening.
g. Reverse the preceding steps for reinstallation. Rig trim system in accordance with
paragraph 9-18. safety turnbuckle (8) and reinstall all items removed for access.

a.
b.
c.
d.
e.
f.

9-8.

DISASSEMBLY. (See figure 9-3.)
a. Remove actuator in accordance with paragraph 9-7.
b. Disassemble actuator assembly (1) as illustrated in Detail A as follows:
1. Remove chain guard (3) if not previously removed in step "e" of paragraph 9-7.
2. Using suitable punch and hammer, remove groov-pins (8) securing sprocket (5)
to screw (9) and remove sprocket from screw.
3. Unscrew threaded rod end (15) and remove rod end from actuator.
4. Remove groov-pins (10) securing bearings (6 and 14) at the housing ends.
5. Lightly tap screw (9) toward the sprocket end of housing, remove bearing (6) and

collar (7).
6.

Lightly tap screw (9) in the opposite direction from sprocket end. remove bearing
(14). O-ring (13) and collar (7).

7. It is not necessary to remove retaining rings (11).

9-5

MODEL 172 SERIES SERVICE MANUAL
9-9.

CLEANING. INSPECTION AND REPAIR. (See figure 9- 3 . )
a.

DO NOT remove bearing (16) from threaded rod end (15) unless replacement of
bearing is necessary.

Clean all component parts, except bearing (16). by washing in Stoddard solvent or
equivalent. Do not clean sealed bearing (16).
c. Inspect all component parts for obvious indications of damage such as stripped
threads. cracks. deep nicks and dents.
d. Check bearings (6 and 14), screw (9) and threaded rod end (15) for excessive wear and
scoring. Dimensions of the parts are as follows:
BEARING (6)
0.373" MIN.
INSIDE DIAMETER
0.374" MAX.
INSIDE DIAMETER
BEARING (14)
INSIDE DIAMETER
0.248" MIN.
SMALL HOLE
0.249" MAX.
SMALL HOLE
0.373" MIN.
HOLE
LARGE
0.374" MAX.
LARGE HOLE
b.

THREADED ROD END (15)
OUTSIDE DIAMETER
(SHANK)

0.245" MIN.
0.246" MAX.

SCREW (9)
OUTSIDE DIAMETER

0.369" MIN.
0.370" MAX.
NOTE

Relative linear movement between internal threaded
screw (9) and bearing (14) should be 0.004 to 0.010 inch at
room temperature.
Examine threaded rod end (15) and screw (9) for damaged threads or dirt particles
that may impair smooth operation.
f. Check sprocket (5) for broken. chipped and/or worn teeth.
g. Check bearing (16) for smoothness of operation.
h. DO NOT attempt to repair damaged or worn parts of the actuator assembly. Discard
all defective items and install new parts during reassembly.
e.

9-10.

9-6

REASSEMBLY. (See figure 9-3.)
a. Always discard the following items and install new parts during reassembly:
1. Groov-Pins (8 and 10).
2. O-Ring (13).
3. Nuts (2).
b. During reassembly, lubricate collars (7), screw (9) and threaded rod end (15) in
accordance with procedures outlined in Section 2.
c. Install collar (7) and bearing (6) on screw (9).
d. Press sprocket (5) into the end of screw (9). align groov-pin holes and install new
groov-pins (8).

MODEL 172 SERIES SERVICE MANUAL

TURNBUCKLE

With elevators in neutral, set trim tab to neutral (streamlined).

Position stop blocks (2) and (3) approximately 1/4" fore-and-aft of
turnbuckle respectively, and secure to cable A.

Place inclinometer on trim tab and run tab to DOWN TRAVEL limit listed in
Section 1.

Position stop block (4) against stop block (3) and secure to cable B.

Run trim tab to UP TRAVEL limit listed in Section 1, place stop block
(1) against stop block (2) and secure to cable B.
Figure 9-2.

Elevator Trim Tab Travel Adjustment

1.
2.
3.
4.
5.
6.
7.
8.

Figure 9-3.

Actuator
Assembly
Nut
Chain Guard
Screw
Sprocket
Bearing
Collar
Groov-Pin

9. Screw
10.
Groov-Pin
11. Retaining Ring
12. Housing
13. O-Ring
14. Bearing
15. Threaded Rod End
16. Bearing

Elevator Trim Tab Actuator Assembly
9-7

MODEL 172 SERIES SERVICE MANUAL
e.

Insert screw (9), with assembled parts, into housing (12) until bearing (6) is flush with
end of housing.
NOTE
When inserting screw (9) into housing (12), locate the
sprocket (5) at the end of housing which is farther away
from the groove for retaining ring (11).

The bearings (6 and 14) are not pre-drilled and
must be drilled on assembly. The groov-pins
(10) are 3/32 inch in diameter, therefore, requiring a 3/32 (0.0937) inch drill.
f.

g.
h.
i.
j.
k.
l.
m.

With bearing (6) flush with end of housing (12). carefully drill bearing so the drill will
emerge from the hole on the opposite side of housing (12). DO NOT ENLARGE
HOLES IN HOUSING.
Press new groov-pins (10) into pin holes.
Insert collar (7). new O-ring (13) and bearing (14) into opposite end of housing (12).
Complete steps "f" and "g" for bearing (14).
If a new bearing (16) is required, a new bearing may be pressed into the boss. Be sure
force bears against the outer race of bearing.
Screw the threaded rod end (15) into screw (9).
Install retaining rings (11). if they were removed.
Test actuator assembly by rotating sprocket (5) with fingers while holding threaded
rod end (15). The threaded rod end should travel in and out smoothly, with no
indication of binding.
Reinstall actuator assembly in accordance with paragraph 9-7.

9-11.

TRIM TAB FREE-PLAY INSPECTION.
a. Place elevator and trim tab in neutral position and secure elevator from movement.
b. Determine maximum amount of allowable free play using formula shown in figure 91A.
c. Using moderate hand pressure (up and down), measure free-play at trailing edge of
trim tab.
d. If trim tab free-play is less than maximum allowable, the system is within prescribed
limits.
e. If trim tab free-play is more than maximum allowable, check the following items for
looseness while moving trim tab up and down.
1. Check push-pull channel to trim tab horn assembly attachment for looseness.
2. Check push-pull channel to actuator assembly threaded rod end attachment for
looseness.
3. Check actuator assembly threaded rod end for looseness in the actuator assembly.
f. If looseness is apparent while checking steps e-1 and e-2. repair by installing new
parts.
g. If looseness is apparent while checking step e-3. refer to paragraphs 9-6 through 9-10.

9-12.

TRIM TAB CONTROL WHEEL. (See figure 9-1.)

9-8

MODEL 172 SERIES SERVICE MANUAL
9-13.

REMOVAL AND INSTALLATION.
a. Relieve cable tension at turnbuckle (8).
CAUTION
Position a support stand under tail tie-down ring to
prevent tailcone from dropping while working inside.
b.
c.
d.
e.
f.

Remove pedestal cover (12). (Refer to applicable paragraph in this section.)
Remove screws attaching control wheel retainer (17).
Remove retainer and pointer (16). using care not to drop control wheel (14).
Disengage roller chain (13) from sprocket (15) and remove control wheel.
Reverse preceding steps for installation. Rig system in accordance with applicable
paragraph in this section. safety turnbuckle and reinstall all items removed for
access.

9-14.

CABLES AND PULLEYS. (See figure 9-1.)

9-15.

REMOVAL AND INSTALLATION.
a. Remove seats, upholstery and access plates as necessary.
b. Disconnect cables at turnbuckle (8) and cable ends (5 and 6).
c. Remove cable guards and pulleys as necessary to work cables free of aircraft.
NOTE
To ease routing of cables, a length of wire may be attached
to end of cable before being withdrawn from aircraft
Leave wire in place, routed through structure, attach
cable being installed and pull cable into position.
d.
e.

After cable is routed in position, install pulleys and cable guards. Ensure cable is
positioned in pulley groove before installing guards.
Rig system in accordance with applicable paragraph in this section. safety turnbuckle and reinstall all items removed in step "a."

9-16.

PEDESTAL COVER. (See figure 9-1.)

9-17.

REMOVAL AND INSTALLATION.
a. Remove fuel selector valve handle and placard.
b. Remove mike and remove mike jack mounting nut.
c. Remove screws attaching pedestal cover to structure and remove cover.

9-18.

RIGGING. (See figure 9-1.)
CAUTION
Position a support stand under tail tie-down ring to
prevent tailcone from dropping while working inside.
a.
b.
c.
d.

Remove rear baggage compartment panel and access plates as necessary.
Loosen travel stop blocks (10) on cables.
Disconnect actuator (3) from trim tab push-pull channel.
Check cable tension and readjust turnbuckle (8) if necessary.

9-9

MODEL 172 SERIES SERVICE MANUAL

NOTE
If chains and/ or cables are being installed. permit actuator screw to rotate freely as chains and cables are
connected. Set cable tension.
e.

Rotate trim wheel (14) full forward (nose down). Ensure pointer (16) does not restrict
wheel movement. If necessary, reposition pointer using a thin screwdriver to pry
trailing leg of pointer out of groove.
NOTE
Full forward (nose down) position of trim wheel is where
further movement is prevented by chain or cable ends
contacting sprockets or pulleys.

With elevator and trim tab both in neutral (streamlined), place inclinometer on tab
and set to zero.
NOTE
An inclinometer for measuring control surface travel is
available from Cessna Supply Division. See figure 6-4.

g.
h.
i.
j.
k.

Rotate actuator screw in or out as required to place tab up with a maximum of 2 °
overtravel. with actuator screw connected to push-pull channel.
Rotate trim wheel to position tab up and down. readjusting actuator screw as
required to obtain overtravel in both directions.
Position stop blocks (10) and adjust as illustrated in figure 9-2 to limit travel as
specified in Section 1.
Check trim wheel pointer travels the same distance from ends of slot in cover.
Reposition trailing leg of pointer if necessary (refer to step "d").
Safety turnbuckle and reinstall all items removed in step "a".
WARNING
Be sure trim tab moves in correct direction when operated by trim wheel. Nose down trim corresponds to tab up
position.

9-10

MODEL 172 SERIES SERVICE MANUAL
SECTION 10
RUDDER AND RUDDER TRIM CONTROL SYSTEMS
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

RUDDER CONTROL SYSTEM ...
Description ...............
Trouble Shooting ...........
Pedal Assembly ............
Removal Installation .......
Rudder ..................
Removal/Installation .......

2A17/10-1
2A17/10-1
2A17/10-1
2A18/10-2
2A18/10-2
2A20/10-4
2A20/10-4

2A20 10-4
2A20/10-4
2A20/10-4
2A20/10-4

Repair .................
Cables and Pulleys ..........
Removal/Installation .......
Rigging .................
RUDDER TRIM CONTROL
SY TEM ..................
Description ...............
Rigging .................

2B1/10-9
2B1/10-9
2B1/10-9

10-1.

RUDDER CONTROL SYSTEM. (See figure 10-1.)

10-2.

DESCRIPTION. Rudder control is maintained through use of conventional rudder pedals
which also control nose wheel steering. The system is comprised of rudder pedals. cables
and pulleys, all of which link the pedals to the rudder and nose wheel steering. Cable tension
is automatically determined when the rudder pedals are rigged against return springs 6.50
inches from firewall.

10-3.

TROUBLE SHOOTING.
NOTE
Due to remedy procedures in the following trouble shooting chart it may be necessary to rerig system, refer to
paragraph 10-11.
TROUBLE

RUDDER DOES NOT
RESPOND TO PEDAL
MOVEMENT.

PROBABLE CAUSE
Broken or disconnected
cables.

REMEDY
Connect or replace cables.

Revision 1

10-1

MODEL 172 SERIES SERVICE MANUAL
10-3.

TROUBLE SHOOTING (Cont).
TROUBLE

BINDING OR JUMPY MOVEMENT OF RUDDER PEDALS.

PROBABLE CAUSE

REMEDY

Cables too tight.

See figure 10-2 for distance between firewall and
pedals. Adjust cable tension
in accordance with paragraph 10-11.

Cables not riding properly
on pulleys.

Route cables correctly over
pulleys.

Binding, broken or defective pulleys or cable
guards.

Replace defective pulleys
and install guards
properly.

Pedal bars need lubrication.

Refer to Section 2.

Defective rudder bar
bearings.

If lubrication fails to eliminate binding, replace
bearing blocks.

Defective rudder hinge
bushings.

Replace defective bushings.

Clevis bolts too tight.

Readjust to eliminate binding.

Steering rods not adjusted
properly.

Rig system in accordance
with paragraph 10-11.

LOST MOTION BETWEEN
RUDDER PEDALS
AND RUDDER.

Insufficient cable tension.

See figure 10-2 for distance
between firewall and pedals.
Adjust cable tension in accordance with paragraph
10-11.

INCORRECT RUDDER
TRAVEL.

Incorrect rigging.

Rig system in accordance
with paragraph 10-11.

10-4.

RUDDER PEDAL ASSEMBLY. (See figure 10-2.)

10-5.

REMOVAL AND INSTALLATION.
a. Remove carpeting, shields and soundproofing from pedal and tunnel areas as
necessary.
b. Disconnect master cylinders (12) at pilot rudder pedals.
c. Disconnect parking brake cables at master cylinders.
d. Remove rudder pedals (2) and brake links (5).
e. Relieve cable tension at clevises (index 11. figure 10-1).
f. Disconnect cables, return springs, trim bungee. and steering tubes from rudder bars.
g. Remove bolts securing bearing blocks (8) and work rudder bars out of tunnel area.

10-2

MODEL 172 SERIES SERVICE MANUAL
1. Shackle

10. Rudder Cable

15. Right Front Cable

2. Bellcrank

11.

16. Left Front Cable

3. Travel Stop
4. Right Rear Cable

12. Washer
13. Bushing

5.
6.
7.
8.
9.

14. Stop Nut

Left Rear Cable
Turnbuckle
Cable Guard
Pulley
Rudder Bar

Clevis

DetailB

4
Detail A

Detail
14

(Typical)

* Safety wire rudder travel stop bolt (3).
NOTE

10
Shaded pulleys used in
this system only.

Detail

E-REFER TO FIGURE 10-5

REFER TO FIGURE 1-1 FOR TRAVEL.10-3
Detail C

Detail C1 (Typical)
REFER TO P RAGRAPH 10-11.

CABLE TENSION
CABLE
CABLE TENSION:

REFER TO PARAGRAPH 10-11.
REFER TO FIGURE 1-1 FOR TRAVEL.

Figure 10-1.

Rudder Control System
10-3

MODEL 172 SERIES SERVICE MANUAL

NOTE
Rudder bar assemblies should be checked for excessive
wear before installation. The bearing blocks are nylon
and require no lubrication unless binding occurs. A few
drops of general purpose oil should eliminate such binding.
h. Reverse preceding steps for installation. Rig system in accordance with applicable
paragraph in this section. Safety turnbuckles or clevises, as applicable, and reinstall
all items removed in step "a".
10-6.

RUDDER. (See figure 10-3.)

10-7.

REMOVAL AND INSTALLATION.
a. Disconnect tail navigation light quick-disconnect (13).
b. Relieve cable tension at clevises (index 11, figure 10-1) and disconnect clevises from
rudder bellcrank (12).
c. With rudder supported, remove hinge bolts (1) and lift rudder free.of vertical fin.
d. Reverse preceding steps for installation. Rig system in accordance with appropriate
paragraph in this section and safety turnbuckles or clevises, as applicable.

10-8.

REPAIR. Repair may be accomplished as outlined in Section 18. Hinge bushings may be
replaced as necessary.

10-9.

CABLES. AND PULLEYS. (See figure 10-1.)

10-10.

REMOVAL AND INSTALLATION.
a. Remove seats, upholstery and access plates as necessary,
b. Disconnect cable at rudder bar (9) and bellcrank (2).
c. Remove cable guards and pulleys as necessary to work cables free of aircraft.

NOTE
To ease routing of cables, a length of wire may be attached
to end of cable before being withdrawn from aircraft.
Leave wire in place, routed through structure, attach
cable being installed and pull cable into position.
d. After cable is routed in position, install pulleys and cable guards. Ensure cable is
positioned in pulley groove before installing guard.
e. Rig system in accordance with appropriate paragraph in this section. Safety
turnbuckles or clevises, as applicable, and reinstall all items removed in step "a".
10-11.

10-4

RIGGING. (See figure 10-1.)
a. Adjust travel stops (3) to attain travel specified in Section 1. Figure 10-4 illustrates
correct travel and one method of checking.

MODEL 172 SERIES SERVICE MANUAL

* THRU 17276019 AND F17202174

* BEGINNING WITH 17276020
AND F17202175

FIREWALL

CLEARANCE HOLE ON

AFT RUDDER BAR
* BEGINNING WITH 17274931

AND F17202135
CLEARANCE HOLE ON
FORWARD RUDDER BAR

1.
2.
3.
4.
5.
6.

Shaft
Rudder Pedal
Anti-Rattle Spring
Spacer .
Brake Links
Pivot Shaft

7. Aft Rudder Bar
8.
9.
10.
11.

Bearing Block
Return Spring
Brake Torque Tube
Forward Rudder Bar

12.
13.

Master Cylinder
Bracket

14.

Bearing

15.
16.
17.

Bellcrank
Single Control Hub
Rudder Pedal Extension

18.
19.

Shaft
Shim

8
10
14
15

NOTE
Brake links (5), bellcranks (15) and attaching
parts are replaced with hubs when dual controls
are NOT installed

Detail

Nylon washers may be installed between shaft

(1) and brake link (5) as required to eliminate
excessive clearance when dual controls ARE
installed.
Figure 10-2. Rudder Pedals Installation
10-5

MODEL 172 SERIES SERVICE MANUAL

BALANCE WEIGHT

Detail C

1.
2.
3.
4.

Bolt
Upper Hinge
Bushing
Nutplate

5. Center Hinge
6. Washer
7. Nut
8. Lower Hinge
9. Upper Tip

Figure 10-3. Rudder Assembly
10-6

10. Trim Tab
11. Lower Tip
12. Bellcrank
13. Quick-Disconnect

MODEL 172 SERIES SERVICE MANUAL

BLOCK RUDDER
HALF THE DISTANCE BETWEEN
STRAIGHTEDGES

MEASURING
RUDDER
TRAVEL

ESTABLISHING NEUTRAL
POSITION OF RUDDER
1.

Establish neutral position of rudder by clamping straightedge (such as wooden 2 X 4) on each side of
fin and rudder and blocking trailing edge of rudder half the distance between straightedges as shown.

Tape a length of soft wire to one elevator in such a manner that it can be bent to index with a point
on rudder trailing edge just above the lower rudder tip (disregard fixed trim tab).

Using soft lead pencil,

Remove straightedges.

Hold rudder against right, then left, rudder stop. Measure the distance from pointer to pencil mark
on rudder in each direction of travel. Distance should be between 5.29" and 5.91".

mark rudder at point corresponding to soft wire indexing point (neutral).

Figure 10-4.

Checking Rudder Travel
10-7

MODEL 172 SERIES SERVICE MANUAL
b.
c.

Disconnect nose wheel steering tubes (refer to section 5) from nose strut.
Adjust cables at clevises (11) to align rudder and pedals in neutral position. 6.50
inches from firewall to pedal pivot shafts (index 6. figure 10-2). This step automatically determines cable tension because of the return springs (index 9. figure 10-2)
attached to the rudder bar.
NOTE
Due to thickness of insulation on firewall. it is recommended that a piece of 1/16 inch welding rod be ground to
a sharp point and notched at the 6.50 inch dimension.
Pierce insulation on firewall and use notch to measure
proper dimension.

Tie down or weight tail to raise nose wheel free of ground.
Center nose gear against external stop.
Extend steering tubes until free play is removed. DO NOT COMPRESS SPRINGS.
Adjust steering tube rod ends to 1.00 inch dimension between steering arm assembly
and bolt hole as illustrated in section 5 and tighten jam nuts.
h. Adjust steering tube clevises to align with rod end bearings.
d.
e.
f.
g.

NOTE
Extend steering tubes to seat rods against internal
springs but do not attempt to preload these springs by
shortening rod end clevises after alignment. Preload is
built into steering tubes.
i.

Install clevises on rod ends.

NOTE
DO NOT adjust rudder trim with steeringtubes. Degree of
steering travel cannot be adjusted.
j. Rig rudder trim control system in accordance with paragraph 10-14.
k. Safety clevises (11) and install all items removed for access.
NOTE
Flight test aircraft to determine if ground adjustment of
fixed trim tab is necessary. DO NOT rig rudder "offcenter" unless trim tab does not provide adequate correction.
WARNING

Be sure rudder moves in correct direction when operated
by pedals.

10-6

MODEL 172 SERIES SERVICE MANUAL
10-12.

RUDDER TRIM CONTROL SYSTEM. (See figure 10-5.)

10-13.

DESCRIPTION. A lever assembly. actuated by the pilot, is linked via a bellcrank to a rudder
trim bungee which is, in turn connected directly to the rudder bar assembly and hence to the
rudder itself. The lever assembly is mounted on the center console structure and utilizes a
pin to positively lock the trim system in any of 3 positions left or right of the center of
"neutral' trim position. The lever also serves as the trim position indicator.

10-14.

RIGGING. (See figure 10-5.)
NOTE

The rudder control system MUST be rigged according to
paragraph 10-11 prior to rigging the rudder trim control
system.
a. Tie down or weight tail of the aircraft to raise nose wheel clear of ground.
b. Ensure nose wheel, rudder and rudder pedals are all in "neutral" position.
c. Ensure top nut on bungee assembly is adjusted to eliminate end play between shaft
and housing.
d. Install bungee (5) between rudder bar (6), and bellcrank (7) as shown in figure 10-5.
detail A.
e. Make sure lever assembly (3) is in neutral position or center hole of bracket (4).
f. Adjust ball ends of push rod (8) so that ball end studs align with holes in bellcrank (7)
and lever assembly (3) and install push rod.
g. Check for security and safetying of all components and reinstall all items removed
for access.
WARNING

Be sure rudder trim lever moves rudder in correct direction.

10-9

MODEL 172 SERIES SERVICE MANUAL

1. Console Structure

2.
3.
4.
5.
6.
7.
8.

Knob
Lever
Bracket
Trim Bungee
Rudder Bar
Bellcrank
Pushrod

Detail

Figure 10-5. Rudder Trim Control System
10-10

MODEL 172 SERIES SERVICE MANUAL
SECTION 11
ENGINE
(O-320-H2AD)
WARNING
When performing any inspection or maintenance that requires turning on the master switch, installing a battery,
or pulling the propeller through by hand, treat the propeller as if the ignition switch were ON. Do not stand, nor
allow any one else to stand, within the arc of the propeller, since a loose or broken wire, or a component malfunction, could cause the propeller to rotate.
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

ENGINE COWLING ..........
2B8/11-2
Description ...............
2B8/11-2
Removal Installation ........
2B8/11-2
Cleaning Inspection .........
2B11/11-3
Repair ...................
2B1111-3
ENGIIE ...................
2B11/11-3
Description ...............
2B1111-3
Engine Data .....
........
2B11/11-3
Time Between Overhaul (TBO) . 2B12/11-4
Overspeed Limitations .......
2B12/11-4
Trouble Shooting ...........
2B13/11-5
Removal ..............
2B16/11-8
Cleaning ................
2B18 11-10
Accessories Removal ........
2B18,11-10
Inspection .
.............
2B20/11-12
Build-Up ..
...........
2B20 11-12
Installation ..............
2B20 11-12
Flexible Fluid Hoses ..... .2B22/11-14
..........
2B22/11-14
Leak Test
Replacement ...........
2B22/11-14
Static Run-up Procedures ....
2B22/11-14
2B23/11-15
Baffles ..................
Description ....
......
2B23 11-15
Cleaning Inspection ......
2B23/11-15
Removal Installation .......
2B23/11-15
Repair ................
2B23/11-15
Mount ...................
2B23/11-15
Description .............
2B23/11-15
Removal Installation .......
2B23/11-15
Repair .................
2B24/11-16
Shock-Mount Pads ..........
2B24 11-16
Oil System ...............
2B24 11-16
Description .............
2B24 11-16
Trouble Shooting .........
2B24/11-16
Full-Flow Oil Filter ........
2C3 11-19

Description ............
Removal/Installation .....
Oil Cooler ...............
Description ............
Fuel System ..............
Description .............
Carburetor ..............
Removal/Installation .....
Idle Speed and Mixture
Adjustments ..........
Induction Air System ........
Description .............
Removal/Installation .......
Ignition System ............
Description .............
Trouble Shooting .........
Magneto ...............
Description ............
Removal/Installation .....
Internal Timing .........
Magneto-to-Engine Timing .
Maintenance .............
Magneto Check ...........
Spark Plugs .............
Controls .................
Description ............
Rigging ................
Throttle Control ........
Mixture Control ........
Carburetor Heat Control .
Starting System ...........
Description ............
Trouble Shooting .........
Primary Maintenance ......
Starter Motor ............

2C3/11-19
2C3/11-19
2C3 11-19
2C4 11-20
2C4 11-20
2C4'11-20
2C411-20
2C4 11-20
2C4 11-20
2C5 11-21
2C5/11-21
2C5 11-21
2C6 11-22
2C6 11-22
2C6 11-22
. 2C7 11-23
2C7 11-23
2C7 11-23
2C8 11-24
. 2C10 11-26
2C11 11-27
2C11 11-28
2C13 11-29
2C13 11-29
. 2C13 11-29
2C14 11-30
2C14 11-30
2C15 11-31
. 2C17'11-33
2C17 11-33
. 2C17 11-33
2C18 11-34
2C19 11-35
2C19 11-35

Revision 1

11-1

MODEL 172 SERIES SERVICE MANUAL
RemovalInstallation .....
Exhaust System ...........
Description .............
Removal Installation .......
Inspection ..............

7.
8.
9.
11.
11.
12.
13.
14.

11-2

Firewall
Cowl Snubber
Snubber

Bracket

Nose
Cap
Nose
Cap
Engine
Shim
Screw

Revision 1

2C19
2V19
2C19
2C19
2C20

11-35
11-35
11-35
11-35
11-36

Extreme Weather Maintenance 2C20
Cold Weather ......
....
2C20
Dusty Conditions
.....
2C22
Seacoast and Humid Areas .2C22

11-36
11-36
11-38
11-38

Detail B
tween snubber (9) and cowl snubber bracket (8).
Detail B

Item (13) shim (PN 0552227-1) can be installed as required (maximum 4) between snupper support (10) and
snubber (9) to obtain a maximum gap of .125 inch be-

MODEL 172 SERIES SERVICE MANUAL
11-1.

ENGINE COWLING.

11-2.

DESCRIPTION. The engine cowling is comprised of an upper and lower cowling segment.
Instead of attaching directly to the fuselage. the cowling attaches to shock mounts, which in
turn, are fastened to the fuselage. A door in the top cowl provides access to the engine oil
dipstick. oil filler neck and strainer drain control. Quick-disconnect fasteners are used at the
cowling-to shock mounts and at the parting surfaces of the upper and lower cowl attach
points. Machine screws secure the cowling segments together at the nose caps.

11-3.

REMOVAL AND INSTALLATION.
a. Release the quick-release fasteners attaching the cowling to the shock mounts and at
the parting surfaces of the upper and lower cowling segments. (See figure 11-1.)
b. Remove machine screws securing the cowling nose caps together.
c. Disconnect electrical wiring at back of landing light.
d. Remove air filter cover from lower cowl by removing 4 attaching screws (Thru Serials 17273579 and F17202029), or 4 quick-release fasteners (Serial 17273580 & On,
and F17202030 & On).
e. Release the 4 quick-release fasteners from the air filter and remove filter from cowl.
f. Reverse the preceding steps for reinstallation. Be sure that the baffle seals are turned
in the correct direction to confine and direct airflow around the engine. The vertical
seals must fold forward and the side seals must fold upward.

Revision 1

11-2A/( 1-2B blank)

MODEL 172 SERIES SERVICE MANUAL
NOTE
When the new shock mounts or brackets are being
installed, careful measurements should be made to posi-

tion these parts correctly on the firewall. These service
parts are not pre-drilled Install shock mounts on
brackets so that cowling stud and shock mount re
correctly aligned. Sheet aluminum may be used as shims
between bracket halves to provide proper cowling contour.
11-4.

CLEANING AND INSPECTION. Wipe the inner surfaces of the cowling segments with a
clean cloth saturated with cleaning solvent (Stoddard or equivalent). If the inside surface of
the cowling is coated heavily with oil or dirt, allow solvent to soak until foreign material can
be removed. Wash painted surfaces of the cowling with a solution of mild soap and water and
rinse thoroughly. After washing, a coat of wax may be applied to the painted surfaces to
prolong paint life. After cleaning, inspect cowling for dents, cracks, loose rivets and spot
welds. Repair all defects to prevent spread of damage.

11-5.

REPAIR. If cowling skins are extensively damaged, new complete sections of the cowling
should be installed. Standard insert-type patches may be used for repair if repair parts are
formed to fit contour of cowling. Small cracks may be stop-drilled and small dents
straightened if they are reinforced on the inner surface with a doubler of the same material
as the cowling skin. Damaged reinforcement angles should be replaced with new parts. Due
to their small size, new reinforcement angles are easier to install than to repair the damaged
part.

11-6.

ENGINE.

11-7.

DESCRIPTION. On 1977 thru 1980 Models, an air cooled, wet-sump four-cylinder, horizontally-opposed, direct-drive carbureted "Blue Streak" (Lycoming) 0-320-H series engine is

used to power the airplane. The cylinders, numbered from front to rear are staggered to
permit a separate throw on the crankshaft for each connecting rod. The right front cylinder
is number 1 and cylinders on the right side are identified by odd numbers 1 and 3. The left
front cylinder is number 2 and the cylinders on the left side are identified as numbers 2 and
4. Refer to paragraph 11-8 for engine data For repair and overhaul of the engine, accessories and propeller, refer to the appropriate publications issued by their manufacturer's.
These publications are available from the Cessna Supply Division.
11-8.

ENGINE DATA.

MODEL (Lycoming)

O-320-H2AD

BHP at RPM

160 BHP at 2700 RPM

Number of Cylinders

4 Horizontally-Opposed

Displacement
Bore
Stroke

319.8 Cubic Inches
5.125 Inches
3.875 Inches

Compression Ratio

9.0:1

11-3

MODEL 172 SERIES SERVICE MANUAL
11-8.

ENGINE DATA (Cont).

Magnetos
Right Magneto
Left Magneto

Bendix D4RN-2021*
Fires 25 ° BTC 1-3 Lower and 2-4 Upper
Fires 25° BTC 1-3 Upper and 2-4 Lower

Firing Order

1-3-2-4

Spark Plugs

18mm (Refer to Avco Lycoming Service
Instruction No. 1042 for factory approved
spark plugs and required gap.)

Torque Value
Carburetor (Marvel-Schebler)

390 ± 30 LB-IN.
MA-4SPA

Oil Sump Capacity
With Filter Change

6 U.S. Quarts
7 U.S. Quarts

Tachometer

Mechanical

Approximate Dry Weight
With Standard Accessories

283 Pounds (Weight is Approximate
and will vary with optional
equipment installed)

Oil Pressure
Minimum Idling
Normal
Maximum

25 PSI
60 to 90 PSI
115 PSI

Oil Temperature
Normal Operation
Maximum Permissible

Within Green Arc
Red Line (245°F)

Cylinder Head Temperature

500°F Maximum (Not Indicated)
Right rotating rotor as viewed
from propeller end.

11-9.

TIME BETWEEN OVERHAUL (TBO). Refer to the latest Revision of Lycoming Service
Instruction No. 1009. and all applicable Service Letters or Service Bulletins, for recommendations applicable to 0-320-H series engines. At the time of overhaul engine accessories
should be overhauled.

11-9A.

OVERSPEED LIMITATIONS. The engine must not be operated above specified maximum
continuous RPM. However. should inadvertant overspeed occur refer to the latest issue of
Avco Lycoming Service Bulletin No. 369 and all applicable Service Letters and Service
Instructions for obligatory recommendations.

11-4

MODEL 172 SERIES SERVICE MANUAL
11-10.

TROUBLE SHOOTING.
TROUBLE

ENGINE WILL NOT START.

PROBABLE CAUSE

REMEDY

Improper use of starting
procedure.

Refer to Pilot's Operating
Handbook.

Fuel tanks or bays

Viually inspect tanks or

empty.

bays. Fill with proper grade and
quantity of gasolin

Mixture control in the
IDLE CUT-OFF position.

Move control to the full
RICH position.

Fuel selector valve in
OFF position.

Place selector valve in the
ON position to a tank
known to contain gasoline.

Defective carburetor.

Repair or replace
carburetor.

Carburetor screen or fuel
strainer plugged.

Remove carburetor and clean
carburetor screen or fuel
strainer thoroughly.

Engine flooded.

Refer to Pilot's Operating
Handbook.

Water in fuel system.

Open fuel strainer drain
and check for water. If
water is present, drain
fuel tank sumps, lines.
strainer and carburetor.

Defective magneto switch
or grounded magneto leads.

Check continuity. Repair
or replace switch or leads.

Spark plugs fouled.

Remove, clean and regap
plugs. Test harness cables
to persistently fouled plugs.
Replace if defective.

11-5

MODEL 172 SERIES SERVICE MANUAL
11-10.

TROUBLE SHOOTING (Cont).
TROUBLE

ENGINE STARTS BUT
DIES. OR WILL NOT IDLE.

PROBABLE CAUSE

REMEDY

Idle stop screw or idle mixture incorrectly adjusted.

Refer to paragraph 11-43.

Carburetor idling jet
plugged.

Clean carburetor
idling jet.

Spark plugs fouled or improperly gapped.

Remove. clean and regap
plugs. Replace if defective.

Water in fuel system.

Open fuel strainer drain and
check for water. If water
is present, drain fuel tank
sumps. lines. strainer and
carburetor.

Defective ignition system.

Refer to paragraph 11-55.

Induction air leaks.

Check visually. Correct
the cause of leaks.

Manual primer leaking.

Disconnect primer outlet
line. If fuel leaks through
primer. repair or replace
primer.

Leaking float valve or
float level set too high.

Perform an idle mixture
check. Attempt to remove
any rich indication with the
idle mixture adjustment. If the
rich indication cannot be removed, the float valve is
leaking or the float level is
set too high. Replace defective parts, reset float level.

Defective carburetor.

If engine will start when
primed but stops when

priming is discontinued
with mixture control in full
RICH position. the carburetor
is defective. Repair or replace
carburetor.

MODEL 172 SERIES SERVICE MANUAL
11-10.

TROUBLE SHOOTING (Cont).
TROUBLE

PROBABLE CAUSE

REMEDY

ENGINE STARTS BUT
DIES. OR WILL NOT IDLE
(Cont).

Defective engine.

Check compression. Liste
for unusual engine noises.
Engine repair is required

ENGINE RUNS ROUGHLY
OR WILL NOT ACCELERATE PROPERLY.

Restriction n aircraft fuel
system.

Refer to Section 12.

Worn or improperly rigged
throttle or mixture control.

Check visually. Replace
worn linkage. Rig properly.

Spark plugs fouled or improperly gapped.

Remove, clean and regap
plugs. Replace if defective.

Defective ignition system.

Refer to paragraph 11-55.

Defective or badly adjusted
accelerator pump in carburetor.

Check setting of accelerator
pump linkage and adjust as
necessary.

Float level set too low.

Check and reset float level.

Defective carburetor.

Repair or replace carburetor.

Defective engine.

Check compression.
for unusual engine

Listen
noises.

Engine repair is required

Restricted carburetor air
filter.

Check visually. Clean in
accordance with Section 2.

Cracked engine mount.

Inspect and repair or replace mount as required.

Defective mounting bushings.

Inspect and install new
bushings as required

11-7

MODEL 172 SERIES SERVICE MANUAL
11-10.

TROUBLE SHOOTING (Cont).
TROUBLE

POOR IDLE CUT-OFF.

11-11.

PROBABLE CAUSE

REMEDY

Worn or improperly rigged
mixture control.

Check that idle cut-off stop
on carburetor is contacted.
Replace worn linkage. Rig
properly.

Manual primer leaking.

Disconnect primer outlet
line. If fuel leaks through
primer, it is defective.
Repair or replace primer.

Defective carburetor.

Repair or replace carburetor.

Fuel contamination.

Check all screens in fuel
system. Drain all fuel and
flush out system. Clean all
screens, lines, strainer and
carburetor.

REMOVAL. If an engine is to be placed in storage or returned to the manufacturer for
overhaul, proper preparatory steps should be taken for corrosion prevention prior to
beginning the removal procedure. Refer to Section 2 for storage preparation. The following
engine removal procedure is based upon the engine being removed from the aircraft with the
engine mount attached to the firewall.

NOTE
Tag each item when disconnected to aid in identifying
wires, hoses, lines and control linkages when engine is
reinstalled. Likewise, shop notes made during removal
will often clarify reinstallation. Protect openings,
exposed as a result of removing or disconnecting units,
against entry of foreign material by installing covers or
sealing with tape.
a.
b.
c.
d.
e.

11-8

Place all cabin switches in the OFF position.
Place fuel selector valve in the OFF position.
Remove engine cowling in accordance with paragraph 11-3.
Disconnect battery cables and insulate terminals as a safety precaution.
Drain fuel strainer and lines with strainer drain control.

MODEL 172 SERIES SERVICE MANUAL
NOTE

During the following procedures, remove any clamps or
lacings which secure controls, wires, hoses or lines to the
engine. engine mount or attached brackets, so they will
not interfere with engine removal. Some of the items
listed can be disconnected at more than one place. It may
be desirable to disconnect some of these items at other
than the places indiated The reason for engine removal
should be the governing factor in deciding at which point
to disconnect them. Omit any of the items which are not
present on a particular engine installation.
f. Drain the engine oil sump and oil cooler.
g. Disconnect magneto primary lead wires at magnetos.
WARNING

The magnetos are in a SWITCH ON condition when the
switch wires are disconnected. Ground the magneto
points or remove the high tension wires from the magnetos or spark plugs to prevent accidental firing.
h. Remove the spinner and propeller in accordance with Section 13.
i. Disconnect throttle and mixture controls at carburetor. Remove clamps attaching
controls to engine and pull controls aft clear of engine. Use care to avoid bending
controls too sharply. Note EXACT position, size and number of attaching washers
and spacers for reference on reinstallation.
j. Loosen clamps and remove flexible duct from engine baffle and oil cooler.
k. Loosen clamps and remove flexible duct from muffler shroud and heater valve.
l. Disconnect carburetor heat control at airbox and remove clamp attaching control to
bracket. Pull control aft to clear engine.
m. Disconnect wires and cables as follows:
1. Disconnect tachometer drive shaft at adapter.
CAUTION

When disconnecting starter cable do not permit starter
terminal bolt to rotate. Rotation of the bolt could break the
conductor between bolt and field coils causing the starter
to be inoperative.
Disconnect starter electrical cable at starter.
Disconnect cylinder head temperature wire at probe.
Disconnect electrical wires and wire shielding ground at alternator.
Disconnect EGT probe (if installed).
Remove all clamps and lacings attaching wires or cables to engine and pull wires
and cables aft to clear engine.
n. Disconnect lines and hoses as follows:
1. Disconnect vacuum hose at firewall fitting.
2. Disconnect engine breather hose at top of accessory case.
2.
3.
4.
5.
6.

11-9

MODEL 172 SERIES SERVICE MANUAL
WARNING
Residual fuel and oil draining from disconnected lines
and hoses constitutes a fire hazard. Use caution to
prevent accumulation of such fuel and oil when lines or
hoses are disconnected.
3. Disconnect oil temperature bulb at adapter.
4. Disconnect primer line at firewall fitting.
5. Disconnect fuel supply hose at carburetor.
6. Disconnect oil pressure line at firewall fitting.
7. Disconnect oil cooler hoses at cooler.
o.

Carefully check the engine again to ensure ALL hoses. lines, wires, cables, clamps
and lacings are disconnected or removed which would interfere with the engine
removal. Ensure all wires, cables and engine controls have been pulled aft to clear
the engine.
p. Attach a hoist to the lifting eye at the top center of the engine crankcase. Lift engine
just enough to relieve the weight from the engine mounts.
CAUTION
Place a suitable stand under the tail tie-down ring before
removing engine. The loss of engine weight will cause
the aircraft to be tail heavy.
q. Remove bolts attaching engine to engine mount and slowly hoist engine and pull it
forward, checking for any items which would interfere with the engine removal.
Balance the engine by hand and carefully guide the disconnected parts out as the

engine is removed.
11-12.

CLEANING. Refer to Section 2 for cleaning of the engine.

11-13.

ACCESSORIES REMOVAL. Removal of engine accessories for overhaul or for engine
replacement involves stripping the engine of parts, accessories and components to reduce it
to the bare engine. During the removal process, removed items should be examined
carefully and defective parts should be tagged for repair or replacement with new components.

NOTE
Items easily confused with similar items should be
tagged to provide a mean of identification when being
installed on a new engine. All openings exposed by the
removal of an item should be closed by installing a
suitable cover or cap over the opening. This will prevent
entry of foreign material. If suitable covers are not
available, tape may be used to cover the openings.

11-10

MODEL 172 SERIES SERVICE MANUAL
ENGINE-TO-MOUNT
(UPPER)

MOUNT-TO-FIREWALL
(UPPER)

TORQUE MOUNT-TO-FIREWALL
BOLTS TO 160-190 LB-IN

9
2

7 4*

NOTE
When installing shock mounts, install
shock mount pad (8) as shown for the
upper and lower mounts.

2
2

4 5

MOUNT- TO-FIREWALL
(LOWER)

3
9

TORQUE ENGINE-TO-MOUNT
BOLTS TO 450-500 LB-IN
*

6
ENGINE-TO-MOUNT
(LOWER)

BEGINNING WITH SERIAL 17267808(LOWER)
F17201518

1. Nut
2. Washer
3. Engine Mount

4. Washer
5. Firewall
6. Bolt
7. Engine Mount Foot

Figure 11-2.
Temporary Revision 4 - Feb 16/96

8.
9.
10.
11.

Shock Mount Pad
Shock Mount Dampener
Shock Mount Pad
Washer

Engine Mount Details
Revision 3 11-11

MODEL 172 SERIES SERVICE MANUAL

11-14.

INSPECTION. For specific items to be inspected, refer to the engine manufacturer's manual.
a.
Visually inspect the engine for loose nuts, bolts, cracks and fin damage.
b.
Inspect baffles, baffle seals and brackets for cracks, deterioration and breakage.
c.
Inspect all hoses for internal swelling, chafing through protective plys, cuts,
breaks, stiffness damaged threads and loose connections. Excessive heat on hoses will cause them to become brittle and easily broken. Hoses and lines are most
likely to crack or break near the end fittings and support points.
d.
Inspect for color bleaching of the end fittings or severe discoloration of the hoses.
NOTE
Avoid excessive flexing and sharp bends when examining hoses for stiffness.
e.
f.

Refer to Section 2 for replacement intervals for flexible fluid carrying hoses.
For major engine repairs, refer to the manufacturer's overhaul and repair manual.

11-15.

BUILD-UP. Engine build-up consists of installation of parts, accessories and components
to the basic engine to build up an engine unit ready for installation on the aircraft. All safety wire, lockwashers, nuts, gaskets and rubber connections should be new parts.

11-16.

INSTALLATION. Before installing the engine on the aircraft, install any items which
were removed from the engine or aircraft after the engine was removed.
NOTE
Remove all protective covers, plugs, caps and identification tags as each item is connected or installed.
Omit any items not present on a particular engine installation.
a.
b.
c.

Hoist the engine to a point near the engine mount.
Install engine shock-mount pads as illustrated in figure 11-2.
Carefully lower engine slowly into place on the engine mount. Route controls,
lines, hoses and wires in place as the engine is positioned on the engine mount.
NOTE
Be sure engine shock-mount pads, spacers and
washers are in place as the engine is lowered into position.

d.
e.

11-12

Install engine mount bolts, washers and nuts, then remove the hoist and tail
support stand. Torque bolts to 450-500 lb-in.
Route throttle, mixture and carburetor heat controls to the carburetor and
airbox and connect. Secure controls in position with clamps.

MODEL 172 SERIES SERVICE MANUAL
NOTE
Throughout the aircraft fuel system. from the tanks to the
carburetor, use NS-40 (RAS-4) (Snap-On-Tools Corp..
Kenosha, Wisconsin), MIL-T-5544 (Thread Compound
Antiseize, Graphite Petrolatum). USP Petrolatum or
engine oil as a thread lubricator or to seal a leaking
connection. Apply sparigly to male threads, exercising
extreme caution to avoid "stringing" sealer across the
end of the fitting. Always ensure that a compound. the
residue from a previously used compound, or any other
foreign material cannot enter the system.
f.

Connect lines and hoses as follows:
1. Connect oil cooler hoses at cooler.
2. Connect oil pressure line at firewall fitting.
3. Connect fuel supply hose at carburetor.
4. Connect primer line at firewall fitting.
5. Connect oil temperature bulb at adapter.
6. Connect engine breather hose at top of accessory case.
7. Connect vacuum hose at firewall fitting.
8. Install clamps and lacings attaching lines and hoses to engine, engine mount and
brackets.
g. Connect wires and cables as follows:
1. Connect electrical wires and wire shielding ground at alternator.
2. Connect cylinder head temperature wire at probe. Do not exceed 4 lb-in. torque.
CAUTION
When connecting starter cable, do not permit starter
terminal bolt to rotate. Rotation of the bolt could break the
conductor between bolt and field coils causing the starter
to be inoperative.
3.
4.

Connect starter electrical cable at starter.
Connect tachometer drive shaft at adapter. Be sure drive cable engages drive in
adapter. Hand tighten, then torque 1/4 turn.
5. Connect EGT probe (if installed).
6. Install clamps and lacings securing wires and cables to engine. engine mount and
brackets.
h. Install flexible duct to heater valve and engine baffle and install clamps.
i. Install flexible duct to engine baffle and oil cooler and install clamps.
j. Install propeller and spinner in accordance with instructions outlined in Section 13.
k. Complete a magneto switch ground-out and continuity check, then connect primary
lead wires to the magnetos. Remove the temporary ground or connect spark plug
leads, whichever procedure was used during removal.
WARNING
Be sure magneto switch is in OFF position when connecting switch wires to magnetos.

11-13

MODEL 172 SERIES SERVICE MANUAL
l. Clean and install induction air filter.
m. Service engine with proper grade and quantity of engine oil. Refer to Section 2 if
engine is new. newly overhauled or has been in storage.
n. Check all switches are in the OFF position, and connect battery cables.
o. Rig engine controls in accordance with paragraphs 11-61. 11-62 and 11-63.
p. Inspect engine installation for security, correct routing of controls. lines, hoses and
electrical wiring, proper safetying and tightness of all components.
q. Install engine cowling in accordance with paragraph 11-3.
r. Perform an engine run-up and make final adjustments on the engine controls.
11-17.

FLEXIBLE FLUID HOSES.

11-18.

LEAK TEST.
a. After each 100 hours of engine operation. all flexible fluid hoses in the engine
compartment should be checked for leaks as follows:
1. Examine the exterior of hoses for evidence of leakage or wetness.
2. Hoses found leaking should be replaced.
3. Refer to paragraph 11-14 for detailed inspection procedures for flexible hoses.

11-19.

REPLACEMENT.
a. Hoses should not be twisted on installation. Pressure applied to a twisted hose may
cause failure or loosening of the nut.
b. Provide as large a bend radius as possible.
c. Hoses should have a minimum of one-half inch clearance from other lines. ducts.
hoses or surrounding objects, or be butterfly clamped to same. or tied together with S1693-3 sta-strap as required to prevent chafing..
d. Rubber hoses will take a permanent set during extended use in service. Straightening a hose with a bend having a permanent set will result in hose cracking. Care
should be taken during removal so that hose is not bent excessively. and during
reinstallation to assure hose is returned to its original position.
e. Refer to AC 43.13-1. Chapter 10, for additional installation procedures for flexible
fluid hose assemblies.

11-20.

STATIC RUN-UP PROCEDURES. In a case of suspected low engine power. a static RPM
run-up should be conducted as follows:
a. Run-up engine, using takeoff power and mixture settings, with the aircraft facing 90 °
right and then left to the wind direction.
b. Record the RPM obtained in each run-up position.
NOTE
Daily changes in atmospheric pressure, temperature and
humidity will have a slight effect on static run-up.
c.

Average the RPM values obtained in step b. The resulting RPM figure should be
within 60 RPM of 2340 RPM.
d. If the resulting average RPM figure is lower than stated above, the following checks
are recommended to determine a possible deficiency.
1. Check carburetor heat control for proper rigging. If partially open it would cause
a slight power loss.
2. Check magneto timing, spark plugs and ignition harness for settings and
conditions.
3. Check condition of induction air filter. Clean if necessary.
4. Perform an engine compression check. (Refer to engine manufacturer's manual.)

11-14

MODEL 172 SERIES SERVICE MANUAL

11-21.

ENGINE BAFFLES.

11-22.

DESCRIPTION. The sheet metal baffles installed on the engine direct the flow of air
around the cylinders and other engine components to provide optimum cooling. These baffles incorporate rubber-asbestos composition seals at points of contact with the engine
cowling and other engine components to help confine and direct the flow to the desired area. It is very important to engine cooling that the baffles and seals are in good condition
and installed correctly. The vertical seals must fold forward and the side seals must fold
upward. Removal and installation of the various baffle segments is possible with the cowling removed. Be sure that any new baffle seals properly. Beginning with Serials 17270188
and F17201730, two access holes have been added to the engine baffling to facilitate the accessibility of spark plugs on number 3 and 4 cylinders. Earlier 1977 and 1978 models (Serials 17267585 thru 17270187 and F17201515 thru F17201729) can be modified by the
instructions contained in Service Letter SE78-22.

11-23.

CLEANING AND INSPECTION. The engine baffles should be cleaned with a suitable solvent to remove oil and dirt.
NOTE
The rubber-asbestos seals are oil and grease resistant but should not be soaked in solvent for long periods.
Inspect baffles for cracks in the metal and for loose and/or torn seals. Repair or replace any
defective parts.

11-24.

REMOVAL AND INSTALLATION. Removal and installation of the various baffle segments is possible with the cowling removed. Be sure that any replaced baffles and seals are
installed correctly and that they seal to direct the airflow in the correct direction. Various
lines, hoses, wires and controls are routed through some baffles. Make sure that these parts
are reinstalled correctly after installation of baffles.

11-25.

REPAIR. Repair of an individual segment of engine baffle is generally impractical since,
due to the small size and formed shape of the part, replacement is usually more economical.
However, small cracks may be stop-drilled and a reinforcing doubler installed. Other repairs may be made as long as strength and cooling requirements are met. Replace sealing
strips if they do not seal properly.

11-26.

ENGINE MOUNT. (See figure 11-2.)

11-27.

DESCRIPTION. The engine mount is composed of sections of steel tubing welded together
and reinforced with gussets. The mount is fastened to the fuselage at four points. The engine is attached to the engine mount with shock-mount assemblies which absorb engine vibrations.

11-28.

REMOVAL AND INSTALLATION. Removal of the engine mount is accomplished by removing the engine as outlined in paragraph 11-11, then removing the engine mount from
the firewall. On reinstallation, torque the mount-to-fuselage bolts to 160-190 lb-in. Torque
the engine-to-mount bolts to 450-500 lb-in.

Temporary Revision 4 - Feb 16/96

Revision 3

11-15

MODEL 172 SERIES SERVICE MANUAL
11-29.

REPAIR. Repair of the engine mount shall be performed carefully as outlined in Section
18. Refer to Section 19 for mount painting.

11-30.

ENGINE SHOCK MOUNT PADS. (See figure 11-2.) The bonded rubber and metal shock
mounts are designed to reduce transmission of engine vibrations to the airframe. The rubber pads should be wiped clean with a clean, dry cloth.
NOTE
Do not clean the rubber pads and dampener assembly with any
type of cleaning solvent.
Inspect the metal parts for cracks and excessive wear due to aging and deterioration. Inspect the rubber pads for separation between the pad and metal backing, swelling, cracking or a pronounced set of the pad. Install new parts for all parts that show evidence of wear
or damage.

11-31.

ENGINE OIL SYSTEM.

11-32.

DESCRIPTION. The lubricating system is of the full pressure, wet sump type. Refer to applicable engine manufacturers overhaul manual for specific details and descriptions.
WARNING
The U.S. Environmental Protection Agency advises that mechanics and other workers who handle engine oil are advised
to minimize skin contact with used oil and promptly remove
used oil from the skin. In a laboratory study, mice developed
skin cancer after skin was exposed to used engine oil twice a
week without being washed off, for most of their life span. Substances found to cause cancer in laboratory animals may also
cause cancer in humans.

11-33.

11-16

TROUBLE SHOOTING.
TROUBLE

PROBABLE CAUSE

REMEDY

NO OIL PRESSURE.

No oil in sump.

Check with dipstick. Fill
sump with proper grade
and quantity of oil. Refer
to Section 2.

Oil pressure line broken,
disconnected or pinched.

Inspect pressure lines.
Replace or connect lines
as required.

Oil pump defective.

Remove and inspect. Examine engine. Metal particles from damaged
pump may have entered
engine oil passage.

Defective oil pressure
gage.

Check with a known
good gage. If second
reading is normal, replace gage.

MODEL 172 SERIES SERVICE MANUAL
11-33.

TROUBLE SHOOTING (Cont).
TROUBLE

NO OIL PRESSURE
(Cont).

LOW OIL PRESSURE.

HIGH OIL PRESSURE.

PROBABLE CAUSE

REMEDY

Oil congealed in gage line.

Disconnect line at engine
and gage; flush with kerosene. Pre-fill with kerosene
and install.

Relief valve defective.

Remove and check for dirty
or defective parts. Clean
and install: replace valve
if defective.

Low oil supply.

Check with dipstick. Fill
sump with proper grade
and quantity of oil. Refer
to Section 2.

Low viscosity oil.

Drain sump and refill with
proper grade and quantity
of oil.

Oil pressure relief valve
spring weak or broken.

Remove and inspect spring.
Replace weak or broken spring.

Defective oil pump.

Check oil temperature and
oil level. If temperature
is higher than normal and
oil level is correct, internal
failure is evident. Remove
and inspect. Examine engine.
Metal particles from damaged pump may have entered
oil passages.

Secondary result of high
oil temperature.

Observe oil temperature
gage for high indication.
Determine and correct reason
for high oil temperature.

Leak in pressure or
suction line.

Inspect gasket between
accessory housing and crankcase. Repair engine as required.

Dirty oil screens.

Remove and clean oil screens.

High viscosity oil.

Drain sump and refill with
proper grade and quantity
of oil.

Relief valve defective.

Remove and check for dirty
or defective parts. Clean
and install: replace valve
if defective.

11-17

MODEL 172 SERIES SERVICE MANUAL
11-33.

TROUBLE SHOOTING (Cont).
TROUBLE

PROBABLE CAUSE

REMEDY

HIGH OIL PRESSURE
Cont).

Defective oil pressure gage.

Check with a known good
gage. If second reading is
normal. replace gage.

LOW OIL TEMPERATURE.

Defective oil temperature
gage or temperature bulb.

Check with a known good
gage. If second reading is
normal, replace gage. If reading is similar. the temperature
bulb is defective. Replace bulb.

Oil cooler thermostatic
valve/bypass valve defective or stuck.

Remove valve and check for
proper operation. Replace
valve if defective.

Oil cooler air passages
clogged.

Inspect cooler core.
Clean air passages.

Oil cooler oil passages
clogged.

Attempt to drain cooler. Inspect for sediment. Remove
cooler and flush thoroughly.

Thermostatic valve or bypass valve damaged or held
open by solid matter.

Feel front of cooler core
with hand. If core is cold.
oil is bypassing cooler. Remove
and clean valve and seat.
If still inoperative, replace.

Low oil supply.

Check with dipstick. Fill
sump with proper grade and
quantity of oil. Refer to
Section 2.

Oil viscosity too high.

Drain sump and refill with
proper grade and quantity
of oil.

Prolonged high speed operation on the ground.

Hold ground running above
1500 RPM to a minimum.

Defective oil temperature
gage.

Check with a known good
gage. If second reading is
normal. replace gage.

HIGH OIL TEMPERATURE.

11-18

MODEL 172 SERIES SERVICE MANUAL
11-33.

TROUBLE SHOOTING (Cont).

TROUBLE

PROBABLE CAUSE

HIGH OIL TEMPERATURE
(Cont.)

OIL LEAK AT FRONT OF

REMEDY

Defective oil temperature
bulb.

Check for correct oil pressure, oil level and cylinder
head temperature. If they are
correct, check oil temperature
gage for being defective: if
similar reading is observed.
bulb is defective. Replace bulb.

Oil congealed in cooler.

This condition can occur
only in extremely cold temperatures. If congealing is suspected, use an external heater
or a heated hangar to warm the
congealed oil.

Damaged crankshaft seal.

Replace.

Damaged push rod housing
oil seal.

Replace.

ENGINE
OIL LEAK AT PUSH ROD
HOUSING.
11-34.

FULL-FLOW OIL FILTER.

11-35.

DESCRIPTION. An external full-flow oil filter may be installed on the engine. If the filter
should become clogged, a bypass valve allows engine oil to flow directly to the engine oil
passages.

11-36.

REMOVAL AND INSTALLATION.
NOTE
Replacement filters are available from the Cessna Supply
Division.
a.
b.
c.
d.

Remove engine cowling in accordance with paragraph 11-3.
Remove safety wire from filter.
Unscrew filter from adapter.
Lightly lubricate gasket with engine oil, (or DC 4 DOW CORNING on CHAMPION
spin-on filters) prior to installation.
e. Install spin-on filter on the stud and torque to 18-20 lb-ft or 3/4 to 1 full turn after
gasket makes contact.
f. Safety wire filter to adapter.
g. After first engine run check for oil leaks.
11-37.

OIL COOLER.

11-19

MODEL 172 SERIES SERVICE MANUAL
11-38.

DESCRIPTION. Beginning with Serials 17271954 & on. and F17201910 & on. the external oil
cooler is mounted on the aft side of the right aft vertical baffle. Flexible fire sleeved hoses
carry the oil to and from the cooler. Cooling air for the cooler enters through a hole in the
baffle assembly. Exhaust air from the cooler is discharged into the engine compartment. A
bypass valve causes oil to bypass the cooler in the event of congealed oil or an obstruction in
the cooler. At each engine oil change, drain the oil cooler.

11-39.

ENGINE FUEL SYSTEM.

11-40.

DESCRIPION. A single barrel, float-type up-draft carburetor is installed on the engine.
The carburetor is equipped with a manual mixture control and an idle cut-off. For repair and
overhaul of the carburetor refer to the manufacturer's overhaul and repair manual.

11-41.

CARBURETOR.

11-42.

REMOVAL AND INSTALLATION.
a. Place fuel selector valve in the OFF position.
b. Remove engine cowling in accordance with paragraph 11-3.
c. Drain fuel from strainer and lines with strainer drain control.
d. Disconnect throttle and mixture controls at the carburetor. Note EXACT position.
size and number of washers and spacers for reference on reinstallation.
e. Disconnect and cap or plug fuel lines at carburetor.
f. Remove induction airbox.
g. Remove nuts and washers attaching carburetor to intake manifold and remove
carburetor.
h. Reverse the preceding steps for reinstallation. Use new gasket between carburetor
and intake manifold. Check carburetor throttle arm to idle stop arm attachment for
security. proper torque and cotter pin installation at each normal engine inspection
in accordance with figure 11-4.

11-43.

IDLE SPEED AND MIXTURE ADJUSTMENTS. Since idle RPM may be affected by idle
mixture adjustment. it may be necessary to readjust idle RPM after setting the idle mixture.
a. Start and run engine until the oil temperature and oil pressure are in the normal
operating range.
b. Check the magnetos for proper operation in accordance with paragraph 11-56.
c. Clear the engine by advancing the RPM to approximately 1000. then retard the
throttle to the idle position. The engine RPM should stabilize at 600 - 25. If not. adjust
the idle speed screw IN to increase and OUT to decrease RPM.
NOTE
An engine should idle smoothly, without excessive
vibrations. The idle speed should be high enough to
maintain idling oil pressure and to preclude any possibility of engine stoppage in flight when the throttle is
closed.
d. After the idle speed has stabilized (600 ± 25 RPM).. move the mixture control slowly
toward the IDLE CUT-OFF position and observe the tachometer for any minute
change during this manual leaning procedure.

11-20

MODEL 172 SERIES SERVICE MANUAL
e.
f.

Quickly return the mixture control to the FULL RICH position before the engine
stops.
A momentary increase of approximately 25 RPM while slowly, manually leaning the
mixture is most desirable. An increase of more than 25 RPM indicates a rich idle
mixture, and an immediate decrease in RPM (if not preceded by a momentary
increase), indicates a lean idle mixture.
If the idle mixture is too rich, turn the idle mixture adjustment center screw one or
two notches in a clockwise direction as viewed from the aft end of the unit, then repeat
steps "d" through "f".
NOTE
After each adjustment to the idle mixture, run engine up
to approximately 1800 RPM to clear the engine of excess
fuel and obtain a correct idle speed.

h. If the idle mixture is too lean, turn the idle mixture adjustment center screw one or
two notches in a counterclockwise direction as viewed from the aft end of the unit.
then repeat steps "d" thru "f".
.This method of adjustment will give the desired idle RPM. If the adjustments do not
remain stable, check the throttle and mixture linkage for evidence of wear and
improper rigging. Any looseness of the throttle and mixture linkage will cause
erratic idling. In all cases, allowance should be made for the effect of weather
condition upon idling adjustment. The relation of the aircraft to the prevailing wind
direction will have an effect on the propeller load and engine RPM. It is advisable to
make idle adjustments with the aircraft crosswind.

11-44.

INDUCTION AIR SYSTEM.

11-45.

DESCRIPTION. Ram air to the engine enters the induction airbox through the induction
filter located in the forward part of the lower engine cowling. From the induction airbox the
air is directed to the inlet of the carburetor, mounted on the lower side of the engine oil sump
through the carburetor to the center zone induction system. which is an integral part of the
oil sump. From the center zone system, the fuel-air mixture is distributed to each cylinder by
separate intake pipes. The intake pipes are attached to the center zone risers with hoses and
clamps and to the cylinder with a two-bolt flange. which is sealed with a gasket. The
induction airbox contains a valve, operated by the carburetor heat control in the cabin.
which permits air from an exhaust heated source to be selected in the event carburetor icing
or filter icing should be encountered.

11-46.

REMOVAL AND INSTALLATION.
a. Remove and install air filter as follows:
1. Thru Serials 17273579 and F17202029. remove 4 machine screws from metal trim
around air filter and remove trim. Beginning with Serials 17273580 & On. and
F17202030 & On, 4 machine screws are replaced by 4 quick-release fasteners
2. Release 4 quick-release fasteners securing filter element to cowl and remove
element for cleaning or replacement. Refer to Section 2 for servicing.
3. Reverse the preceding steps for reinstallation.
b. Remove and install induction airbox as follows:
1. Remove cowling as required for access in accordance with paragraph 11-3.
2. Mark the intake pipes as they are removed from the engine so they may be
reassembled in the same location from which they were removed.
3. Loosen hose clamps and slide hose connections from sump. Remove any clamps
attaching wires or lines to the intake pipes.

11-21

MODEL 172 SERIES SERVICE MANUAL
4.
5.
6.

11-47.

Remove the nuts. washers and lock washers at cylinder.
Remove intake pipe and clean gasket from cylinder mounting pad and intake
pipe flange.
Reverse the preceding steps for reinstallation. Use new gaskets and install intake
pipes in the same location from which they were removed.

IGNITION SYSTEM.

11-48.

DESCRIPTION. The ignition system is comprised of dual magnetos, two spark plugs in each
cylinder, an ignition wiring harness, an ignition switch mounted on the instrument panel
and required wiring between the ignition switch and magnetos.

11-49.

TROUBLE SHOOTING.
TROUBLE

ENGINE WILL NOT START.

REMEDY

PROBABLE CAUSE
Defective ignition switch.

Check switch continuity.
Replace if defective.

Spark plugs defective.
improperly gapped or
fouled by moisture or
deposits.

Clean. regap and test plugs.
Replace if defective.

Defective ignition harness.

If no defects are found by
a visual inspection.
check with a harness
tester. Replace defective
parts.

Magneto "P" lead
grounded.

Check continuity. "P"lead
should not be grounded in
the ON position, but should
be grounded in OFF posi-

tion. Repair or replace "P"
lead.
Failure of impulse coupling.

Impulse coupling pawls
should engage at cranking
speeds. Listen for loud
clicks as impulse couplings
operate. Remove magnetos
and determine cause. Replace defective magnetos.

Defective magneto.

Refer to paragraph 11-55.

Broken drive gear.

Remove magneto and check
magneto and engine gears.
Replace defective parts.
Make sure no pieces of
damaged parts remain in
engine or engine disassembly

will be required

11-22

MODEL 172 SERIES SERVICE MANUAL
11-49.

TROUBLE SHOOTING. (Cont).
TROUBLE

ENGINE WILL NOT
IDLE OR RUN PROPERLY.

PROBABLE CAUSE

REMEDY

Spark plugs defective,
improperly gapped or
fouled by moisture or
deposits.

Clean regap and test plugs.
Replace if defective.

Defective ignition harness

If no defects are found by
a visual inspection. check
with a harness tester. Replace defective parts.

Defective magneto.

Refer to paragraph 11-55.

Impulse coupling pawls
remain engaged.

Listen for loud clicks as
impulse coupling operates.
Remove magneto and determine cause. Replace defective magneto.

Spark plugs loose.

Check and install properly.

11-50.

MAGNETOS.

11-51.

DESCRIPTION. The Bendix D-2000 series magneto consists of two electrically independent
ignition circuits in one housing. A single four pole rotor provides the magnetic energy for
both circuits. The magneto uses an impulse coupling to provide reliable ignition at engine
cranking speed. Suppression of breaker contact point arcing is accomplished by feed-thru
type capacitors mounted in the magneto cover which forms a part of the magneto harness
assembly.

11-52.

REMOVAL AND INSTALLATION.
WARNING
The magneto is in a SWITCH ON condition when the
switch wire is disconnected. Therefore, ground the
breaker contact points or disconnect the high-tension
wires from the magneto or the spark plugs.
a.
b.

Remove engine cowling in accordance with paragraph 11-3.
Remove the eight screws securing the high-tension outlet cover to the magneto. The
"P" leads may be disconnected for additional clearance if necessary.

11-23

MODEL 172 SERIES SERVICE MANUAL
NOTE
It is a good practice to position No. 1 cylinder at its
approximate advance firing position before removing
the magneto.
c.

11-53.

Remove nuts. washers and clamps attaching the magneto to the engine accessory
housing. Note the approximate angular position at which the magneto is installed.
then remove the magneto.
Reverse the preceding steps for reinstallation and time magneto-to-engine in
accordance with paragraph 11-54.

INTERNAL TIMING. (MAGNETO REMOVED FROM ENGINE.)
NOTE
A magneto. correctly timed internally. will have the red
painted tooth of the large distributor gears approximately centered in the timing windows. the R "E" gap
mark on the rotor shaft in alignment with the pointer and
both sets of breaker contacts opening, all at the same
time.
a. Remove breaker contact point assembly cover. if installed. by removing the cover
screws, pulling cover directly aft away from housing and disconnecting both
capacitor leads from breaker contact assemblies.
b. Remove timing inspection hole plugs from magneto.
c. Slowly turn the rotor shaft until the red painted tooth of the large distributor gear for
each side is approximately centered in the inspection windows with the R ("E" gap)
mark on the rotor aligned with the pointer. Lock the rotor in this EXACT position
using Bendix Holding Tool. Part No. 11-8465 or equivalent.
NOTE
Position the 11-8465 Rotor Holding Tool on drive end of
rotor shaft in the 4 o'clock position so that any shaft
deflection caused by clamping action will be in a plane
parallel to the breaker contacts.
d. Connect the timing light (Bendix Part No. 11-9110 or equivalent) black lead to any

unpainted surface of the magneto. Connect the red lead to the left breaker contact
terminal and the green lead to the right breaker contact terminal.
Carefully adjust the LEFT breaker contacts to just begin to open (light will go out)
with the timing pointer within the width of the R ("E" gap) mark.
f. Repeat step "e" for the RIGHT breaker contacts.
g. Loosen the rotor holding tool and turn rotor shaft in normal direction of rotation until
cam followers of contact assemblies are on the high point of cam lobes. Contact point
clearance should be 0.016 ± 0.002 inch and 0.016 ± 0.004 inch on LEFT and RIGHT
contacts respectively. If dimensions do not fall within limits, readjust contact points
and recheck to be sure the points just begin to open when the timing pointer is within
the width of the R ("E" gap) mark.

11-24

MODEL 172 SERIES SERVICE MANUAL
NOTES
Wire feeler gages are recommended when checking
contact point clearance.
No attempt should be made to stone or dress contact
points.
If the above conditions are met and within tolerance, the
magneto is timed internally and ready for installation If
the above conditions are not within tolerance, proceed to
step "h".
h.

While holding the rotor shaft, loosen the screw securing breaker contact cam to rotor
shaft and back screw out approximately half way. Place the end of a broad bladed
screw driver between the bottom of the cam and housing. Strike the screw driver
handle with a sharp downward blow to "pop" the cam loose from taper of shaft.
i. Rotate cam until breaker-contact cam followers are on the high point of cam lobes.
Adjust breaker points to obtain a clearance of 0.016 ±0.002 inch and 0.016 ±0.004 inch
on LEFT and RIGHT contacts respectively. Tighten breaker contact securing screws
to 20-25 lb-in.
j. Repeat step c.
k. While holding rotor shaft in this EXACT position. rotate the breaker contact cam in
the opposite direction of rotation a few degrees BEYOND where the breaker contacts
close, then rotate cam in the normal direction of rotation until the breaker contacts
just begin to open. Point opening should be determined by the use of a timing light.
(Bendix Part No. 11-9110 or equivalent.)
1. While holding cam in this EXACT position, push cam on rotor shaft as far as possible
with the fingers. Tighten cam securing screw thereby drawing the cam down evenly
and tightly. Torque cam securing screw to 16-20 lb-in.
NOTE
Extreme care must be exercised in this operation. If cam
adjustment is changed in the slightest degree. the timing
of the magneto will be thrown off. Do not drive cam on
rotor shaft with a mallet or other instrument.
m. Recheck timing to make sure both sets of breaker contact begin to open within the
width of the R ("E" gap) mark and that the contact point clearance is in accordance
with dimensions in step "g".

NOTE
When reinstalling the inspection hole plugs, make sure
the ventilated plugs are installed in the ends of the
magneto. Torque plugs to 12-15 lb-in.

11-25

MODEL 172 SERIES SERVICE MANUAL
11-54.

MAGNETO-TO-ENGINE TIMING. The magneto must be installed with its timing marks
carefully aligned. with number one cylinder on its compression stroke and with the number
one piston at its advanced firing position. Refer to paragraph 11-8 for the advanced firing
position of number one piston. To locate the compression stroke of the number one cylinder.
remove the lower spark plug from number 2.3 and 4 cylinders. Remove the upper spark plug
from number 1 cylinder. Place the thumb of one hand over the spark plug hole of number one
cylinder and rotate crankshaft in the direction of normal rotation until the compression
stroke is indicated by positive pressure inside the cylinder lifting the thumb off the spark
plug hole. After the compression stroke is attained, locate the number one piston at its
advanced firing position. Locating the advanced firing position of the number one piston
may be obtained by rotating the crankshaft opposite to its normal direction of rotation until
it is approximately 30 degrees before top dead center (BTC) on the compression stroke of
number one cylinder. Rotate crankshaft in a normal direction to align the timing mark on the
front face of the starter ring gear support with the drilled hole in the starter, making sure the
final motion of the ring gear is in the direction of normal rotation.
NOTE
An accurate top center indicator which screws into a
spark plug mounting hole, and a pendulum pointer
mounted on a 360-degree timing disc may also be used to
locate the advanced firing position. The timing disc
should be adapted to fit over the end of the propeller
spinner in such a manner that it may be rotated as
necessary. In all cases, it must be definitely determined
that the number one cylinder is at the correct firing
position and on the compression stroke, when the engine
is turned in its normal direction of rotation.
After the engine has been placed in the correct firing position, install the magneto to the
engine in the following manner:
a. Remove the timing window plug from the most convenient side of the magneto
housing.
b. Remove the rotor viewing location plug from the top center of the housing.
c. Turn the rotating magnet drive shaft in the normal direction of magneto rotation
until the red painted tooth of the large distributor gear is centered in the timing hole
(hole at each side of magneto).
d. Also observe at this time that the built in pointer just ahead of the rotor viewing
window aligns with the R ("E" gap) mark on the rotor.
e. Install the magneto-to-engine gasket on the magneto flange.
WARNING
Do not attach harness spark plug leads to the spark plugs
until all magneto-to-engine timing procedures are completed and the switch leads ("P" leads) are connected.
f.

Remove the engine-to-magneto drive gear train backlash by turning magneto drive
opposite to normal rotation as far as possible.
g. With the No. 1 cylinder at its correct firing position as close to its No. 1 firing position
as possible red tooth in center of window and pointer over R ("E" gap) mark on rotor
and install magneto to the engine. Loosely tighten magneto in position.

11-26

MODEL 172 SERIES SERVICE MANUAL
NOTE
To facilitate connection of a timing light to the switch
lead ("P" lead) terminals, short adapter leads may be
fabricated. These can be made by using two switch lead
terminals and two short pieces of insulated wire. Install
the fabricated adapter leads in the switch lead outlet
terminals of the cover.
h. Attach the red lead of the timing light (Bendix Part No. 11-9110 or equivalent) to the
left switch lead adapter, the green lead of the timing light to the right switch lead
adapter and the black lead of the timing light to the magneto housing (common
ground).
NOTE
An internal timing tolerance is allowed when adjusting
the two main breakers. Therefore, one of the main breakers may open slightly before the other. Magneto-toengine timing should be accomplished using the first
main breaker to open as the reference point when the
engine is in the firing position for No. 1 cylinder. This
will ensure that ignition created by either spark plug will
not occur prior to the desired engine firing point.
i.
j.

Turn the entire magneto in direction of rotor rotation until the timing lights are on.
Turn magneto in direction of rotor rotation, right-hand rotation to right and left-hand
rotation to left, until one of the timing lights just goes off. Then tighten the magneto
mounting clamps evenly in this position.
k. Back the engine up approximately 10 ° and then carefully "bump" the engine forward
while observing the timing lights.
1. At the No. 1 cylinder firing position, one of the timing lights should go off. Continue
turning the engine in its normal direction of rotation until the other timing light goes
off. This should be not more than 3 engine degrees later than the first light. If not.
repeat steps "i" thru "k" until these conditions are obtained.
m. Make sure the magneto clamps are tightened securely, recheck timing once more and
remove timing equipment.
n. Reinstall inspection plugs and torque plugs to 12-15 lb-in.
11-55.

MAINTENANCE. At the first 25-hour inspection, first 50-hour inspection. first 200-hour
inspection and thereafter at each 100-hour inspection, the contact breaker point compartment and magneto-to-engine timing should be inspected and checked. If magneto-to-engine
timing is correct within plus zero and minus two degrees, internal timing need not be
checked. If timing is out of tolerance, remove magneto and set internal timing (paragraph
11-53), then install and time to the engine.

NOTE
If engine operating troubles develop which appear to be
caused by the ignition system, it is advisable to check the
spark plugs and ignition harness first before working on
the magnetos. If the trouble appears definitely associated
with a magneto, the following may be used to help
disclose the source of trouble without overhauling the
magneto.

11-27

MODEL 172 SERIES SERVICE MANUAL
a.

Moisture check.
1. Remove contact breaker point assembly cover and inspect cover. cables and
capacitor for moisture in the area.
2. Inspect distributor block high tension outlets for moisture.
3. If any moisture is evident, lightly wipe with a soft. dry. clean. lint-free cloth.
CAUTION
Do not use gasoline or any other solvent, as these will
remove the wax coating on some parts and cause an

electrical leak.
b.

Breaker contact compartment check.
1. Check all parts of the contact breaker assembly for security. Check distributor
block high-tension outlet springs for evidence of spark erosion and proper
height. The end of spring should not be more than 0.422 inch from top of tower.
2. Check breaker contact assembly points for excessive wear, burning, deep pits
and carbon deposits. Breaker points may be cleaned with a hard finish paper. If
breaker points are found defective, install a new assembly. Make no attempts to
stone or dress breaker points. Clean new breaker points with clean unleaded
gasoline and hard finish paper before installing.
3. Check condition of the cam follower felt. Squeeze felt between thumb and finger.
If fingers are not moistened with oil, re-oil using 2 or 3 drops of lubricant (Bendix
Part No. 10-86527 or equivalent). Allow approximately 30 minutes for felt to
absorb the lubricant. Blot off excess lubricant with a clean. lint-free cloth. Too
much lubricant could foul breaker points and cause excessive burning.
4. Check capacitors for looseness in the magneto cover of the harness assembly and
for any physical damage. If equipment is available, check the capacitors for
leakage, series resistance and capacitance. The capacitance should be 0.34 to 0.41
microfarads.
NOTE
Spring in capacitor outlet may cause an indication of a
short to ground if an adapter lead is not used.

If the trouble has not been corrected after accomplishing the moisture and breaker
contact compartment check, check magneto-to-engine timing in accordance with
paragraph 11-54. If timing is incorrect. remove magneto and adjust internal timing in
accordance with paragraph 11-53.
d. Reinstall magneto and time to engine in accordance with paragraph 11-54.
e. If the trouble has not been corrected, magneto overhaul or replacement is indicated.
11-56.

11-28

MAGNETO CHECK.
a. Start and run engine until the oil and cylinder head temperatures are in the normal
operating ranges.
b. Advance engine speed to 1700 RPM.
c. Turn the ignition switch to the "R" position and note the RPM drop. then return the
switch to the "BOTH" position to clear the opposite set of plugs.
d. Turn the switch to the "L" position and note the RPM drop, then return the switch to
the "BOTH" position.

MODEL 172 SERIES SERVICE MANUAL
e.

The RPM drop should not exceed 150 RPM on either magneto setting or show greater
than 50 RPM differential between magneto settings. A smooth RPM drop-off past
normal is usually a sign of a too lean or too rich mixture. A sharp RPM drop-off past
normal is usually a sign of a fouled plug, a defective harness lead or a magneto out of
time. If there is doubt concerning operation of the ignition system. RPM checks at a
leaner mixture setting or a higher engine speeds will usually confirm whether a
deficiency exists.

NOTE
An absence of RPM drop may be an indication of faulty
grounding of one side of the ignition system, a disconnected ground lead at magneto or possibly the magneto
timing is set too far in advance.
11-57.

SPARK PLUGS. Two 18-mm spark plugs are installed in each cylinder and screw into
helicoil type thread inserts. The spark plugs are shielded to prevent spark plug noise in the
radios and have an internal resistor to provide longer terminal life. Spark plug life will vary
with operating conditions. A spark plug that is kept clean and properly gapped will give
better and longer service than one that is allowed to collect lead deposits and is improperly
gapped.
NOTE
Refer to Section 2 for inspection interval. Remove, clean.
inspect and regap all spark plugs at each inspection.
Install lower spark plugs in upper portion of cylinders
and install upper spark plugs in lower portion of cylinders. Since deterioration of lower spark plugs is usually
more rapid than that of the upper spark plugs, rotating
helps prolong spark plug life.

11-58

ENGINE CONTROLS.

11-59

DESCRIPTION. The throttle. mixture, propeller, and carburetor heat controls are of the
push-pull type. The mixture control is equipped to lock in any position desired. To move the
control. the spring-loaded button, located in the end of the control knob. must be depressed.
When the button is released, the control is locked. The mixture control also has a vernier
adjustment. Turning the knob in eitherdirectionwillchange the control setting. The vernier
is primarily for precision control setting. The throttle control has neither a locking button
nor a vernier adjustment, but contains a knurled friction knob which is rotated for more or
less friction as desired. The friction knob prevents vibration induced "creeping" of the
control. The carburetor heat control has no locking device. Prior to 1979 Models the ball
bearing-type rod ends on the throttle, mixture, and propeller control cable ends are secured
to the engine with AN bolt, washers, and self-locking nut Beginning with 1979 Models, the
bolt is replaced with a pre-drilled AN bolt, and the self-locking nut is replaced with a
castellated nut and cotter pin. (See figure 11-3.)
NOTE
Steel AN bolts with an undrilled shank are identified with
an "A" suffix (AN3-6A). A steel bolt of the same size, with
the shank drilled for castellated nut and cotter pin, is
identified as AN3-6. Aluminum AN bolts are not to be
used in this application.

11-29

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.

Bolt
Washer
Nut
Lock Nut

5. Washer
6.
7.
8.

Cotter Pin
Castellated Nut
Rod End
Figure 11-3. Control Cable End (Typical)

11-60.

RIGGING. When adjusting any engine control, it is important to check that the control slides
smoothly throughout its full range of travel, that it locks securely if equipped with a locking
device and the arm or lever it operates moves through its full arc of travel.
CAUTION
Whenever engine controls are being disconnected, pay
particular attention to the EXACT position, size and
number of attaching washers and spacers. Be sure to

install attaching parts as noted when connecting controls.

11-61.

THROTTLE CONTROL. (See figure 11-4.)
NOTE
Before rigging throttle control, check that clamping
sleeve (13) is secure. If any indication of looeness (total
linear movement exceeds .050 in.) or breakage is apparent, replace throttle control.
a. Screw friction lock nut (2) into threads of barrel (7).
b. Ensure washer (5) is installed, and nut (6) on forward side of panel is secured against
washer.
c. Push knob assembly (1) full in against friction lock nut (2), then pull knob assembly
out approximately 118-inch to obtain "cushion."

11-30

MODEL 172 SERIES SERVICE MANUAL
d.
e.

Tighten friction lock nut (2) against barrel (7).
At the carburetor, position throttle lever to the full forward power stop position
against throttle stop screw.
NOTE
Ensure palnut (17) is on threads of plunger (18) before
installing rod end (16).

f. See figure 11-3. Place larger washer (2) on bolt (1).
g. Insert bolt (1) through hole in throttle lever from the INBOARD SIDE of throttle
lever.
h. Screw rod end (16) on threads of plunger (18). until hole in rod end bearing is aligned
with end of bolt (1).
NOTE
Ensure that rod end (16) is threaded on to plunger (18) so
that .020-inch safety wire cannot be installed through
drilled hole in rod end.
i.
j.
k.
1.
m.
n.
o.

Connect rod end to bolt (1) in throttle lever.
Place washer (5) on bolt and secure with castellated nut (7) and cotter pin (6).
Check clamping sleeve (13) in bracket (12) and clamp (15).
Loosen friction lock nut (2).
Pull knob assembly full out and check that idle stop on carburetor is contacted.
Push knob assembly full in and check that full power stop on carburetor is contacted.
Check that throttle has maintained the approximate 1/8-inch "cushion" set in step

Work throttle control in and out several times to check for binding.

"c".

NOTE
Refer to the inspection chart in Section 2 for inspection.
lubrication. and/ or replacement interval for the throttle
control.
11-62.

MIXTURE CONTROL.
a. Push mixture control full in, then pull it out approximately 1/8 inch for cushion.
b. Loosen clamp securing the control to the engine.
c. Shift control housing in the clamp so that the mixture arm on the carburetor is in the
full open position (RICH). Tighten the clamp in this position.
d. Unlock and pull mixture control full out. Check that idle mixture arm on carburetor
is full closed (IDLE CUT-OFF).
e. Check that the bolt and nut at the mixture arm on carburetor secures the control wire
and that the bolt will swivel in the arm.
f. Bend the wire tip 90 degrees to prevent it from being withdrawn if the attaching nut
should become loose.
g. When installing a new control, it may be necessary to shorten the wire and/ or control
housing.
h. The mixture arm on the carburetor must contact the stops in each direction, and the
control should have approximately 1/8 inch cushion when pushed in.

11-31

MODEL 172 SERIES SERVICE MANUAL

19
20
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.

Knob Assembly
Friction Lock Nut
Locking Collet
Instrument Panel
Washer
Nut
Barrel
Core
Casing
Clamping Sleeve
Firewall
Bracket
Clamping Sleeve
Packing
Clamp
Rod End
Palnut
Plunger
Plunger Seal
Plunger Guide

NOTE SERRATED FACES OF
THROTTLE ARM AND STOP

82-43 COTTER
81-311 NUT
TIGHTEN TO
25/60 LB. IN.
TORQUE

Figure 11-4. Throttle Control
11-32

MODEL 172 SERIES SERVICE MANUAL
NOTE
Refer to the inspection chart in Section 2 for inspection
and/or replacment interval for the mixture control.
11-63.

CARBURETOR HEAT CONTROL
a. Loosen clamp securing the control to the bracket on engine.
b. Push control full in. then pull it out approximately 1/8 inch from panel for cushion.
c. Shift control housing in its clamp so that the valve in the airbox is seated in the full
open position. Tighten clamp in this position.
d. Pull out on the control and check that the air valve inside the airbox seats in the
opposite direction.
e. Check that bolt and nut on the air valve lever secures the control wire and that the bolt
will swivel in the lever.
f. Bend the wire tip 90 degrees to prevent it from being withdrawn if the attaching nut
should become loose.
NOTE
Refer to the inspection chart in Section 2 for inspection.
lubrication, and/ or replacement interval for the carburetor heat control.

11-64.

STARTING SYSTEM.

11-65.

DESCRIPTION. The starting system employs an electrical starter motor mounted at the
front (propeller end) lower left side of the engine. A starter solenoid is activated by the
ignition key on the instrument panel. When the solenoid is activated, its contacts close and
electrical current energizes the starter motor. Initial rotation of the starter armature shaft.
engaged with the reduction gear. drives the Bendix shaft and pinion. When the armature
turns the reduction gear. the Bendix drive pinion meshes with the crankshaft ring gear
assembly by inertia and action of the screw threads within the Bendix sleeve. A detent pin
engages in a notch in the screw threads which prevents demeshing if the engine fails to start
when the starting circuit is de-energized. When the engine reaches a predetermined speed.
centrifugal action forces the detent pin out of the notch in the screw shaft and allows the
pinion to demesh from the ring gear.
CAUTION
Never operate the starter motor more than 12 seconds at a
time. Allow starter motor to cool between cranking
periods to avoid overheating. Longer cranking periods
without cooling time will shorten the life of the starter
motor.

11-33

MODEL 172 SERIES SERVICE MANUAL
1-66.

TROUBLE SHOOTING.
TROUBLE

STARTER WILL NOT
OPERATE.

STARTER MOTOR RUNS.
BUT DOES NOT TURN
CRANKSHAFT.

STARTER MOTOR DRAGS.

STARTER EXCESSIVELY
NOISY.

11-34

PROBABLE CAUSE

REMEDY

Defective master switch or
circuit.

Check continuity of master
switch and circuit. Install
new switch or wires.

Defective starter switch or
switch circuit.

Check continuity of switch
and circuit. Install new
switch or wires.

Defective starter motor.

Check voltage to starter. If
voltage is present. Remove. repair or install
new starter motor.

Defective Bendix drive.

Remove starter and inspect
Bendix drive. Replace defective parts.

Damaged starter pinion
gear or ring gear.

Inspect starter pinion gear
and ring gear. Replace
defective parts.

Low battery.

Check battery. Charge or
install new battery.

Starter switch or relay contacts burned or dirty.

Install servicable unit.

Defective starter motor
power cable.

Inspect cable. Install new
cable.

Loose or dirty connections.

Inspect connections. Remove
clean and tighten all terminal connections.

Defective starter motor.

Check starter motor brushes.
brush spring tension. thrown
solder on brush cover. Repair or install new starter
motor.

Dirty or worn commutator.

Inspect commutator. Clean
and turn commutator.

Worn starter pinion gear
or broken teeth on ring
gear.

Inspect starter pinion gear
and ring gear. Replace defective parts.

MODEL 172 SERIES SERVICE MANUAL
11-67.

PRIMARY MAINTENANCE. The starting circuit should be inspected at regular intervals.
the frequency of which should be determined by the service and conditions under which the
equipment is operated. Inspect the battery and wiring. Check battery for fully charged
condition, proper electrolyte level with approved water and terminals for cleanliness.
Inspect wiring to be sure that all connections are clean and tight and that the wiring
insulation is sound. Check that the brushes slide freely in their holders and make full contact
on the commutator. When brushes are worn to one-half of their original length. installnew
brushes (compare brushes with new ones). Check the commutator for uneven wear,
excessive glazing or evidence of excessive arcing. If the commutator is only slightly dirty,
glazed or discolored, it may be cleaned with a strip of No. 00 or No. 000 sandpaper. If the
commutator is rough or worn, it should be turned in a lathe and the mica undercut. Inspect
the armature shaft for rough bearing surfaces. New brushes should be properly seated when
installing by wrapping a strip of No. 00 sandpaper around the commutator (with sanding
side out) 1-1/4 to 1-1/2 times maximum. Drop brushes on sandpaper covered commutator
and turn armature slowly in the direction of normal rotation. Clean sanding dust from motor
after sanding.

11-68.

STARTER MOTOR.

11-69.

REMOVAL AND INSTALLATION.
a. Remove engine cowling in accordance with paragraph 11-3.
CAUTION
When disconnecting or connecting the starter cable, do
not permit starter terminal bolt to rotate. Rotation of the
bolt could break the conductor between terminal and field
coils causing the starter to be inoperative.
b.

Disconnect electrical cable at starter motor. Insulate the disconnected cable terminal
as a safety precaution.
c. Remove three nuts and washers and one bolt securing starter to crankcase. Work
starter from engine.
d. To install starter, position starter on mounting pad, aligning dowel pins in starter
mounting pad with holes in mounting pad on engine.
e. Secure starter with washer, lockwasher and nut in three places and install bolt and
washers.
f. Tighten nuts and bolt evenly to a torque value of 150 lb-in.
g. Connect electrical cable to starter terminal and install engine cowling.
11-70.

EXHAUST SYSTEM. (See figure 11-5.)

11-71.

DESCRIPTION. The exhaust system consists of an exhaust pipe from each cylinder to the
muffler located beneath the engine. The muffler assembly is enclosed in a shroud which
captures exhaust heat that is used to heat the aircraft cabin. A shroud on number three
exhaust pipe is used to capture carburetor heat for the engine intake system. The tailpipe
welded to the muffler routes the exhaust gasses overboard.

11-72.

REMOVAL AND INSTALLATION.
a. Remove engine cowling in accordance with paragraph 11-3.
b. Disconnect flexible ducts from shrouds on muffler assembly and exhaust pipe.
c. Remove EGT probe (optional) if installed.
d. Remove nuts, bolts, washers and clamps attaching exhaust pipes to muffler assembly.

11-35

MODEL 172 SERIES SERVICE MANUAL
Loosen nuts attaching exhaust pipes to the cylinders and remove muffler assembly
Remove nuts and washers attaching exhaust pipes to the cylinders and remove pipes
and gaskets.
g. Reverse the preceding steps for reinstallation. Install a new copper-asbestos gasket
between each exhaust pipe and its mounting pad. When installing the attaching nuts,
install a plain washer, an internal tooth washer and nut. Make sure all clamps
attaching muffler to exhaust pipes are tight and all air ducts are installed.

e.
f.

11-73.

INSPECTION.
WARNING
Any time exhaust fumes are detected in the cabin, an
immediate inspection must be performed.
The exhaust system must be thoroughly inspected, especially the heat exchange section of
the muffler. An inspection of the exhaust system must be performed every 50 hours of
operating time. All components that show cracks and general deterioration must be
replaced with new parts. Using a flashlight and mirror inspect diffuser tubes through the
tailpipe. Replace muffler if defective.
a. Remove engine cowling in accordance with paragraph 11-3.
b. Loosen or remove shrouds so that ALL surfaces of the exhaust system are visible.
c. Check for holes, cracks and burned spots. Especially check the areas adjacent to
welds. Look for exhaust gas deposits in surrounding areas which indicate an exhaust
leak.
d. Where a surface is not accessible for visual inspection or for a positive test, proceed
as follows;

1. Remove exhaust pipes and muffler.
2.

Remove shrouds.

3. Seal openings with expansion rubber plugs.
4. Using a manometer or gage.apply approximately 3±1/2 psi (6 inches of mercury)
air pressure while the unit is submerged in water. Any leaks will appear as
bubbles and can be readily detected.
5. It is recommended that any components found defective be replaced with new
parts before the next flight.
6. If no defects are found, remove plugs and dry components with compressed air.
e. Install the exhaust system and engine cowling.
11-74.

EXTREME WEATHER MAINTENANCE.

11-75.

COLD WEATHER. Cold weather starting is made easier by the installation of the manuallyoperated engine primer system. Fuel is supplied by a line from the fuel strainer to the
plunger type primer. Operating the primer forces fuel to the intake valve port of the
cylinder. Primer lines should be replaced when crushed or broken and should be properly
clamped to prevent vibration and chafing. The following may also be used to assist engine
starting in extreme cold weather. After the last flight of the day, drain the engine oil into a
clean container so the oil can be preheated. Cover the engine to prevent ice or snow from
collecting inside the cowling. When preparing the aircraft for flight or engine run-up after
these conditions have been followed, preheat the drained oil.

11-36

Revision 1

MODEL 172 SERIES SERVICE MANUAL

TAILPIPE

11-37

MODEL 172 SERIES SERVICE MANUAL
WARNING
Do not heat the oil above 121 ° C (250°F). A flash fire may
result. Before pulling the propeller through. ascertain
that the magneto switch is in the OFF position to prevent
accidental firing of the engine.
After preheating the oil, fuel may be mixed with the heated oil in a ratio of 1 part fuel to 12
parts oil before pouring into the engine oil sump. If the free air temperature is below -29°C (20°F). the engine compartment should be preheated by a ground heater. Pre-heating the
engine compartment is accomplished by inducing heated air up through opening in lower
cowl assembly: thus heating up both the cylinders and oil. After the engine compartment has
been preheated, inspect all engine drain and vent lines for presence of ice. After this
procedure has been complied with, pull the propeller through several revolutions by hand
before starting engine.
CAUTION
Due to the desludging effect of the diluted oil. engine
operation should be observed closely during the initial
warm-up of the engine. Engines that have considerable
amount of operational hours accumulated since their last
dilution period may be seriously affected by the dilution
process. This will be caused by the diluted oil dislodging
sludge and carbon deposits within the engine. This
residue will collect in the oil sump and possibly clog the
screened inlet to the oil pump. Small deposits may
actually enter the oil pump and be trapped by the main oil
filter screen. Partial or complete loss of engine lubrication may result from either condition. If these conditions
are anticipated after oil dilution. the engine should be run
for several minutes at normal operating temperatures
and then stopped and inspected for evidence of sludge and
carbon deposits in the oil sump and oil filter screen.
Future occurrence of this condition can be prevented by
diluting the oil prior to each oil change. This will prevent
the accumulation of the sludge and carbon deposits.

11-76.

DUSTY CONDITIONS. Dust inducted into the intake system of the engine is probably the
greatest single cause of early engine wear. When operating under high dust conditions.
service the induction air filter daily as outlined in Section 2. Also. change engine oil and
lubricate the airframe more often than specified.

11-77.

SEACOAST AND HUMID AREAS. In salt water areas, special care should be taken to keep
the engine and accessories clean to prevent oxidation. In humid areas, fuel and oil should be
checked frequently and drained of condensed moisture.

11-38

MODEL 172 SERIES SERVICE MANUAL
SECTION 11A
ENGINE
(MODEL O-320-D2J AND MODEL O-360-A4N)
WARNING
When performing any inspection or maintenance that
requires turning on the master switch, installing a
battery, or pulling the propeller through by hand, treat
the propeller as if the ignition switch were ON. Do not
stand, nor allow anyone else to stand, within the arc of the
propeller, since a loose or broken wire, or a component
malfunction, could cause the propeller to rotate.
Page No.
Aerofiche/
Manual

TABLE OF CONTENTS

ENGINE COWLING
.........
Description ...............
Removal and Installation .....
Cleaning and Inspection .....
Repair ...................
ENGINE ...................
Description ..............
Engine Data ..............

2D4/11A-2
2D4,'11A-2
2D4/11A-2
2D4/11A-2
2D4/11A-2
2D4/11A-2
2D4/11A-2
2D4/11A-2

Trouble Shooting .........
2D11/11A-9
Full-Flow Oil Filter ........
2D16/11A-14
Description ..........
2D16/11A-14
Removal and Installation . . 2D16/11A-14
Oil Cooler ...............
2D16/11A-14
Description ............
2D16/11A-14
Fuel System ..............
2D16/11A-14
Description .............
2D16/11A-14

ENGINE (Model 172Q Only) ....

2D5/11A-3

Carburetor

Description ...............
2D5/11A-3
Engine Data ..............
2D5/11A-3
Time Between Overhaul (TBO) . 2D6/11A-4
Overspeed Limitations .......
2D7/11A-5
Trouble Shooting ..........
2D7/11A-5
Removal

.................

2D10/1A-8

Cleaning
................
Accessories Removal ........
Inspection ................
Build-Up .................
Installation .....
.........
Flexible Fluid Hoses ........
Leak Test ...............
Replacement .............
Static Run-up Procedures

2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
....

Baffles ..................
Description ..............
Cleaning and Inspection .....
Removal and Installation .....
Repair ...................
Mount ...................
Description ............
Removal and Installation

Repair .................
Shock-Mount Pads ..........
Oil System ..............
Description .............

2D10/11A-8

2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8
2D10/11A-8

...............

2D16/11A-14

Removal and Installation
Idle Speed and Mixture
Adjustments ............
Induction Air System ........
Description .............

...

2D16/11A-14

2D16/11A-14
2D16/11A-14
2D16/11A-14
Removal and Installation . . 2D16 11A-14
Ignition System ............
2D16 11A-14
Description .............
2D16 11A-14
Trouble Shooting .........
2D16 11A-14
Magnetos ...............
2D18 11A-16
Description ............
2D18 11A-16
Removal and Installation . 2D18 11A-16
Internal Timing .........
2D18 11A-16
Magneto-to Engine Timing .. 2D18 11A-16
Maintenance .............
2D19 11A-17
Magneto Check ...........
2D20 11A-18
Spark Plugs .............
2D20 11A-18
Controls .................
2D20 11A-18
Description .............
2D20 11A-18
Rigging ................
2D20 11A-18
Throttle Control ........
2D20 11A-18
Mixture Control ........
2D20 11A-18

. . . 2D11/11A-9

Carburetor Heat Control

2D11/11A-9
2D11/11A-9
2D11/11A-9
2D11/11A-9

Starting System ...........
Description .............
Trouble Shooting .........
Primary Maintenance ......

. .2D20

2D20
2D20
2D20
2D21

Revision 1

11A-18

11A-18
11A-18
11A-18
11A-19
11A-1

MODEL 172 SERIES SERVICE MANUAL
Starter Motor ............
Removal and Installation . .
Exhaust System ...........
Description .............
Removal and Installation . ..

2D21/11A-19
2D21/11A-19
2D21/11A-19
2D21/11A-19
2D21/11A-19

Inspection ..............
2D21 11A-19
Extreme Weather Maintenance . 2D21 11A-19
Cold Weather ............
2D21
A-19
Dusty Conditions .........
2D21 11A-19
Seacoast and Humid Areas . 2D21 11A-19

11A-1. ENGINE COWLING. Refer to paragraph 11-.
11A-2.

DESCRIPTION. Refer to paragraph 11-2.

11A-3.

REMOVAL AND INSTALLATION. Refer to paragraph 11-3.

11A-4.

CLEANING AND INSPECTION. Refer to paragraph 11-4.

11A-5.

REPAIR. Refer to paragraph 11-5.

11A-6.

ENGINE.

11A-7.

DESCRIPTION. Beginning with 1981 Models an air-cooled, wet-sump, four-cylinder, horizontally-opposed, direct-drive, carbureted Lycoming Model O-320-D2J engine is used to
power the airplane. The cylinders, numbered from front to rear, are staggered to permit a
separate throw on the crankshaft for each connecting rod. The right front cylinder is
number one, and cylinders on right side are identified by odd numbers one and three. The
left front cylinder is number two and the cylinders on the left side are identified as numbers
two and four. Refer to Paragraph 11A-8 for engine data. For repair and overhaul of the engine, accessories and propeller, refer to the appropriate publications issued by their manufacturers. These publications are available from the Cessna Supply Division.

11A-8.

ENGINE DATA. (O-320-D2J.)

MODEL (Lycoming)

O-320-D2J

BHP at RPM

160 at 2700 RPM

Number of Cylinders

4 Horizontally-Opposed

Displacement
Bore
Stroke

319.8 Cubic Inches
5.125 Inches
3.875 Inches

Compression Ratio

8.50:1

Magnetos (Dual)
Right Magneto

Slick 4251 (Impulse coupling)*
Fires 25 ° BTC
1-3 Lower and 2-4 Upper
Fires 25° BTC
1-3 Upper and 2-4 Lower

Left Magneto
Firing Order

1-3-2-4

Spark Plugs

18mm (Refer to Avco Lycoming Service
Instruction No. 1042 for factory approved
spark plugs and required gap.)

Torque Value

11A-2

Revision 1

390±30 LB-IN.

MODEL 172 SERIES SERVICE MANUAL
11A-8.

ENGINE DATA (Cont).

Carburetor (Marvel-Schebler)

MA-4SPA

Oil Sump Capacity
With Filter Change

7 U.S. Quarts
8 U.S. Quarts

Tachometer

Mechanical

Approximate Dry Weight

275 Lbs. (Weight is Approximate and will

With Standard Accessories

vary with optional equipment installed.)

Oil Pressure
Minimum Idling
Normal
Maximum

25 PSI
60-90 PSI
115 PSI

Oil Temperature
Normal Operation
Maximum Permissible

Within Green Arc
Red Line (245°P)

Cylinder Head Temperature

500°F Maximum (Not Indicated)

*20 PSI
50-90 PSI
115 PSI

*The direction of rotation of the magneto shafts, viewed from anti-propeller end of the engine is
clockwise.
**1984 and On, and all aircraft equipped with 0509087 modification kit.

11A-8A. ENGINE. (172Q Models Only.)
11A-8B. DESCRIPTION. The Model 172Q airplane is powered by a four-cylinder, horizontally-opposed, air-cooled, direct-drive, wet-sump. carbureted Lycoming Model O-360-A4N engine.
The cylinders, numbered from front to rear, are staggered to provide each cylinder connecting rod its own crankthrow. Cylinders are numbered one through four with number one cylinder on the right front and number three cylinder on the right rear. Cylinders two and
four are on the left front and left rear, respectively. Refer to Paragraph 114-8C for engine
data. For repair and overhaul of the enigne accessories and propeller, refer to the appropriate publications issued by their manufacturers. These publications are available from the
Cessna Supply Division.
11A-8C. ENGINE DATA. (O-360-A4N.)
MODEL (Lycoming)

O-360-A4N

BHP at RPM

180 BHP at 2700 RPM

Number of Cylinders

4 Horizontally-Opposed

Displacement
Bore
Stroke

361.0 Cubic Inches
5.125 Inches
4.375 Inches

Compression Ratio

9.0:1

11A-3

MODEL 172 SERIES SERVICE MANUAL
11A-8C. ENGINE DATA (Cont).
Magnetos (Dual)
Right Magneto

Slick 4251
Fires 25 ° BTC
1-3 Lower and 2-4 Upper
Fires 25 ° BTC
1-3 Upper and 2-4 Lower

Left Magneto

Firing Order 1-3-2-4
Spark Plugs

18mm (Refer to Avco Lycoming Service
Instruction No. 1042 for factory approved
spark plugs and required gap.)

Torque Value

390

30 LB-IN.

Carburetor

Marvel-Schebler

Oil Sump Capacity
With Filter Change

7 U.S. Quarts
8 U.S. Quarts

Tachometer

Mechanical

Approximate Dry Weight
With Standard Accessories

291 Lbs. (Weight is Approximate and will
vary with optional equipment installed.)

Oil Presure
Minimum Idling
Normal
Maximum

25 PSI
60-90 PSI
115 PSI

Oil Temperature
Normal Operation

Maximum Permissible
Fuel Pressure
Red Line
Normal
Red Line

MA4-5

*20 PSI
50-90 PSI
115 PSI

Within Green Arc
Red Line (245°F)

0.5 PSI
0.5-8.0 PSI
8.0 PSI

1984 and On, and all aircraft equipped with 0509087 modification kit.

11A-9.

11A-4

TIME BETWEN OVERHAUL (TBO). Refer to the latest Revision of Avco Lycoming Service
Instruction No. 1009, and all applicable Service Letters or Service Bulletins, for recommendations applicable to O-320-D and O-360-A4N Series engines. At the time of overhaul, engine
accessories should be overhauled.

MODEL 172 SERIES SERVICE MANUAL
11A-9A. OVERSPEED LIMITATIONS. The engine must not be operated above specified maximum
continuous RPM. However, should inadvertent overspeed occur, refer to the latest issue of
Avco Lycoming Service Bulletin 369, and all applicable Service Letters and Service Instructions for obligatory recommendations.
11A-10. TROBLE SHOOTING.
TROUBLE

PROBABLE CAUSE

REMEDY

ENGINE WILL NOT START.

Improper use of starting

Review starting procedure.

procedure.
Fuel tanks or bays
empty.

Visually inspect tanks or
bays. Fill with proper grade and
quantity of gasoline.

Mixture control in the
IDLE CUT-OFF position.

Move control to the full
RICH position.

Fuel selector valve in
OFF position.

Place selector valve in the
ON position to a tank

known to contain gasoline.

ENGINE STARTS BUT
DIES, OR WILL NOT IDLE.

Defective carburetor.

Repair or replace
carburetor.

Carburetor screen or fuel
strainer plugged.

Remove carburetor and clean
carburetor screen or
fuel strainer thoroughly.

Vaporized fuel. (Most
likely to occur in hot
weather with a hot engine.)

Refer to Pilot's Operating
Handbook.

Engine flooded.

Refer to Pilot's Operating
Handbook.

Water in fuel system.

Open fuel strainer drain
and check for water. If
water is present, drain
fuel tank sumps, lines,
strainer and carburetor.

Defective magneto switch
or grounded magneto leads.

Check continuity. Repair
or replace switch or leads.

Spark plugs fouled.

Remove, clean and regap
plugs. Test harness cables
to persistently fouled plugs.
Replace if defective.

Idle stop screw or idle mixture incorrectly adjusted.

Refer to paragraph 11-43.

Carburetor idling jet
plugged.

Clean carburetor
idling jet.

Spark plugs fouled or improperly gapped.

Remove, clean and regap
plugs. Replace if defective.

Water in fuel system.

Open fuel strainer drain and
check for water. If water
is present, drain fuel tank
sumps, lines, strainer and
carburetor.

11A-5

MODEL 172 SERIES SERVICE MANUAL
11A-10. TROUBLE SHOOTING (Cont).
TROUBLE
ENGINE STARTS BUT
DIES. OR WILL NOT IDLE
(Cont).

ENGINE RUNS ROUGHLY
OR WILL NOT ACCELERATE PROPERLY.

11A-6

PROBABLE CAUSE

REMEDY

Defective ignition system.

Refer to paragraph 11A-55.

Vaporized fuel. (Most
likely to occur in hot
weather with a hot engine.)

Refer to Pilot's Operating
Handbook-

Induction air leaks.

Check visually. Correct
the cause of leaks.

Manual primer leaking.

Disconnect primer outlet
line. If fuel leaks through
primer. repair or replace
primer.

Leaking float valve or
float level set too high.

Perform an idle mixture
check. Attempt to remove
any rich indication with the
idle mixture adjustment. If the
rich indication cannot be removed. the float valve is
leaking or the float level is
set too high. Replace defective parts. reset float level.

Defective carburetor.

If engine will start when
primed but stops when
priming is discontinued.
with mixture control in full
RICH position. the carburetor
is defective. Repair or replace
carburetor.

Defective engine.

Check compression. Listen
for unusual engine noises.
Engine repair is required.

Restriction in aircraft fuel
system.

Refer to Section 12.

Worn or improperly rigged
throttle or mixture control.

Check visually. Replace
worn linkage. Rig properly.

Spark plugs fouled or improperly gapped.

Remove, clean and regap
plugs. Replace if defective.

Defective ignition system.

Refer to paragraph 11A-55.

MODEL 172 SERIES SERVICE MANUAL
11A-10. TROUBLE SHOOTING (Cont).
TROUBLE
ENGINE RUNS ROUGHLY
OR WILL NOT ACCELERATE PROPERLY. (Cont).

POOR IDLE CUT-OFF.

PROBABLE CAUSE

REMEDY

Defective or badly adjusted
accelerator pump in carburetor.

Check setting of accelerator
pump linkage and adjust as
necessary.

Float level set too low.

Check and reset float level.

Defective carburetor.

If engine will start when
primed but stops when
priming is discontinued.
with mixture control in full
RICH position, the carburetor is defective. Repair
or replace carburetor.

Defective engine.

Check compression. Listen
for unusual engine noises.
Engine repair is required.

Restricted carburetor air
filter.

Check visually. Clean in
accordance with Section 2.

Cracked engine mount.

Inspect and repair or replace mount as required.

Defective mounting bushings.

Inspect and install new
bushings as required.

Worn or improperly rigged
mixture control.

Check that idle cut-off stop
on carburetor is contacted.
Replace worn linkage. Rig
properly.

Manual primer leaking.

Disconnect primer outlet
line. If fuel leaks through
primer, it is defective.
Repair or replace primer.

Defective carburetor.

Repair or replace carburetor.

Fuel contamination.

Check all screens in fuel
system. Drain all fuel and
flush out system. Clean all
screens, lines, strainer and
carburetor.

11A-7

MODEL 172 SERIES SERVICE MANUAL
11A-11

REMOVAL. Refer to paragraph 11-11.

11A-12. CLEANING. Refer to Section 2.
11A-13. ACCESSORIES REMOVAL. Refer to paragraph 11-13.
11A-14. INSPECTION. Refer to paragraph 11-14.
11A-15. BUILD-UP. Refer to paragraph 11-15.
11A-16. INSTALLATION. Refer to paragraph 11-16.
11A-17. FLEXIBLE FLUID HOSES. Refer to paragraph 11-17.
11A-18. LEAK TEST. Refer to paragraph 11-18.
11A-19. REPLACEMENT. Refer to paragraph 11-19.
11A-20. STATIC RUN-UP PROCEDURES. In a case of suspected low engine power. a static RPM
run-up should be conducted as follows:
a. Run-up engine, using takeoff power and mixture settings. with the aircraft facing 90 °
right and then left to the wind direction.
b. Record the RPM obtained in each run-up position.
NOTE
Daily changes in atmospheric pressure, temperature and
humidity will have a slight effect on static run-up.
c.
d.

Average the RPM values obtained in step b. The resulting RPM figure should be 2300
to 2420 for O-320-D2J engine or 2350 to 2450 RPM for O-360-A4N engine.
If the resulting average RPM figure is lower than stated above, the following checks
are recommended to determine a possible deficiency.
1. Check carburetor heat control for proper rigging. If partially open it would cause
a slight power loss.
2. Check magneto timing, spark plugs and ignition harness for settings and
conditions.
3. Check condition of induction air filter. Clean if necessary.
4. Perform an engine compression check. (Refer to engine manufacturer's manual.

11A-21. ENGINE BAFFLES. Refer to paragraph 11-21.
11A-22. DESCRIPTION. Refer to paragraph 11-22.
11A-23. CLEANING AND INSPECTION. Refer to paragraph 11-23.
11A-24. REMOVAL AND INSTALLATION. Refer to paragraph 11-24.
11A-25. REPAIR. Refer to paragraph 11-25.
11A-26. ENGINE MOUNT. Refer to paragraph 11-26.
11A-27. DESCRIPTION. Refer to paragraph 11-27.

11A-8

MODEL 172 SERIES SERVICE MANUAL
11A-28. REMOVAL AND INSTALLATION. Refer to paragraph 11-28.
11A-29. REPAIR. Refer to paragraph 11-29.
11A-30. ENGINE SHOCK MOUNT PADS. Refer to paragraph 11-30. See Figure 11A-1.
11A-31. ENGINE OIL SYSTEM. Refer to paragraph 11-31.
11A-32. DESCRIPTION. Refer to paragraph 11-32.
11A-33. TROUBLE SHOOTING.
TROUBLE
NO OIL PRESSURE.

PROBABLE CAUSE

REMEDY

No oil in sump.

Check with dipstick.
Fill sump with proper
grade and quantity of oil.
Refer to Section 2.

Oil pressure line broken.
disconnected or pinched.

Inspect pressure lines.
Replace or connect lines

as required.

LOW OIL PRESSURE.

Oil pump defective.

Remove and inspect. Examine engine. Metal particles
from damaged pump may
have entered engine oil
passages.

Defective oil pressure
gage.

Check with a known good
gage. If second reading is
normal, replace gage.

Oil congealed in gage line.

Disconnect line at engine
and gage; flush with kerosene. Pre-fill with kerosene
and install.

Relief valve defective.

Remove and check for dirty
or defective parts. Clean
and install: replace valve
if defective.

Low oil supply.

Check with dipstick.
Fill sump with proper
grade and quantity of oil.
Refer to Section 2.

Low viscosity oil.

Drain sump and refill with
proper grade and quantity
of oil.

11A-9

MODEL 172 SERIES SERVICE MANUAL
11A-33. TROUBLE SHOOTING (Cont).
TROUBLE
LOW OIL PRESSURE
(Cont).

HIGH OIL PRESSURE.

LOW OIL TEMPERATURE.

11A-10

PROBABLE CAUSE

REMEDY

Oil pressure relief valve
spring weak or broken.

Remove and inspect spring.
Replace weak or broken spring.

Defective oil pump.

Secondary result of high
oil temperature.

Observe oil temperature
gage for high indication.
Determine and correct reason
for high oil temperature.

Leak in pressure or
suction line.

Inspect gasket between
accessory housing and crankcase. Repair engine as required.

Dirty oil filter.

Remove and install new filter.

High viscosity oil.

Drain sump and refill with
proper grade and quantity
of oil.

Relief valve defective.

Remove and check for dirty
or defective parts. Clean
and install: replace valve
if defective.

Defective oil pressure gage.

Check with a known good
gage. If second reading is
normal, replace gage.

Defective oil temperature
gage or temperature bulb.

Check with a known good
gage. If second reading is
normal, replace gage. If reading is similar, the temperature
bulb is defective. Replace bulb.

Oil cooler thermostatic
valve/bypass valve defective or stuck.

Remove valve and check for
proper operation. Replace
valve if defective.

MODEL 172 SERIES SERVICE MANUAL
11A-33. TROUBLE SHOOTING (Cont).
TROUBLE
HIGH OIL TEMPERATURE.

REMEDY

PROBABLE CAUSE
Oil cooler air passages
clogged.

Inspect cooler core.
Clean air passages.

Oil cooler oil passages
clogged.

Attempt to drain cooler. Inspect for sediment. Remove
cooler and flush thoroughly.

Thermostatic valve or bypass valve damaged or held
open by solid matter.

Feel front of cooler core
with hand. If core is cold.
oil is bypassing cooler. Remove
and clean valve and seat.
If still inoperative. replace.

Low oil supply.

Check with dipstick.
Fill sump with proper
grade and quantity of oil.
Refer to Section 2.

Oil viscosity too high.

Drain sump and refill with
proper grade and quantity
of oil.

Prolonged high speed operation on the ground.

Hold ground running above
1500 RPM to a minimum.

Defective oil temperature
gage.

Check with a known good
gage. If second reading is
normal, replace gage.

Defective oil temperature
bulb.

Check for correct oil pressure. oil level and cylinder
head temperature. If they are
correct, check oil temperature
gage for being defective: if
similar reading is observed.
bulb is defective. Replace bulb.

Oil congealed in cooler.

This condition can occur
only in extremely cold temperatures. If congealing is suspected. use an external heater
or a heated hangar to warm the
congealed oil.

OIL LEAK AT FRONT OF
ENGINE.

Damaged crankshaft seal.

Replace. Also refer to Service News
Letter, SNL85-8, Feb. 15, 1985.

OIL LEAK AT PUSH ROD
HOUSING.

Damaged push rod housing
oil seal.

Replace.

11A-11

MODEL 172 SERIES SERVICE MANUAL
UPPER RIGHT HAND SHOCK MOUNT
C299501-0106

LOWER RIGHT HAND SHOCK MOUNT

C299501-0101

1.
2.
3.
4.
,5.

Bolt
Washer
Mounting
Spacer
Engine Mount

Damper

Nut

2
MODEL 172Q

2
7

Figure 11A-1. Shock Mount Details (Sheet 1 of 2)
11A-12

MODEL 172 SERIES SERVICE MANUAL

LOWER LEFT HAND SHOCK MOUNT
C299501-0106

Figure 11A-1. Shock Mount Details (Sheet 2 of 2)
11A-13

MODEL 172 SERIES SERVICE MANUAL
11A-34. FULL-FLOW OIL FILTER.
IA-35. DESCRIPTION. An external full-flow. spin-on oil filter is installed on the engine. If the filter
should become clogged. a bypass valve allows engine oil to flow directly to the engine oil
passages.
11A-36. REMOVAL AND INSTALLATION. Refer to paragraph 11-36.
11A-37. OIL COOLER. Refer to paragraph 11-37.
11A-38. DESCRIPTION. Refer to paragraph 11-38.
11A-39. ENGINE FUEL SYSTEM. Refer to paragraph 11-39.
11A-40. DESCRIPTION. Refer to paragraph 11-40.
11A-41. CARBURETOR. Refer to paragraph 11-41.
11A-42. REMOVAL AND INSTALLATION. Refer to paragraph 11-42.
11A-43. IDLE SPEED AND MIXTURE ADJUSTMENTS. Refer to paragraph 11-43.
11A-44. INDUCTION AIR SYSTEM. Refer to paragraph 11-44. The Model 172Q airplanes incorporate
an induction air filter assembly featuring a replacement filter element.
11A-45. DESCRIPTION. Refer to paragraph 11-45.
11A-46. REMOVAL AND INSTALLATION. Refer to paragraph 11A-46.
11A-47. IGNITION SYSTEM.
11A-48. DESCRIPTION. The ignition system is comprised of dual Slick 4251 magnetos. two spark
plugs in each cylinder, an ignition wiring harness, an ignition switch mounted on the
instrument panel and required wiring between the ignition switch and the magnetos.
11A-49. TROUBLE SHOOTING.
TROUBLE
ENGINE WILL NOT START.

PROBABLE CAUSE

REMEDY

Defective ignition switch.

Check switch continuity
Replace if defective.

Spark plugs defective,
improperly gapped or
fouled by moisture or
deposit.

Clean. regap and test plugs.
Replace if defective.

Defective ignition harness.

If no defects are found by
a visual inspection.
check with a harness
tester. Replace defective
parts.

MODEL 172 SERIES SERVICE MANUAL
11A-49. TROUBLE SHOOTING (Cont).
TROUBLE
ENGINE WILL NOT START
(Cont).

PROBABLE CAUSE

REMEDY

Magneto "P" lead
grounded.

Check continuity. "P"lead
should not be grounded in
the ON position but should
be grounded in OFF position. Repair or replace "P"
lead

Failure of impulse coupling.

Impulse coupling pawls
should engage at cranking
speeds. Listen for loud
clicks as impulse couplings
operate. Remove magnetos
and determine cause. Replace defective magnetos.

Defective magneto.

Refer to paragraph 11A-55.

Broken drive gear.

Remove magneto and check
magneto and engine gears.
Replace defective parts.
Make sure no pieces of
damaged parts remain in
engine or engine disassembly

will be required.
ENGINE WILL NOT
IDLE OR RUN PROPERLY.

Spark plugs defective,
improperly gapped or
fouled by moisture or
deposits.

Clean. regap and test plugs.
Replace if defective.

Defective ignition harness

If no defects are found by
a visual inspection. check
with a harness tester. Replace defective parts.

Defective magneto.

Refer to paragraph 11A-55.

Impulse coupling pawls
remain engaged.

Listen for loud clicks as
impulse coupling operates.
Remove magneto and determine cause. Replace defective magneto.

Spark plugs loose.

Check and install properly.

11A-15

MODEL 172 SERIES SERVICE MANUAL
11A-50. MAGNETOS.
11A-51. DESCRIPTION. The engine is equipped with dual Slick 4251 (impulse coupling) magnetos.
The magnetos incorporate an integral feed-thru capacitor and require no external noise
filter in the ground lead. The direction of rotation of the magneto shafts, viewed from the
anti-propeller end of the engine, is clockwise. Refer to Slick 4200/6200 Series Aircraft
Magnetos Maintenance and Overhaul Instructions Bulletin, and all revisions and supplements thereto, for a detailed description, disassembly and reassembly of the magneto.
11A-52. REMOVAL AND INSTALLATION.
WARNING
The magneto is in a SWITCH ON condition when the
switch wire is disconnected. Therefore, ground the
breaker contact points or disconnect the high-tension
wires from the magneto or the spark plugs.
a.
b.

Remove engine cowling in accordance with paragraph 11-3.
Remove screws securing the high-tension outlet cover to the magneto. The "P" leads
may be disconnected for additional clearance if necessary.
NOTE
It is a good practice to position No. 1 cylinder at its
approximate advance firing position before removing
the magneto.

Remove nuts, washers and clamps attaching the magneto to the engine accessory
housing. Note the approximate angular position at which the magneto is installed,
then remove the magneto.
d. Reverse the preceding steps for reinstallation and time magneto-to-engine in
accordance with paragraph 11A-54.

NOTE
Magneto (primary) lead nut torque range is 11-13 in.-lbs.
Exceeding this torque range could result in possible condenser damage.
11A-53. INTERNAL TIMING. (MAGNETO REMOVED FROM ENGINE.) Refer to Slick 4200/6200
Series Aircraft Magnetos Maintenance and Overhaul Instructions Bulletin, and all revisions and supplements thereto, for internal timing instructions.
11A-54. MAGNETO-TO-ENGINE TIMING. After 100 hours of operation and every 100 hours
thereafter, or at annual inspection, whichever comes first, the magneto-to-engine timing
should be checked. This is accomplished in the following manner
WARNING
Be sure switch is in "OFF" position and the "P" lead is
grounded.

11A-16

Revision 1

MODEL 172 SERIES SERVICE MANUAL
a.

Turn the engine crankshaft in the normal direction of rotation until the No. 1 cylinder
is in the full-advance firing position, following the engine manufacturer's procedure
for timing of magnetos.
Loosen the magneto mounting bolts, and connect a standard timing light between
engine ground and the magneto condenser terminal.
NOTE
Switch must be "ON".

Rotate the complete magneto opposite normal rotation of the mageto on the engine
mounting, until the timing light indicates the contact breaker points are just
opening. Secure the magneto in this position.
WARNING
During all magneto maintenance, always take proper
precautions to make sure the engine can not fire or start
when the propeller is moved. TURN SWITCH "OFF".

11A-55. MAINTENANCE. Refer to Slick 4200/6200 Series Aircraft Magnetos Maintenance and
Overhaul Instructions Bulletin, and all revisions and supplements thereto, for disassembly.
cleaning, inspection, and reassembly instructions. At 500-hour intervals, the contact
assemblies should be checked for burning or wear. If the points are not discolored and have a
white frosty surface around the edges, the points are functioning properly and should not be
touched Apply M-1827 cam grease sparingly to each lobe of the cam before reassembly. If
the points are blue (indicating excessive arcing) or pitted, they should be discarded. Replace
both condenser and damaged points. At 500-hour inspections, it is necessary to check the
carbon brush in the distributor gear for wear, cracks and chipping. Measure carbon brush
length from distributor gear shaft to end of brush. Minimum acceptable length is 1/32 inch. If
worn. cracked or chipped, the distributor gear must be replaced. Put a drop of SAE #20 nondetergent machine oil in each oilite bearing in the distributor block and bearingbar. Inspect
the high tension lead from the coil to make sure it makes contact with the carbon brush on the
distributor gear shaft. At 500-hour inspection, visually inspect the impulse coupling shell
and hub for cracks, loose rivets or rounded pawls that may slip when latching up on the pin.
If any of these conditions are evident, the coupling should be replaced.
NOTE
If the engine operating troubles develop which appear to
be caused by the ignition system, it is advisable to check
the spark plugs and ignition harness first before working
on the magnetos. If the trouble appears definitely associated with a magneto, perform moisture check and
breaker contact compartment check in accordance with
procedures outlined in paragraph 11-55, steps "a" thru
"b". If trouble has not been corrected after accomplishing
the moisture and breaker contact compartment checks.
check magneto-to-engine timing in accordance with
paragraph 11A-54. If timing is incorrect, remove magneto and adjust internal timing in accordance with
paragraph 11A-53. Reinstall magneto and time to engine
in accordance with paragraph 11A-54. If the trouble has
not been corrected, magneto overhaul or replacement is
indicated.

Revision 1

11A-17

MODEL 172 SERIES SERVICE MANUAL
1A-56. MAGNETO CHECK. Refer to paragraph 11-56.
11A-57. SPARK PLUGS. Refer to paragraph 11-57.
11A-58. ENGINE CONTROLS. Refer to paragraph 11-58.
11A-59. DESCRIPTION. Refer to paragraph 11-59.
11A-60. RIGGING. Refer to paragraph 11-60.
11A-61. THROTTLE CONTROL. Refer to paragraph 11-61.
1A-62. MIXTURE CONTROL. Refer to paragraph 11-62.
11A-63. CARBURETOR HEAT CONTROL. Refer to paragraph 11-63.
11A-64. STARTING SYSTEM. Refer to paragraph 11-64.
11A-65. DESCRIPTION. Refer to paragraph 11-65.
11A-66. TROUBLE SHOOTING.
TROUBLE
STARTER WILL NOT
OPERATE.

STARTER MOTOR RUNS.
BUT DOES NOT TURN
CRANKSHAFT.

STARTER MOTOR DRAGS.

11A-18

PROBABLE CAUSE

REMEDY

Defective master switch or
circuit.

Check continuity of master
switch and circuit. Install
new switch or wires.

Defective starter switch or
switch circuit.

Check continuity of switch
and circuit. Install new
switch or wires.

Defective starter motor.

Check voltage to starter. If
voltage is present. Remove. repair or install
new starter motor.

Defective Bendix drive.

Remove starter and inspect
Bendix drive. Replace defective parts.

Damaged starter pinion
gear or ring gear.

Inspect starter pinion gear
and ring gear. Replace
defective parts.

Low battery.

Check battery. Charge or
install new battery.

Starter switch or relay contacts burned or dirty.

Install servicable unit.

Defective starter motor
power cable.

Inspect cable. Install new
cable.

MODEL 172 SERIES SERVICE MANUAL
11A-66. TROUBLE SHOOTING (Cont).
TROUBLE
STARTER MOTOR DRAGS.
(Cont.)

STARTER EXCESSIVELY
NOISY.

PROBABLE CAUSE

REMEDY

Loose or dirty connections.

Inspect connections. Remove
clean and tighten all terminal connections.

Defective starter motor.

Check starter motor brushes.
brush spring tension thrown
solder on brush cover. Repair or install new starter
motor.

Dirty or worn commutator.

Inspect commutator. Clean
and turn commutator.

Worn starter pinion gear
or broken teeth on ring
gear.

Inspect starter pinion gear
and ring gear. Replace defective parts.

11A-67. PRIMARY MAINTENANCE. Refer to paragraph 11-67.
11A-68. STARTER MOTOR. Refer to paragraph 11-68.
11A-69. REMOVAL AND INSTALLATION. Refer to paragraph 11-69.
11A-70. EXHAUST SYSTEM. Refer to paragraph 11-70.
11A-71. DESCRIPTION. Refer to paragraph 11-71.
11A-72. REMOVAL AND INSTALLATION. Refer to paragraph 11-72.
11A-73. INSPECTION. Refer to paragraph 11-73.
11A-74. EXTREME WEATHER MAINTENANCE. Refer to paragraph 11-74.
11A-75. COLD WEATHER. Refer to paragraph 11-75.
11A-76. DUSTY CONDITIONS. Refer to paragrah 11-76.
11A-77. SEACOAST AND HUMID AREAS. Refer to paragraph 11-77.

11A-19/(11A-20 blank)

MODEL 172 SERIES SERVICE MANUAL
SECTION 12
FUEL SYSTEM
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

FUEL SYSTEM ............
2E3/12-1
Description ...............
2E3/12-1
Precautions ...............
2E4/12-2
Trouble Shooting .........
. 2E4/12-2
Tanks ...................
2E5/12-3
Description .............
2E5/12-3
RemovalInstallation .......
2E5/12-3
Quantity Transmitters .......
2E5/12-3
Vents ...................
2E5/12-3
Description .............
2E11/12-7
Checking ...............
2E11/12-7
Selector Valve .............
2E1412-10
Description .............
2E14/12-10
Removal'Installation .......
2E14 12-10
Disassembly .............
2E14/12-10
Cleaning. Inspection and
Repair
...............
2E14/12-10
Reassembly .............
2E16/12-12
Strainer
................ 2E1612-12
Description .............
2E16 12-12
Removal Installation .......
2E17 12-13
Disassembly Assembly ..... 2E17/12-13

Priming System ...........
Description ...........
.
Removal ................
Inspection ..............
Installation .............
INTEGRAL FUEL BAYS .......
Description ...............
Classification of Fuel Leaks . . .
Fuel Bay Purging ..........
Integral Fuel Bay Sealant ....
Mixing Sealant ...........
Sealing During and After
Structural Repair ........
Sealing Fuel Leaks ........
Curing Time .............
Testing ................
Fuel Quantity Transmitters . ..
Vented Fuel Filler Cap .......
Description .............
Inspection, Cleaning and
Repair ................

2E17/12-13
2E17 12-13
2E17/12-13
2E19/12-15
2E20 12-16
2E21 12-17
2E21 12-17
2E21/12-17
2E21/12-17
2F7 12-27
2F8/12-28
2F8 12-28
2F11 12-31
2F12/12-32
2F12 12-32
2F12 12-32
2F13 12-33
2F13 12-33
2F13 12-33

12-1.

FUEL SYSTEM.

12-2.

DESCRIPTION The 172 and 172Q Series airplanes are equipped with either a standard fuel
system, an optional long-range fuel system, or beginning with Serials 17274010.
F17202070, and 17275869 (172Q), an optional extended range "wet wing" system. The standard and long-range systems are essentially the same, differing mainly in fuel tank capacity. The extended range system consists of an integral fuel bay in the inboard end of each
wing. Fuel flows by gravity from two aluminum tanks (one per wing) in the standard and
long-range systems, and from an integral fuel bay area in each wing in the extended range
system, to a four-position selector valve, through an electric auxiliary fuel pump (172Q)
through a firewall-mounted fuel strainer to the carburetor and engine primer. Depending
upon selector valve handle position, fuel is directed from either or both tanks or bays to the
engine, or flow can be shut off completely. An important aspect of the gravity type fuel system is positive venting of all tanks or bays. Venting is accomplished in all three systems by
an overboard vent line equipped with a vent check valve, incorporated in the left fuel tank or
bay. The vent line protrudes through the bottom of the left wing into the airstream. In addition, a vent crossover line connects the airspace in the left tank to the airspace in the right
tank where a vented fuel tank cap is installed. An electric fuel quantity indicating system
consisting of two float type transmitters (one per tank or bay) and two indicators mounted
on the instrument panel display approximate fuel quantity to the pilot. The pilot primes the
engine for starting using a manual primer which takes fuel from the fuel strainer and directs it to number four cylinder (172), or three cylinders (172Q).

Revision 1

12-1

MODEL 172 SERIES SERVICE MANUAL
12-3.

PRECAUTIONS. Observe the following general precautions and rules during fueling, defueling, tank or integral fuel bay purging, repairing, assembly or disassembly of system components, and electrical system checks and repairs on the airplane fuel system:
WARNING
During all fueling procedures, fire fighting equipment
must be available. Attach a ground wire from approved
ground stakes to the mooring eyebolt on LH and RH
wing struts or mooring ring on LH and RH wings.
Ground fuel nozzle to airplane during fueling operations.
a.

12-4.

Plugs or caps should be placed on all disconnected hoses, lines and fittings to prevent residual fuel drainage, thread damage, or entry of dirt or foreign material into
fuel system.

TROUBLE SHOOTING.
TROUBLE

NO FUEL TO CARBURETOR.

FUEL STARVATION AFTER
STARTING.

12-2

PROBABLE CAUSE

REMEDY

Fuel selector valve not
turned on.

Turn valve on.

Fuel tanks or bays empty.

Service with proper grade
and amount of fuel.

Plugged fuel strainer.

Remove and clean strainer
and screen.

Fuel line plugged.

Clean out or replace fuel
line.

Fuel tank or bay outlet
strainers plugged.

Remove and clean strainers
and flush out fuel tanks or
bays.

Inlet elbow or inlet screen
in carburetor plugged.

Clean and/or replace.

Fuel line disconnected or
broken.

Connect or repair fuel lines.

Defective fuel selector valve.

Repair or replace selector valve.

Partial fuel flow from the
preceding causes.

Use the preceding remedies.

Plugged fuel vent.

See paragraph 12-11.

MODEL 172 SERIES SERVICE MANUAL

12-4.

TROUBLE SHOOTING (CONT).
TROUBLE

PROBABLE CAUSE

REMEDY

FUEL STARVATION AFTER
STARTING (CONT).

Water in fuel.

Drain fuel tank or bay sumps,
fuel lines and fuel strainer.

NO FUEL QUANTITY
INDICATION.

Fuel tanks or fuel
bays empty.

Service with proper grade and
amount of fuel.

Open circuit breaker.

Reset circuit breaker. Refer to
Section 15.

Loose connections or
open circuit.

Tighten connections; repair or
replace wiring. Refer to Section
20.

Defective fuel quantity
indicator or transmitter.

Refer to Section 15.

Plugged bleed hole in fuel
vent.

Check per paragraph 12-11.

PRESSURIZED FUEL TANK
OR BAY.
12-5.

FUEL TANKS.

12-6.

DESCRIPTION. A rigid metal tank is installed in the inboard panel of each wing. Sump
drain valves, one in each tank, are provided for draining trapped water and sediment. Airplanes 17261445, 17267585 and On and F17201515 and On incorporating SK172-116 have
one additional quick drain valve installed in the lower outboard corner of the tank for
draining trapped water and sediments. Airplanes incorporating SK172-135 have four additional quick drain valves in each tank for draining trapped water and sediment.

12-7.

REMOVAL AND INSTALLATION.
a. Remove sump drain valve and drain fuel from applicable tank. (Observe precautions
in paragraph 12-3.)
b. Remove fuel tank cover by removing attaching screws.
c. Remove wing root fairings.
d. Disconnect and plug or cap all fuel and vent lines from tank. Remove fittings as necessary for clearance when removing tank.
e. Disconnect electrical lead and ground strap from fuel quantity transmitter.
f. Disconnect straps securing fuel tank and remove tank. Use care to avoid damage to
protruding fittings and hose connections when removing the tank.
g. To install tank, reverse the preceding steps. Be sure grounding is secure in accordance with figure 12-3.

12-8.

FUEL QUANTITY TRANSMITTERS. Fuel quantity transmitters are installed in
the top of fuel tanks. A complete description, along with procedures for removal.
installation and adjustment are contained in Section 15.

12-9.

FUEL VENTS.

Revision 3

12.3

MODEL 172 SERIES SERVICE MANUAL

FUEL QUANTITY INDICATORS

FUEL
QUANTITY
TRANSMITTER

VENTED
FILLER CAP

FILLER CAP

SELECTOR
VALVE

VENT
CHECK
VALVE)

LEFT FUEL TANK
DRAIN
VALVE

DRAIN
VALVE

RIGHT FUEL TANK

SELECTOR VALVE
DRAIN PLUG

FUEL
STRAINER
- -

TO ENGINE

FUEL
-

STRAINER
DRAIN
CONTROL

ENGINE
PRIMER

CONDITION:
SYSTEM SHOWN WITH
FUEL SELECTOR VALVE
IN BOTH POSITION.

CONTROL
THROTTLE

CODE
CARBURETOR
FUEL SUPPLY
VENT

MIXTURE

ENGINE

ELECTRICAL
CONNECTION

CONTROL

TO ENSURE MAXIMUM FUEL
CAPACITY WHEN REFUELING
AND MINIMIZE CROSS-FEEDING
WHEN PARKED ON A SLOPING
SURFACE. PLACE THE FUEL
SELECTOR VALVE IN EITHER
LEFT OR RIGHT POSITION.

Figure 12-1. 172 Fuel System Schematic (Sheet 1 of 2)
12-4

MODEL 172 SERIES SERVICE MANUAL

FUEL QUANTITY INDICATORS

FUEL
QUANTITY
TRANSMITTER

VENTED
FILLER CAP

FILLER CAP

VENT
IWITH
CHECK
VALVE)

FUEL
QUANTITY
TRANSMITTER

SELECTOR
VALVE

SCREEN

LEFT FUEL TANK
DRAIN
VALVE

DRAIN
VALVE

RIGHT FUEL TANK

FUEL
SELECTOR
DRAIN VALVE

TO ENSURE MAXIMUM FUEL
CAPACITY WHEN REFUELING
AND MINIMIZE CROSS-FEEDING
WHEN PARKED ON A SLOPING
SURFACE. PLACE THE FUEL
SELECTOR VALVE IN EITHER
LEFT OR RIGHT POSITION.

CONDITION:
SYSTEM SHOWN WITH
FUEL SELECTOR VALVE
IN BOTH POSITION

AUXILIARY
FUEL PUMP
AUXILIARY
FUEL PUMP
SWITCH

ENGINE
PRIMER

FUEL
STRAINER
ENGINE-DRIVEN
FUEL PUMP

TO ENGINE

VALVE
DRAIN CONTROL

CODE

FUEL
PRESSURE
GAGE

FUEL SUPPLY

THROTTLE

CARBURETOR

VENT
VENT
-

MIXTURE
CONTROL

TO ENGINE

MECHANICAL
LINKAGE
ELECTRICAL
CONNECTION

MODEL 172Q SERIES AIRPLANES
Figure 12-1. 172 Fuel System Schematic (Sheet 2 of 2)
12-4A/(12-4B blank)

MODEL 172 SERIES SERVICE MANUAL.

1. Right Fuel Tank
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.

Tank Vent Interconnect Line
Fuel Supply Line
Left Fuel Tank
Overboard Vent Line
Primer
Strainer Drain Control
Primer Supply Line
Primer Delivery Line
Selector Valve Handle
Shaft
Bracket

15. Selector Valve
16. Placard
17. O-Ring

Detail B
- ,,
17267585 THRU 17275034
F17201515 THRU F17202134
15

18. Nipple
19. Angle
20. Lower Wing Skin

SEE
FIGURE 12-5

Detail

Figure 12-2. Fuel System (Sheet 1 of 2)

12-5

MODEL 172 SERIES SERVICE MANUAL

SEE

FIGURE 12-6
SEEFIGURE 12-8
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Right Fuel Tank
Vent Crossover Line
Vent Tank Interconnect Line
Fuel Supply Line
Left Fuel Tank
Overboard Vent Line
Primer
Strainer Drain Control
Primer Supply Line
Primer Delivery Line

BEGINNING WITH 17275035
AND F17202135

VIEW OF THE PILOT
IN CLEAR

Figure 12-2. FuelSystem (Sheet 2 of 2)

12-6

Revision 2

SEE
FIGURE 12-3

MODEL 172 SERIES SERVICE MANUAL
12-10.

DESCRIPTION. A vent line is installed in the outboard end of the left fuel tank and extends
overboard down through the lower wing skin The inboard end of the vent line extends into
the fuel tank then forward and slightly upward. A vent valve is installed on the inboard end
of the vent line inside of the fuel tank A crossover line connects the two tanks together. A tee
is installed on each end of the crossover line. A separate vent line is attached to the tees.
connecting the crossover line to each of the aft fuel supply lines from each fuel tank. See
figure 12-2. In addition, the right-hand fuel tank cap includes a small vent safety valve to

ensure positive fuel tank venting.
12-11.

CHECKING. If stoppage of either the fuel vent or vent bleed hole occurs. with the engine
running, it can lose power. and eventually stop due to fuel starvation which can lead to
collapsing of fuel tank If the above stoppage occurs during a non-run period, fuel expansion
can pressurize the fuel tanks causing fuel spillage, or can even rupture the tank
a. Attach a rubber tube to the end of vent line beneath the wing.
b. Blow into tube to slightly pressurize tank Ifair can be blown into tank, vent line is
open.
c. After tank is slightly pressurized, insert end of rubber tube into a container of water
and watch for a continuous stream of bubbles, which indicates the bleed hole in valve
assembly is open and relieving pressure..
d. After completion of step "c", blow into tube againto slightly pressurize the tank and
loosen but do not remove filler cap on opposite wing to check tank crossover line. If
pressure escapes from filler cap, crossover line is open.
NOTE
Remember that a plugged vent line or bleed hole can
cause either fuel starvation and collapsing of fuel tanks
or the pressurization of tanks by fuel expansion.
e.

Any fuel vent found plugged or restricted must be corrected prior to returning
aircraft to service.
WARNING
The fuel vent line protruding beneath the wing near the
wing strut must be correctly aligned to avoid possible
icing of the vent tube. Dimensions are shown in figure 124.

12-7

MODEL 172 SERIES SERVICE MANUAL

TRANSMITTER

GROUNDING

NOTES
Long range tank is shown: standard range
tank is similar except for capacity
Hinge for vent valve (22) must be at top
Remove shims (16) when required to
increase tension of leaf spring (17)
Airplanes 17261445. 17267585 and On
and F17201515 and On incorporating
Airplanes incorporating SK172-135 have
four additional drain valves.

Detail A

2.
3.
4.
10

Washer
Drain Valve
Fuel Sampler Cup
Fuel Quantity Transmitter

6. Gasket

7. Top Wing Skin
8. Ground Strap

11.
12.
13.

Cap(LH)
Plate
Washer

14.
15.
16.

Gasket
Spacer
Shim

18.
19.
20.
21.
22.
23.

Chain
Vented Cap (RH)
Overboard Vent Line
Vent Valve Tube
Vent Valve
Quick Drain Valve (typical)*

Figure 12-3.

12-8 Revision 3

Fuel Tank

MODEL 172 SERIES SERVICE MANUAL

3.75"

LOOKING
FORWARD

LOOKING
1. Wing
2. Vent
3. Grommet

4. Fairing
5. Wing Strut
6. Tie-Down Ring

Figure 12-4. Fuel Vent Location
12-9

MODEL 172 SERIES SERVICE MANUAL
12-12.

FUEL SELECTOR VALVE. (See figure 12-5.)

12-13.

DESCRIPTION. A four position fuel selector valve is located beneath the floorboard just aft
and slightly to the left of the pedestal structure. A shaft links the valve to a handle mounted
on the pedestal structure. The positions of the handle are labelled "OFF. LEFT. BOTH ON
and RIGHT". Beginning with 17275035 and F17202135. a drain valve assembly is located in
the bottom of the selector valve body for sampling and draining of fuel. Valve repair is
limited to replacement of component parts only.

12-14.

REMOVAL AND INSTALLATION. (See figure 12-2.)
a. Drain all fuel from wing tanks, fuel strainer, lines and selector valve, observing
precautions outlined in paragraph 12-3.
b. Remove selector valve handle (11) and pedestal cover.
c. Peel back carpet as required to gain access to inspection plates aft of pedestal
structure.
d. Disconnect lower universal joint (14) at valve shaft.
e. Disconnect and cap inlet and outlet fuel lines to valve.
f. Remove screws (21) attaching valve to mounting bracket (13) and withdraw valve.
g. Reverse preceding steps for installation. Service aircraft in accordance with Section
2. turn fuel selector valve to ON position and check for leaks.
h. Replace items removed for access.

12-15.

DISASSEMBLY. (See figure 12-5.)
a. Remove fuel selector valve in accordance with paragraph 12-14.
b. Remove screws (1) securing cover (2) to valve body (7) and carefully remove cover.
Discard O-rings (15) and (6), but retain ball (3) and spring (4) for reinstallation.
c. Slowly withdraw rotor (5) from valve body.
NOTE
Removal of rotor (5) will allow seal (8). O-ring (9), washer
(10) and spring (11) (one each installed in both inlet ports)
to pop free.
d.

12-16.

Remove washer (16), plug (13) and O-ring (12).

CLEANING, INSPECTION AND REPAIR. (See figure 12-5.)

NOTE
Repair of damaged or worn parts of the selector valve
assembly is NOT authorized and therefore, is limited to
replacement of component parts only.
a.

12-10

Clean disassembled parts by washing in Stoddard solvent or equivalent. Blow parts
dry using clean compressed air.

MODEL 172 SERIES SERVICE MANUAL

* 17267585 THRU 17275034
F17201515 THRU F17202134

Inlet Ports

Beginning with 17275035

Wrap with tape

equivalent)

NOTES
Fabricate two spring compressors (14)
from 1/16 inch diameter #1 OX-WELD
AC welding rod (or
according to dimensions shown.
All dimensions in inches.

1. Screw
2. Cover
5.
6.
7.
8.

Rotor
O-Ring
Body
Seal

9. O-Ring
10. Washer
13.
14.
15.
16.
17.

Plug
Spring Compressor
O-Ring
Washer
Drain Valve Assembly

Figure 12-5. Fuel Selector Valve and Spring Compressor
12-11

MODEL 172 SERIES SERVICE MANUAL
b.

12-17.

Inspect all parts for obvious wear or damage as follows:
1. Check detent holes in cover (2) for excessive wear and examine bearing surfaces
with rotor (5).
2. Inspect shaft and bearing surfaces of rotor (5) for removal of black anodized
finish indicating wear. Check for internal corrosion of drilled passages.
3. Examine valve body (7) for wear. cracks, distortion and internal corrosion. Any
damage to thread surfaces at inlet and outlet ports or cover attach screw holes is
cause for rejection.

REASSEMBLY. (See figure 12-5.)
NOTE
Reassembly of selector valve is facilitated by mounting
in a bench vise or equivalent bench support. making sure
valve body (7) is protected from damage. Fabrication of
spring compressors (14) (two required) is recommended
before reassembly. Replace O-rings (6. 9 and 15) whenever rotor is removed from valve body.
a.
b.
c.

d.
e.
f.
g.
h.

Insure all component parts are clean, then coat sparingly with lightweight engine
oil.
Insert washer (16) and springs (11) into body (7).
With spring compressors (14) in place as shown in Section A-A. compress springs
(11) and install washers (10), new O-rings (9) and seals (8) into inlet ports.
ports.
Holding springs compressed. carefully insert rotor (5) into valve body (7). Release
spring compressors and check for proper seating of seals to rotor.
Insert new O-ring (6) into recess at top of valve body (7).
Place new O-ring (15) over shaft of rotor.
Lubricate spring (4) and ball (3) with lubricant conforming to Military Specification
VV-P-236 (USP Petrolatum or equivalent), insert spring into hole in top of rotor.
Place ball on spring and turn rotor as required to index one of the detent holes in

cover (2).
Attach cover (2) and test rotation of rotor shaft for ease of operation and positive
detent engagement
j. Replace plug (13) using new O-ring (12).
k. Reinstall selector valve in accordance with paragraph 12-14.
i.

12-18.

FUEL STRAINER. (See figure 12-6.)

12-19.

DESCRIPTION. The fuel strainer is mounted at the firewall in the lower engine compartment. The strainer is equipped with a quick-drain valve which provides a means of draining
trapped water and sediment from the fuel system. The quick-drain control is located
adjacent to the oil dipstick and is accessible through the oil dipstick door in the upper engine
cowl.
NOTE
The fuel strainer can be disassembled, cleaned and
reassembled without removing the assembly from the
aircraft (Refer to paragraph 12-21.)

12-12

MODEL 172 SERIES SERVICE MANUAL
12-20.

REMOVAL AND INSTALLATION. (See figure 12-6.)
a. Remove cowling as necessary to gain access to strainer.
b. With selector valve in "OFF" position. drain fuel from strainer and lines with
strainer quick-drain control.
c. Disconnect and cap or plug all fuel lines and controls from strainer. (Observe
precautions in paragraph 12-3.)
d. Remove bolts attaching assembly to firewall and remove strainer.
e. Reverse the preceding steps for installation. With selector valve in "ON" position
check for leaks and proper operation of quick-drain valve.

12-21.

DISASSEMBLY AND ASSEMBLY. (See figure 12-6.)
a. With selector valve in "OFF" position. drain fuel from bowl and lines with quickdrain control.
b. Remove drain tube, safety wire, nut and washer at bottom of filter bowl and remove
bowl.
c. Carefully unscrew standpipe and remove.
d. Remove filter screen and gasket. Wash filter screen and bowl with solvent (Federal
Specification P-S-661, or equivalent) and dry with compressed air.
e. Using a new gasket between filter screen and top assembly, install screen and
standpipe. Tighten standpipe only finger tight.
f. Using all new O-rings, install bowl. Note that step-washer at bottom of bowl is
installed so that step seats against O-ring. Connect drain tube.
g. With selector valve in "ON" position, check for leaks and proper operation of quickdrain valve.
h. Safety wire bottom nut to top assembly. Wire must have right-hand wrap, at least 45
degrees.

12-22.

PRIMING SYSTEM.

12-23.

DESCRIPTION. The Model 172-Series airplanes employ a standard manually-operated priming system which primes one cylinder. Fuel is supplied by a line from the strainer to the
plunger-type primer. Operating the primer delivers fuel to the intake port of the cylinder. A
three-cylinder priming system is available as optional equipment. Operating the primer on
this optional system delivers fuel to the intake port of each individual cylinder except No. 3.

12-24.

REMOVAL. (See figure 12-7.)
NOTE
Removal of primer from instrument panel requires
disassembly of primer.
a.
b.
c.
d.
e.
f.
g.

Place fuel shutoff valve in the OFF position.
Spread drip cloth under left-hand instrument panel.
Disconnect and cap or plug primer lines at primer.
Unlock primer knob and pull aft to clear packing nut (5).
Unscrew packing nut (5).
Withdraw primer knob and piston rod from instrument panel.
The primer barrel assembly can now be worked free from the instrument panel on the
firewall side of the panel.

12-13

MODEL 172 SERIES SERVICE MANUAL

9 10

NOTE
Torque nut (22) to 25-30 lb in.

27
NOTE
Afte inserting drain control (6) wire through
clamp (3) bend wire tip 90° (degrees) to prevent
it from being with drawn if the attaching clamp
(3) should come loose.

SAFETY WIRE HOLE

22
Detail A

1.
2.
3.
4.
5.
6.
7.
8.
9.

Drain Tube
Fuel Strainer
Clamp
Bracket
Bracket
Strainer Drain Control
Spring Nut
Shield
Firewall

10.
11.
12.
13.
14.
15.
16.
17.
18.

Grommet
Elbow
Fuel Line
Plate
O-Ring
Top Assembly
Gasket
Filter
O-Ring

Figure 12-6.
12-14

Fuel Strainer

19.
20.
21.
22.
23.
24.
25.
26.
27.

Bowl
O-Ring
Step Washer
Nut
Standpipe
Collar
Plunger
Washer
Spring

MODEL 172 SERIES SERVICE MANUAL

4
3

1. Fitting
2. Locknut
3. O-Ring

4.
5.
6.

Washer
Packing Nut
Knob

7.
8.

Piston Rod
Barrel

Figure 12-7. Primer Assembly
12-25.

INSPECTION. (See figure 12-7.) Visually inspect the primer lines for crushed. kinked, or
broken condition. Ensure proper clamping to prevent fatigue due to vibration or chafing.
Ensure barrel assembly (8) cylinderwall-is free of signs of pitting. corrosion, or scoring and
that O-rings (3) are in good condition.
NOTE
To remove O-rings (3) from piston rod (7). squeeze 0rings in grooves of piston rod with thumb and index
finger. Work O-rings over end of piston rod. O-rings can
be refitted to their grooves on piston rod (8) in a similar
manner.
CAUTION
Do not damage O-rings (3).

12-15

MODEL 172 SERIES SERVICE MANUAL
12-26.

INSTALLATION. (See figure 12-7.)
a. From the firewall side of the instrument panel. insert barrel assembly (8) through
hole in panel. Ensure that washer (4) is installed on barrel between locknut (2) and
firewall side of panel.
CAUTION
Do not damage O-rings (3) during step "b".
b. While holding barrel assembly (8) firmly in place. insert piston rod assembly (7) into
barrel.
c. The distance the barrel protrudes through hole in panel can be adjusted by turning
locknut (2).
d. Tighten packing nut (5) against panel.
e. Unplug or uncap fittings on primer lines and attach to primer fittings (1).
f. Turn fuel shutoff valve to the ON position.
g. Check primer for proper pumping action and positive fuel shutoff in the locked
position.

12-26A. AUXILIARY ELECTRIC FUEL PUMP. (MODEL 172Q).
of the
12-26B. DESCRIPTION. The electric fuel pump is located under the floorboards on the RH side
auxThe
pump.
fuel
engine-driven
the
with
parallel
system
fuel
the
cabin. It is plumbed into
failpump
fuel
engine-driven
of
case
in
standby
a
as
uses
be
may
iliary electric fuel pump
adjapanel
control
and
switch
the
on
located
rocker-switch
a
by
ure. The pump is controlled
cent to the master switch.
12-26C. REMOVAL AND INSTALLATION. (See figure 12-8.)
a. Place fuel selector valve in OFF position.
b. Turn the master switches and auxiliary fuel pump switch OFF.
. Disconnect fuel lines (16) and drain line (14) from pump (11). OBSERVE precautions

outlined in paragraph 12-3.
d.
e.
f.
g.

12-16

Disonnect electrical wires from pump (11).
Loosen clamp (13) and remove fuel pump (11) from bracket (12).
Reverse preceding steps for installation of pump.
Check for proper operation and fuel leaks after installing pump.

MODEL 172 SERIES SERVICE MANUAL

12-27.

INTEGRAL FUEL BAYS.

12-28.

DESCRIPTION. Beginning with Serials 17274010 and F17202070, an extended range fuel
system is available. The extended range system is a wet wing configuration that consists of
integral fuel bays in the inboard end of each wing, vented fuel cap for right wing fuel bay,
non-vented fuel cap for left wing fuel bay, fuel quantity transmitters, mounted on the side
of the left and right wing root rib assemblies, fuel vent valve assembly mounted on the inboard side of the left outboard fuel bay rib, fuel sump drain valves in the bottom inboard
end of each fuel bay, fuel screens over the end of each fuel supply line, and baffles mounted
on the bottom inboard surface of each fuel bay. In addition, airplanes incorporating SK182100 have four quick drain fuel sump valves installed in each fuel bay.

12-29.

CLASSIFICATION OF FUEL LEAKS. Fuel leaks which do not constitute a flight hazard
are stains, seeps and heavy seeps NOT in an enclosed area. However, they should be repaired when the aircraft is grounded for other maintenance. Fuel leaks which constitute a
flight hazard are running leaks in any area, seeps, heavy seeps, or stains in an enclosed area, such as the wing leading edge, the sections of wing inboard and outboard of the fuel bay
and the area between the rear fuel spar and the main spar. These leaks must be repaired
before that bay is used for another flight. The wet or stained spot on the wing in the area of
the bay is an indication of the intensity of the leak. Fuel leak classifications are shown in
figure 12-9.
NOTE
Stains and seeps that are not considered a flight hazard must be
inspected after each flight to ensure that they have not grown in
intensity to the point of causing a flight hazard.
If a leak causing a flight hazard should occur at a place where there are no facilities available to make an acceptable repair, it is recommended that the leaking bay be drained and
some suitable material placed over the leak, if it is within an enclosed area of the wing, to
eliminate escaping fumes. By switching the fuel selector valve to the other bay, the aircraft can then be flown to a base where the fuel leak can be repaired.

12-30.

FUEL BAY PURGING.
WARNING
Purge fuel bays with an inert gas prior to repairing fuel leaks, to
preclude the possibility of explosions.
The following procedure may be used to purge the bay with argon or carbon dioxide.
a. Ground the aircraft to a suitable ground stake.
b. Remove safety wire from shutoff valve control knob and pull control to "OFF" position. (Resafety control knob after completion of repair.)
c. Drain all fuel from bay being repaired. (Observe the precautions in paragraph 12-3.)
d. Remove access door and insert hose into bay.
e. Allow inert gas to flow into bay for several minutes (time dependent upon hose size,
rate of flow, etc.) to remove all fuel vapors.
Since argon and carbon dioxide are heavier than air, these gases will remain in the bay
during the repair. The repair shall be made using non-sparking tools (air motors, plastic
scrapers, etc.).

Revision 3

12-17

MODEL 172 SERIES SERVICE MANUAL

MAXIMUM TORQUE
8- 10 LB-INCHES
(4 - Places)

17274010 & ON
F17202070 & ON

12-8

12-2

12-6

12-2

Bay
Right Integral Fuel

Vent Crossover Line

Left Integral Fuel Bay
Overboard Vent Line

Tank Vent Interconnect Line

Primer

Fuel Supply Line

10.

Primer Supply Line

5. Hose

11.Strainer Drain Control

12.

Clamp

Primer Delivery Line

Figure 128. Integral Bay Fuel System (Sheet 1 of5)
12-18

MODEL 172 SERIES SERVICE MANUAL

SEE FIGURE 12-6

17275035 AND ON
F17202040 THRU F17202233

172 SERIES AIRPLANES
1.
2.

Right Integral Fuel Bay
Vent Crossover Line

6.
7.

Overboard Vent Line
Primer

3.
4.
5.

Vent Interconnect Line
Fuel Supply Line
Left Integral Fuel Bay

8.
9.

Primer Supply Line
Primer Delivery Line

Figure 12-8. Integral Bay Fuel System (Sheet 2 of 5)
12-19

MODEL 172 SERIES SERVICE MANUAL

SEE FIGURE 12-9

17275869
AND ON
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.,
13.
16.

Right Integral Fuel Bay
Vent Crossover Line
Vent Interconnect Line
Fuel Supply Line
Left Integral Fuel Bay
Overboard Vent Line
Primer
Primer Supply Line
Primer Delivery Line
Fuel Pressure Gage
Fuel Pump
Puel Pump Braket
Clamp
Drain Line
Grommet
Puel Lines

15
16
Detail

Figure12-8. Integral Bay Fuel Sytem (Sheet 3 of 5)
12-20

MODEL 172 SERIES SERVICE MANUAL

Deail

B
17275035 THRU 17276259
F17202135 THRU F17202233

1.
2.

Fuel Selector Valve Handle
Placard

Bracket

Shaft

5. Bolt
6. Selector Valve
7. O-Ring
8. Nipple

Figure 12-8. Integral Bay Fuel System (Sheet 4 of 5)
12-21

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.

Fuel Selector Valve Handle
Placard
Bracket
Roll Pin
Shaft

Spring

Selector Valve

8. O-Ring
9. Nipple

FIGURE
SEE
12-5

9
Detail

17276260 AND ON

NOTE
Roll pin (4) must be bonded to shaft (5) with EA9316,
EA9309 or EA9314. The products may be purchased
from Hystol Div. Dexter Corp., Willow Pass Rd;
Pittburg, CA 94565. Equivalent product, EC2216, may
be purchased from 3M Co., St. Paul MN. 55119. Clean

roll pin (4) and shaft (5) with MEK, and thoroughly dry
parts before applying bonding agent. At 75°F, bond cures
to 80% ultimate tensile strength within 24 hours. Accelerated cure times are as follows:
(a) Five minutes at 250°F.
(b) Ten minutes at 200°F.

Figure 12-8. Integral Bay Fuel System (Sheet 5 of 5)
12-22

MODEL 172 SERIES SERVICE MANUAL

NOTE
After performing maintenance inside the
fuel bay areas, seal according to paraNOTE
graph 12-33.
NOTE
* Airplanes 17274010 and On
and F17202070 and On
incorporating SK182-100.

LEFT HAND FUEL BAY SHOWN

Inspection Cover 10

1.
2.
3.
4.
5.
6.
7.

InspectionCover
Upper Trailing Edge Skin
Gusset
Screen
Stiffener
Flap Track Rib
LH Channel

14
8.
9.
10.
11.

Baffle
Fuel Spar
Rib
Trailing Edge
Skin Stiffener

12.
13.
14.
15.
16.

Fuel Drain Valve
Lower Forward Skin
Hat Section Stiffener
Doubler, Inspection Port
Quick Drain Valve

Figure 12-9. Integral Fuel Bay Installation (Sheet 1 of 4)
Revision 3 12-23

MODEL 172 SERIES SERVICE MANUAL

4 5

DetailA

Fuel Vent Valve

Tube

3.
4.
5.
6.
7.
8.
9.
10.
11.

9
10

Inner Gasket
Rib
Outer Gasket
Washer
Nut
Fuel Cap
Upper Wing Skin
Fuel Filler Neck
Filler Collar

Detail

NOTES
Hinge for vent valve (1) must be at top.
Install tube (2) with bend down.
LH fuel cap is non-vented, RH fuel cap is vented type (See
figure 12-2).

Figure 12-9. Integral Fuel Bay Installation (Sheet 2 of 4)
12-24

MODEL 172 SERIES SERVICE MANUAL

Nutring

Root Rib Gasket

3.
4.
5.

Root Rib
Transmitter Gasket
Fuel Quantity Transmitter

Washer

Screw

1
2
3
4

Beginning with Serial 17267585 thru
17276330.
17276331,
nutring
(1)
is
bonded to root rib (2). Order sealant kits
SK210-56, or SK210-101
from Cessna
Supply Division.

17276331 AND ON

Detail C
NOTE
After installing washers (6) and screws (7)
torque screws to 20 in/lbs (once only).
using a cross-pattern sequence.

Figure 12-9. Integral Fuel Bay Installation (Sheet 3 of 4)
12-25

MODEL 172 SERIES SERVICE MANUAL

FUEL
100LL, 100 MIN. GRADE AVIATION GASOLINE
CAP. 21.5 U.S. GAL.
Fuel Quantity Placard - Standard Tanks

FUEL
100LL/100 MIN. GRADE AVIATION GASOLINE

CAP. 27 U.S. GAL.
Fuel Quantity Placard - Long Range Tanks

FUEL
100LL/100 MIN. GRADE AVIATION GASOLINE
CAP. 34 U.S. GAL.
CAP. 24.0 U.S. GAL. TO BOTTOM OF FILLER COLLAR
Fuel Quantity Placard - Integral Tank

AVGAS ONLY

Fuel Grade Placard

Fuel Cap (See

figure 12-12)
2.

Fuel Fller Collar

Figure 12-9. Integral Fuel Bay Installation (Sheet 4 of 4)
12-26

MODEL 172 SERIES SERVICE MANUAL

3/4" Max.

STAIN

with location
and intensity.
3/4" to 11/2"

RUNNING
LEAK

SEEP

Fuel will usually flow in
this area along skin contour after it is wiped dry.
1 1/2" to 4"

HEAVY
SEEP

WARNING

Fuel usually drips
at this point.

REFER TO PARAGRAPH 12-13 FOR FUEL BAY PURGING WHICH
SHOULD BE ACCOMPLISHED BEFORE REPAIRING FUEL BAYS.
Figure 12-10. Classification of Fuel Leaks
NOTE
Portable vapor detectors are available to determine
presence of explosive mixtures and are calibrated for
leaded fuel. These detectors can be used to determine
when it is safe to make repairs.
12-31.

INTEGRAL FUEL BAY SEALANT. Two kinds of sealants are used, one to seal the fuel bay
and the other to seal the access doors and fuel quantity transmitter adapter. The access door
sealant is more pliable and will not adhere to metal as firmly as the bay sealant does. This
permits the access doors and fuel quantity transmitter adapter to be removed without damage to them. Service Kits SK210-56 (6 ounce tube) and SK210-101 (2.5 ounce tube) . available from the Cessna Supply Division, contain these sealants with the proper quantity of accelerator for each sealant. The sealants can be identified by color. The bay sealant is white
and its accelerator is a black paste. The access door sealant is gray and its accelerator is a
clear liquid.
WARNING
The accelerator, EC-1608B contains cumene hydroperoxide. Keep away from heat and flame. Use only in a well
ventilated area. Avoid skin and eye contact. WEAR EYE
SHIELDS. In case of eye contact, flush with water and get
prompt medical attention.

12-27

MODEL 172 SERIES SERVICE MANUAL
12-32

MIXING SEALANT. Use all the accelerator and sealant in the container when mixing, to
ensure the proper ratio of accelerator to sealant. Stir the accelerator to absorb all floating
liquid before it is mixed with the sealant. The accelerator can then be poured into the
container of sealant for mixing: otherwise, a wax-free container must be used. Stir
accelerator and sealant until it becomes a uniform mixture. Do not allow air bubbles to mix
in. If this occurs, work air bubbles out.

12-33.

SEALING DURING AND AFTER STRUCTURAL REPAIR.
CAUTION
Protect drain holes and fuel outlet screens when applying
sealants. DO NOT plug drain channels between stiffeners
(4) at inboard end of stringers (5) on lower skin (6). See
figure 12-12 (typical lower skin section).
Any repair that breaks the fuel bay seal will necessitate resealing of that area of the bay.
Repair parts that need sealing must be installed and riveted during the sealing operation.
All joints within the boundary of the bay, but which do not provide a direct fuel path out of the
bay. such as stringers and rib flanges within the bay, must be fay surface sealed only. Joints
which provide a direct fuel path out of the bay area, such as fuel spar flanges and inboard and
outboard rib flanges, must be fay surface sealed and fillet sealed on the fuel side. Fay surface
sealing is applying sealant to one mating part before assembly. Enough sealant must be
applied so it will squeeze out completely around the joint when the parts are riveted or
fastened together. The fillet seal is applied after the joint is fay surface sealed and riveted or
fastened together. Fillet sealing is applying sealant to the edge of all riveted joints, joggles.
bend reliefs, voids, rivets or fasteners through the boundary of the bay and any place that
could produce a fuel leak. The fay sealant need not be cured before the fillet seal is applied.
but the squeezed out sealant, to which the fillet sealant is applied, must be free of dirt and
contamination. Fillets laid on intersecting joints shall be joined together to produce a
continuous fillet. Filler sealant must be pressed into the joint, working out all entrapped air.
The best method of applying sealant is with an extrusion gun. Then work the sealant into the
joint with a small paddle. being careful to eliminate all air bubbles.
NOTE
During structural repair, parts must be predrilled. countersunk or dimpled and cleaned before being sealed and
positioned for final installation.
a.

Remove all existing sealant from area to be sealed, leaving a taper on the remaining
sealant. The taper will allow a scarf bond and a continuous seal when the new sealant
is applied.
NOTE
The best method of removing sealant is with a chisel-type
tool made of hard fiber. Remaining sealant may then be
removed with aluminum wool. Steel wool or sandpaper
must not be used.

12-28

Vacuum thoroughly to remove all chips, filings, dirt. etc.. from the bay area.

MODEL 172 SERIES SERVICE MANUAL

NOTE
Refer to paragraph 12-33.

TYPICAL
INSPECTION PLATE

TYPICAL

RIB SECTION
1. Faying
2. Fillet Seal
3. Rivet and Fastener Seal

Figure 12-11. Typical Fuel Bay Sealing (Sheet 1 of 2)
12-29

MODEL 172 SERIES SERVICE MANUAL

TYPICAL
FASTENER

Fastener

3
.25"

TYPICAL
FUEL BAY
SPAR

Fillet

TYPICAL

END SECTION

4
1. Fuel Side

2. Nutplate
3.
4.
5.
6.
TYPICAL
LOWER SKIN
SECTION

Figure 12-11. Typical Fuel Bay Sealing (Sheet 2 of 2)
12-30

Fillet Seal
Stiffener
Stringer
Lower Skin

MODEL 172 SERIES SERVICE MANUAL
c.

All surfaces and areas to be sealed shall be thoroughly cleaned by wiping with a
clean cloth dampened with Methyl Ethyl Ketone (MEK). acetone or similar solvent
and dried with a clean cloth before the solvent evaporates. Always pour the solvent
on the cloth. Never use contaminated solvent. The cloth shall not be so saturated that
dripping occurs.
NOTE
Allowable work life of EC-1675B/ A sealant is four hours
from the starting time of mixing. Allowable work life of
EC-1608B/ A sealant is one hour. These apply to standard
conditions of 77° Fahrenheit and 50% relative humidity.
An increase in temperature or a decrease in humidity will
shorten the work life of the sealant

Apply fay surface sealant to one mating part and install rivets or fasteners while
sealant is still within its allowable work life.
NOTE
During the sealing operation, sealant must be checked at
various times to determine that it has not exceeded its
allowable work life. Use a small wood paddle, such as a
tongue depressor, to gather some sealant Touch the
sealant to a piece of clean sheet metal. If the sealant
adheres to the sheet metal, it is still within its allowable
work life. If the sealant does not adhere to the sheet metal.
it is beyond its allowable work life and must not be used.

e.
f.

Apply a fillet seal to the repaired area on the inside of the bay.
Apply fay surface door sealant to access doors and fuel quantity transmitter adapter.
if removed. and install the doors and adapter.
g. Allow the sealant to cure. Refer to paragraph 12-34 for curing time.
h. Clean stains from outside of bay area.
i. Test fuel bay for leaks as described in paragraph 12-35.

12-34

SEALING FUEL LEAKS. First determine the source of the fuel leaks. Fuel can flow along a
seam or the structure of the wing for several inches, making the leak source difficult to find.
A stained area is an indication of the leak source. Fuel leaks can be found by testing the
complete bay as described in paragraph 12-35. Another method of detecting the source of a
fuel leak is to remove access doors and blow with an air nozzle from the inside of the bay in
the area of the leak while a soap bubble solution is applied to the outside of the bay. After the
leak source has been found, proceed as follows:
a. Remove existing sealant in the area of the leak as described in paragraph 12-32. step
"a".
b. Clean the area and apply a fillet seal. Press sealant into leaking area with a small
paddle, being sure to work out all entrapped air.
c. If a leak occurs around a rivet or bolt, restrike the rivet or torque the bolt to the
maximum allowable torque, and repair any damaged sealant.
d. Apply fay surface door sealant to access doors or fuel quantity transmitter adapter, if
removed, and install the doors and adapter.
e. Test fuel bay for leaks as described in paragraph 12-35.

12-31

MODEL 172 SERIES SERVICE MANUAL
12-35.

CURING TIME. Service Kits SK210-56 and SK210-101 contain SP654890B2 Fuel Tank Area
Sealant Kit and SP654706B2 Access Door Sealant Kit. Normal curing time for SP264706B2
Sealant Kit is 24 hours. These values are based on a Standard condition of 77° Fahrenheit
and 50% humidity. Curing time may be accelerated as shown in the following chart.

Temperature of Sealant °F

Time in Hours

160
140
120

3
4
7
NOTE

Temperature shall not exceed 160°F. Bay must be vented
to relieve pressure during accelerated curing.
WARNING
Access door sealant must not be heated above 90 ° until
sealant is cured for 24 hours based on a standard condition of 77° Fahrenheit and 50% relative humidity. Harmful vapors are released if sealant is heated above 90°F.
12-36

TESTING INTEGRAL FUEL BAY.
a. Remove vent line from vent fitting and cap the fitting.
b. Remove forward and aft fuel lines-from bay.
c. To one of the bay fittings, attach a water manometer capable of measuring 20 inches
of water.
d. To the other bay fitting. connect a well-regulated supply of air (1/2 PSI MAXIMUM or
13.8 INCHES OF WATER). Nitrogen may be used where the bay might be exposed to
temperature changes while testing.
e. Make sure filler cap is installed and sealed.
CAUTION
Do not attempt to apply pressure to the bay without a
good regulator and a positive shutoff in the supply line.
Do not inflate the fuel bay to more than 1/2 psi or damage
may occur.
f.
g.
h.
i.
j.

Apply pressure slowly until 1/2 psi is obtained.
Apply soap solution as required.
Allow 15 to 30 minutes for pressure to stabilize.
If bay holds for 15 minutes, without pressure loss, bay is acceptable.
Reseal and retest if any leaks are found.

12-37. , FUEL QUANTITY TRANSMITTERS. One float-actuated, variable-resistive transmitter is
located in each fuel bay. They are connected electrically to separate galvanometric gages,
one for each bay, thereby indicating fuel level in each bay. A complete description of the
transmitters, operation, and maintenance procedures is contained in Section 15.

12-32

MODEL 172 SERIES SERVICE MANUAL

12-38.

VENTED FUEL FILLER CAP. (See figure 12-11.)

12-39.

DESCRIPTION. The RIGHT-HAND fuel filler cap incorporates a vent and safety valve that
provides both vacuum and positive pressure relief.

12-40.

INSPECTION, CLEANING AND REPAIR.
a. Remove RIGHT-HAND fuel filler cap from the adapter assembly.
b. Disconnect the safety chain from the cap and cover or plug the tank opening to keep
out foreign matter.
c. Check condition of gasket and frictionless washer, replace as required.
d. Using cotton swabs and Stoddard solvent or equivalent, gently lift edges of rubber
umbrella and clean seat and umbrella removing all contaminates. Using a second
swab wipe seat and umbrella thoroughly, removing all cotton fibers. Repeat until
swabs show no discoloration.
e. If the umbrella continues to leak or is deteriorated, remove and replace. To remove
the umbrella, lubricate the umbrella stem with (MIL-H-5606) hydraulic fluid to
prevent tearing the stem. When installing the new umbrella, lubricate the stem with
(MIL-H-5606) hydraulic fluid and use a small blunt tool to insert the retaining knob
on the umbrella, into the check valve body.
f. Connect fuel cap to safety chain and reinstall cap in the adapter assembly.

NOTE
Check valve (2) shall open at or before 4.0
inches of water vacuum pressure, and be
able to withstand .5 PSI positive pressure

without leakage.

1.
2.
3.
4.
5.
6.
7.

Umbrella
Check Valve (Vent)
Gasket
Frictionless Washer
Fuel Cap Body
Cover
Screw

Figure 12-12. Vented Fuel Filler Cap
12-33/(12-34 blank)

MODEL 172 SERIES SERVICE MANUAL
SECTION 13
PROPELLER
WARNING
When performing any inspection or maintenance that
requires turning on the master switch, installing a
battery, or pulling the propeller through by hand, treat
the propeller as if the ignition switch were ON. Do not
stand, nor allow anyone else to stand, within the arc of the
propeller, since a loose or broken wire, or a component
malfunction, could cause the propeller to rotate.
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

PROPELLER ..............
Description ...............
Repair ...................
Removal .................
Installation ...............
Time Between Overhaul (TBO) .

2F19/13-1
2F19/13-1
2F19/13-1
2F19/13-1
2F21/13-3
2F21/13-3

13-1.

PROPELLER. (See figure 13-1.)

13-2.

DESCRIPTION. An all-metal, fixed-pitch propeller, equipped with a spinner, is used on the
aircraft.

13-3.

REPAIR. Repair of a metal propeller first involves evaluating the damage and determining
whether the repair is to be a major or minor one. Federal Aviation Regulations, Part 43 (FAR
43). and Federal Aviation Agency Advisory Circular No. 43.13 (FAA AC No. 43.13), define
major and minor repairs, alterations and who may accomplish them. When making
alterations or repairs to a propeller, FAR 43, FAA AC No. 43.13 and the propeller
manufacturer's instructions must be observed. The propeller manufacturer's Service
Manual may be obtained from the Cessna Service Parts Center.
NOTE
For information not covered in this section, refer to the
applicable McCauley Service Manual and supplements
thereto.

13-4.

REMOVAL. (See figure 13-1.)
WARNING
Be sure magneto switch is in OFF position before turning
propeller.

Revision 1

13-1

MODEL 172 SERIES SERVICE MANUAL
NOTE

TORQUE PROPELLER MOUNTING BOLTS TO
540 - 560 LB-IN OR 45 - 46.5 LB-FT AND

SAFETY WIRE.

NOTE

Propeller (4) and spacer (8) are balanced
as a set. The spacer is stamped with a
9

propeller.

10
1.
2.
3.
4.
5.

Spinner
Mounting Bolt
Forward Bulkhead
Propeller
Engine Crankshaft
13-1.

13-2

Revision 3

matching propeller serial number.
When installing the propeller and spacer, the serial number on the spacer must
be toward the number one blade of the

6.
7.
8.
9.
10.

Crankshaft Bushing
Ring Gear Support Assembly
Spacer
Aft Bulkhead
Dowel Pin

Propeller Installation

MODEL 172 SERIES SERVICE MANUAL
a. Remove spinner (1).
b. Remove safety wire from mounting bolts.
c. Remove mounting bolts (2) and remove forward spinner bulkhead (3). propeller (4).
rear spinner bulkhead (9) and spacer (8).
NOTE
Propeller mounting bolts should be magnafluxed whenever propeller is removed from the engine for reconditioning or repair.
d.

13-5.

If removal of the ring gear support assembly (7) is necessary, loosen the alternator
adjusting arm and disengage the drive pulley belt from pulley on the aft face of the
starter ring gear support assembly.

INSTALLATION. (See figure 13-1.)
WARNING
Be sure magneto switch is in OFF position before turning
propeller.
a.

If the starter ring gear support assembly (7) was removed, clean the mating surface
of support assembly and engine crankshaft
b. Place alternator drive belt in the pulley groove of the starter ring gear support. Fit
support assembly over propeller flange bushing of the crankshaft.
NOTE
Make sure the bushing hole in the ring gear support that
bears the identification "O". is assembled at the "O"
identified crankshaft flange bushing. This bushing is
marked "O" by an etching on the crankshaft flange next
to the bushing. The starter ring gear must be located
correctly to assure proper alignment of the timing marks
on the ring gear.
c.

Clean mating surfaces of the propeller, bulkheads and spacer and assemble as
illustrated in figure 13-1.
d. Find the top center (TC) mark on the aft face of the starter ring gear support. Locate
one of the propeller blades over the TC mark, rotate the propeller clockwise (as
viewed from front of engine) to the first bushing and install propeller.
e. Tighten propeller mounting bolts evenly, torque bolts to 45 lb-ft, and safety wire.
NOTE
The propeller mounting bolt torque should be checked at
least once per year.
f. Install spinner.
g. Adjust alternator drive belt tension as outlined in Section 16.
13-6

TIME BETWEEN OVERHAUL (TBO). There is no recommended overhaul period for fixedpitch propellers. These shall be reconditioned or repaired as required for blade surface
conditions.

13-3/(13-4 blank)

MODEL 172 SERIES SERVICE MANUAL
SECTION 14
UTILITY SYSTEMS
TABLE OF CONTENTS
UTILITY SYSTEMS ...........
Heating System ...........
Description ............
Operation ...............
Trouble Shooting .........
Removal, Repair and
Installation .............
Defroster System ...........
Description .............
Operation ...............
Trouble Shooting .........
Removal, Repair and
Installation .............

Page No.
Aerofiche/
Manual
2G3/14-1
2G3/14-1
2G3/14-1
2G3/14-1
2G3/14-1
23/14-1
2G6/14-4
2G6/14-4
2G6/14-4
2G6/14-4

Ventilating System ........
Description .............
Operation ..............
Trouble Shooting ........
Removal, Repair and
Installation ............
Air Circulation Fan
System .................
Description ............
Removal ................
Inspection/Repair .......
Installation ............

2G6 14-4
2G6 14-4
2G6 14-4
2G7/14-5
2G7 14-5
2G7/14-5
2G7/14-5
2G7/14-5
2G7/14-5
2G7/14-5

2G6/14-4

14-1.

UTILITY SYSTEMS.

14-2.

HEATING SYSTEM. (See figure 14-1.)

14-3.

DESCRIPTION. The heating system is comprised of the heat exchange section of the
exhaust muffler. a shut-off valve, mounted on the right forward side of the firewall, a pushpull control on the instrument panel, outlets and flexible ducting connecting the system.

14-4.

SYSTEM OPERATION. Ram air is ducted through an engine baffle inlet and heat exchange
section of the exhaust muffler, to the shut-off valve at the firewall. The heated air flows from
the shut-off valve into a duct across the aft side of the firewall, where it is distributed into the
cabin. The shut-off valve, operated by a push-pull control marked "CABIN HT," located on
the instrument panel, regulates the volume of heated air entering the system. Pulling the
control full out supplies maximum flow, and pushing control in gradually decreases flow.
shutting off flow completely when the control is pushed full-in.

14-5.

TROUBLE SHOOTING. Most of the operational troubles in the heating, defrosting and
ventilating systems are caused by sticking or binding air valves and their controls.
damaged air ducting or defects in the exhaust muffler. In most cases, valves or controls can
be freed by proper lubrication. (Refer to Section 2 of this manual for lubrication information.) Damaged or broken parts must be repaired or replaced. When checking controls.
ensure that valves respond freely to control movement, that they move in the correct
direction, and that they move through their full range of travel and seal properly. Check that
hoses are properly secured, and replace hoses that are burned, frayed or crushed. If fumes
are detected in the cabin, a thorough inspection of the exhaust system should be accomplished. Refer to applicable paragraph in Section 11 of this manual for this inspectin. Since
any holes or cracks may permit exhaust fumes to enter the cabin, replacement of defective
parts is imperative, because fumes constitute an extreme danger. Seal any gaps in shutoff
valves at the firewall with Pro-Seal #700 (Coast Pro-Seal Co.. Los Angeles, California)
compound, or equivalent compound.

14-6.

REMOVAL, REPAIR AND INSTALLATION. The heating and defrosting systems are
illustrated in figure 14-1. The figure may be used as a guide for removal, repair or

Revision 1

14-1

MODEL 172 SERIES SERVICE MANUAL

BEGINNING WITH

THRU
1979 MODELS

1980 MODELS

*10

Refer to Section 2 for

hinge point lubrication

iformation.

1.
2.
3.
4.
5.
6.
7.
8.

Heater Hose
Clamp
Vave Body
Shim
Valve Plate

17267585 thru 17275034
F17201515 thru F17202134

Clamp Bolt

Control Arm
Cabin Heat Control

9. Valve Spring

10. Valve Seat
11. Knob
12.
13.

17275035 & On
F17202135 & On

Vale
Valve Guide

14. Nozzle
15. Clamp
16. Defroster Hose
17. Screw

16
Detail

Figure 14-1.
14-2

Heating and Defrosting Systems

MODEL 172 SERIES SERVICE MANUAL

Detail D

Detail

Refer to Section 2 for
hinge point lubrication
information.

1. Hose
2. Clamp
3. Inlet
4. Seal
5. Clamp Bolt

19.

Washer

7.
8.
9.

Fuselage Skin
Air Vent Silencer
Escutcheon

21.
22.
23.

Nut
Felt Washer
Tube Assembly

Spring
Knob
nsert
Outlet Assembly
Bullet Catch
Seal

26.

Nutplate
Element
Adapter
Bracket
Cap
O-Ring

12.

14.
15.
16.
17.
18.

Detail C

28.
29.
30.
31.
32.

Insert (15) is cemented to knob (10) with EC1300L.
(3M Co., St. Paul. Minn. 55101) Beginning with
17275991 and F17202215 thru F17202233, insert
(15) is retained by screw (11).

Figure 14-2.

Ventilating Systems
14-3

MODEL 172 SERIES SERVICE MANUAL
installation of system components. Burned. frayed or crushed hose may be replaced with
new hose. cut to correct length and installed in the original routing. Trim hose windings
shorter than complete hose length to allow clamps to be installed. Defective air valves
should be repaired or replaced. Check for correct operation of valves and their controls after
repair and/or installation.
14-7

DEFROSTER SYSTEM. (See figure 14-1.)

14-8.

DESCRIPTION. The defrosting system is comprised of a duct across the aft side of the
firewall, defroster outlets, mounted on the cowl deck, immediately aft of the windshield, and
flexible ducting connecting the system.

14-9.

SYSTEM OPERATION. Air from the duct across the aft side of the firewall flows through the
flexible ducting to the defroster outlet. Temperature and volume of this air is controlled by
settings of the heater system control.

14-10.

TROUBLE SHOOTING. Since the defrosting system depends on proper operation of the
heating system, trouble shooting procedures outlined in paragraph 14-5 should be followed
for checking the defroster system.

14-11.

REMOVAL. REPAIR AND INSTALLATION. The defroster system is illustrated in figure
14-1 in conjunction with the heating system. The figure may be used as a guide for removal.
repair or installation of system components. Burned, frayed or crushed hose must be
replaced with new hose, cut to correct length and installed in the original routing. Trim hose
windings shorter than complete hose length to allow clamps to be installed. A defective
defroster outlet should be repaired or replaced. Check for correct operation of control after
repair and/or installation.

14-12.

VENTILATING SYSTEMS. (See figure 14-2.)

14-13.

DESCRIPTION. Three separate systems are installed for cabin ventilation. One system is
comprised of an airscoop, located in each wing root fillet, with flexible ducting connecting
each airscoop to an adjustable air vent silencer unit, located on each side of the rear cabin
area. Another system is comprised of an airscoop. located in the leading edge of each wing.
just outboard of the airscoop in the wing root fillets. These airscoops are connected to cabin
outlets, installed on each side of the cabin, near the upper corners of the windshield. These
outlets are manually-adjustable with knobs on the outlet assemblies. A third system is
comprised of a fresh airscoop door on the right side of the fuselage, just forward of the
copilot seat. Flexible ducting connects this airscoop to the duct across the aft side of the
firewall. This system is controlled by a push-pull control on the instrument panel.

14-14.

SYSTEMS OPERATION. Heating, defrosting and ventilating systems work together to provide the conditions desired by the pilot. When the heating system, defrosting system and
one ventilating control is pushed in, no heated air can enter the firewall duct; therefore, if
the "CABIN AIR" control (to the scoop door on the right forward fuselage) is pulled out,
only fresh air from the scoop will flow through the duct into the cabin. As the "CABIN HT"
control is gradually pulled out, more and more heated air will blend with the fresh air from
the scoop, and be distributed into the cabin. Either one, or both of the controls may be set at
any position from full open to full closed. Rear seat ventilation is provided by air vent silencer assemblies, mounted in the left and right rear cabin wing root areas. These units receive ram air from the airsoops in the wing root fillets. Each silencer assembly is equipped
with a valve which meters incoming cabin ventilating air, which greatly reduces inlet air
noise. The outlet assemblies, installed near the upper corners of the windshield are manu-

ally operated, increasing or decreasing flow of ram air into the cabin.

14-4

MODEL 172 SERIES SERVICE MANUAL
NOTE
Beginning with 17276260 CABIN HT and CABIN AIR

controls are replaced with locking type controls. To operate a locking type control, push in and hold the center
button before moving knob in either diretion-

14-15.

TROUBLE SHOOTING. Most of the operational troubles in the ventilating systems are
caused by sticking or binding of the inlet scoop door or its control. Check airscoop filter
elements in the wing leading edges for obstructions. The elements may be removed and
cleaned or replaced. Since air passing through the filters is emitted into the cabin, do not use
a cleaning solution which would contaminate the air. The filters may be removed to increase
air flow. However, their removal will cause a slight increase in noise level.

14-16.

REMOVAL, REPAIR AND INSTALLATION. The ventilating system is illustrated in figure
14-2. The figure may be used as a guide for removal, repair or installation of system
components. A defective ventilator or scoop must be repaired or replaced. Check for proper
operation of controls after repair and/or installation.

14-17.

AIR CIRCULATION FAN SYSTEM. (See figure 14-3.)

14-18.

DESCRIPTION. An optional cabin ventilating fan may be located above the extended
baggage compartment. The system consists of a high-speed blower and overhead ductwork.
similar to that offered with the air conditioning option. This fan only circulates air and no
cooling components are attached. The blower is controlled by a four-position switch, located
on the pilot's console. The four switch positions are labeled HI. MED. LOW and OFF.

14-19.

REMOVAL. (See figure 14-3.) Access to the blower assembly and ducting is gained through
the baggage door.
a. Remove baggage compartment panel.
b. Disconnect forward and aft ends of hoses (8) by removing hose clamps.
c. Remove 8 screws attaching blower assembly (5) and duct assembly (9) to supports (3)
and (6).
d. Remove lower support (6).
e. Disconnect electrical connections.
f. Remove blower assembly.

14-20.

INSPECTION AND REPAIR. Hoses should be checked for security. and replaced if frayed or
crushed. Check that hose clamps are properly tightened: check electrical connections. and
check that blower rotates freely.

14-21.

INSTALLATION. (See figure 14-3.)
a. Install blower unit (5) and duct assembly (9) to upper support (3).
b. Connect electrical connections.
c. Install lower support (6). and attach blower assembly and duct (9).
d. Install hoses and hose clamps.
e. Install baggage compartment panel.

14-5

MODEL 172 SERIES SERVICE MANUAL

--------------------.......

1. Switch
2. Circuit Breaker

3. Support
4.
S.
6.
7.
8.
9.

Bulkhead
Blower Assembly
Support
Clamp
Duct
Duct Assembly

Figure 14-3. Circulating Fan Installation
14-6

MODEL 172 SERIES SERVICE MANUAL
SECTION 15
INSTRUMENTS AND INSTRUMENT SYSTEMS

TABLE OF CONTENTS

INSTRUMENTS AND INSTRUMENT SYSTEMS .............
General .....................
Instrument Panel ............
Description ...............
Removal/Installation ......
Shock-Mounts ............
Instruments ............
Removal .
............
Installation ...........
Pitot and Static Systems ......
Description
............
Maintenance ...........
Static System Inspection/
Leakage Test ........
Pitot System Inspection/
Leakage Test ...........
Blowing Out Lines ........
Removal/Installation Of
Components ............
Encoding Altimeter .......
Description ..........
Removal/Installation ....
Trouble Shooting .........
True Airspeed Indicator ....
Description ...........
Removal/Installation ....
Trouble Shooting .......
Trouble Shooting-Altimeter
Trouble Shooting-Vertical
Speed Indicator .........
Vacuum System .............
Description ...............
Trouble Shooting ..........
Trouble Shooting-Gyros ....
Trouble Shooting-Pump ....
Maintenance Practices .....
Removal of Vacuum
Pump ..................
Mounting Pad Inspection ...
Installation of Vacuum
Pump .
............
Cleaning .................
Low-Vacuum System ......
Vacuum Relief Valve
Adjustment ............
Standby Vacuum System ..
Description .............

Page No.
Aerofiche/
Manual

2G14/15-2
2G14/15-2
2G14/15-2
2G14/15-2
2G14/15-2
2G14/15-2
2G14/15-2
2G14/15-2
2G16/15-4
2G16/15-4
2G16/15-4
2G16/15-4
2G16/15-4
2G17/15-5
2G17/15-5
2G18/15-6
2G18/15-6
2G18/15-6
2G18/15-6
2G18/15-6
2G21/15-9
2G21/15-9
2G21/15-9
2G21/15-9
2G23/15-11
2G24/15-12
2H115-13
2H1/15-13
2H1/15-13
2H2/15-14
2H3/15-15
2H6/15-18
2H6/15-18
2H6/15-18
2H7/15-19
2H8/15-20
2H8/15-20

Trouble Shooting .........
Removal .................
Installation ..............
Engine Indicators ...........
Tachometer ..............
Description ............
Oil Pressure Gage ........
Description ............
Trouble Shooting ......
Oil Temperature Gage ....
Description ............
Cylinder Head Temperature
Gage .................
Description ............
Carburetor Air Temperature
Gage ................
Description ............
Trouble Shooting ......
Economy Mixture Indicator
Description ............
Calibration ............
Removal/Installation ...
Trouble Shooting ......
Fuel Quantity Indicating
System ...............
Description ............
Removal/Installation ...
Trouble Shooting ......
Transmitter Calibration
Hourmeter ..............
Description ............
Magnetic Compass .......
Description ............
Removal/Installation ...
Stall Warning ............
Description ............
Removal/Installation ...
Turn Coordinator ........
Description ............
Trouble Shooting ......
Turn-and-Slip Indicator ...
Description ............
Trouble Shooting ......
Outside Air Temperature
Gage .................

2H11/15-20C
2H11/15-20C
2H12/15-20D
2H12/15-20D
2H12/15-20D
2H12/15-20D
2H13/15-21
2H13/15-21
2H13/15-21
2H14/15-22
2H14/15-22
2H14/15-22
2H1415-22
2H14/15-22
2H14/15-22
2H14/15-22
2H15/15-23
2H15/15-23
2H15/15-23
2H17/15-25
2H17/15-25
2H17/15-25
2H17/15-25
2H17/15-25
2H18/15-26
2H19/15-26A
2H21/15-27
2H21/15-27
2H21/15-27
2H21/15-27
2H23/15-29
2H23/15-29
2H23/15-29
2H23/15-29
2H23/15-29
2H23/15-29
2H23/15-29
2H24/15-30
2H24/15-30
2H24/15-30
2H25/15-31

2H8/15-20
2H8/15-20
2H8/15-20
Revision 3

15-1

MODEL 172 SERIES SERVICE MANUAL
15-1.

INSTRUMENTS AND INSTRUMENT SYSTEMS.

15-2.

GENERAL. This section describes typical instrument installations and their respective
operating systems. Emphasis is placed on trouble shooting and corrective measures only. It
does NOT deal with specific instrument repairs since this usually requires special
equipment and data and should be handled by instrument specialists. Federal Aviation
Regulations require malfunctioning instruments to be sent to an approved instrument
overhaul and repair station or returned to manufacturer for servicing. Our concern here is
with preventive maintenance and correction of system faults which result in instrument
malfunctions. The descriptive material. maintenance and trouble shooting information in
this section is intended to help the mechanic determine malfunctions and correct them. up to
the defective instrument itself at which point an instrument technican should be called in.
Some instruments, such as fuel quantity and oil pressure gages, are so simple and
inexpensive, repairs usually will be more costly than a new instrument. On the other hand.
aneroid and gyro instruments usually are well worth repairing. The words "replace
instrument" in the text, therefore, should be taken only in the sense of physical replacement
in the aircraft. Whether replacement is to be with a new instrument, an exchange one, or
original instrument is to be repaired must be decided on basis of individual circumstances.

15-3.

INSTRUMENT PANEL.

15-4.

DESCRIPTION. The instrument panel assembly consists of a stationary (right side) and
shock-mounted (left side) panel. Beginning with 1983 models, the left side also contains a
stationary panel. The stationary panel contains engine, radio and flight hour recording instruments. The shock-mounted panel contains major flight-instruments such as horizontal
and directional gyros. Most of the instruments are screw-mounted on the panel backs.

15-5.

REMOVAL AND INSTALLATION. (See figure 15-1.) The stationary panel is secured to
engine mount stingers and a forward fuselage bulkhead and ordinarily is not considered
removable. The shock-mounted panel is secured to the stationary panel with rubber shockmounted assemblies. To remove shock-mounted panel proceed as follows:
a. Unscrew threaded buttons securing decorative cover and remove cover.
b. Remove nuts and washers from shock-mounts.
c. Tag and disconnect instrument wiring.
d. Disconnect plumbing and cap all open fittings and lines.
e. Pull.panel straight back to remove.

f. For installation reverse the preceding procedure. Ensure ground strap is properly
installed.

15-6.

SHOCK MOUNTS. Service life of instruments is directly related to adequate shockmounting of panel If removal of panel is necessary, check mounts for deterioration.

15-7.

INSTRUMENTS.

15-8.

REMOVAL. (See figure 15-.) Most instruments are secured to panel with screws inserted
through panel face. To remove an instrument, remove decorative cover, disconnect wiring
or plumbing to the instrument, remove mounting screws and take instrument out from
behind, or in some cases, from front of panel Instrument clusters are installed as units and
are secured by a screw at each end. A cluster must be removed from panel to replace an
individual gage. In all cases when an instrument is removed, disconnected lines or wires
should be protected. Cap open lines and cover pressure connections on instrument to
prevent thread damage and entrance of foreign matter. Wire terminals should be insulated or
tied up to prevent accidental grounding or short-circuiting.

15-2

MODEL 172 SERIES SERVICE MANUAL

3
4
9

NOTE POSITION OF GROUND
STRAP AND SEQUENCE OF
ATTACHING PARTS WHEN
REMOVING OR INSTALLING
SHOCK PANEL.

Detail A

1.
2.
3.
4.

Shock-Mounted Panel
Radio Panel
Heating and Ventilating Controls
Engine Controls

5.
6.
7.
8.

Detail B

Switch and Circuit Breaker Panel
Engine Instruments
Shock-Mount
Ground Strap

Figure 15-1.

9.
10.
11.
12.

Stud
Instrument Panel
Decorative Cover
Threaded Button

Typical Instrument Panel
15-3

MODEL 172 SERIES SERVICE MANUAL
15-9.

INSTALLATION. Generally, installation procedure is the reverse of removal procedure.
Ensure mounting screw nuts are tightened firmly, but do not over-tighten. particularly on
instruments having plastic cases. The same rule applies to connecting plumbing and
wiring.
NOTE
All instruments (gages and indicators), requiring a
thread seal or lubricant, shall be installed using teflon
tape on male fittings only. This tape is available through

Cessna Supply Division.
When replacing an electrical gage in an instrument cluster assembly. avoid bending pointer
or dial plate. Distortion of dial or back plate could change calibration of gages.
15-10.

PITOT AND STATIC SYSTEMS. (See figure 15-2.)

15-11.

DESCRIPTION. The pitot system conveys ram air pressure to the airspeed indicator. The
static system vents vertical speed indicator, altimeter and airspeed indicator to atmospheric pressure through plastic tubing connected to a static port. A static line sump is
installed at source button to collect condensation in static system. A pitot tube heater may be
installed. The hating element is controlled by a switch at instrument panel and powered by
the electrical system. An alternate static source valve may be installed in the static system
for use when the external static source is malfunctioning. Refer to the Pilot's Operating
Handbook for flight operation using the alternate static source.

15-12.

MAINTENANCE. Proper maintenance of pitot and static system is essential for proper
operation of altimeter, vertical speed and airspeed indicators. Leaks, moisture and obstructions in pitot system will result in false airspeed indications, while static system malfunctions will affect readings of all three instruments. Under instrument flight conditions, these
instrument errors could be hazardous. Cleanliness and security are the principal rules for
system maintenance. The pitot tube and static ports MUST be kept clean and unobstructed.

15-13.

STATIC PRESSURE SYSTEM INSPECTION AND LEAKAGE TEST. The following procedure outlines inspection and testing of static pressure system, assuming altimeter has been
tested and inspected in accordance with current Federal Aviation Regulations.
a. Ensure static system is free from entrapped moisture and restrictions.
b. Ensure no alterations or deformations of airframe surface have been made which
would affect the relationship between air pressure in static pressure system and true
ambient static air pressure for any flight configuration.
c. Close static pressure alternate source control, if installed.
d. Attach a source of suction to static pressure source opening. Figure 15-3 shows
method of obtaining suction.
e. Slowly apply suction until altimeter indicates a 1000-foot increase in altitude.

CAUTION
When applying or releasing suction, do not exceed range
of vertical speed indicator or airspeed indicator.

15-4

MODEL 172 SERIES SERVICE MANUAL
Cut off suction source to maintain a "closed" system for one minute. Leakage shall
not exceed 100 feet of altitude loss as indicated on altimeter.
g. If leakage rate is within tolerance, slowly release suction source.

NOTE
If leakage rate exceeds maximum

allowable, first tighten

all connections, then repeat leakage test. If leakage rate
still exceeds maximum allowable, use following procedure.
h. Disconnect static pressure lines from airspeed indicator and vertical speed indicator. Use suitable fittings to connect lines together so altimeter is the only instrument
still connected into static pressure system.
i. Repeat leakage test to check whether static pressure system or the bypassed
instruments are cause of leakage. If instruments are at fault, they must be repaired by
an "appropriately rated repair station" or replaced. If static pressure system is at
fault, use following procedure to locate leakage.
j. Attach a source of positive pressure to static source opening. Figure 15-3 shows one
method of obtaining positive pressure.
CAUTION
Do not apply positive pressure with airspeed indicator or
vertical speed indicator connected to static pressure
system.
k. Slowly apply positive pressure until altimeter indicates a 500-foot decrease in
altitude and maintain this altimeter indication while checking for leaks. Coat line:
connections and static source flange with solution of mild soap and water, watching
for bubbles to locate leaks.
1. Tighten leaking connections. Repair or replace parts found defective.
m. Reconnect airspeed and vertical speed indicators into static pressure system and
repeat leakage test per steps "c" thru "g".
15-14.

PITOT SYSTEM INSPECTION AND LEAKAGE TEST. To check pitot system for leaks,
place a piece of tape over small hole in lower aft end of pitot tube, fasten a piece of rubber or
plastic tubing over pitot tube, close opposite end of tubing and slowly roll up tube until
airspeed indicator registers in cruise range. Secure tube and after a few minutes recheck
airspeed indicator. Any leakage will have reduced the pressure in system, resulting in a
lower airspeed indication. Slowly unroll tubing before removing it, so pressure is reduced
gradually. Otherwise instrument may be damaged. If test reveals leak in system, check all
connections for tightness.

15-15.

BLOWING OUT LINES. Although pitot system is designed to drain down to pitot tube
opening, condensation may collect at other points in system and produce a partial
obstruction. To clear line, disconnect at airspeed indicator. Using low pressure air. blow
from indicator end of line toward pitot tube.

15-5

MODEL 172 SERIES SERVICE MANUAL
CAUTION
Never blow through pitot or static lines toward instruments.
Like pitot lines, static pressure lines must be kept clear and connections tight. All models
have a static source sump which collects moisture and keeps system clear. However. when
necessary. disconnect static line at first instrument to which it is connected, then blow line
clear with low-pressure air. Check all static pressure line connections for tightness. If hose
or hose connections are used, check for general condition and clamps for security. Replace
hose which cracked, hardened or show other signs of deterioration.
15-16.

REMOVAL AND INSTALLATION OF COMPONENTS. (See figure 15-2.) To remove pitot
mast remove four mounting screws on side of connector (13) and pull mast out of connector
far enough to disconnect pitot line (5). Electrical connections to heater assembly (if
installed) may be disconnected through wing access opening just inboard of mast. Pitot and
static lines are removed in the usual manner, after removing wing access plates, lower wing
fairing strip and upholstery as required. Installation of tubing will be simpler if a guide wire
is drawn in as tubing is removed from wing. The tubing may be removed from wing. The
tubing may be removed intact by drawing it out through cabin and right door. Tighten
connections firmly but avoid overtightening and distorting fittings. It twisting of plastic
tubing is encountered when tightening fittings, VV-P-236 (USP Petrolatum). may be applied
sparingly between tubing and fittings.

15-17.

ENCODING ALTIMETER.

15-18.

DESCRIPTION. An encoding altimeter may be installed which is also connected to static
system pressure. The encoding altimeter supplies coded altitude signals to the aircraft's
transponder for transmission to ground based interrogating radar. The encoding altimeter
installation requires the use of a fully operational secondary altimeter as backup.

15-19.

REMOVAL AND INSTALLATION. Figure 15-2, sheet 2 may be used as a guide for removal
and installation of the encoding altimeter.

15-20.

TROUBLE SHOOTING -- PITOT STATIC SYSTEM.
TROUBLE

LOW OR SLUGGISH AIRSPEED INDICATION. (Normal altimeter and vertical

PROBABLE CAUSE
Pitot tube obstructed, leak
or obstruction in pitot line.

speed.)
INCORRECT OR SLUGGISH
RESPONSE. (All three
instruments.)

15-6

REMEDY
Test pitot tube and line for
leaks or obstructions. Blow
out tube and line. repair

or replace damaged line.
Leaks or obstruction in
static line.

Test line for leaks and obstructions. Repair or replace
line, blow out obstructed line.

MODEL 172 SERIES SERVICE MANUAL

INSTALLATION

Detail

HEATED

Detail E

WITHOUT ALTERNATE

E
Detail

Detail C

Vertical Speed Indicator
1.
3. Altimeter
3.Shock-Mounted Panel
4.

Airspeed Indicator

5. Pitot Line
7.
8.
9.
10.

Mounting Screw
Cover
Retainer
True Airspeed Ring

STATIC

WITH ALTERNATE
STATIC SOURCE
11. Instrument Panel
12. Spacer
13. Connector

SOURCE

NOTE
Do not overtighten screws (7)
and do not lubricate any parts.

Mast Body

Use spacers (12) as required
for adequate friction on ring

15. Heater Element
Valve
16.
17. Knob

THRU 17276468 AND

18. Insert
20.
21.
22.
31.

Static Sump (Plastic)
Flange
Static Port
Statc Sump (Metal)

Figure 15-2.

F17202233
*

BEGINNING WTTH 17276469
AND F17202234

Pitot Static Systems (Sheet 1 of 2)
15-7

MODEL 172 SERIES SERVICE MANUAL

ENCODING ALTIMETER INSTALLATION

Detail F

23.
24.
25.
26.
27.
28.
29.
30.

Backup Altimeter
Vertical Speed Indicator
Encoding Altimeter
Static Line
Airspeed Indicator
Pttot Line
Static Line
Cable (to Transponder)

Figure 15-2. Pttot Static Systems (Sheet 2 of 2)
15-8

MODEL 172 SERIES SERVICE MANUAL
15-21.

TRUE AIRSPEED INDICATOR.

15-22.

DESCRIPTION. The true airspeed indicator is equipped with a conversion ring, which may
be rotated until pressure altitude is aligned with outside air temperature. then airspeed
indicated on the instrument is read as true airspeed on the adjustable ring.

15-23.

REMOVAL AND INSTALLATION. (See figure 15-2.) Upon installation, before tightening
mounting screws (7), calibrate instrument as follows: Rotate ring (10) until 105 knots on the
adjustment ring aligns with 105 knots on the indicator. Holding this setting, move retainer
(9) until 60°F aligns with zero pressure altitude, then tighten mounting screws (7) and
replace decorative cover (8).

15-24.

TROUBLE SHOOTING -- AIRSPEED INDICATOR.
TROUBLE

HAND FAILS TO RESPOND.

INCORRECT INDICATION
OR HAND OSCILLATES.

HAND VIBRATES.

PROBABLE CAUSE

REMEDY

Pitot pressure connection
not properly connected to
pressure line from pitot
tube.

Test line and connection for
leaks. Repair or replace damaged line, tighten connections.

Pitot or static lines clogged.

Check line for obstructions.
Blow out lines.

Leak in pitot or static lines.

Test lines and connections
for leaks. Repair or replace
damaged lines, tighten connections.

Defective mechanism or
leaking diaphragm.

Substitute known good indicator and check reading. Replace instrument.

Excessive vibration.

Check panel shock mounts.
Replace defective shock
mounts.

Excessive tubing vibration.

Check clamps and line connections for security. Tighten
clamps and connections. replace tubing with flexible hose.

15-9

MODEL 172 SERIES SERVICE MANUAL
NOTE
Air bulb with check valves may be obtained
locally from a surgical supply company. This
is the type used in measuring blood pressure.

THICK-WALLED
SURGICAL HOSE

PRESSURE

PRESSURE BLEED-OFF
SCREW (CLOSED)
AIR BULB
WITH CHECK
VALVES
CLAMP
THICK-WALLED
SURGICAL HOSE-

CLAMP

CHECK VALVE

SUCTION

CHECK VALVE

TO APPLY SUCTION:
1.

Squeeze air bulb to expel as much air as possible.

Hold suction hose firmly against static pressure source opening.

Slowly release air bulb to obtain desired suction, then pinch hose shut tightly to trap suction in
system.

After leak test, release suction slowly by intermittently allowing a small amount of air to enter
static system. To do this, tilt end of suction hose away from opening, then immediately tilt it
back against opening. Wait until vertical speed indicator approaches zero, then repeat. Continue to admit this small amount of air intermittently until all suction is released, then remove
test equipment.

TO APPLY PRESSURE:

CAUTION
Do not apply positive pressure with airspeed indicator or vertical speed
indicator connected into static system.
1.

Hold pressure hose firmly against static pressure source opening.

Slowly squeeze air bulb to apply desired pressure to static system. Desired pressure may be
maintained by repeatedly squeezing bulb to replace any air escaping through leaks.

Release pressure by slowly opening pressure bleed-off screw, then remove test equipment.
Figure 15-3.

15-10

Static Test Equipment

MODEL 172 SERIES SERVICE MANUAL
15-25.

TROUBLE SHOOTING -- ALTIMETER.
TROUBLE

INSTRUMENT FAILS TO
OPERATE.

INCORRECT INDICATION.

HAND OSCILLATES.

PROBABLE CAUSE

REMEDY

Static line plugged.

Check line for obstructions.
Blow out lines.

Defective mechanism.

Substitute known-good altimeter and check reading.
Replace instrument.

Hands not carefully set

Reset hands with knob.

Leaking diaphragm.

Substitute known-good altimeter and check reading.
Replace instrument.

Pointers out of calibration.

Compare reading with knowngood altimeter. Replace
instrument.

Static pressure irregular.

Check lines for obstruction
or leaks. Blow out lines.
tighten connections.

Leak in airspeed or vertical
speed indicator installations.

Check other instruments and
system plumbing for leaks. Blow out lines, tighten connections.

15-11

MODEL 172 SERIES SERVICE MANUAL
15-26.

TROUBLE SHOOTING -- VERTICAL SPEED INDICATOR.
TROUBLE

INSTRUMENT FAILS TO
OPERATE.

INCORRECT INDICATION.

POINTER OSCILLATES.

HAND VIBRATES.

15-27.

15-12

Deleted.

PROBABLE CAUSE

REMEDY

Static line plugged.

Check line for obstructions.
Blow out lines.

Static line broken.

Check line for damage. connections for security. Repair or replace damaged line.
tighten connections.

Partially plugged static line.

Check line for obstructions.
Blow out lines.

Ruptured diaphragm.

Substitute known-good indicator and check reading.
Replace instrument.

Pointer off zero.

Reset pointer to zero.

Partially plugged static line.

Check line for obstructions.
Blow out lines.

Leak in static line.

Test lines and connections
for leaks. Repair or replace damaged lines.
tighten connections.

Leak in instrument case.

Substitute know-good indicator and check reading.
Replace instrument.

Excessive vibration.

Check shock mounts. Replace
defective shock mounts.

Defective diaphragm.

Substitute known-good indicator and check for vibration.
Replace instrument.

MODEL 172 SERIES SERVICE MANUAL
15-28.

VACUUM SYSTEM.

15-29.

DESCRIPTION. Suction to operate the gyros is provided by a dry-type engine-driven
vacuum pump, gear-driven through a spline-type coupling. A suction relief valve, to control
system pressure, is connected between the pump inlet and instruments In the cabin. the
vacuum line is routed from gyro instruments to the relief valve at the firewall. A throw away
type central air filtering unit is installed. The reading of the suction gage indicates net
difference in suction before and after air passes through a gyro. This differential pressure
will gradually decrease as the central air filter becomes dirty, causing a lower reading on the
suction gage.
NOTE
Excessive smoking will cause premature filter clogging.

15-30.

TROUBLE SHOOTING -- VACUUM SYSTEM.
TROUBLE

PROBABLE CAUSE

REMEDY

HIGH SUCTION GAGE
READINGS.

Gyros function normallyrelief valve screen clogged,
relief valve malfunction.

Check screen, then valve.
Compare gage readings with
new gage. Clean screen.
reset valve. Replace gage.

NORMAL SUCTION GAGE
READING, SLUGGISH OR
ERRATIC GYRO RESPONSE.

Instrument air filters
clogged.

Check filter. Replace if
required

LOW SUCTION GAGE
READINGS.

Leaks or restriction between
instruments and relief valve,
relief valve out of adjustment, defective pump.

Check lines for leaks. disconnect and test pump.
Repair or replace lines,
adjust or replace relief valve,
repair or replace pump.

Central air filter dirty.

Check filter. Replace if
required.

Defective gage or sticking
relief valve.

Check suction with test gage.
Replace gage. Clean sticking
valve with Stoddard solvent
Blow dry and test. If valve
sticks after cleaning, replace valve.

SUCTION GAGE
FLUCTUATES.

15-13

MODEL 172 SERIES SERVICE MANUAL
15-31.

TROUBLE SHOOTING -- GYROS.
TROUBLE

HORIZON BAR OSCILLATES OR VIBRATES
EXCESSIVELY.

REMEDY

PROBABLE CAUSE
Central filter dirty.

Check filter. Replace if
required.

Suction relief valve improperly adjusted.

Adjust or replace relief
valve.

Faulty suction gage.

Substitute known-good
suction gage and check gyro
indication. Replace suction

gage.

EXCESSIVE DRIFT IN
EITHER DIRECTION.

DIAL SPINS IN ONE
DIRECTION CONTINUOUSLY.

15-14

Defective mechanism.

Substitute known-good gyro
and check indication.
Replace instrument.

Excessive vibration.

Check panel shock-mounts.
Replace defective shockmounts.

Central air filter dirty.

Check filter. Replace if
required

Low vacuum, relief valve
improperly adjusted.

Adjust or replace relief
valve.

Faulty suction gage.

Substitute known-good
suction gage and check gyro
indication. Replace suction
gage.

Vacuum pump failure.

Check pump. Replace pump.

Vacuum line kinked or
leaking.

Check lines for damage and
leaks. Repair or replace
damaged lines, tighten
connections.

Operating limits have been
exceeded

Replace instrument.

Defective mechanism.

Substitute known-good gyro
and check indication. Replace instrument.

MODEL 172 SERIES SERVICE MANUAL
15-31.

TROUBLE SHOOTING -- GYROS. (Cont).
TROUBLE

HORIZON BAR FAILS TO

Central filter dirty.

Check filter. Replace if

required.

RESPOND.

HORIZON BAR DOES NOT
SETTLE.

15-32.

REMEDY

PROBABLE CAUSE

Suction relief valve improp-

Adjust or replace relief

erly adjusted.

valve.

Faulty suction gage.

Substitute known-good suction
gage and check gyro response.
Replace suction gage.

Vacuum pump failure.

Check pump. Replace pump.

Vacuum line kinked or
leaking.

Check lines for damage and
leaks. Repair or replace damaged lines, tighten connections.

Defective mechanism.

Substitute known-good gyro
and check indication.
Replace instrument.

Insufficient vacuum.

Adjust or replace relief
valve.

Excessive vibration.

Check panel shock-mounts.
Replace defective shock-mounts.

TROUBLE SHOOTING -- VACUUM PUMP.
TROUBLE

PROBABLE CAUSE

REMEDY

OIL IN DISCHARGE.

Damaged engine drive seal.

Replace gasket.

HIGH SUCTION.

Suction relief valve filter
clogged.

Check filter for obstructions.
Clean or replace filter.

LOW SUCTION.

Relief valve leaking.

Replace relief valve.

Vacuum pump failure.

Substitute known-good pump
and check pump suction.
Replace vacuum pump.

Safety valve leaking.

Replace safety valve.

Vacuum pump failure.

Substitute known-good pump
and check pump pressure.
Replace vacuum pump.

LOW PRESSURE.

15-15

MODEL 172 SERIES SERVICE MANUAL

BEGINNING WITH

17267749

*THRU 17267748

2. Overboard Vent Tube

3.
4.
5.
6.

Firewall
Bracket
Filter Assembly
Gyro Horizon

Directional Gyro

8. Suction Gage

THRU 17274199
and F1722039

9. Suction Relief Valve
10. Firewall
Figure 15-4.

15-16

Vacuum System (Sheet 1 of 2)

MODEL 172 SERIES SERVICE MANUAL

BEGINNING WITH

2. Overboard Vent Tube
3. Firewall
5. Filter Assembly
6.

7.
8.
9.
10.
1.
12.
13.
14.

SERIAL
--

17274200 AND ON
F17202040 AND ON

Gyro Horizon

Directional Gyro
Suction Gage
Suction Relief Valve
Firewall
Low Vacuum Light
Pressure Switch
Overboard Vent Hose
Cover

* SERIAL 17275834 AND ON
F17202195 AND ON

BEGINNING WITH
17276193

Figure 15-4. Vacuum System (Sheet 2 of 2).
15-17

MODEL 172 SERIES SERVICE MANUAL
15-33.

MAINTENANCE PRACTICES.
CAUTION
When replacing a vacuum system component, ensure all
connections are made correctly to avoid damage to gyro
system When a component is removed. cap off and identify all open lines, hoses, and fittings to prevent dirt from
entering system and to ensure proper reinstallation.
Upon component replacement check all hoses carefully
to be sure they are clean and free of debris, oil, solvent.

collapsed inner liners, and external damage. Replace old.
hard cracked, or brittle hoses. particularly on pump
inlet, to avoid possible pump damage. On vacuum pump.
where hose clearance is tight, making it difficult to
reinstall hoses, apply a light film of petrolatum to the fitting. Install hoses by pushing them straight on, and do
not wiggle hoses from side to side as this could cause
particles to be out from inside of hose, allowing particles
to enter system.
CAUTION
Do not use teflon tape, pipe dope, or thread lubricants of
any type on fitting threads, and avoid over-tightening of
connections. All filters in vacuum system must be

changed when intalling a new pump. Failure to do so
will void pump warranty. DO NOT CONNECT A PUMP
BACKWARDS. Since the manifold check valves provide
no pressure relief, the pump will be destroyed within a
matter of seconds after starting the engine.
15-33A. REMOVAL OF VACUUM PUMP.
a. Remove upper engine cowling in accordance with procedures in Section 11.
b. Disconnect, cap off and identify hose on inlet side of vacuum pump.
c. Identify and disconnect hose on outlet side of vacuum pump.
d. Remove nuts, lockwashers, and flat washers securing vacuum pump to engine.
e. Remove vacuum pump from mounting studs on engine.
f. Remove elbow from pump and retain if it is reusable.
NOTE
Discard any twisted fittings or nuts with rounded corners.
15-33B. MOUNTING PAD INSPECTION.
a. Check condition of the AND 20000 pad seal. If the seal shows any signs of oil leakage, replace the seal.

MODEL 172 SERIES SERVICE MANUAL
15-33C. INSTALLATION OF VACUUM PUMP.
a. Before installing a new vacuum pump, purge all lines in system to remove carbon
particles or other pump components that may have been deposited in lines by previous pump.
NOTE
Before installing vacuum pump an engine, ensure that
mating surfaces are clean and free of any old gasket material.
b.

Consult the applicable Parts Catalog, the pump vendor's application list, or the PMA
label on pump box to verify that the pump is the correct model for the engine and/or
system.
Position vacuum pump in a jaw-protected vise, with drive coupling downward.
CAUTION

The pump housing should never be placed directly in a
vise, since clamping across center housing will cause an
internal failure of carbon rotor. Protect pump mounting
flange with soft metal or wood. NEVER install a vacuum
pump that has been dropped.
d.

Install elbow in pump; hand-tighten only.
NOTE
Do not use teflon tape, pipe dope, or thread lubricants of
any type, and avoid over-tightening of connections.
NOTE
Use only a box wrench to tighten fittings to desired position. Do not make more than one and one half (1 1/2)
turns beyond hand-tighten position.

e.
f.
g.

Position new mounting pad gasket on mounting studs on engine.
Position vacuum pump on mounting studs.
Secure pump to engine with flat washers, new lockwashers. and nuts.
CAUTION

Always replace all lockwashers with new ones when installing a new vacuum pump. Tighten all four mounting
nuts (4) to 50 to 70 pound-inches.
h.
i.

Connect hose to inlet side of vacuum pump.
Install upper engine cowling in accordance with procedures in Section 11.

15-19

MODEL 172 SERIES SERVICE MANUAL
15-34.

CLEANING. In general. low-pressure, dry compressed air should be used in cleaning vacuum system components. Suction relief valve, exposed to engine oil and dirt, should be replaced. Check hose for collapsed inner liners as well as external damage.
CAUTION
Never apply compressed air to lines or components installed in aircraft. The excessive pressures will damage
gyros. If an obstructed line is to be blown out, disconnect
at both ends and blow from instrument panel out.

15-34A. LOW-VACUUM WARNING LIGHT. A red low-vacuum light is installed on the instrument
panel. The light is controlled by a vacuum switch mounted on the back of the gyro horizon.
The switch contacts are normally closed. The light may be checked by turning ON the master switch. With the engine running, the light should illuminate when the vacuum drops
below 3 ± .5 inches Hg.
15-35.

VACUUM RELIEF VALVE ADJUSTMENT. A suction gage reading of 5.3 inches of mercury
is desirable for gyro instruments. However, a range of 4.5 to 5.4 inches of mercury is acceptable. To adjust the relief valve, remove central air filter, run engine to 2200 rpm on the
ground and adjust relief valve to 5.3 ± .1 inches of mercury.
CAUTION
Do not exceed maximum engine temperature.
Be sure filter element is clean before installing. If reading drops noticeably, install new filter
element.

15-35A. STANDBY VACUUM SYSTEM.
5-35B. DESCRIPTION. A standby vacuum system may be installed in the airplane. The system consists of an electric motor driven vacuum pump and associated hoses mounted on the aft side
of the firewall. One hose is the vacuum pump vent hose and the other connects to a manifold
with the engine-driven vacuum pump, just prior to the system relief valve. A two-position
circuit breaker switch, mounted adjacent to the master switch on the instrument panel, controls and protects the system.

15-20

MODEL 172 SERIES SERVICE MANUAL

Circuit Breaker Switch

Instrument Panel

Detail

Figure 15-4A. Standby Vacuum System (Sheet

of 2)

15-20A

MODEL 172 SERIES SERVICE MANUAL

Relief Valve

3.
3.

Hose
Gyro Horizon)
Hose (to
(to Directional
Gyro)

Nut

r3
o

toM
.1

11.
12.

Fittings
Ground Wire

14.
15.
16.

Washer
Bolt
Bracket

17.
18.
19.
20.
21.
22.

Voltage
Input Wire
Washer
Nut
Pump
Vaccuum
Hose
Manifo l d

23.

Firewall
Figure 15-4A. Standby Vacuum System (Sheet 2 of 2)

15-20B

MODEL 172 SERIES SERVICE MANUAL
15-35C. TROUBLE SHOOTING - STANDBY VACUUM SYSTEM.
TROUBLE
NO SUCTION GAGE
READING.

PROBABLE CAUSE
Circuit breaker switch
has opened.

REMEDY
Reset circuit breaker switch.
If switch reopens, check wire
from switch to bus bar for

short. Repair or replace wire.

LOW SUCTION GAGE
READING.

Defective motor.

Check voltage input wire and
ground wire. Repair or replace wires.

Defective pump.

Check pump operation. Replace
pump.

Leak or restriction
between pump and
suction gage.

Check hoses and connections
for leaks and obsuctions. Install new clamps at connection.
clear or replace hoses.

Relief valve not

Adjust relief valve.

properly adjusted.
Defective pump.

Check pump. Replace pump.

Central air filter
dirty.

Replace central air filter.

15-35D. REMOVAL. (See figure 15-4A.)
a. Release clamps securing hoses (7) and (8) to pump (20).
b. Cap hoses (7), (8) and pump fittings (11) so dirt cannot enter system.
c. Make sure circuit breaker switch (1) and battery switch are off.
d. Disconnect motor voltage input wire (17) and ground wire (12).
e. Remove safety from bolts (15).
f. Support pump and motor assembly and remove bolts (15) and washers (14).
g. If pump is to be removed from motor, remove nuts (19) and washers (18).

15-20C

MODEL 172 SERIES SERVICE MANUAL
15-35E. INSTALLATION. (See figure 15-4A.)
a. If removed, install pump (20) on motor (13) drive studs and install washers (18) and
nuts (19).

b.
c.
d.
e.
f.

Position pump and motor assembly up against bracket (16) and install washers (14)
and bolts (15).
Safety-wire bolts (15).
Connect motor voltage input wire (17) and ground wire (12).
Remove caps from hoses (7), (8). and fittings (11) then install hoses and clamps.
Turn on battery switch and circuit breaker switch (1) then check suction gage to see
that system is operating properly. Then turn off switches.
CAUTION
Check that voltage input wire (17) is not pushed down
into motor as it could become entangled with the armature, locking it.

15-36.

ENGINE INDICATORS.

15-37.

TACHOMETER.

15-38.

DESCRIPTION. The tachometer used on Cessna single-engine aircraft is a mechanical
indicator driven at half crankshaft speed by a flexible shaft. Most tachometer difficulties
will be found in the drive-shaft. To function properly, shaft housing must be free of kinks,
dents and sharp bends. There should be no bend on a radius shorter than six inches and no
bend within three inches of either terminal. If a tachometer is noisy or pointer oscillates.
check cable housing for kinks, sharp bends and damage. Disconnect cable at tachometer and
pull it out of housing. Check cable for worn spots, breaks and kinks.

15-20D

Revision 1

MODEL 172 SERIES SERVICE MANUAL

NOTE
Before replacing a tachometer cable in housing, coat
lower two thirds with AC Type ST-640 speedometer cable
grease or Lubriplate No. 110. Insert cable in housing as
far as possible, then slowly rotate to make sure it is
seated in engine fitting. Insert cable in tachometer,
making sure it is seated in drive shaft then reconnect
housing and hand tighten then torque 1/4 turn
15-39.

OIL PRESSURE GAGE.

15-40.

DESCIPTION. The Bourdon tube-type oil pressure gage is a direct-reading instrument, operated by a pressure pickup line connected to the engine main oil gallery at the rear of the
engine below the engine mount. The oil pressure line on 1984 and On and all aircraft
equipped with a 0509087 Modification Kit, is located at the front of the engine near the
upper right corner. The oil pressure line from the instrument to the engine should be filed
with kerosene, especially during cold weather operation to attain an immediate oil indication.

15-41.

TROUBLE SHOOTING.
TROUBLE

GAGE DOES NOT
REGISTER.

GAGE POINTER FAILS
TO RETURN TO ZERO.

GAGE DOES NOT REGIS-

PROBABLE CAUSE

REMEDY

Pressure line clogged.

Check line for obstructions.
Clean line.

Pressure line broken.

Check line for leaks and
damage. Repair or replace
damaged line.

Fractured Bourdon tube.

Replace instrument

Gage pointer loose on staff.

Replace instrument.

Damaged gage movement

Replace instrument

Foreign matter in line.

Check line for obstructions.
Clean line.

Foreign matter in Bourdon
tube.

Replace instrument

Bourdon tube stretched.

Replace instrument

Faulty mechanism.

Replace instrument

TER PROPERLY.

15-21

MODEL 172 SERIES SERVICE MANUAL
15-41.

TROUBLE SHOOTING (Cont).
TROUBLE

GAGE HAS ERRATIC
OPERATION.

PROBABLE CAUSE

REMEDY

Worn or bent movement.

Replace instrument.

Foreign matter in Bourdon
tube.

Replace instrument.

Dirty or corroded movement

Replace instrument.

Pointer bent and rubbing on
dial, dial screw or glass.

Replace instrument.

Leak in pressure line.

Check line for leaks and
damage. Repair or replace
damaged line.

15-42.

OIL TEMPERATURE GAGE.

15-43.

DESCRIPTION. The oil temperature gage is an electrically operated indicator mounted in the instrument cluster with the oil pressure gage. One electrical lead is routed from the indicator to the sending
unit installed in the engine. The other lead supplies power from the bus bar to the indicator. Refer to
Table 1 on page 15-26A when trouble shooting the oil temperature gage.

15-43A.

CYLINDER HEAD TEMPERATURE GAGE.

15-43B.

DESCRIPTION. The temperature sending unit regulates electrical power through the cylinder head
temperature gage. The gage and sending unit require little or no maintenance other than cleaning,
making sure lead is properly supported and all connections are clean, tight and properly insulated.
Rochester gages are connected the same as the Stewart Warner gages, but the Rochester gages do not
have the calibration pot and are not adjustable. Refer to Table 2 on page 15-26B when trouble shooting the cylinder head temperature gage.

15-44.

CARBURETOR AIR TEMPERATURE GAGE.

15-45.

DESCRIPTION. The carburetor air temperature gage is a resistance bridge type. Changes in electrical resistance of the element are indicated by the gage, calibrated for temperature. The system requires power from the airplane electrical system and operates only when the master switch is on. Although both instrument and sending unit are grounded, two leads are used to avoid possibility of instrument error induced by poor electrical bonds in the air frame

15-46.

TROUBLE SHOOTING - CARBURETOR AIR TEMPERATURE GAGE.
TROUBLE

GAGE POINTER STAYS OFF
LOW END OF SCALE.

15-22

Revision 3

PROBABLE CAUSE

REMEDY

Open circuit breaker.

Reset breaker..

Master switch "OFF" or
switch defective. -

Check switch "ON". Replace
defective switch.

Broken or grounded leads
between gage and sending
unit.

Repair or replace defective
wiring.

MODEL 172 SERIES SERVICE MANUAL
15-46.

TROUBLE SHOOTING -- CARBURETOR AIR TEMPERATURE GAGE (Cont).

TROUBLE
GAGE POINTER GOES OFF
HIGH END OF SCALE.

PROBABLE CAUSE

REMEDY

Broken or grounded lead.

Repair or replace defective
wiring.

Defective gage or sensing
unit.

Replace gage or sensing
unit.

Defective master switch.
broken or grounded lead.

Replace switch, repair or
replace defective wiring.

Defective gage or sensing
unit.

Replace gage or sensing
unit.

Loose or broken lead.

Repair or replace defective
wiring.

Defective gage or sensing
unit.

Replace gage or sensing
unit.

Excessive panel vibration.

Tighten panel mounting
screws.

OBVIOUSLY INCORRECT
TEMPERATURE READING.

Defective gage or sensing
unit.

Replace gage or sensing
unit.

POINTER FAILS TO GO
OFF SCALE WITH
CURRENT OFF.

Defective master switch.

Replace switch.

Defective gage.

Replace gage.

GAGE OPERATES INTERMTTTENTLY.

EXCESSIVE POINTER
OSCILLATION.

15-46A. ECONOMY MIXTURE INDICATOR (EGT) (BEGINNING WITH 1979 MODELS.)
15-46B. DESCRIPTION. The economy mixture indicator is an exhaust gas temperature (EGT)
sensing device which is used to aid the pilot in selecting the most desirable fuel-air mixture
for cruising flight at less than 75% power. Exhaust gas temperature (EGT) varies with ratio
of fuel-to-air mixture entering the engine cylinders. Refer to the Pilot's Operating Handbook
for operating procedure of the system.
15-46C. CALIBRATION. A potentiometer adjustment screw is provided behind the plastic cap at the
back of the instrument for calibration. This adjustment screw is used to position the pointer
over the reference increment line (4/5 of scale) at peak EGT. Establish 75% power in level
flight, then carefully lean the mixture to peak EGT. After the pointer has peaked. using the
adjustment screw. position pointer over reference increment line (4/5 scale).

15-23

MODEL 172 SERIES SERVICE MANUAL

A
Detail A

1.
2.
3.
4.
5.
6.
7.

15-4A. Economy Mixture Indicating System E.G.T.
15-24

Probe
Panel Cover
Screw
Instrument Panel
Indicator
Lockwasher
Nut

MODEL 172 SERIES SERVICE MANUAL
NOTE
This setting will provide selective temperature indications for normal cruise power settings within range of the
instrument.
Turning the screw clockwise increases the meter reading and counterclockwise decreases
the meter reading. There is a stop in each direction and damage can occur if too much torque
is applied against stops. Approximately 600°F total adjustment is provided. The adjustable
yellow pointer on the face of the instrument is a reference pointer only.
15-46D. REMOVAL AND INSTALLATION. (See figure 15-4A.)
a. Indicator.
1. Remove instrument panel decorative cover.
2. Disconnect EGT indicator leads.
3. Remove screws, nuts and washers securing indicator and remove indicator.
4. To install reverse the preceding steps.
b. Probe.
1. Disconnect probe leads.
2. Remove clamp and probe assembly.
3. When installing probe, tighten clamp to 30-35 lb-in.
4. Coil or fold excess lead and tie in a covenient out of the way location.
15-46E. TROUBLE SHOOTING.
TROUBLE

PROBABLE CAUSE

REMEDY

GAGE INOPERATIVE

Defective gage, probe or
circuit.

Repair or replace defective
part.

INCORRECT READING

Indicator needs calibrating.

Calibrate indicator in accordance with paragraph 15-46C.

FLUCTUATING READING

Loose, frayed or broken
lead, permitting alternate
make and break of circuit.

Tighten connection and
repair or replace defective leads.

15-47.

FUEL QUANTITY INDICATING SYSTEM.

15-48.

DESCRIPTION. The magnetic type fuel quantity indicators are used in conjunction with a
float-operated variable-resistance transmitter in each fuel tank. The full position of float
produces a minimum resistance through transmitter. permitting maximum current flow
through the fuel quantity indicator and maximum pointer deflection. As fuel level is
lowered, resistance in the transmitter is increased, producing a decreased current flow
through fuel quantity indicator and a smaller pointer deflection.

15-49.

REMOVAL AND INSTALLATION OF FUEL QUANTITY TRANSMITTER.
a. Drain fuel from tank. (Observe precautions in Section 12.)
b. Remove access plate above fuel tank for access to transmitter.
c. Disconnect electrical lead and ground strap from transmitter.
d. Remove screws attaching transmitter and carefully work transmitter from tank. DO
NOT BEND FLOAT ARM.

15-25

MODEL 172 SERIES SERVICE MANUAL
e.
f.

Install transmitter by reversing preceding steps, using new gaskets around opening
in fuel tank and under screw heads. Be sure to righten screws evenly.
Service fuel tanks. Check for leaks and correct quantity indication.
NOTE
Ensure transmitter is properly grounded in accordance
with Section 12.

15-50.

TROUBLE SHOOTING.
TROUBLE

FAILURE TO INDICATE.

OFF CALIBRATION.

PROBABLE CAUSE
No power to indicator or
transmitter. (Pointer stays
below E.)

Check fuse and inspect for
open circuit Replace fuse.
repair or replace defective
wire.

Grounded wire. (Pointer
stays above F.)

Check for partial ground between transmitter and gage.
Repair or replace defective
wire.

Low voltage.

Check voltage at indicator.
Correct voltage.

Defective indicator.

Substitute known-good indicator. Replace indicator.

Defective indicator.

Substitute known-good indicator. Replace indicator.
Substitute known-good transmitter. Recalibrate or replace.

Defective transmitter.

STICKY OR SLUGGISH
INDICATOR OPERATION.

ERRATIC READINGS.

15-26

REMEDY

Low or high voltage.

Check voltage at indicator.
Correct voltage.

Defective indicator.

Substitute known-good indicator. Replace indicator.

Low voltage.

Check voltage at indicator.
Correct voltage.

Loose or broken wiring on
indicator or transmitter.

Inspect circuit wiring. Repair
or replace defective wire.

Defective indicator or transmitter.

Substitute known-good component. Replace indicator or
transmitter.

Defective master switch.

Replace switch.

MODEL 172 SERIES SERVICE MANUAL
15-51.

TRANSMITTER ADJUSTMENT.
WARNING
Using the following fuel transmitter calibration procedure on components other than the originally installed (Stewart Warner) components
will result in a faulty fuel quantity reading.

15-51A.

STEWART WARNER GAGE TRANSMITTER CALIBRATION. Chances of transmitter calibration
changing in normal service is remote; however, it is possible that float arm or float arm stops may become bent if transmitter is removed from cell. Transmitter calibration is obtained by adjusting float
travel. Float travel is limited by float arm stops.
WARNING
Use extreme caution while working with electrical components of the
fuel system. The possibility of electrical sparks around an "empty" fuel
cell creates a hazardous situation.
Before installing transmitter, attach electrical wires and place master switch in "ON" position. Allow
float arm to rest against lower float arm stop and read indicator. The pointer should be on E (empty)
position. Adjust the float arm against lower stop so pointer indicator is on E. Raise float until arm is
against upper stop and adjust upper stop to permit indicator pointer to be on F (full). Install transmitter in accordance with paragraph 15-49.

15-51B.

ROCHESTER GAGE TRANSMITTER. Do not attempt to adjust float arm or stop. No adjustment is
allowed.
Table 1
NOTE
Select the oil temperature sending unit part number from the left column and the temperature from the column headings. Read the ohms
value under the appropriate temperature column.

72°F

120°F

165°F

250°F

220°F

Part Number

Type

S1630-1

Oil Temp

S1630-3

Oil Temp

620.0

52.4

S1630-4

Oil Temp

620.0

52.4

S1630-5

Oil Temp

S2335-1

Oil Temp

46.4

192.0
990.0

34.0

15-26A

Revision 3

MODEL 172 SERIES SERVICE MANUAL

Table 2

NOTE
Select the cylinder head temperature sending unit part number that is
used in your aircraft from the left column and the temperature from the
column headings. Read the ohms value under the appropriate temperature column.

475°F

220°F

450°F

CHT

310.0

34.8

S1372-2

CHT

310.0

34.8

S1372-3

CHT

113.0

S1372-4

CHT

113.0

S2334-3

CHT

745.0

38.0

S2334-4

CHT

745.0

38.0

Part Number

Type

S1372-1

15-26B

Revision 3

200°F

MODEL 172 SERIES SERVICE MANUAL
15-51.

TRANSMITTER ADJUSTMENT.
(Refer to page 15-26A.)

15-52.

HOURMETER. (See figure 15-5.)

15-53.

DESCRIPTION. The hourmeter is electrically operated and is actuated by a pressure switch in the oil
pressure system. Electrical power is supplied through a one-amp fuse from the electrical clock circuit,
and therefore, will operate independent of the master switch. If no clock is installed, a line direct from
the battery contactor provides power independent of the master switch through a one-amp fuse located
adjacent to the battery box. An indicator on the dial face rotates when the meter is actuated. If the meter is inoperative and the clock is operating, the meter or its wiring is faulty and must be replaced.
NOTE
When installing the hourmeter, the positive (red) wire must be connected to the white (+) terminal. Connecting wires incorrectly will
damage the meter.

15-54.

MAGNETIC COMPASS.

15-55.

DESCRIPTION. The magnetic compass is liquid-filled, with expansion provisions to compensate for
temperature changes. It is equipped with compensating magnets adjustable from the front of the case.
The compass is internally lighted, controlled by the panel lights rheostat. No maintenance is required
on the compass except for a check on a compass rose each 200 hours for adjustment.

Revision 3

15-27

MODEL 172 SERIES SERVICE MANUAL

6
1.
2.
3.
4.
5.
..
7.
8.
9.
10.
11.
12.

Doorpost Cover
Horn Assembly
Scoop
Adapter
Felt Seal
Adjustable Plate
Screen
Compass
Compass Card
Bracket
Hourmeter
Adapter

13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Pressure Switch
Positive Wire
Ground Wire
Wire from Clock
Circuit
O.A.T. Gage
Rubber Washer
Knob
Air Vent
Washer
Plastic Washer
Nut

Detail

NOTE
Bug screen (7) should be inspected
and cleaned periodically.

Figure 15-5. Miscellaneous Instruments and Stall Warning System
15-28

MODEL 172 SERIES SERVICE MANUAL
15-56.

REMOVAL AND INSTALLATION. See figure 15-5 for removal and installation.

15-57.

STALL WARNING SYSTEM.

15-58.

DESCRIPTION. The system is composed of an adjustable plate on left wing leading edge,
connected to a reed type horn by means of plastic tubing. The horn is actuated approximately 5 to 10 knots above stalling speed as a negative air pressure area at wing leading
edge causes a reverse flow of air through horn. By moving adjustable plate (6) up, actuation
of horn will occur at a higher speed and moving plate down causes actuation to occur at a
slower speed. Center adjustable plate opening in wing leading edge upon installation, then
flight test aircraft, observing horn actuation during stall. Readjust plate to obtain desired
results if necessary. Approximatley 3/32 inch adjustment of plate will change speed at
which horn actuation occurs by 5 knots. To test horn operation, cover opening in plate (6)
with a clean cloth, such as a handkerchief and apply a slight suction by mouth to draw air
through horn.

15-59.

REMOVAL AND INSTALLATION. Refer to figure 15-5 for removal and installation.

15-60.

TURN COORDINATOR.

15-61.

DESCRIPTION. The turn coordinator is an electrically operated, gyroscopic, roll-rate turn
indicator. Its gyro simultaneously senses rate of motion roll and yaw axes which is
projected on a single indicator. The gyro is a non-tumbline type requiring no caging
mechanism and Incorporates an a. c. brushless spin motor with a solid state inverter.

15-62.

TROUBLE SHOOTING.
TROUBLE

PROBABLE CAUSE

REMEDY

Friction cause by contamination in the indicator
dampening.

Replace instrument.

Friction in gimbal assembly.

Replace instrument.

DOES NOT INDICATE A
STANDARD RATE TURN
(TOO SLOW).

Low voltage.

Correct voltage.

Inverter frequency changed.

Replace instrument.

NOISY MOTOR.

Faulty bearings.

Replace instrument.

ROTOR DOES NOT START.

Faulty electrical connection.

Correct voltage or replace
faulty wire.

Inverter malfunctioning.

Replace instrument.

Motor shorted.

Replace instrument.

Bearings frozen.

Replace instrument.

INDICATOR DOES NOT
RETURN TO CENTER.

15-29

MODEL 172 SERIES SERVICE MANUAL
15-62.

TROUBLE SHOOTING (Cont).

TROUBLE
IN COLD TEMPERATURES.
HAND FAILS TO RESPOND
OR IS SLUGGISH.

NOISY GYRO.

PROBABLE CAUSE

REMEDY

Oil in indicator becomes
too thick.

Replace instrument.

Insufficient bearing end
play.

Replace instrument.

Low voltage.

Check voltage at instrument.
Correct voltage.

High voltage.

Check voltage to instrument.

Correct voltage.
Loose or defective rotor
bearings.

Replace instrument

15-63.

TURN-AND-SLIP INDICATOR.

15-64.

DESCRIPTION. The turn-and-slip indicator is an electrically operatedinstrument powered
by the aircraft electrical system, therefore, operating only when the master switch is ON.

15-65.

TROUBLE SHOOTING.
TROUBLE

INDICATOR POINTER FAILS
TO RESPOND.

HAND SLUGGISH IN
IN RETURNING TO ZERO.

POINTER DOES NOT INDICATE PROPER TURN.

15-30

PROBABLE CAUSE

REMEDY

Internal fuse blown.

Check wiring for continuity.
check voltage at indicator.
Replace fuse. if fuse still
blows. replace instrument.

Master switch "OFF" or
switch defective.

Check switch "ON." Replace defective switch.

Broken or grounded lead to
indicator.

Check circuit wiring. Repair
or replace defective wiring.

Indicator not grounded.

Check ground wire. Repair
or replace defective wire.

Defective mechanism.

Replace instrument.

Defective mechanism.

Replace instrument.

Low voltage.

Check voltage at indicator.
Correct voltage.

Defective mechanism.

Replace instrument.

MODEL 172 SERIES SERVICE MANUAL
15-65.

TROUBLE SHOOTING (Cont).

TROUBLE
HAND DOES NOT SIT
ON ZERO.

IN COLD TEMPERATURES,
HAND FAILS TO RESPOND
OR IS SLUGGISH.

NOISY GYRO.

15-66.

PROBABLE CAUSE

REMEDY

Gimbal and rotor out of
balance.

Replace instrument.

Hand incorrectly sits on rod.
Sensitivity spring adjustment pulls hand off zero.

Replace instrument.
Replace instrument.

Oil in indicator becomes too
thick.

Replace instrument.

Insufficient bearing end play.

Replace instrument.

Low voltage.

Check voltage at indicator.
Correct voltage.

High voltage.

Check voltage at indicator.
Correct voltage.

Loose or defective rotor
bearings.

Replace instrument.

OUTSIDE AIR TEMPERATURE GAGE (See figure 15-5).

15-31/(15-32 blank)

MODEL 172 SERIES SERVICE MANUAL
SECTION 16
ELECTRICAL SYSTEMS
WARNING
When performing any inspection or maintenance that requires turning on the master switch, installing a battery,
or pulling the propeller through by hand, treat the propeller as if the ignition switch were ON. Do not stand, nor
allow anyone else to stand, within the arc of the propeller, since a loose or broken wire, or a component malfunction, could cause the propeller to rotate.

TABLE OF CONTENTS
ELECTRICAL SYSTEMS .......
General ..................
Electrical Power Supply
System .................
Description .............
Split Bus Bar ............
Description ............
Master Switch ...........
Description ............
Ammeter ...............
Description ............
Battery Power System .......
Battery ................
Description ............
Trouble Shooting ........
Removal/Installation ....
Cleaning the Battery .....
Adding Electrolyte or
Water to Battery .......
Testing the Battery ......
Charging the Battery .....
Battery Box .............
Description ............
Removal/Installation .....
Maintenance of Battery
Box ..................
Battery Contactor .........
Description ............
Removal/Installation .....
Battery Contactor Closing
Circuit ..............
Description ..........

Page No.
Aerofiche/
Manual
2I8/16-2
2I8/16-2
2I9/16-3
2I9,16-3
2I9/16-3
2I916-3
2I9/16-3
2I9/16-3
2I9/16-3
2I9/16-3
2I9/16-3
2I9/16-3
2I9/16-3
2I21/16-13
2I22/16-14
2I23/16-15
2I23/16-15
2I23/16-15
2I24/16-16
2I24/16-16
2I24/16-16
2J1/16-17
2J1/16-17
2J1/16-17
2J1/16-17
2J1/116-17
2J2/16-18
2J2/16-18

Ground Service Receptacle ....
Description .............
Trouble Shooting .........
Removal/Installation .......
Alternator Power System .....
Description .............
.....
Alternator ........
Description ...........
Trouble Shooting the
Alternator System
(Thru 1977 Models) ......
Trouble Shooting the
Alternator System
(1978 Models) ..........
Trouble Shooting the
Alternator System
(Beginning with
.
1979 Models) ..........
RemovalInstallation .......
Over-Voltage Warning System .
Description ..............
Alternator Voltage Regulator ..
Description .............
Alternator Control Unit ......
Description ............
Removal Installation .......
Aircraft Lighting System .....
Description .............
Trouble Shooting .........
Landing Taxi Light .........
Description .............
Removal Installation .......

2J2
2J2
2J5
2J6
2J6
2J6
2J6
2J6

16-18
16-18
16-21
16-22
16-22
16-22
16-22
16-22

2J8 16-24

2J11 16-27

2J15 16-31
2J19 16-35
2J19 16-35
2J19 16-35
2J20 16-36
2J20 16-36
2J20 16-36
2J20 16-36
2K3 16-41
2K3 16-41
2K3 16-41
2K3 16-41
2K8 16-46
2K8 16-46
2K8 16-46

Revision 1

16-1

MODEL 172 SERIES SERVICE MANUAL

Adjustment .............
Landing Taxi Lights (Dual)

2K8 16-46
2K8 16-46

Control Wheel Map Light .....
Description ............

Description ............
Removal Installation .......
Navigation Lights ..........

2K8 16-46
2K8 16-46
2K12 16-50

Removal Installation
Pitot Heater ...............
Description ...........

Description .............
Removal Installation .......

2K12 16-50
2K12 16-50

Cigar Lighter
Description

...

......

............
.............

2K21 16-57
2K21 16-57

2K21 16-57
2K21 16-57
. 2K21 16-57
. 2K21 16-57
2K21 16-57

Anti-Collision Strobe Light ....
2K12/16-50
Description .............
2K12/16-50
Removal Installation .......
2K12. 16-50
Operational Requirements .. 2K12/16-50
Flashing Beacon
...........
2K1216-50
Description .............
2K12,16-50
Removal Installation .......
2K12/ 16-50
Instrument, Dome Lights .....
2K16/16-54
Description ............
2K16/16-54
Removal Installation .......
2K16/16-54
Courtesy Lights ...........
2K16/16-54
Description ............
2K16/16-54
Removal Installation .......
2K16/16-54
Compass Radio Dial Lighting .. 2K16/16-54
Description .............
2K16/16-54

Clock ...................
Description .............
Emergency Locator Transmitter
(Thru 17268576) ..........
Description .............
Operation ...............
Checkout Interval .........
Removal/Installation of
Transmitter ............
Removal/Installation of
Antenna ................
Removal/Installation of
Lithium Four Cell
Battery Pack ...........
Trouble Shooting .........

Instrument Post Lighting

Emergency Locator Transmitter

....

2K16,16-54

Description .............
2K16,16-54
Removal Installation .......
2K16,16-54
Trouble Shooting .........
2K17 16-54A
Trouble Shooting Transistor
Heat Sink ..............
2K1816-54B
Transistorized Light Dimming . 2G23 16-54B
Description .............
2G23 16-54B
Removal Installation .......
2G23,16-54B
Trouble Shooting .........
2G23/16-54B
Map Lighting .............
2K21 16-57
Description

............

Removal Installation .......

2K21/16-57

2L3,16-61
2L3/16-61
2L3 16-61
2L3 16-61
2L4,16-62
2L4 16-62
2L416-62
2L16-64

2L6/16-64
2L8/16-66

(Beginning with 17268577) .. 2L10/16-68
Description .............
2L10/1668
Operation ...............
2L10 16-68
Checkout Interval .........
2L11 /16-69
Removal/Installation of
Transmitter ............
2L11 16-69
Remova/Installation of
Antenna ...............
2L11 16-69
Removal/Installation of
Battery Pack ...........
2L15 16-72A
Trouble Shooting

.........

Electrical Load Analysis
Chart ..................

2L1816-74

2L19 16-75

16-1.

ELECTRICAL SYSTEMS.

16-2.

GENERAL. This section contains service information necessary to maintain the Aircraft
Electrical Power Supply System. Aircraft Lighting System. Pitot Heater. Cigar Lighter and
Electrical Load Analysis Chart.

16-2

Revision 1

MODEL 172 SERIES SERVICE MANUAL
16-3.

ELECTRICAL POWER SUPPLY SYSTEM.

16-4.

DESCRIPTION. Electrical energy for the aircraft is supplied by a 14-volt. direct-current.
single wire, negative ground electrical system. A single 12-volt battery supplies power for
starting and furnishes a reserve source of power in the event of alternator failure thru 1977
models. Beginning with 1978 models the electrical system is 28-volt and a 24-volt battery is
utilized An engine-driven alternator is the normal source of power during flight and
maintains a battery charge controlled by a voltage regulator. An external power receptacle
is offered as optional equipment to supplement the battery system for starting and ground
operation.

16-5.

SPLIT BUS BAR.

16-6.

DESCRIPTION. Electrical power is supplied through a split bus bar. One side of the bus bar
supplies power to the electrical equipment while the other side supplies the electronic
installations. When the master switch is closed, the battery contactor engages and the
battery power is supplied to the electrical side of the split bus bar. The electrical bus feeds
battery power thru a relay, thru 1977 models and an avionics master switch beginning with
1978 models, to the electronics bus.

16-7.

MASTER SWITCH.

16-8.

DESCRIPTION. The operation of the battery and alternator systems is controlled by a
master switch. The switch is an interlocking split rocker with battery mode on the righthand side and alternator mode on the left-hand side. This arrangement allows the battery to
be on the line without the alternator, however, operation of the alternator without the battery
on the line is not possible.

16-9.

AMMETER.

16-10.

DESCRIPTION. The ammeter is connected between the battery and the aircraft bus. The
meter indicates the amount of current flowing either to or from the battery. With a low
battery and the engine operating at cruise, the ammeter will show the full alternator output.
When the battery is fully charged and cruise is maintained with all electrical equipment off.
the ammeter will show a minimum charging rate.

16-11.

BATTERY POWER SYSTEM.

16-12.

BATTERY.

16-13.

DESCRIPTION. Thru 17269309 and F17201639 a 12-volt battery with an approximate 25
ampere-hour capacity is installed. On aircraft serials 17269310 thru 17269605 and F17201640
thru F17201729 the battery is 24-volt and approximately 17 ampere-hour capacity. Beginning with 17269742 and F17201730 the battery is also 24-volts with an approximate 12.75
ampere-hour capacity as standard and an optional battery with an approximate 15.5
ampere-hour rating. The battery is mounted on the forward left hand side of the firewall.

16-3

MODEL 172 SERIES SERVICE MANUAL

.--

16-4

THRU 1980 MODELS

1. Screw
2. Lockwasher
3. Circuit Breaker
4. Instrument Panel
5. Decorative Cover

Figure 16-1.
16-4

6. Lockwasher
7. Nut
8. Avionics Switch
9. Avionics Bar
10. Primary Bus

Circuit Breaker and Bus Bar Installation (Sheet 1 of 3)

MODEL 172 SERIES SERVICE MANUAL

1.
3.
8.
9.
10.

Screw
Circuit Breaker
Avionics Switch
Avionics Bus Bar
Primary Bus
Figure 16-1. Circuit Breaker and Bus Bar Installation (Sheet 2 of 3)
16-5

MODEL 172 SERIES SERVICE MANUAL

1. Screw

3.
8.
9.
10.

Circuit Breaker
Avionics Switch
Avionics Bus Bar
Primary Bus
Figure 16-1. Circuit Breaker and Bus Bar Installation (Sheet 3 of 3)

16-6

MODEL 172 SERIES SERVICE MANUAL

12 or 24 VOLT INSTALLATION
1.
2.
3.
4.

Battery Box Lid
Battery
Battery Box
Nut.
Lockwasher

7. Insulating Washer
8. Bracket
10. Solder Terminal
11. Diode
12.
ire to Battery Contactor
13. Resistor
14. Screw
15.

16.

Fuse - Battery Con tactor
Closing Circuit

Fuse -Clock

18. Wire to Diode Board
19. Ground Service Receptacle
Contactor
20. Wire from Fuse to Battery
Contactor
21. Wire to Clock
22. Wire from Starter Contactor
to Battery Contactor
23.
24.

Cover
Starter Contactor

25. Wire to Ignition Switch
26. Wire to Starter
27. Wire from Starter Contactor
to Battery Contactor
28. Positive Battery Lead
29. Diode Assembly
12 VOLT INSTALLATION

30.

Wire to Master Switch

31.
32.

Negative Ground Strap
Battery Contactor

Figure 16-2. Battery and Electrical Equipment Installation (Sheet 1 of 7)
16-6A/(16-6B blank)

MODEL 172 SERIES SERVICE MANUAL

20
Detail A

Detail B

THRU 17269605 AND F17201729

24 VOLT INSTALLATION

1. Battery
2. Battery Box Lid
3. Positive Cable
4. Firewall
5. Side Panel

6.
7.
8.
9.
10.

Vent Tube
Screw
Ground Strap
Cover
Sta-Strap

Figure 16-2.

11.
12.
13.
14.
15.

Nut
Lockwasher
Starter Contactor
Wire (to Master Switch)
Diode Assembly

16.
17.
18.
19.
20.

Battery Contactor
Wire (to Starter Contactor,
Wire (to Starter)
Wire (to Ignition Switch)
Bolt

Battery and Electrical Equipment Installation (Sheet 2 of 7)
16-7

MODEL 172 SERIES SERVICE MANUAL

Detail A
17269606 THRU 17272884 AND
F17201730 THRU F17201909

Figure 16-2. Battery and Electrical Equipment Installation (Sheet 3 of 7)
16-8

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Washer
Bolt
Cover
Terminal Cover
Sta-strap
Battery
Positive Cable
Elbow
Drain Tube
Battery Contactor
Wire (to Master Switch)
Diode
Starter Contactor
Wire (to Ammeter)
Wire (to Ignition Switch)
Wire (to Starter)
Wire (to Diode Board)
Wire (to Receptacle)
Ground Service Contactor
Pan
Ground Strap
Clamp
Cover (Starter Contactor)

14
16
15
17272885 THRU 17274009 AND
F17201910 THRU F17201828

Figure 16-2. Battery and Electrical Equipment Installation (Sheet 4 of 7)
16-9

MODEL 172 SERIES SERVICE MANUAL

BEGINNING WITH 17274010
AND F17202070
24.
25.
26.
27.
28.
29.

Cover (Ground Service)
Cover (Starter Contactor)
Clock Fuse
Fuse Battery Contactor Closing Circuit
Diode
Ground Service Receptacle

Figure 16-2 Battery and Electrical Equipment Installation (Sheet 5 of 7)
16-10

MODEL 172 SERIES SERVICE MANUAL

* Used on All Three Contactors

THRU 17275339

AND

F17202169

Detail B
BEGINNING WITH 17274010
AND F17202070
30.
31.
32.
33.
34.
35.
36.
-37.
38.

Wire (to Starter Contactor)
Wire (to Ground Service)
Ground Wire
Wire (to Battery Contactor)
Wire (to Diode)
Wire (to Starter Contactor)
Wire (to Clock Fuse)
Jumper Wire
Wire (to Battery)

Figure 16-2. Battery and Electrical Equipment Installation (Sheet 6 of 7)
16-11

MODEL 172 SERIES SERVICE MANUAL

Used on All Three Contactors

BEGINNING WITH 17275340
AND F17202170

2. 3.Bolt Cover
4.
5.
8.
1 9.
20.
21.
22.
29.
39.
40.
41.

Terminal Cover
Sta-strap
Elbow
a h r
Drain Tube
Pan
Ground Strap
Clamp
Ground Service Receptacle
Shield
Cooling Duct
Clamp

.W
se

Figure 16-2. Battery and Electrical Equipment Installation (Sheet 7 of 7)
16-12

MODEL 172 SERIES SERVICE MANUAL
16-14.

TROUBLE SHOOTING THE BATTERY POWER SYSTEM.
TROUBLE

BATTERY WILL NOT SUPPLY POWER TO BUS OR IS
INCAPABLE OF CRANKING
ENGINE.

PROBABLE CAUSE

REMEDY

Battery discharged.

1. Measure voltage at "BAT"
terminal of battery contactor
with master switch and a suitable load such as a taxi light
turned on. Normal battery
will indicate 11.5 volts or
more on a 14 volt system
or 23 volts or more on a
28 volt system. If voltage
is low, proceed to Step 2.
If voltage is normal, proceed
to Step 3.

Battery faulty.

2. Check fluid level in cells
and charge 12-volt battery
at 14 volts or 24-volt battery
at 28 volts for approximately
30 minutes or until the battery voltage rises to 14
volts on 12-volt battery
or 28 volts on 24-volt battery. If tester indicates a
good battery, the malfunction may be assumed to be
a discharged battery. If the
tester indicates a faulty battery replace the battery.

Faulty contactor or wiring
between contactor or master
switch.

3. Measure voltage at master switch terminal (smallest)
on contactor with master
switch closed. Normal indication is zero volts. If
voltage reads zero. proceed
to step 4. If a voltage
reading is obtained check
wiring between contactor
and master switch. Also
check master switch.

Open coil on contactor.

4. Check continuity between
"BAT" terminal and master
switch terminal of contactor.
Normal indication on 14 volt
aircraft is 16-24 ohms. Normal indication on 28 volt
aircraft is 50-70 ohms.
If ohmmeter indicates an
open coil. replace contactor.
If ohmmeter indicates a good
coil. proceed to step 5.

16-13

MODEL 172 SERIES SERVICE MANUAL
16-14.

TROUBLE SHOOTING THE BATTERY POWER SYSTEM (Cont).
TROUBLE

BATTERY WILL NOT SUPPLY POWER TO BUS OR IS
INCAPABLE OF CRANKING
ENGINE. (Cont).

16-15.

PROBABLE CAUSE

REMEDY

Faulty contactor contacts.

5. Check voltage on "BUS"
side of contactor with master
switch closed. Meter normally
indicates battery voltage
If voltage is zero or intermittant. replace contactor. If voltage is normal, proceed to Step 6.

Faulty wiring between contactor and bus.

6. Inspect wiring between
contactor and bus. Repair
or replace wiring.

REMOVAL AND INSTALLATION. (See figure 16-2.)

CAUTION
When installing or removing battery always observe the
proper polarity with the aircraft electrical system (negative to ground), reverse the polarity, even momentarily.

may result in failure of semiconductor devices (alternator diodes, radio protection diodes and radio transistors).
Always remove the battery ground cable first and replace
it last to prevent accidental short circuits.
a.

THRU 1979 MODELS..
1. Remove upper half of cowl.
2. Remove battery box cover and beginning with 1978 models also remove side panel.
3. Disconnect the ground cable from the negative battery terminal.
4. Disconnect the cable from the positive terminal of the battery.
5. Lift the battery out of the battery box
6. To replace the battery, reverse this procedure.

16-14

BEGINNING WITH 1980 MODELS.
1. Remove upper half of engine cowl.
2. Disconnect ground strap from negative battery terminal.
3. Cut sta-strap and remove cover from positive battery terminal.
4. Disconnect the cable from the positive battery terminal.
5. Remove clamp and battery drain tube.
6. Remove bolts and washers securing battery and cover, then remove cover and lift
battery out of pan.

MODEL 172 SERIES SERVICE MANUAL
16-16.

CLEANING THE BATTERY. For maximum efficiency, the battery and connections should
be kept clean at all times.
a. Remove the battery in accordance with the preceding paragraph.
b. Tighten battery cell filler caps to prevent the cleaning solution from entering the
cells.
c. Wipe the battery cable ends, battery terminals and entire surface of the battery with a
clean cloth moistened with a solution of bicarbonate of soda (baking soda) and water.
d. Rinse with clear water, wipe off excess water and allow battery to dry.
e. Brighten up cable ends and battery terminals with emery cloth or a wire brush.
f. Install the battery according with the preceding paragraph
g. Coat the battery terminals with petroleum jelly or an ignition spray product to
reduce corosion.

16-17.

ADDING ELECTROLYTE OR WATER TO THE BATTERY. A battery being charged and
discharged with use will decompose the water from the electrolyte by electrolysis. When the
water is decomposed, hydrogen and oxygen gases are formed which escape into the
atmosphere through the battery vent system. The acid in the solution chemically combines
with the plates of the battery during discharge or is suspended in the electrolyte solution
during charge. Unless the electrolyte has been spilled from a battery, acid should not be
added to the solution. The water, however, will decompose into gases and should be replaced
regularly. Add distilled water as necessary to maintain the electrolyte level with the
horizontal baffle plate or the split ring on the filler neck inside the battery. When "dry
charged" batteries are put into service, fill as directed with electrolyte. When the electrolyte
level falls below normal with use, add only distilled water to maintain the proper level. On
Aircraft Serials 17269310 thru 17269605 and F1721640 thru F1721729 refer to Cessna SingleEngine Service Letter, SE78-6 Dated February 13, 1978 when filling the battery. The battery
electrolyte contains approximately 25% sulphuric acid by volume. Any change in this
volume will hamper the proper operation of the battery.
CAUTION
Do not add any type of "battery rejuvenator" to the
electrolyte. When acid has been spilled from a battery, the
acid balance may be adjusted by following instructions
published by the Association of American Battery Manufacturers.

16-18.

TESTING THE BATTERY. The specific gravity of the battery may be measured with a
hydrometer to determine the state of battery charge. If the hydrometer reading is low, slowcharge the battery and retest. Hydrometer readings of the electrolyte must be compensated
for the temperature of the electrolyte. Some hydrometers have a built-in thermometer and
conversion chart. The following chart shows the battery condition for various hydrometer
readings with an electrolyte temperature of 80° Fahrenheit.

16-15

MODEL 172 SERIES SERVICE MANUAL
BATTERY HYDROMETER READINGS
READINGS

1280
1250
1220
1.190
1.160

Specific
Specific
Specific
Specific
Specific

BATTERY
CONDITION
Gravity
Gravity
Gravity
Gravity
Gravity

100% Charged
75% Charged
50% Charged
25% Charged
Practically Dead
NOTE

All readings shown are for an electrolyte temperature of
80 ° Fahrenheit. For higher temperatures the readings
will be slightly lower. For cooler temperatures the readings will be slightly higher. Some hydrometers have a
built-in temperature compensation chart and a thermometer. If this type tester is used, disregard this chart.
16-19.

CHARGING THE BATTERY. When the battery is to be charged, the level of electrolyte
should be checked and adjusted by adding distilled water to cover the tops of the internal
battery plates. Remove the battery from the aircraft and place in a well ventilated area for
charging.
WARNING
When a battery is being charged, hydrogen and oxygen
gases are generated. Accumulation of these gases can
create a hazardous explosive condition. Always keep
sparks and open flame away from the battery.
Allow unrestricted ventilation of the battery area during

charging.
The main points of consideration during a battery charge are excessive battery temperature
and violent gassing. Test the battery with a hydrometer to determine the amount of charge.
Decrease the charging rate or stop charging temporarily if the battery temperature exceeds
125°F.
16-20.

BATTERY BOX (THRU 17272884 AND F17201909).

16-21.

DESCRIPTION. The battery is completely enclosed in a boxwhich is painted with acid proof
paint. The box has a vent tube which protrudes through the bottom of the aircraft allowing
battery gases and spilled electrolyte to escape. The battery box is riveted to the forward side
of the firewall.

16-16

MODEL 172 SERIES SERVICE MANUAL
16-22.

REMOVAL AND INSTALLATION. (See figure 16-1A.) The battery box is riveted to
mounting brackets on the firewall. The rivets must be drilled out to remove the box. When a
battery box is installed and riveted into place, all rivets and scratches inside the box should
be painted with acid proof lacquer Part No. CES1054-381. available from the Cessna Service
Parts Center.

16-23.

MAINTENANCE OF BATTERY BOX The battery box should be inspected and cleaned
periodically. The box and cover should be cleaned with a strong solution of bicarbonate of
soda (baking soda) and water. Hard deposits may be removed with a wire brush. When all
corrosive deposits have been removed from the box. flush it thoroughly with clean water.
WARNING
Do not allow acid deposits to come in contact with skin or
clothing. Serious acid burns may result unless the
affected area is washed immediately with soap and water.
Clothing will be ruined upon contact with battery acid.
Inspect the cleaned box and cover for physical damage and for areas lacking proper acid
proofing. A badly damaged or corroded box should be replaced. If the box or lid require acid
proofing, paint the area with acid proof lacquer Part No. CES1054-381. available from the
Cessna Service Parts Center.

16-24.

BATTERY CONTACTOR.

16-25.

DESCRIPTION. The battery contactor is bolted to the side of the battery box thru 1977 models
and on the firewall beginning with 1978 models. The contactor is a plunger type which is
actuated by turning the master switch on. When the master switch is off, the battery is
disconnected from the electrical system. A silicon diode is used to eliminate spiking of
transistorized radio equipment. The large terminal of the diode connects to the battery
terminal of the battery contactor. The small terminal of the diode and the master switch wire
connect to the minus terminal of the contactor coil. A nylon cover is installed over the
contactor terminals to prevent accidental short circuits.

16-26.

REMOVAL AND INSTALLATION. (See figure 16-2.)
a. THRU 1980 MODELS.
1. Remove engine cowl per Section 11.
2. Thru 1979 models, remove battery box cover and disconnect ground strap from
negative battery terminal.
3. Beginning with 1980 models, disconnect ground strap from negative battery terminal.
4. Cut sta-straps and remove nylon covers from contactor terminals.
5. Remove nuts and washers securing each side of the battery contactor and remove
contactor.
6. Remove bolt and washer securing each side of the battery contactor and remove
contactor.
7. To install contactor, reverse the preceding steps: be sure to install diode assembly if
removed. Use new sta-straps on nylon covers.

16-17

MODEL 172 SERIES SERVICE MANUAL
b.

BEGINNING WITH 1981 MODELS.
1. Remove engine cowl per Section 11.
2. Disconnect ground strap from negative battery terminal.
3. Cut sta-straps and remove contactor cover.
4. Remove nuts and washers, then remove and tag wires for reinstallation.
5. Remove bolt and washer securing each side of the battery contactor and remove
contactor.
6. To install contactor. reverse the preceding steps: be sure to install diode assembly if
removed. Use new sta-straps on cover.

16-27.

BATTERY CONTACTOR CLOSING CIRCUIT.

16-28.

DESCRIPTION. This circuit consists of a 5 amp fuse, a resistor and a diode located on the
firewall fuse bracket adjacent to the battery. This serves to shunt a small charge around the
battery contactor so that ground power may be used to close the contactor when the battery is
too dead to energize the contactor by itself.

16-29.

GROUND SERVICE RECEPTACLE.

16-30.

DESCRIPTION. A ground service receptacle is offered as optional equipment to permit use
of external power for cold weather starting or when performing lengthy electrical maintenance. A reverse polarity protection system is utilized whereby ground power must pass
through an external power contactor to be connnected to the bus. A silicon junction diode is
connected in series with the coil on the external power contactor so that if the ground power
source is inadvertently connected with a reversed polarity, the external power contactor
will not close. This feature protects the diodes in the alternator, and other semi-conductor
devices used in the aircraft from possible reverse polarity damage.
NOTE
On Aircraft Serials 17267585 thru 17269971 refer to
Cessna Single-Engine Service Letter SE78-19, dated
March 27, 1978.
NOTE
Thru 1977 models application of external power opened
the relay supplying voltage to the electronics bus. Beginning with 1978 models this relay is replaced by an
avionics master switch. The avionics master switch must
be OFF when external power is applied.
NOTE
When using ground power to start the aircraft, close the
master switch before removing the ground power plug.
CAUTION
Failure to observe polarity when connecting an external
power source directly to the battery or directly to the
battery side of the battery contactor, will damage the
diodes in the alternator and other semiconductor devices
in the aircraft.

16-18

MODEL 172 SERIES SERVICE MANUAL

..-

Figure 16-3. Ground Service Receptacle Installation (Sheet 1 of 2)

16-19

THRU 1980 MODELS
THRU
MODELS
1.
1.
2.
3.
3.
4.
5.
5.
6.
7.
8.
8.
9.
9.
10.
11.
12.
13.

Diode Board
Cable (To Contactor)
Nut
Nut
Ground Strap
Strap
Washer
Brace
Bracket Assembly
Firewall
Receptacle
Doubler
Door
CowlSkin
Rubber Nipple

Figure 16-3. Ground Service Receptacle Installation (Sheet 1 of 2)
16-19

MODEL 172 SERIES SERVICE MANUAL

Detail A
BEGINNING WITH 1981 MODELS

Figure 16-3. Ground Service Receptacle Installation (Sheet 2 of 2)
18-20

MODEL 172 SERIES SERVICE MANUAL
16-31.

TROUBLE SHOOTING.
TROUBLE

PROBABLE CAUSE

REMEDY

STARTER ENGAGES WHEN
GROUND POWER IS CONNECTED. (THRU 1977
MODELS)

Shorted or reversed diode
in split bus-bar system.

Check wiring to. and condition of diode mounted on the
split bus relay bracket adjacent to the magneto switch.
Correct wiring. Replace diode
board assembly.

GROUND POWER WILL
NOT CRANK ENGINE.

Ground service connector
wired incorrectly.

1. Check for voltage at all
three terminals of external
power contactor with ground
power connected and master
switch off. If voltage is present on input and coil terminals but not on the output
terminal proceed to step 4.
If voltage is present on the
input terminal but not on the
coil terminal, proceed to
step 2. If voltage is present
on all three terminals, check
wiring between contactor and
bus.
2. Check for voltage at
small terminal of ground service receptacle. If voltage
is not present, check ground
service plug wiring. If voltage is present, proceed to
step 3.

Open or mis-wired diode
on ground service diode
board assembly.

3. Check polarity and contiuity of diode board at
rear of ground service receptacle. If diode is open or improperly wired. replace diode
board assembly.

Faulty external power contactor.

4. Check resistance from
small (coil) terminal of external power contactor to
ground (master switch off
and ground power unplugged.
Normal indication is 16-24
ohms on the 12 volt and 5070 on the 24 volt. If resistance indicates an open
coil. replace contactor. If
resistance is normal. proceed to step 5.

16-21

MODEL 172 SERIES SERVICE MANUAL
16-31.

TROUBLE SHOOTING (Cont).

TROUBLE

PROBABLE CAUSE

REMEDY

GROUND POWER WILL
NOT CRANK ENGINE
(Cont.)

Faulty contacts in exterpower
nal
contactor.

5. With master switch off
and ground power applied.
check for voltage drop between two large terminals of
external power (turn on taxi
light for a load). Normal indication is zero volts If
voltage is intermittently
present or present all the
time, replace contactor.

16-32.

REMOVAL AND INSTALLATION. (See figure 16-2.)
a. Open battery box and disconnect the ground cable from the negative terminal of the
battery and pull the cable from the battery box.
b. Remove the nuts, washers, ground strap and diode board from the studs of the
receptacle and remove the battery cable.
c. Remove the screws and nuts holding the receptacle. The receptacle will then be free
from the bracket.
d. To install a ground service receptacle, reverse this procedure. Be sure to place the
ground strap on the negative stud of the receptacle.

16-33.

ALTERNATOR POWER SYSTEM.

16-34.

DESCRIPTION. The alternator system consists of a belt-driven alternator, a voltage
regulator/ alternator control unit, mounted on the left hand side of the firewall and a circuit
breaker located on the instrument panel. The system is controlled by the left hand portion of
the split rocker, master switch labeled "ALT". Thru 1978 models an over-voltage sensor
switch and red warning light labeled "HIGH VOLTAGE" are incorporated to protect the
system. Beginning with 1979 models, over-voltage and under-voltage switches are contained within the alternator control unit. A red warning light labeled "LOW VOLTAGE" is
installed on the instrument panel. The aircraft battery supplies the source of power for
excitation of the alternator.

16-35.

ALTERNATOR.

16-36.

DESCRIPTION. The 60-ampere alternator is three phase, delta connected with integral
silicon diode rectifiers. The alternator is belt driven and is rated at 14 volts at 60 amperes
continuous output thru 1977 models and 28 volts at 60 amperes beginning with 1978 models.

18-22

MODEL 172 SERIES SERVICE MANUAL

THRU 17273938 AND F17202033
BEGINNING WITH 17273934 AND
F17202040

Detail

Washer

3. Lower Adjustment Bracket
4. Safety Wire
5. Upper Adjustment Bolt
6. Nut
7. Mounting Bracket
8.
9.
10.
11.

Bracket
Bolt
Alternator Mounting Bolt
Alternator

Figure 16-4. Belt-Driven Alternator Installation
16-23

MODEL 172 SERIES SERVICE MANUAL
16-37.

TROUBLE SHOOTING THE ALTERNATOR SYSTEM (THRU 1977 MODELS)
TROUBLE

AMMETER INDICATES
HEAVY DISCHARGE WITH
ENGINE NOT RUNNING OR
ALTERNATOR CIRCUIT
BREAKER OPENS WHEN
MASTER SWITCH IS
TURNED ON.

PROBABLE CAUSE
Shorted radio noise filter
or shorted wire.

REMEDY
1. Remove cable from output terminal of alternator.
Check resistance from end
of cable to ground (MASTER
SWITCH MUST BE OFF).
If resistance does not indicate a direct short, proceed to step 4. If resistance indicates a direct
short. proceed to step 2.
2. Remove cable connections
from radio noise filter.
Check resistance from the
filter input terminal to
ground. Normal indication is
infinite resistance. If reading indicates a direct short.
replace filter. If no short
is evident, proceed to
step 3.
3. Check resistance from
ground to the free ends of
the wires which were connected to the radio noise
filter (or alternator if no
noise filter is installed).
Normal indication does not
show a direct short. If a
short exists in wires, repair or replace wiring.

Shorted diodes in alternator.

16-24

4. Check resistance from
output terminal of alternator to alternator case.
Reverse leads and check
again. Resistance reading
may show continuity in one
direction but should show
an infinite reading in the
other direction. If an infinite reading is not obtained in at least one direction. repair or replace alternator.

MODEL 172 SERIES SERVICE MANUAL
16-37.

TROUBLE SHOOTING THE ALTERNATOR SYSTEM (THRU 1977 MODEL) (Cont).

TROUBLE

PROBABLE CAUSE

REMEDY

ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED.

Regulator faulty or improperly adjusted.

1. Start engine and adjust for
1500 RPM. Ammeter should
indicate a heavy charge
rate with all electrical
equipment turned off. Rate
should taper off in 1-3 minutes. A voltage check at
the bus should indicate
a reading consistant with
the voltage vs temperature
chart in the Cessna Alternator
Charging System Service/
Parts Manual. If charge rate
tapers off very quickly and
voltage is normal, check battery for malfunction. If ammeter
shows a low charge rate or
any discharge rate, and
voltage is low, proceed to
step 2.
2. Stop engine, remove cowl,
and remove cover from voltage regulator. Turn master
switch ON/OFF several
times and observe field
relay in regulator. Relay
should open and close with
master switch and small arc
should be seen as contacts
open. If relay is inoperative.
proceed to step 3. If relay
operates, proceed to step 4.
3. Check voltage at "S" terminal of regulator with master
switch closed. Meter should indicate bus voltage. If voltage
is present. replace regulator. If voltage is not present.
check wiring between regulator and bus.

16-25

MODEL 172 SERIES SERVICE MANUAL
16-37.

TROUBLE SHOOTING THE ALTERNATOR SYSTEM (THRU 1977 MODEL) (Cont).
PROBABLE CAUSE

TROUBLE

REMEDY

CAUTION
Before performing step 4. remove radios from the panel.
ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED. (Cont.)

Regulator faulty or improperly adjusted. (Cont.)

4. Remove plug from regulator and start engine. Momentarily jumper the "A+"
and "F" terminals together
on the plug. Ship's ammeter
should show heavy rate of
charge. If heavy charge rate
is observed, replace regulator. If heavy charge rate is
not observed. proceed to
step 5.
5. Check resistance from
"F" terminal of regulator to
"F" terminal of alternator.
Normal indication is a very
low resistance. If reading
indicates no or poor contiuity, repair or replace wiring from regulator to alternator.
6. Check resistance from
"F" terminal of alterntor to
alternator case. Normal indication is 6-7 ohms. If resistance is high or low. repair or replace alternator.
7. Check resistance from
case of alternator to airframe ground. Normal indication is very low resistance.
If reading indicates no. or
poor continuity, repair or replace alternator ground wiring.

ALTERNATOR OVERCHARGES BATTERY - BATTERY
USES EXCESSIVE WATER.

16-26

Regulator faulty or improperly adjusted.

Check bus voltage with engine running. Normal indication agrees with the Cessna
Alternator Charging System
Service/Parts Manual. Observe ship's ammeter, ammeter should indicate near
zero after a few minutes of
engine operation. Replace
regulator.

MODEL 172 SERIES SERVICE MANUAL
16-37.

TROUBLE SHOOTING THE ALTERNATOR SYSTEM (THRU 1977 MODEL) (Cont).

TROUBLE

PROBABLE CAUSE

REMEDY

OVER-VOLTAGE WARNING LIGHT ON.

Regulator faulty or improperly adjusted. Faulty sensor
switch,

1. With engine running turn
off and on battery portion
of the master switch. If the
light stays on shut down
engine then turn on the "BAT"
and "ALT" portion the master
switch. Check for voltage at
the "S" terminal of the voltage regulator. If voltage is
present adjust or replace regulator. If voltage is not present check master switch and
wiring for short or open condition. If wiring and switch
are normal replace sensor.

16-37A. TROUBLE SHOOTING THE ALTERNATOR SYSTEM. (1978 MODELS)
a. ENGINE NOT RUNNING.
TROUBLE

PROBABLE CAUSE

REMEDY

AMMETER INDICATES
HEAVY DISCHARGE OR
ALTERNATOR CIRCUIT
BREAKER OPENS. (Battery Switch ON, Alternator Switch OFF, all
other electrical switches
OFF.)

Shorted diode in alternator.

Turn off Battery Switch and
remove "B" Lead from alternator. Check resistance from
"B" Terminal to alternator
case. Reverse leads and
check again. Resistance
reading may show continuity
in one direction but should
show an infinite reading in the
other direction. If an infinite
reading is not obtained in at
least one direction, repair or
replace alternator.

ALTERNATOR REGULATOR
CIRCUIT BREAKER OPENS
WHEN BATTERY AND
ALTERNATOR SWITCHES
ARE TURNED ON.

Short in Over-Voltage
sensor.

Disconnect Over-Voltage
Sensor plug and recheck.
If circuit breaker stays in
replace Over-Voltage Sensor.

Short in alternator voltage
regulator.

Disconnect regulator plug
and recheck. If circuit
breaker stays in. replace
regulator.

Short in alternator field.

Disconnect "F" terminal
wire and recheck. If circuit
breaker stays in. replace
alternator.

16-27

MODEL 172 SERIES SERVICE MANUAL
16-37A. TROUBLE SHOOTING THE ALTERNATOR SYSTEM. (Cont.)
b. ENGINE RUNNING (Cont).
TROUBLE

PROBABLE CAUSE

REMEDY

ALTERNATOR CIRCUIT
BREAKER OPENS WHEN
BATTERY AND ALTERNATOR SWITCHES ARE
TURNED ON, OVERVOLTAGE LIGHT DOES
NOT COME ON.

Defective circuit breaker.

Replace circuit breaker.

ALTERNATOR REGULATOR
CIRCUIT BREAKER OPENS
WHEN BATTERY AND
ALTERNATOR SWITCHES
ARE TURNED ON. OVERVOLTAGE LIGHT DOES
NOT COME ON.

Shorted field in alternator.

Check resistance from "F"
terminal of alternator to
alternator case. if resistance
is less than 5 ohms repair/
replace.

CAUTION
This malfunction frequently causes a shorted regulator
which will result in an over-voltage condition when
system is again operated.
ALTERNATOR MAKES
ABNORMAL WHINING
NOISE.

Shorted diode in alternator.

Turn off Battery Switch and
remove "B" Lead from
alternator. Check resistance
from "B" Terminal of alternator to alternator case.
Reverse leads and check
again. Resistance reading
may show continuity in one
direction but should show
an infinite reading in the
other direction. If an infinite reading is not obtained
in at least one direction.
repair or replace alternator.

OVER-VOLTAGE LIGHT
DOES NOT GO OUT WHEN
ALTERNATOR AND BATTERY SWITCHES ARE
TURNED ON.

Shorted regulator.

Replace regulator.

Defective over-voltage

Replace sensor.

sensor.

16-28

MODEL 172 SERIES SERVICE MANUAL
16-37A. TROUBLE SHOOTING THE ALTERNATOR (Cont).
b.

ENGINE RUNNING.
PROBABLE CAUSE

TROUBLE
AFTER ENGINE START
WITH ALL ELECTRICAL
EQUIPMENT TURNED OFF
CHARGE RATE DOES NOT
TAPER OFF IN 1-3 MINUTES.

Regulator faulty or high
resistance in field circuit.

REMEDY
With engine not running turn
off all electrical loads and
turn on battery and alternator
switches. Measure bus voltage to ground, then measure
voltage from terminal of alternator to ground. If there is
more than 2 volts difference
check field circuit wiring
shown on alternator system
wiring diagram in Section 20.
Clean all contacts. Replace
components until there is
less than 2 volts difference
between bus voltage and
field voltage.

NOTE
Also refer to battery power system trouble shooting
chart.
ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED.

Alternator output voltage
insufficient.

1. Connect voltmeter between D.C. Bus and ground.
Turn off all electrical loads.
Turn on Battery Switch, start
engine and adjust for 1500
RPM. voltage should read approximately 24 volts. Turn
on alternator switch, voltage
should read between 27.4 and
28.0 volts. Ammeter should
indicate a heavy charge rate
which should taper off in 1-3
minutes. If charge rate tapers
off very quickly and voltage
is normal, check battery for
malfunction. If ammeter
shows a low charge rate
or any discharge rate, and
voltage does not rise when
alternator switch is turned
on proceed to Step 2.

16-29

MODEL 172 SERIES SERVICE MANUAL
16-37A. TROUBLE SHOOTING THE ALTERNATOR SYSTEM (Cont).
b. ENGINE RUNNING (Cont).
TROUBLE
ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED. (Cont.)

PROBABLE CAUSE
Alternator output voltage
insufficient (Cont.)

REMEDY
2. Stop engine. turn off all
switches. Connect voltmeter
between "F" terminal of
alternator and ground. Do
NOT start engine. Turn on
battery switch and alternator
switch. Battery voltage
should be present at "F"
terminal. less 1 volt drop
thru regulator, if not refer
to Step 3.
3. Starting at "F" terminal
of alternator trace circuit
to voltage regulator. at "B"
terminal of regulator trace
circuit to over-voltage sensor. to master switch, to
Bus Bar. Replace component
which does not have voltage
present at output. Refer to
alternator system wiring
diagram in Section 20.

Alternator field winding
open.

1. If voltage is present turn
off alternator and battery
switches. Check resistance
from "F" terminal of alternator to alternator case. turning alternator shaft during
measurement. Normal indication is 12-20 ohms. If resistance is high or low. repair or
replace alternator. If ok refer
to step 2.
2. Check resistance from
case of alternator to airframe
ground. Normal indication is
very low resistance. If reading indicates no. or poor continuity. repair or replace
alternator ground wiring.

MODEL 172 SERIES SERVICE MANUAL
16-37B. TROUBLE SHOOTING -- ALTERNATOR SYSTEM (BEGINNING 1979 MODELS).
a. ENGINE NOT RUNNING.
TROUBLE

PROBABLE CAUSE

REMEDY

AMMETER INDICATES
HEAVY DISCHARGE OR
ALTERNATOR CIRCUIT
BREAKER OPENS.
(Battery Switch ON, Alternator Switch OFF, all
other electrical switches
OFF.)

Shorted diode in alternator.

Turn off Battery Switch and
remove "B" Lead from alternator. Check resistance from
"B" Terminal of alternator to
alternator case. Reverse
leads and check again. Resistance reading may show
continuity in one direction
but should show an infinite
reading in the other direction.
If an infinite reading is not obtained in at least one direction.
repair or replace alternator.

ALTERNATOR REGULATOR CIRCUIT BREAKER
OPENS WHEN BATTERY
AND ALTERNATOR
SWITCHES ARE TURNED
ON.

Short in alternator control
unit.

Disconnect Over-Voltage
Sensor plug and recheck. If
circuit breaker stays in replace Over-Voltage Sensor.
Disconnect control unit plug
and recheck. If circuit breaker
stays in, replace alternator con-

trol unit.
Short in alternator field.

Disconnect "F" terminal wire
and recheck. If circuit breaker stays in. replace alternator.

Defective circuit breaker.

Replace circuit breaker.

b. ENGINE RUNNING.
ALTERNATOR CIRCUIT
BREAKER OPENS WHEN
BATTERY AND ALTERNATOR SWITCHES ARE
TURNED ON, LOW-VOLTAGE LIGHT DOES NOT
COME ON.

16-31

MODEL 172 SERIES SERVICE MANUAL
16-37B. TROUBLE SHOOTING -- ALTERNATOR SYSTEM (Cont).
b. ENGINE RUNNING (Cont).
TROUBLE
ALTERNATOR REGULATOR CIRCUIT BREAKER
OPENS WHEN BATTERY
AND ALTERNATOR
SWITCHES ARE TURNED
ON. LOW-VOLTAGE
LIGHT MAY OR MAY
NOT COME ON.

PROBABLE CAUSE
Shorted field in alternator.

REMEDY
Check resistance from "F"
terminal of alternator to
alternator case. if resistance is less than 5 ohms
repair/replace.

CAUTION
This malfunction may cause a shorted alternator control
unit which will result in an over-voltage condition when
system is again operated.
ALTERNATOR MAKES
ABNORMAL WHINING
NOISE.

Shorted diode in alternator.

Turn off Battery Switch and
remove "B" Lead from alternator. Check resistance
from "B" Terminal of alternator to alternator case. Reverse leads and check again
Resistance reading may show
continuity in one direction but
should show an infinite reading
in the other direction. If an infinite reading is not obtained
in one direction, repair or replace alternator.

LOW-VOLTAGE LIGHT
DOES NOT GO OUT WHEN
ALTERNATOR AND BATTERY SWITCHES ARE
TURNED ON.

Shorted alternator control
unit.

Replace alternator control
unit.

Defective low-voltage
sensor.

Replace alternator control
unit.

16-32

MODEL 172 SERIES SERVICE MANUAL
16-37B. TROUBLE SHOOTING -- ALTERNATOR SYSTEM (Cont).
b. ENGINE RUNNING (Cont).
PROBABLE CAUSE

TROUBLE
AFTER ENGINE START
WITH ALL ELECTRICAL
EQUIPMENT TURNED OFF
CHARGE RATE DOES NOT
TAPER OFF IN 1-3
MINUTES.

Alternator control unit
faulty or high resistance in field circuit.

REMEDY
With engine not running turn
off all electrical loads and
turn on battery and alternator
switches. Measure bus voltage
to ground, then measure voltage from terminal of alternator to ground. If there is
more than 2 volts difference
check field circuit wiring
shown on alternator system
wiring diagram in Section
20. Clean all contacts. Replace
components until there is less
than 2 volts difference between bus voltage and field
voltage.

NOTE
Also refer to battery power system trouble shooting
chart.
ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED.

Alternator output voltage
insufficient.

1. Connect voltmeter between
D.C. Bus and ground. Turn
off all electrical loads. Turn
on Battery Switch, start
engine and adjust for 1500
RPM. voltage should read
approximately 24 volts. Turn
on alternator switch, voltage
should read between 28.4 and
28.9 volts. Ammeter should
indicate a heavy charge rate
which should taper off in
1-3 minutes. If charge rate
tapers off very quickly and
voltage is normal, check
battery for malfunction. If
ammeter shows a low charge
rate or any discharge rate.
and voltage does not rise
when alternator switch is
turned on proceed to Step 2.

16-33

MODEL 172 SERIES SERVICE MANUAL
16-37B. TROUBLE SHOOTING -- ALTERNATOR SYSTEM (Cont).
b. ENGINE RUNNING (Cont).
TROUBLE
ALTERNATOR SYSTEM
WILL NOT KEEP BATTERY CHARGED. (Cont.)

PROBABLE CAUSE
Alternator output voltage
insufficient (Cont.)

REMEDY
2. Stop engine, turn off all
switches. Connect voltmeter
between "F" terminal of
alternator and ground. Do
NOT start engine. Turn on
battery switch and alternator
switch- Battery voltage
should be present at "F"
terminal, less 1 volt drop
thru regulator. if not refer
to Step 3.
3. Starting at "F" terminal
of alternator. trace circuit
to alternator control unit at
Pin 1 (Blue Wire). Trace circuit from Pin 3 (Red Wire)
to master switch, to Bus Bar.
Trace circuit from alternator
control unit Pin 2 (Orange
Wire) to alternator "BAT"
terminal Check connections
and replace component
which does not have voltage
present at output. Refer
to alternator system.
wiring diagram in Section 20.

Alternator field winding
open.

1. If voltage is present turn
off alternator and battery
switches. Check resistance
from "F" terminal of alternator to alternator case.
turning alternator shaft during measurement. Normal
indication is 12-20 ohms.
If resistance is high or low.
repair or replace alternator.
If ok refer to Step 2.
2. Check resistance from
case of alternator to airframe ground. Normal indication is very low resistance.
If reading indicates no, or
poor continuity. repair or
replace alternator ground
wiring.

16-34

MODEL 172 SERIES SERVICE MANUAL
16-38.

REMOVAL AND INSTALLATION. (See figure 16-4.)
a. Ensure that the master switch is off and the negative lead is disconnected from the
battery.
b. Remove wiring from the alternator and label.
c. Remove safety wire from the upper adjusting bolt and loosen bolt.
d. Remove safety wire from lower adjusting bolt and remove bolt.
e. Remove the locknut from the alternator mounting bolt.
f. Remove the alternator drive belt and the alternator mounting bolt. the alternator will
then be free for removal
g. To replace the alternator, reverse this procedure.
h. Apply a torque wrench to the nut on alternator pulley and adjust the belt tension so
the belt slips when the following torque value is applied.
TORQUE VALVES
FOR
CHECKING ALTERNATOR BELT TENSION
Used Belt

New Belt

Slips At
7 to 9 Ft. Lb.

Slips At
11 to 13 Ft. Lbs.
NOTE
On new aircraft or whenever a new belt is installed, belt
tension should be checked within 10 to 25 hours of operation.

i. Tighten and safety wire upper and lower adjusting bolts.
Tighten alternator mounting bolt.

16-39.

OVER-VOLTAGE WARNING SYSTEM.

16-40.

DESCRIPTION. Thru 1978 Models the over-voltage system consists of an over-voltage
sensor switch and a red warning light labeled "HIGH VOLTAGE". The over-voltage sensor
is attached to the wire bundle behind the instrument panel thru 1977 models and on a
mounting bracket just forward of the instrument panel on the left hand side beginning with
1978 models. When an over-voltage tripoff occurs the over-voltage sensor turns off the
alternator system and the red warning light comes on. The ammeter will show a discharge.
Turn off bolt sections of the master switch to recycle the over-voltage sensor. If the overvoltage condition was transient, the normal alternator charging will resume and no further
action is necessary. If the over-voltage tripoff recurs, then a generating system malfunction
has occurred such that the electrical accessories must be operated from the aircraft battery
only. Conservation of electrical energy must be practiced until the flight can be terminated.
The over-voltage light filament may be tested at any time by turning off the "Alternator"
portion of the master switch and leaving the battery portion on. This test does not induce an
over-voltage condition on the electrical system.

16-35

MODEL 172 SERIES SERVICE MANUAL

NOTE
The over-voltage sensor switch contains solid state
devices. Observe proper polarity before supplying
power. Grounding the orange lead or interconnecting
orange and black leads will destroy the device. When
removal is required for replacement. identify (tag) wiring and follow the wiring diagram in Section 20 for
rewiring.
Beginning with 1979 Models the over-voltage sensor is contained within the alternator
control unit. The unit also contains a low-voltage sensor. A red warning light labeled"LOW
VOLTAGE" is installed on the instrument panel. When an over-voltage condition occurs the
over-voltage sensor turns off the alternator and the voltage in the system drops. When
system voltage drops below 24.5 volts the low-voltage sensor turns on the low-voltage light
indicating a drain on the battery and the ammeter will show a discharge. Turn off both
sections of the master switch to recycle the over-voltage sensor. If the over-voltage
condition was transient. the normal alternator charging will resume and no further action is
necessary. If the over-voltage tripoff recurs, then a generating system malfunction has
occurred such that the electrical accessories must be operated from the aircraft battery only.
Conservation of electrical energy must be practiced until the flight can be terminated. The
over-voltage light filament may be tested at any time by turning off the "Alternator" portion
of the master switch and leaving the battery portion on. This test does not induce an overvoltage condition on the electrical system.
16-41.

ALTERNATOR VOLTAGE REGULATOR.

16-42.

DESCRIPTION. Thru 1977 Models the voltage regulator is semi-solid state. The mechanical
relay in the regulator is actuated by the aircraft master switch and connects the regualtorto
the battery. The solid state portion is voltage sensitive and controls the current applied to
the field windings of the alternator. The regulator is a remove and replace item and not
repairable. The regulator is adjustable, but adjustment on the aircraft is not recommended.
A bench adjustment procedure is outlined in the Cessna Alternator Charging Systems
Service/ Parts Manual Thru 1978 Models the voltage regualtor is solid-state. The regualtor
is a remove-and replace item and not repairable. The regulator is adjustable. but adjustment
on the aircraft is not recommended. A bench adjustment procedure is outlined in the Cessna
Alternator Charging Systems Service/Parts Manual A Cessna Alternator Charging
System Test Box Assembly (PN-9870000-1) is available through the Cessna Service/Parts
Center for use in isolating failures in the 28-volt regulator and the 28-volt alternator. Refer to
paragraph 16-43 for removal and installation.

16-42A. ALTERNATOR CONTROL UNIT.
16-42B. DESCRIPTION. The alternator control unit is a solid state voltage regulator with an overvoltage sensor and low-voltage sensor incorporated in the unit The control unit is not
adjustable and is a remove and replace item. A Cessna Alternator Charging System Test
Box Assembly (PN9870005) is available through the Cessna Service/Parts Center for use in
isolating failures in the 28-volt alternator control units (C811005-0101 and C611005-0102) and
the 28-volt alternator.

16-36

MODEL 172 SERIES SERVICE MANUAL

Detail

THRU 1977 MODELS

1.
2.
3.
4.
5.
6.

Voltage Regulator
Screw
Housing
Wire Shields to Ground
Wire to Alternator "F"
Wire to Alternator "A+"

7.
8.
9.
10.
11.
12.

Wire to Overvoltage Light
Wire to Filter
Wire to Alternator Ground
Filter - Radio Noise
Wire to Master Switch
Shield - Ground

Figure 16-5. Voltage Regulator Installation (Sheet 1 of 5)
16-37

MODEL 172 SERIES SERVICE MANUAL

Detail A

Detail B
Rotated 180°

1.
2.
3.
4.

Housing Plug
Housing Cap
Ground Wire
Over-Voltage Sensor

5. Mounting Bracket
6. Screw
7. Voltage Regulator
8. Firewall
1978 MODELS

Figure 16-5. Voltage Regulator Installation (Sheet 2 of 5)
16-38

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.

Detail A

Housing Plug
Alternator Control Unit
Firewall
Ground Wire
Housing Cap
Bolt

1979 MODELS

Figure 16-5. Voltage Regulator Installation (Sheet 3 of 5)
16-39

MODEL 172 SERIES SERVICE MANUAL

BEGINNING WITH 17271453
AND F17201795

7
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

Wire to Alternator
Wire to Alternator Circuit Breaker
Terminal Block
Alternator Ground
Alternator Control Unit
Housing-Plug
Sta-Strap
Housing Cap
Ground Wire
Cover
Washer

BEGINNING WITH 1981 MODELS

17276885 THRU 17276199 AND
F17201910 THRU F17202233

Figure 16-5. Voltage Regulator Installation (Sheet4 of 5)
16-40

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

Wire to Alternator
Wire to Alternator Circuit Breaker
Terminal Block
Alternator Ground
Alternator Control Unit
Housing-Plug
Sta-Strap
Housing Cap
Ground Wire
Cover
Spacer

BEGINNING WITH 17276200
AND F17202234

Figure 16-5. Voltage Regulator Installation (Sheet 5 of 5)
16-40A/(16-40B blank)

MODEL 172 SERIES SERVICE MANUAL
16-43.

REMOVAL AND INSTALLATION. (See figure 16-5.)
a. Remove upper half of engine cowl.
b. Place master switch in the "OFF" position.
c. Disconnect negative lead from the battery and pull lead free of the battery box.
d. Disconnect housing plug from the regulator/ alternator control unit.
e. Remove screws securing the regulator/alternator control unit to the firewall.
f. To install regulator/alternator control unit, reverse the preceding steps. Be sure the
connections for grounding are clean and bright before assembly. Otherwise faulty
voltage regulation and/or excessive radio noise may result.

16-44.

AIRCRAFT LIGHTING SYSTEM.

16-45.

DESCRIPTION. The aircraft lighting system consists of landing and taxi lights. navigation
lights, anti-collision strobe lights, flashing beacon light. dome. instrument flood lights and
courtesy light, control wheel map light, compass and radio dial lights.

16-46.

TROUBLE SHOOTING.
TROUBLE

LANDING AND TAXI
LIGHT(S) OUT.

LANDING AND/OR TAXI
LIGHT OUT.

FLASHING BEACON DOES
NOT LIGHT.

PROBABLE CAUSE

REMEDY

Short circuit in wiring.

1. Inspect circuit breaker.
If open. proceed to Step 2.
If ok. proceed to Step 3.

Defective wiring.

2. Test each circuit separately until short is located.
Repair or replace wiring.

Defective switch.

3. Check voltage at lights
with master and landing and
taxi light switches ON.
Should read battery voltage.
Replace switch.

Lamp burned out.

1. Test lamp with ohmmeter
or new lamp. Replace lamp.

Open circuit in wiring.

2. Test wiring for continuity.
Repair or replace wiring.

Short circuit in wiring.

1. Inspect circuit breaker.
If open. proceed to Step 2.
If ok, proceed to Step 3.

Defective wiring.

2. Test circuit until short
is located. Repair or
replace wiring.

Lamp burned out.

3. Test lamp with ohmmeter
Replace lamp. If lamp is
good, proceed to Step 4.

16-41

MODEL 172 SERIES SERVICE MANUAL
16-46.

TROUBLE SHOOTING (Cont).
PROBABLE CAUSE

TROUBLE
FLASHING BEACON DOES
NOT LIGHT (Cont).

REMEDY

Open circuit in wiring.

4. Test circuit from lamp
to flasher for continuity. If
no continuity is present. repair or replace wiring. If
continuity is present. proceed to Step 5.

Defective switch.

5. Check voltage at flasher
with master and beacon
switch on. Should read bat-

tery voltage. Replace switch.
If voltage is present, proceed to Step 6.
Defective flasher.

6. Intall new flasher.

FLASHING BEACON
CONSTANTLY LIT.

Defective flasher.

1. Install new flasher.

ALL NAV LIGHTS OUT.

Short circuit in wiring.

1. Inspect circuit breaker.
If open. proceed to Step 2.
If ok. proceed to Step 3.

Defective wiring.

2. Isolate and test each nav
light circuit until short is
located. Repair or replace
wiring.

Defective switch.

3. Check voltage at nav light
with master and nav light
switches on. Should read battery voltage. Replace switch.

Lamp burned out.

1. Inspect lamp. Replace
lamp.

Open circuit in wiring.

2. Test wiring for continuity.
Repair or replace wiring.

ONE NAV LIGHT OUT.

WARNING
The anti-collision system is a high voltage device. Do not
remove or touch tube assembly while in operation. Wait
at least 5 minutes after turning off power before starting
work.

1642

MODEL 172 SERIES SERVICE MANUAL
16-46.

TROUBLE SHOOTING (Cont).
PROBABLE CAUSE

TROUBLE
BOTH ANTI-COLLISION
STROBE LIGHTS WILL
NOT LIGHT.

Open circuit breaker.

REMEDY
1. Check. if open reset. If
circuit breaker continues to
open proceed to Step 2.
2. Disconnect red wire between aircraft power supply
(battery/external power) and
strobe power supplies, one
at a time. If circuit breaker
opens on one strobe power
supply, replace strobe power.
If circuit breaker opens
on both strobe power supplies proceed to Step 3. If
circuit breaker does not
open proceed to Step 4.
3. Check aircraft wiring.
Repair or replace as necessary.
4. Inspect strobe power
supply ground wire for contact with wing structure.

CAUTION
Extreme care should be taken when exchanging flash
tube. The tube is fragile and can easily be cracked in a
place where it will not be obvious visually. Make sure the
tube is seated properly on the base of the nav light
assembly and is centered in the dome.
NOTE
When checking defective power supply and flash tube,
units from opposite wing may be used. Be sure power
leads are protected properly when unit is removed to
prevent short circuit.

16-43

MODEL 172 SERIES SERVICE MANUAL
16-46.

TROUBLE SHOOTING (Cont).
TROUBLE

ONE ANTI-COLLISION
STROBE LIGHT WILL
NOT LIGHT.

PROBABLE CAUSE
Defective Strobe Power
Supply. or flash tube.

REMEDY
1. Connect voltmeter to red
lead between aircraft power
supply (battery/external power)
and strobe power supply. connecting negative lead to wing
structure. Check for 12 volts.
thru 1977 models and 24 volts
beginning with 1978 models.
If ok proceed to Step 2 If
not, check aircraft power supply
(battery/ external power).
2. Replace flash tube with
known good flash tube. If
system still does not work.
replace strobe power supply.

DOME LIGHT TROUBLE.

Short circuit in wiring.

1. Inspect circuit breaker.
If circuit breaker is open.
proceed to Step 2. If circuit
breaker is ok. proceed to
Step 3.

Defective wiring.

2. Test circuit until short
is located. Repair or
replace wiring.
3. Test for open circuit.
Repair or replace wring. If
no short or open circuit is
found. proceed to Step 4.

INSTRUMENT LIGHTS
WILL NOT LIGHT.

16-44

Lamp burned out.

4. Test lamp with ohmmeter
if defective. Replace lamp.

Defective switch.

5. Check for voltage at dome
light with master and dome
light switch on. Should read
battery voltage. Replace switch.

Short circuit in wiring.

. Inspect circuit breaker.
If open, proceed to Step 2.
If ok. proceed to Step 3.

Defective wiring.

2. Test circuit until short
is located. Repair or
replace wiring.

MODEL 172 SERIES SERVICE MANUAL
16-46.

TROUBLE SHOOTING (Cont).

TROUBLE

PROBABLE CAUSE

REMEDY

INSTRUMENT LIGHTS
WILL NOT LIGHT (Cont).

Defective wiring.

3. Test for open circuit.
Repair or replace wiring.
If no short or open circuit
is found, proceed to Step 4.

Faulty section in dimming potentiometer.

4. Lights will work when
control is placed in brighter
position. Replace potentiometer.

Faulty light dimming
transistor.

5. Test both transistors
with new transistor. Replace
faulty transistor.

Faulty selector switch.

6. Inspect. Replace switch.

Open resistor or wiring
in minimum intensity end
of potentiometer.

1. Test for continuity. Replace resistor or repair
wiring.

Shorted transistor.

2. Test transistor by substitution. Replace defective transistor.

Nav light switch turned off.

1. Nav light switch has to
be ON before map light will
light.

Short circuit in wiring.

2. Check lamp fuse on terminal board located on back
of stationary panel with ohmmeter. If fuse is open. proceed
to Step 3. If fuse is ok. proceed to Step 4.

Defective wiring.

3. Test circuit until short
is located. Repair or
replace wiring.

INSTRUMENT LIGHTS
WILL NOT DIM.

CONTROL WHEEL MAP
LIGHT WILL NOT LIGHT.

4. Test for open circuit.
Repair or replace wiring.
If a short or open circuit
is not found, proceed to
Step 5.
Defective map light
assembly.

5. Check voltage at map
light assembly with master
and nav switches on. If battery voltage is present. replace map light assembly

16-45

MODEL 172 SERIES SERVICE MANUAL
16-47.

LANDING AND TAXI LIGHT. (THRU 17275034 AND F17202135.)

16-48.

DESCRIPTION. The landing and taxi light is mounted in the nose cap of the lower cowl. The
lamp is controlled by a rocker type switch on the instrument panel. A circuit breaker on the
panel protects the system.

16-49.

REMOVAL AND INSTALLATION. (See figure 16-6.)
a. Remove upper half of engine cowl.
b. Disconnect lamp wires then remove lower half of cowl.
c. Remove screws (7) and remove lamp assembly.

NOTE
Note position and number of washers-between support (2)
and bracket (3).
d. Remove screws (9) then remove gaskets (5) and lamp.
e. To install reverse the preceding steps.
16-50.

ADJUSTMENT OF LANDING AND TAXI LIGHT. (THRU 17275034 AND F17202134.) (See
figure 16-6.) Adjustment of the landing and taxi light is pre-set at the factory, however
changes to this adjustment may be made as desired by adding or subtracting from the
number of washers (8). A maximum of two washers may be used.

16-51.

LANDING AND TAXI LIGHTS (DUAL).

16-52.

DESCRIPTION. Thru 17275034 and F17202134 the landing and taxi lights are cowl mounted.
Beginning with 17275035 and F17202135, the landing and taxi lights are wing-mounted. The
left hand light is used for taxi and the right hand for landing. Two rocker type switches on the
pilots switch panel control the lights. A 20 amp circuit breaker is installed to protect the
system. See figure 16-6 for adjustment.

NOTE
On Aircraft Serials 17261899 thru 17270181 and F17201035
thru F17201675, refer to Cessna Single-Engine Service
Letter SE78-15 dated March 20. 1978.
16-53. - REMOVAL AND INSTALLATION. (See figure 16-6.)
a. THRU 17275034 AND F17202134.
1. Remove screws (1) and pull bracket assembly (2) from nose cap to gain access to
electrical leads.
2. Disconnect electrical leads from lamps making sure switches are off and leads do
not short out.
3. Remove screws (9) from plate (7) and remove lamp assembly from bracket (2). If
left hand (taxi) light is being removed, not position of spacers (3) and (11) for
reinstallation.
4. Remove screws (10) from bracket (4) and remove gaskets and lamp.
5. Install new lamp reassemble.
b.

16-46

BEGINNING WITH 17275035 AND F17202135.
1. Remove screws (2) and remove lens assembly (1).
2. Remove screws (3) and remove brackets (4) and (5).
3. Pull lamp (6) forward and disconnect electrical leads.
4. If plates (8) are to be removed, remove screws (7), plates (8), and spacers (9), (10).
(11), (12). (13), and (14). Note position of spacers for reinstallation.
5. To install, reverse the preceding procedure.

MODEL 172 SERIES SERVICE MANUAL

Park the aircraft 3 feet from
a wall or any suitable light
reflecting surface (distance
is measured between landing
light and wall). With the nose
gear shock strut extended 2
inches, the center of the landing
light beam on the wall should
be 35 3/4 inches above the floor.

5
4

Detail A

1.
2.
3.
4.
5.
6.
7.
8.
9.

Figure 16-6.

Landing Light Support
Bracket Assembly
Plate
Lamp
Gasket
Bracket
Adjustment Screw
Washer
Screw

Landing and Taxi Light Installation (Sheet 1 of 3)
16-47

MODEL 172 SERIES SERVICE MANUAL
OPTIONAL

A minimum of one gasket and
a maximum of two (2) gaskets
may be installed to secure lamp.

are
lightposition
or taxi
landing
wall
on the above
beam (right hand) should
to note
be sure
removed
35 3/4 inchesWhen
be
Park the aircraft 3 feet from
a wall or any suitable light

Detail A

4.
7. Bracket
Plate

light
landinglight
measured
of the landing
the
center between
and wall). With the nose gear

beam (right hand) on the wall
should be 35 3/4 inches above
the floor. The center of the taxi
light beam, (left hand) on the
wall should be 32 1/8 Inches
above the floor.

Figure 16-6.
16-48

2. Bracket Assembly

. Spacer

reflecting surface (distanc e is
shock strut extended 2 inches,
the center of the landing light

8. Nose Cap

ScreW
1.9. Screw

NOTE
Cap
8. Nose
When landing or taxi light are
9. Screw
removed be sure to note position
10. Screw
of spacers for reinstallation
11. Washer

Landing and Taxi Light Installation (Sheet 2 of 3)

MODEL 172 SERIES SERVICE MANUAL
Park the aircraft on a level
surface in front of a light reflecting surface. Distance
from surface to be three feet
measured from the front spar
bottom rivet line. The aircraft
waterline shall be level. the
center of the light beam above
ground shall be; landing light
74.41 inches and taxi light
73.29 inches. Add AN960-10
washers between and plate to
obtain proper adjustment.

1. Lens Assembly
2. Screw
3. Screw
4. Bracket
5. Bracket
6. Lamp
7. Screw
8. Plate

9.
10.
11.
12.
13.
14.
15.

Spacer
Spacer
Spacer
Spacer
Spacer
Spacer
Nutplate

Figure 16-6. Landing and Taxi Light Installation (Sheet 3 of 3)

16-49

MODEL 172 SERIES SERVICE MANUAL
16-54.

NAVIGATION LIGHTS.

16-55.

DESCRIPTION. The navigation lights are mounted on each wing tip and the aft end of the
vertical fin tip. The lights are controlled by a rocker type switch located on the instrument
panel. A circuit breaker is installed on the panel to protect the system.

16-56.

REMOVAL AND INSTALLATION. For removal and installation of the navigation lights.
see figure 16-7.

16-57.

ANTI-COLLISION STROBE LIGHTS.

16-58.

DESCRIPTION. A white strobe light may be installed on each wing tip with the navigation
lights. Strobe lights are vibration resistant and operate on the principle of a capacitor
discharge into a xenon tube, producing an extremely high intensity flash. Energy is
supplied to the lights from individual power supplies mounted on each wing tip rib.

16-59.

REMOVAL AND INSTALLATION. For removal and installation of strobe light and power
supply, see to figure 16-7.
WARNING
This anti-collision system is a high voltage device. Do
not remove or touch tube assembly while in operation.
Wait at least 5 minutes after turning off power before
starting work.

16-60.

OPERATIONAL REQUIREMENTS (THRU 1977 MODELS).
CAUTION
The capacitors in the strobe light power supplies must be
reformed if not used for a period of (6) months. The
following procedure must be used.
Connect the power supply, red wire to plus. black to ground to 6 volt DC source. Do not
connect strobe tube. Turn on 6 volt supply. Note current draw after one minute. If less than 1
ampere. continue operation for 24 hours. Turn off DC power source. Then connect to proper
voltage. 12 volt. Connect tube to outputof strobe power supply and allow to operate. flashing.
for 15 minutes. Remove strobe tube. Operating power supply at 12 volts, note the current
drain after one minute. If less than 0.5 amperes. operate for 6 hours. If current draw is greater
than 0.5 amperes, reject the unit.

16-61.

FLASHING BEACON.

16-62.

DESCRIPTION. The flashing beacon light is attached to the vertical fin tip. The lamp is
iodine-vapor, electrically switched by a solid-state flasher assembly. The flasher assembly
is mounted in the aft section of the tailcone. The switching frequency of the flasher assembly
operates the beacon at approximately 45 flashes per minute. A 1.5 ohm resistor is installed
thru 1977 models and a 6 ohm resistor is installed to eliminate a pulsing effect on the cabin
lighting and ammeter.

16-63.

REMOVAL AND INSTALLATION. For removal and installation of flashing beacon, see
figure 16-8.

16-50

MODEL 172 SERIES SERVICE MANUAL

1. Electrical Leads
2. Cap
3. Washer
4. Insulated Washer
5. Spring
6. Insulator
7. Wing Tip
8. Receptacle
9. Gasket

10.
11.
12.
13.
14.
15.
16.
17.
18.

Figure 16-7.

Flash Tube Assembly
Screw
Lens Retainer
Lens
Bulb
Seal
Mount
Wing Tip Rib
Power Supply

Detail B
THRU 17268211

Navigation and Anti-Collision Strobe Light Installation
Revision 3

16-51

MODEL 172 SERIES SERVICE MANUAL
THRU 17272894
BEGINNING WITH 17272895

Detail A

1.
2.
3.
4.

Dome
Gasket
Lamp
Screw

5. Baffle
6. Clamp Assembly
7. Plate - Mounting
8. Socket Assembly
9. Nut Plate

10.
11.
12.
13.

Tip Assembly - Fin
Housing- Plug
Housing- Cap
Fin Assembly

14.
15.
16.
17.
18.

Flasher Assembly
Bulkhead
Resistor
Spacer
Z Bracket

Figure 16-8. Flashing Beacon Light Installation (Sheet 1 of 2)
16-52

MODEL 172 SERIES SERVICE MANUAL

NOTE
When installing lamp be sure
socket. assembly is installed in
mounting plate so lamp may be
installed with filament perpendicular to the longitudinal axis of the
aircraft

Detail C
BEGINNING WITH 17273742
AND F17202000
Figure 16-8. Flashing Beacon Light Installation (Sheet 2 of 2)
16-53

MODEL 172 SERIES SERVICE MANUAL
16-64.

INSTRUMENT AND DOME LIGHTS.

16-65.

DESCRIPTION. The instrument flood light and dome light are installed in the overhead
console. The dome light consists of a frosted lens and a single bulb controlled by a switch
mounted forward of the light. The instrument flood light consists of a red lens and a single
bulb controlled by an off/on switch mounted aft of the light. Intensisty of the lamp is
controlled by a rheostat switch located on the instrument panel.

16-66.

REMOVAL AND INSTALLATION. For removal and installation of instrument and dome
light, see figure 16-9.

16-67.

COURTESY -LIGHTS.

16-68.

DESCRIPTION. The courtesy lights are mounted in the underside of each wing, inboard of
the upper wing strut attach. The light consists of a lens socket and a single bulb. The lights
are controlled by the dome light switch.

16-69.

REMOVAL AND INSTALLATION. For removal and installation of the courtesy lights. see
figure 16-9.

16-70.

COMPASS AND RADIO DIAL LIGHTING.

16-71.

DESCRIPTION. The compass and radio dial lights are contained within the individual units.
The lights are controlled by the instrument flood light switch on the overhead console.
Intensity is controlled by a rheostat located on the instrument panel.

16-72.

INSTRUMENT POST LIGHTING.

16-73.

DESCRIPTION. Individual post lighting may be installed to provide non-glare instrument
lighting. The post light consists of a cap and a clean lamp assembly with a tinted lens bonded
to the decorative covers. The intensity of the post lights is controlled by the radio light
dimming rheostat located on the instrument panel.

16-74.

REMOVAL AND INSTALLATION. For removal and installation of post lamp. slide the cap
and lens assembly from the base. Slide the lamp from the socket and replace.

NOTE
When installing postlight assemblies, assemblies shall be
coated with RTV-102, General Electric, Waterford, New
York. on forward side of panel where postlight could
come in contact with sheet metal subpanel. This coating
shall insulate postlight assembly from contact with
airplane structure. Maximum coating thickness to be .03.

16-54

MODEL 172 SERIES SERVICE MANUAL
16-74A. TROUBLE SHOOTING - POSTIGHTING.
TROUBLE
LAMP WILL NOT LIGHT.

PROBABLE CAUSE

REMEDY

Defective lamp.

1. Test lamp with ohmmeter or
replace with a new lamp. If lamp
is OK, proceed to step 2.

Defective socket or open
circuit.

2. With switch on, test socket. If
defective, replace socket or

wiring.
ONE SECTION OF LAMPS
WILL NOT LIGHT.

Defective connector.

1. Test for voltage on lamp side
of connector. If voltage is not
present, check opposite side of
connector. If voltage is present.
replace pins and sockets as necessary. If voltage is not present,
check connections at terminal
block.

Defective circuit in dimming
assembly.

2. Refer to paragraph 16-74B.

Defective rheostat.

3. Check voltage at output side of
rheostat with battery switch on.
Should read battery voltage with
rheostat turned full clockwise.
Voltage should decrease as rheostat is turned counterclockwise.
If no voltage is present or voltage
has a sudden drop before rheostat
has been turned full counterclockwise replace rheostat.

ALL LAMPS OUT.

Open circuit breaker.

1. With battery switch on, check
circuit breaker. Reset if open. If
circuit breaker is set, check voltage at output side of breaker. If
no voltage is present, replace circuit breaker.

LAMPS WILL NOT DIM.

Defective resistor or rheostat.

1. Check resistor and rheostat for
continuity and resistance value.
Also, check transistors for partial
short. Refer to paragraph 16-74B.
Replace rheostat and transistor.

16-54A

MODEL 172 SERIES SERVICE MANUAL
16-74B. TROUBLE SHOOTING - TRANSISTOR BEAT SINK. Remove heat sink from airplane. Check
transistors for opens and shorts, check transistor sockets for evidence of shorting out
against heat sink, especially on the bottom side. Check that legs of transistor socket have
not been bent up against heat sink. If this has happened. you may see burned spot on the
socket leg. If the transistor sockets and wiring appear to be in good condition install trans-

istor back in heat sink and make a continuity check. Attach one lead of an ohmmeter to the
heat sink then check every pin of the pigtail plug with the other lead for continuity. (These
should not be continuity). If continuity is found, this will burn out transistors immediately.
16-75.

TRANSISTORIZED LIGHT DIMMING.

16-76.

DESCRIPTION. A remotely located, two-circuit transistorized dimming assembly is
installed to control instrument lighting. One circuit controls the compass light. map light
and instrument flood lights. The other circuit controls radio lighting. A concentric knob
arrangement on a dual rheostat assembly mounted on the instrument panel.

16-77.

REMOVAL AND INSTALLATION. For removal and installation of transistorized dimming
assembly, see figure 16-10.

16-77A. TROUBLE SHOOTING - HEAT SINK. Refer to paragraph 16-74B.

16-54B

MODEL 172 SERIES SERVICE MANUAL

Detail B
1.
2.
3.
4.
5.
6.

Tinnerman Nut
Tinnerman Screw
Reflector
Lamp
Lens
Cover

Figure 16-9.

7.
8.
9.
10.
11.
12.

Machine Screw
Grommet
Nut
Support
Pin
Adjustment Screw

13.
14.
15.
16.
17.
18.
19.

Washer
Nut Plate
Socket
Switch
Seal
Plug Button
Lens Retainer

Instrument, Dome and Courtesy Light Installation
16-55

MODEL 172 SERIES SERVICE MANUAL

4.
5.
6.
7.
8.
9.
10.
11.
12.

Knob (Radio)
Mounting Bracket
Screw
Insulator
Transistor
Washer
Relay
Diode Board
Diode

* THRU 17269308

AND F17201638

Figure 16-10. Transistorized Dimming
16-56

MODEL 172 SERIES SERVICE MANUAL
16-78.

MAP LIGHTING.

16-79.

DESCRIPTION. White map lighting and red non-glare instrument lighting are provided by
an adjustable light mounted on the upper forward part of the left door post. The switch is a
three position type with red. white and off positions. The map light contains a white bulb for
general purpose lighting and a red bulb for adjustable instrument lighting. The intensity of
the red bulb is controlled by the center portion of a concentric knob arrangement thru a dual
rheostat assembly located on the pilot's switch panel.

16-80.

REMOVAL AND INSTALLATION. (See figure 16-11.)
a. For replacement of defective lamp slide the hood and lens from the map light
assembly and remove the bayonet type bulb.
b. For removal of the map light assembly, remove the screws from the front door post
shield. Remove the washer and nut attaching the map light Remove the ground wire
from the map light screw. Detach the wires at the quick disconnect fasteners and
remove the map light assembly.

16-81.

CONTROL WHEEL MAP LIGHT.

16-82.

DESCRIPTION. The control wheel map light is mounted on the lower side of
the control wheel. Light intensity is controlled by a rheostat. For dimming
the rheostat should be turned clockwise.

16-83.

REMOVAL AND INSTALLATION. (See figure 16-12, sheet 1 of 2) (THRU
17275674)

b.
c.
d.

For easy access to map light assembly rotate control wheel 90 ° .

Label the wires connected to the map light assembly (terminal
block) and remove screws securing wires to the terminal block.
The assembly is now free for removal, Remove the two screws
securing the map light to the control wheel and remove map light
assembly.
For reassembly reverse this procedure.

16-83A. REMOVAL AND INSTALLATION. (See figure 16-12, sheet 2 of 2)
BEGINNING WITH 17275675)
a. For easy access to map light assembly rotate control wheel 90 ° .
b. To remove lamp press in and rotate counterclockwise.
c. To remove rheostat remove screws securing bracket (10).
d. Disconnect electrical leads from rheostat (8).
e. Eor reassembly reverse this procedure.
16-84.

PITOT HEATER.

16-85.

DESCRIPTION. An electrical heater unit is installed in some pitot tubes. The heater offsets
the possibility of ice formations on the pitot tube. The heater is integrally mounted in the
pitot tube and is operated by a switch on the instrument panel. (See figure 16-13.)

16-86.

CIGAR LIGHTER.

16-87.

DESCRIPTION. Thru 17275035 and F17202135 the cigar lighter (located on
the instrument panel) is equipped with a thermal-actuated circuit breaker

16-57

MODEL 172 SERIES SERVICE MANUAL

13
10

1.
2.
3.
4.
5.
6.

Nut
Washer
Grommet
Adjustment Screw
Maplight Assembly
Socket Assembly

Lamp

8.
9.
10.
11.
12.
13.
14.

Red Lamp
Lens
Hood
Screw
Front Doorpost Shield
Maplight Switch
Insulator

Figure 16-11. Map Light Installation
16-58

MODEL 172 SERIES SERVICE MANUAL

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Fuse
Nut
Washer
Control Wheel Assembly
Spacer
Map Light Assembly
Cover
Screw
Clamp
Cable Assembly

Detai A

11. Lamp

THRU 17275674

Figure 16-12. Control Wheel Map Light Installation (Sheet 1 of 2)
16-59

MODEL 172 SERIES SERVICE MANUAL

1. Fuse
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

2.Nut
Washer
Control Wheel Assembly
Insert
Map Light Assembly
Pad
Rheostat
Insert
Bracket
Knob
Setscrew
Screw
Clamp
Cable

BEGINNING WITH 17275675

Figure 16-12. Control Wheel Map Light Installation (Sheet 2 of 2)
16-60

MODEL 172 SERIES SERVICE MANUAL

Electrical Leads

2. Pitot Tube
3. Heating Element

Detail A

Figure 16-13. Heated Pitot Installation

1.
2.
3.
4.

Decorative Cover
Screw
Instrument Panel
Clock

Figure 16-14. Digital Clock Installation

16-60A/(16-60B blank)

MODEL 172 SERIES SERVICE MANUAL
which is attached to the rear of the cigar lighter. The circuit breaker will
open if the lighter becomes jammed in the socket or held in position too long.
The circuit breaker may be reset by inserting a small probe into the .078
diameter hole in the back of the circuit breaker and pushing lightly until a
click is heard.
CAUTION
Make sure master switch is "OFF"before inserting probe
into circuit breaker on cigar lighter to reset
1687A. CLOCK.
16-87B. DECRIPTION. Thru 1978 Models an electric clock may be installed in the aircraft. During
the 1979 Models a digital clock may be installed. The digital clock has the capability of date
and second rea out as well as time. Both clocks are installed in. the instrument panel in the
same manner, see figure 16-14.
16-88.
16-89.

EMERGENCY LOCATOR TRANSMITTER. (THRU 17268576)
DESCRIPTION. The ELT is a self-contained, solid state unit, having its own power supply.
with an externally mounted antenna. The C589511-0209 transmitter is designed to transmit
simultaneously on dual emergency frequencies of 121.5 and 243.0 Megahertz. The C5895100211 transmitter thru 17265192 and the C589510-0212 beginning with 17265193 used for
Carnadian registry, operates on 121.5 only. The unit is mounted in the tailcon, aft of the baggage curtain on the right hand side. The transmitters are designed to provide a broadcast
tone that is audio modulated in a swept manner over the range of 1600 to 300 Hz in a distinct, easily recognizable distress signal for reception by search and rescue personnel and
others monitoring the emergency frequencies. Power is supplied to the transmitter by a battery-pack which has the service life of the batteries placarded on the batteries and also on
the outside end of the transmitter. ELT's are equipped with a battery-pack containing
alkline "D" size batteris batteries (See figure 16-13). The ELT exhibits line of sight transmisson characteristics which correspond approximately to 100 miles at a search altitude of
10,000 feet. When battery inspection and replacement schedules are adhered to, the transmitter will broadcast an emergency signal at rated power (75 MW-minimum), for a continuous period of time as listed in the following table.
TRANSMITTER LIFE
TO 75 MILLIWATTS OUTPUT

Temperature

+130°F
+ 70°F
- 4°F
- 40°F

4 Cell
Lithium
Battery Pack
115
115
95
23

hrs
hrs
hrs
hrs

Battery-packs have a normal shelf life of five to ten (5-10) years and must be replaced at 1/2
of normal shelf life in accordance with TSO-C91. Cessna specifies 5 years replacement of
lithium (4-cell) battery packs.

16-61

MODEL 172 SERIES SERVICE MANUAL
16-90.

NOTE
Transmitter is also attached to the mounting bracket by
velcro strips: pull transmitter to free from mounting
bracket and velcro.

CAUTION
Do not leave the emergncy locator transmitter in the ON
position longer than 1 second (3 sweeps of the warble
tone) or you may activate downed aircraft procedures by
C.A.P., D.O.T. or F.A.A. personnel.
16-91.

CHECKOUT INTERVAL
100 HOURS OR THREE MONTHS, WHICHEVER COME FIRST.
a. Turn aircraft master switch ON.
b. Turn aircraft transceiver ON and set frequency on receiver to 121.5 MHz.
c. Remove the ELT's antenna cable from the ELT unit.
d. Place the ELTs function selector switch in the ON position for 1 second or less. Immediately replace the ELT function selector switch in the ARM position after testing
ELT.
e. Test should be conducted only within the time period made up of the first five minutes after any hour.

CAUTION
Tests with the antenna connected should be approved and
confirmed by the nearest control tower. The FAA/DOT allows free space transmission tests from the airplane anytime within five minutes after each hour. The tst

time

allowed is generally three sweeps of the warble tone, or
approximately one second. The control tower should be
notified that a test is about to be performed.
NOTE
After accumulated test or operation time equals 1 hour,

battery-pack replacement is required Do Not use substitute battery-pack.
f.
16-92

16-62

Check calendar date for replacement of battery-pack. This date is supplied on a
sticker attached to the outside of the ELT case and to each battery.

REMOVAL AND INSTALLATION OF TRANSMITTER (See figure 16-15.)
a. Remove baggage curtain to gain access to the transmitter and antenna
b. Disconnect co-axial cable from end of transmitter.
c. Cut sta-strap securing antenna cable and unlatch metal strap to remove transmitter.

MODEL 172 SERIES SERVICE MANUAL

NOTE
Metal Strap (4) must be positioned so that
latch is on top of transmitter as installed
in the aircraft and not across transmitter
cover.

1.
2.
3.
4.
5.
6.
7.
8.

Tailcone Skin
Bracket
Fabric Fastener - Hook
Metal Strap
Fabric Fastener - Pile
Transmitter
Cover
Access Cover

9.
10.
11.
12.
13.
14.
15.
16.

Connector
Arm Switch
Co-axial Cable
Sta-strap
Rubber Washer
Rubber Boot
Antenna
Doubler

Figure 16-15. Emergency Locator Transmitter Installation
16-63

MODEL 172 SERIES SERVICE MANUAL
NOTE
To replace velcro strips, clean surface thoroughly with
clean cloth saturated in one of the following solvents:
Trichloric thylene. Aliphatic Napthas. Methyl Ethyl
Ketone or Enmar 6094 Lacquer Thinner. Cloth should be
folded each time the surface is wiped to present a clean
area and avoid redepositing of grease. Wipe surface
immediately with clean dry cloth, do not allow solvent to
dry on surface. Apply Velcro #adhesiveto each surface in
a thin even coat and allow to dry until quite tacky. but no
longer transfers to the finger when touched (usually
between 5 and 30 minutes). Porous surfaces may require
two coats. Place the two surfaces in contact and press
firmly together to ensure intimate contact. Allow 24
hours to complete cure.
d.

To reinstall transmitter, reverse preceding steps.
NOTE
An installation tool is required to properly secure stastrap. This tool may be purchased locally or ordered from
the Panduit Corporation. Tinley Park, III,
part number
GS-2B (Conforms to MS90387-1).
CAUTION
Ensure that the direction of flight arrows (placarded on
the transmitter) are pointing towards the nose of the
aircraft.

16-93.

REMOVAL AND INSTALLATION OF ANTENNA. (See figure 16-15.)
a. Disconnect co-axial cable from base of antenna.
b. Remove the nut and lockwasher attaching the antenna base to the fuselage and the
antenna will be free for removal.
c. To reinstall the antenna, reverse the preceding steps.
NOTE
Upon reinstallation of antenna, cement rubber boot (14)
using RTV102. General Electric Co. or equivalent, to
antenna whip only; do not apply adhesive to fuselage
skin or damage to paint may result.

16-94.

REMOVAL AND INSTALLATION OF LITHIUM FOUR (4) CELL BATTERY-PACK. (See
figure 16-16.)
NOTE
When existing battery fails or exceeds normal expiration
date, convert ELT System to new D/M alkaline powered
ELT per Avionics Service Letter AV78-31. dated
November 10, 1978.

16-64

MODEL 172 SERIES SERVICE MANUAL

TRANSMITTER
C5895100209

BATTERY PACK
C589510-0210

NOTE
A PVC spacer is installed in this position on the C5895100213 battery pack used in the C589510-0212 transmitter
used on Canadian aircraft

Figure 16-16. Lithium 4 Cell Battery Pack Installations
16-65

MODEL 172 SERIES SERVICE MANUAL
NOTE
Transmitters equipped with the 4 cell battery-pack can
only be replaced with another 4 cell battery-pack.
a.
b.

After the transmitter has been removed from aircraft in accordance with para 16-92.
place the transmitter switch in the OFF position.
Remove the four screws attaching the cover to the case and then remove the cover to
gain access to the battery-pack.
NOTE
Retain the rubber gasket and screws for reinstallation.

c.
d.
e.

Disconnect the battery-pack electrical connector and remove battery-pack.
Place new battery-pack in the transmitter with four batteries as shown in the case in
figure 16-16.
Connect the electrical connector as shown in figure 16-16.

NOTE
Before installing the new 4 cell battery-pack, check to
ensure that its voltage is 112 volts or greater.
CAUTION
It is desirable to replace adhesive material on the 4 cell
battery-pack, use only 3M Jet Melt Adhesive #3738. Do not
use other adhesive materials since other materials may
corrode the printed circuit board assembly.
f. Replace the transmitter cover and gasket.
g. Remove the old battery-pack placard from the end of transmitter and replace with
new battery-pack placard supplied with the new battery-pack.
CAUTION
Be sure to enter the new battery-pack expiration date in
the aircraft records. It is also recommended this date be
placed in your ELT Owner's Manual for quick reference.
16-95.

16-66

TROUBLE SHOOTING. Should your Emergency Locating Transmitter fail the 100 Hours
performance checks, it is possible to a limited degree to isolate the fault to a particular area
of the equipment. In performing the following trouble shooting procedures to test peak
effective radiated power, you will be able to determine if battery replacement is necessary or
if your unit should be returned to your dealer for repair.

MODEL 172 SERIES SERVICE MANUAL
16-95.

TROUBLE SHOOTING.
TROUBLE

*POWER LOW

PROBABLE CAUSE
Low battery voltage.

REMEDY
1. Set toggle switch to off.
2. Remove plastic plug from

the remote jack and by means
of a Switchcraft #750 jackplug, connect a Simpson 260
model voltmeter and measure voltage. If the batterypack transmitters is 11.2
volts or less, the batterypack is below specification.
Faulty transmitter.

3. If the battery-pack voltage meets the specifications
in Step 2, the battery-pack
is ok. If the battery is ok.
check the transmitter as
follows:
a. Remove voltmeter.
b. By means of Switchcraft
#750 jackplug and 3 inch
maximum long leads, connect
a Simpson Model 1223 ammeter to the jack.
c. Set the toggle switch to
ON and observe the ammeter
current drain. If the current
drain is in the 85-100 ma
range, the transmitter or
the co-axial cable is faulty.

Faulty co-axial
antenna cable.

4. Check co-axial antenna
cable for high resistance
joints. If this is found to
be the case, the cable should
be replaced.

*This test should be carried out with the co-axial cable provided with your unit.

16-67

MODEL 172 SERIES SERVICE MANUAL
16-96.

EMERGENCY LOCATOR TRANSMITTER. (BEGNNING WITH 17268577)

16-97.

DESCRIPTION. The ELT is a self-contained, solid state unit, having its own power supply
with an externally mounted antenna. The unit is mounted in the tailcone, aft of the baggage
curtain on the right hand side. The transmitters are designed to provide a broadcast tone
that is audio modulated in a swept manner over the range of 1600 to 300 Hz in a distinct,
easily recogniable distress signal for reception by search and rescue personnel and others
monitoring the emergency frequencies. The ELT exhibits line of sight transmission characteristics which correspond approximately to 100 miles at a search altitude of 10000 feet.
The C589511-0103 transmitter on domestic aircraft, and the C589511-0104 transmitter on
aircraft with Canadian registry, are used thru 17271034 and F17201749. The C5895110117 transmitter on domestic aircraft, and the C589511-0113 transmitter on aircraft with
Canadian registry, are used 17271035 thru 17275871 and F17201750 thru F17202194. Be
ginning with 17275915 and F17202195 the C589512-0103 transmitter is used on all aircraft.
The C589511-0104 transmits on 121.5 MHz at 25 mw rated power output for 100 continuous hours in the temperature range of -40°F (-40°C to + 55°C). The C589511-0113 transmits
on 121.5 MHz at 25 mw rated power output for 100 continuous hours in the temperature
range of -4°F to + 131°F (-20°C to + 55°C). The C589511-0103 transmits on 121.5 and 243.0
MHz simultaneously at 75 mw rated power output for 48 continuous hours in the temperature range of -40°F to + 131°F (-40°C to + 55°C). The C589511-0117 and C58912-0103
transmits on 121.5 and 343.0 MHz at 75 mw rated power output for 48 continuous hours in
the temperature range of -4°F to + 131°F (-20°C to 55°C).
Power is supplied to the transmitter by a battery-pack. The C589511-0104 and C5895110103 ELTs equipped with a lithium battery-pack must be modified by SK185-20 as outlined
in Avionics Service Letter AV78-31, dated 20 November, to incorporate alkaline batterypacks. The C589511-0114
alkaline battery-packs have the service life of the battery-pack
stamped on the battery-pack, on the end of the transmitter below the switch and on top of
the transmitter. The C589512-0107 alkaline battery-packs have the replacement date and
date of installation on the battery-pack and the replacement date on the top of the transmitter.

16-98.

OPERATION. A three position switch on the forward end of the unit controls operation.
Placing the switch in the ON position will energize the unitto starttransmittingemergency
signals. In the OFF position, the unit is inoperative. Placing the switch in the ARM position
will set the unit to start transmitting emergency signals only aftertheunithas received a5g
(tolerances are -2g and -0g) impact force, for a duration of 11-16 milliseconds.
CAUTION
Do not leave the emergency locator transmitter in the ON
position longer than 1 second (3 sweeps of the warble
tone) or you may activate downed aircraft procedures by
C.A.P., D.O.T. or F.A.A. personnel.

MODEL 172 SERIES SERVICE MANUAL
16-99.

CHECKOUT INTERVAL:
100 HOURS, OR THREE MONTHS. WHICHEVER COMES FIRST.
a.
b.
c.
d

Turn aircraft master switch ON.
Turn aircraft transceiver ON and set frequency on receiver to 121.5 MHz.
Remove the ELT's antenna cable from the ELT unit.
Place the ELT's function selector switch in the ON position for 1 second or less. Immediately replace the ELT function selector switch in the ARM position after testing
ELT.
Test should be conducted only within the time period made up of the first five minutes after any hour.
CAUTION
Tests with the antenna connected should be approved and
confirmed by the nearest control tower. The FAA/DOT allows free space transmision tests from the airplane anytime within five minutes after each hour. The test time
allowed is generally three sweeps of the warble tone, or
approxiamtely one second The control tower should be
notified that a test is about to be performed.
NOTE
After accumulated test or operation time equals 1 hour,

battery-pack replacement is required. Do Not use substitute battery pack.
f.

Check calendar date for replacement of battery-pack. This date is supplied on a
sticker attached to the outside of the ELT case and to each battery.

16-100. REMOVAL AND INSTALLATION OF TRANSMITTER. (See figure 16-17.)
a. Remove baggage curtain to gain access to the transmitter and antenna.
b. Disconnect co-axial cable from end of transmitter.
c. Remove the two #10 screws from the baseplate of the ELT and remove ELT
d. To reinstall transmitter, reverse preceding steps.
CAUTION
Ensure that the direction of flight arrows (placarded on
the transmitter) are pointing towards the nose of the
aircraft
16-101. REMOVAL AND INSTALLATION OF ANTENNA. (See figure 16-17.)
a. Disconnect co-axial cable from base of antenna.
b. Remove the nut and lockwasher attaching the antenna base to the fuselage and the
antenna will be free for removal.
d. To reinstall the antenna, reverse the preceding steps.
CAUTION
The C589511-0111 and C589511-0119 co-axial cable must
be installed as indicated on the cable sleeve. Cable end
marked "TO ANT" must be connected to the ELT antenna,
and the end marked "TO ELT" must be connected to the
C589511-0113/ -0117 and C589511-0103/-0104 transmitters.

16-69

MODEL 172 SERIES SERVICE MANUAL

Detail A
THRU 17271034 AND F17201749

1.
2.
3.
4.
5.
6.

Cabin Skin
Bracket
Transmitter
Cover
Screw
Battery Pack

Figure 16-17.
16-70

7. Arm Switch
Co-axial Cable
9. Rubber washer
10. Rubber Boot
11. Antenna
12. Doubler
13. Access Cover

Detail C
ROTATED 180°

Emergency Locator Transmitter Installation (Sheet 1 of 3)

MODEL 172 SERIES SERVICE MANUAL

PLACARD

Detail B

ROTATED 180°

Figure 16-17.

Emergency Locator Transmitter Installation (Sheet 2 of 3)

16-71

MODEL 172 SERIES SERVICE MANUAL

PLACARD

Detail A
BEGINNING WITH
AND F17202195

17275872

ELT IS LOCATED BEHIND
THIS SURFACE
PLACARD LOCATED ON RIGHT
HAND SIDE OF TAILCONE ADJACENT
TO ELT. ON CANADIAN AIRCRAFT.

Detail C
ROTATED 180°

Figure 16-17.
16-72

Emergency Locator Transmitter Installation (Sheet 3 of 3)

MODEL 172 SERIES SERVICE MANUAL
NOTE
Upon reinstallation of antenna, cement rubber boot (14)
using RTV102. General Electric Co. or equivalent, to
antenna whip only; do not apply adhesive to fuselage
skin or damage to paint may result.
16-102. REMOVAL AND INSTALLATION OF BATTERY PACK. (See figure 16-18.)

NOTE
Transmitters equipped with the C589511-0105 or C5895110106 battery-packs can only be replaced with a C5895110114 after modification by SK185-20 has been completed.
CAUTION
Lithium battery-pack must be replaced with alkaline
battery-packs per SK185-20.
CAUTION

Replacement battery-packs other than Dorne and Margolin (C589511-0114 or C589512-0107) battery-packs may

seriously degrade operating life, signal strength and. in
come cases, the mechanical configuration of the ELT.
a. After the transmitter has been removed from aircraft in accordance with para. 16-100.
place the transmitter switch in the OFF position.
b. Remove the four screws attaching the cover to the case and then remove the cover to
gain access to the battery-pack.
c. Disconnect the battery-pack electrical connector and remove battery-pack.
d. Place new battery-pack in the transmitter with four batteries as shown in the case in

figure 16-18.
e. Connect the electrical connector as shown in figure 16-18.
NOTE
Before installing the battery-pack, check to ensure that
its voltage is 7.5 volts or greater.
f.
g.

Replace the transmitter baseplate on the unit and pressing the baseplate and unit
together attach baseplate with four nylok patch screws.
Stamp the new replacement date on the outside of the ELT. The date should be noted
on the switching nameplate on the side of the unit as well as on the instruction
nameplate on top of the unit.
WARNING
The battery-pack has pressurized contents. Do not
recharge, short circuit or dispose of in fire.
CAUTION
Be sure to enter the new battery-pack expiration date in
the aircraft records. It is also recommended this date be
placed in your ELT Owner's Manual for quick reference.
16-72A/(16-72B blank)

MODEL 172 SERIES SERVICE MANUAL
C589511-0103 TRANSMITTER
C589511-0104 TRANSMITTER (CANADIAN)

C589511-0105 BATTERY PACK
C589511-0106 BATTERY PACK (CANADIAN)

C589511-0117 TRANSMITTER
C589511-0113 TRANSMITTER (CANADIAN

C589511-0114 DOMESTIC &
CANADIAN

Figure 16-18. Battery Pack Installation
16-73

MODEL 172 SERIES SERVICE MANUAL
16-103. TROUBLE SHOOTING. Should your Emergency Locating Transmitter fail the 100 Hours
performance checks, it is possible to a limited degree to isolate the fault to a particular area
of the equipment. In performing the following trouble shooting procedures to test peak
effective radiated power. you will be able to determine if battery replacement is necessary or
if your unit should be returned to your dealer for repair.
TROUBLE
*POWER LOW

PROBABLE CAUSE
Low battery voltage.

REMEDY
1. Set toggle switch to off.
2. Disconnect the batterypack from the transmitter
and connect a Simpson 260
model voltmeter and mea-

sure voltage. If the batterypack transmitter is 7.5
volts or less, the battery-

pack is below specification
Faulty transmitter.

3. If the battery-pack voltage meets the specifications

in Step 2. the battery-pack
is ok. If the battery is ok,
check the transmitter as
follows:
a. Reconnect battery pack
to the transmitter.

b. By means of E.F. Johnson 105-0303-001 jackplugs
and 3 inch maximum long
leads, connect a Simpson
Model 1223 ammeter to

the jack.
c. Set the toggle switch to
AUTO and observe the ammeter
current drain If the current
drain is in the 15-25 ma
range. the transmitter or
the co-axial cable is faulty.
Faulty co-axial
antenna cable.

4. Check co-axial antenna
cable for high resistance
joints. If this is found
to be the case. the cable
should be replaced.

*This test should be carried out with the co-axial cable provided with your unit.

16-74

MODEL 172 SERIES SERVICE MANUAL

ELECTRICAL LOAD ANALYSIS CHART
STANDARD EQUIPMENT (Running Load)
1978
0.45
0.11
6.0
0.67
2.5
0.28

AMPS REQD
1979
1980
1981
0.5
0.5
0.5
0.1
0.1
0.1
6.0
0.7
0.7
0.7
2.5
2.5
2.5
0.3
0.3
0.3

1982
0.5
0.1
6.0
0.7
2.5
0.3

0.1
3.0
1.0

1.0
2.25
1.09.0-

1.0
2.25
1.09.0

1.0.
2.25
1.09.0

1.0
2.25

1.0.
2.25

32
1.0

2.0

0.4

0.5

0.3

0.1

5.0

2.5
7.5
2.5
2.5
0.1
2.0
1.52.9

2.57.5
2.5
2.5
0.1
2.0

2.57.5
2.5
2.5
0.1

2.9

2.0

2.9
0.6
1.0

1977
Battery Contactor ............................
0.6
Fuel Indicators .........
...............
. 0.4
Flashing Beacon Light
....................... 7.0
Instrument Lights ...........................
1.3
Position Lights ..............................
5.6
Turn Coordinator ............................
0.8
OPTIONAL EQUIPMENT (Running Load)
Altitude Blind Encoder ......................
Strobe Lights ................................
Cessna 300 ADF (Type R-546E) ..............
1.0
Cessna 300 Nav/Com (100 Channel)
(Type RT-308C) ...................
.........
1.5
Cessna 300 Nav/Com (Type RT-385A) .......
Cessna 300 HF Transceiver (PT10-A) ........ 1.5
Cessna 300 Transceiver (Type RT-524A) .....
Cessna 300 Transponder (Type RT-359A) ....
Cessna 400 Glide Slope (Type R-443B)
(40 Channel) ...............................
Cessna 400 Glide Slope (Type R-446B)
Cessna 400 Marker Beacon (Type R-402A/B).
Sunair SS Bank HF Transceiver
(Type ASB-125) ............................

Cessna 300 A Navomatic (Type AF-395A) ... 2.0
Cessna 200 Navomatic (Type AF-295B) ...... 2.0
Cessna EA-401A Encoding Altimeter ........ 0.1
Cessna 400 Transponder (RT-459A) ..........
Cessna 300 Nav/Com (720 Channel RT-328T) 1.5
Narco 190 DME ..............................
2.9
DM E-451 .....................................
Cessna 400 XPDR (ARC Type RT-459A) ..... 2.0
2.0
Bendix GM-247A Marker Beacon ............
0.1
1.0
Pitot Heat ....................................
2.9
Post Lights .................................
.
0.6
RNAV 511....................................
RNAV AN5-351 ..............................
Interphone System ...........................
Avionics Fan ................................
ITEMS NOT CONSIDERED AS PART OF RUNNING LOAD
Cigarette Lighter ............................
10.0
7.0
Clock ...................
.....................
t
t
Control Wheel Map Light ....................
0.33
0.1
Courtesy & Dome Lights ......................
2.5
1.2
Flap Motor .................................
. 15.0
8.5
Landing and Taxi Lights (Single)............ 20.0
8.9
Landing and Taxi Lights (Dual) .............
15.6
3.6 ea
Landing and Taxi Lights .....................
Map Light (Door Post) .......................
0.33
0.2
Air Conditioner (High Blower) ..............
Ventilation System Blower (High Speed) ....
t Negligible
* Export Only

2.25 Transmitting
7.50 Transmitting

9.02.0
0.5
0.1
2.5
7.5
2.5
2.5
0.1
2.0
12
2.9
0.6
0.65
t
1.0

7.0
t
0.1
1.2
8.5
8.9
3.6 ea

0.2
6.7
5.0

9.00 Transmitting
* 6.00 Transmitting

1.0

0.1
1.2
8.5
9.0 ea
0.2
6.7
5.0

Receiving

16-75

MODEL 172 SERIES SERVICE MANUAL

ELECTRICAL LOAD ANALYSIS CHART
ALL MODELS
AMPS REQD

STANDARD EQUIPMENT (Running Load)
......
Battery Contactor .................................................
Fuel Indicators ............................................................
Flashing Beacon Light .................................................
Instrum ent Lights .......................................................
Position Lights ............................................................
Turn Coordinator ........................................................
OPTIONAL EQUIPMENT (Running Load)
Altitude Blind Encoder ................................................
Strobe Lights ..............................................................
Cessna 300 ADF (Type R-546E) ....................................
Cessna 300 Nav/Com (RT-385A) ....................................

1983

1984

1985

1986

0.5
0.1
6.0
0.7
2.5
0.3

0.5
0.1
7.0
0.7
2.5
0.3

0.1
2.0
1.0
1..0
2.25*
2.0
0.5 0.5
0.1

0.1
2.0
1.0
1.02.25*
2.0

2.5
7.5*
2.5
2.5
0.1
2.0

2.5
7.5*
7.5*
2.5
2.5
0.1
2.0

2.9
0.6

1.0

0.1
.1
3.0
3.0
1.0
1.0
1.0
1.0
2.25* 2.25*
2.0
Cessna 300 Transponder (Type RT-359A) ..................... 2.0
0.5
Cessna 400 Glide Slope (Type R-443B) (40-Channel) ...... 0.5
0.1
Cessna 400 Marker Beacon (Type R-402A or R-402B) ... 0.1
Sunair SS Bank HF Transceiver
(Type ASB-125) ..................................................... 2.5- 2.5
7.5*
Cessna 300A Navomatic (Type AF-395A) ...................... 2.5
2.5
Cessna 200 Navomatic (Type AF-295B) ......................... 2.5
2.5
0.1
Cessna EA-401A Encoding Altimeter ......................... 0.1
2.0
Cessna 400 Transponder (Type RT-459A) ..................... 2.0
1.2
1.2
DME-451 ...................................................
2.9
2.9
Pitot Heat ....................................................................
0.6
0.6
Post Lights ................................................................
0.65
RNAV AN5-351 ........................................................... 0.65
Interphone System ......................................................
0.6
0.6
.
..............................................
Avionics Fan ..
ITEMS NOT CONSIDERED PART OF RUNNING LOAD
C lock ......................................................................
0.1
Control Wheel Map Light ............................................. 0.1
1.2
1.2
..............................................
Courtesy & Dome Lights
8.5
Flap M otor .................................................................. 8.5
Landing and Taxi Lights ............................................. 9.0 ea 9.0 ea
0.2
...............................
Map Light (Door Post) ..................
6.7
6.7
Air Conditioner (High Blower) ..................................... 6.7
5.0
Ventilation System Blower (High Speed) ....................... 5.0
Standby Vacuum System ............................................
Sperry RT-377A DME .................................................
Negligible
Receiving
Transmitting

16-76

Revision 1

0.1

0.1
0.1
1.2
1.2
1.8
1.8
9.0 ea 9.0 ea
0.2
0.2
6.7
5.0
5.0
13.0
13.0
0.3
0.3

MODEL 172 SERIES SERVICE MANUAL
SECTION 18
STRUCTURAL REPAIR

TABLE OF CONTENTS

STRUCTURAL REPAIR ........
Repair Criteria ............
Equipment and Tools ........
Support Stands ...........
Fuselage Repair Jigs ......
Wing Jigs ..............
Wing Twist and Stabilizer
Angle-of-Incidence .........
Repair Materials ...........
Wing ...................
Description .............
Wing Skin ..............
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Wing Stringers
.........
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Wing Auxiliary Spars ......
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Wing Ribs ..............
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Wing Spars .............
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Ailerons .................
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Balancing
.....
....
Wing Flaps .............
Negligible Damage ......
Repairable Damage ......

Page No.
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Manual
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3A5/18-3
3A5/18-3
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3A5/18-3
3A6/18-4
3A6/18-4
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3A6/18-4
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3A6/18-4
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3A6,18-4
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3A6/18-4
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3A6/18-4
3A7/18-5
3A7/18-5
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3A7/18-5
3A7/18-5
3A7/18-5
3A7/18-5

Damage Necessitating
Replacement of Parts ....
Wing Leading Edge .......
Negligible Damage ......
Repairable Damage ......
Damage Necessitating
Replacement of Parts ....
Elevators and Rudders .......
Negligible Damage ........
Repairable Damage .......
Damage Necessitating
Replacement of Parts .....
Fin and Stabilizer .........
Negligible Damage ........
Repairable Damage ........
Damage Necessitating
Replacement of Parts .....
Fuselage ................
Description ............
Negligible Damage ........
Repairable Damage ........
Damage Necessitating
Replacement of Parts . ...
Bonded Doors .............
Repairable Damage .......
Bulkheads ................
Landing Gear Bulkheads ...
Repair After Hard
Landing
.........
Firewall Damage ..
.....
Fasteners
............
Rivets
.....
...
.....
Replacement of Hi-Shear
Rivets
. ...........
Substitution of Rivets .....
Engine Mount .............
Description .............
General Considerations ..
..
Engine Mount Radial
Support Damage .........
Damage Involving Engine
Mounting Lugs and Engine
Mount-to-Fuselage AttachFittings ............
..
Baffles .................

3A7
3A7
3A7
3A8

18-5
18-5
18-5
18-6

3A8
3A8
3A8
3A8

18-6
18-6
18-6
18-6

3A8
3A8
3A8
3A8

18-6
18-6
18-6
18-6

3A8
3A8
3A9
3A9
3A9

18-6
18-6
18-7
18-7
18-7

3A9
3A9
3A9
3A9
3A9

18-7
18-7
18-7
18-7
18-7

3A10
3A10
3A10
3A10
3A10
3A10
3A15
3A15
3A15

18-8
18-8
18-8
18-8
18-8
18-9
18-13
18-13
18-13

3A15 18-13

3A15 18-13
3A15 18-13

Revision 1

18-1

MODEL 172 SERIES SERVICE MANUAL
I Engine Cowling ............
Skin Repair .............
Reinforcement Angle
Repair
..............

3A15 18-13

Repair of Glass-Fiber

3A15 18-13

Constructed Components
Corrosion and Corrosion
Control ..............

3A15 18-13

....

3A15 18-13
3A15 18-13

18-1

STRUCTURAL REPAIR.

18-2

REPAIR CRITERIA. Although this section outlines repair permissible on structure of the
aircraft, the decision of whether to repair or replace a major unit of structure will be
influenced by such factors as time and labor available, and by a comparison of labor costs
with the price of replacement assemblies. Past experience indicates that-replacement, in
many cases, is less costly than major repair. Certainly, when the aircraftmustbe restoredto
its airworthy condition in a limited length of time, replacement is preferable. Restoration of
a damaged aircraft to its original design strength, shape, and alignment involves careful
evaluation of the damage, followed by exacting workmanship in performing the repairs.
This section suggests the extent of structural repair practicable on the aircraft, and
supplements Federal Aviation Regulation, Part 43. Consult the factory when in doubt about
a repair not specifically mentioned here.

18-3.

EQUIPMENT AND TOOLS.

18-4.

SUPPORT STANDS. Padded, reinforced sawhorse or tripod type support stands, sturdy
enough to support any assembly placed upon them, must be used to store a removed wing or
tailcone. Plans for local fabrication of support stands are contained in figure 18-1. The
fuselage assembly, from the tailcone to the firewall, must NOT be supported from the
underside. since the skin bulkheads are not designed for this purpose. Adapt support stands
to fasten to the wing attach points or landing gear attach points when supporting a fuselage.

18-5

FUSELAGE REPAIR JIGS. Whenever a repair is to be made which could affect structural
alignment, suitable jigs must be used to assure correct alignment of major attach points,
such as fuselage, firewall, wing and landing gear. These fuselage repair jigs are obtainable
from the factory.

18-6

WING JIGS. These jigs serve as a holding fixture during extensive repair of a damaged
wing, and locates the root rib, leading edge and tip rib of the wing. These jigs are also
obtainable from the factory.

18-7

WING TWIST AND STABILIZER ANGLE-OF-INCIDENCE.

18-8.

Wing twist (washout) and horizontal stabilizer angle of incidence are shown below.
Stabilizers do not have twist. Wings have no twist from the root to the lift strut station. All
twist in the wing panel occurs between this station and the tip rib. See figure 18-2 for wing
twist measurement.
WING
Twist (Washout)

3 ° 00'

STABILIZER
Angle of Incidence
18-9.

18-2

-3 ° 30'

REPAIR MATERIALS. Thickness of a material on which a repair is to be made can easily be

Revision 1

MODEL 172 SERIES SERVICE MANUAL
determined by measuring with a micrometer. In general. material used in Cessna aircraft
covered in this manual is made from 2024 aluminum alloy, heat treated to a -T3. -T4. or -T42
condition. If the type of material cannot readily be determined. 2024-T3 may be used in
making repairs. since the strength of -T3 is greater than -T4 or -T42 (-T4 and -T42 may be used
interchangeably, but they may not be substituted for -T3). When necessary to form a part
with a smaller bend radius than the standard cold bending radius for 2024-T4. use 2024-0 and
heat treat to 2024-T42 after forming. The repair material used in making a repair must equal
the gauge of the material being replaced unless otherwise noted. It is often practical to cut
repair pieces from service parts listed in the Parts Catalog. A few components (empennage
tips, for example) are fabricated from thermo-formed plastic or glass-fiber constructed
material.
18-10.

WING.

18-11.

DESCRIPTION. The standard wing assemblies are a semicantilever type. employing
semimonocoque type of structure. Basically, the internal structure consists of built-up front
and rear spar assemblies, a formed auxiliary spar assembly and formed sheet metal nose
intermediate, and trailing edge ribs. Stressed skin. riveted to the rib and spar structures.
completes the rigid structure. Access openings (hand holes with removable cover plates)
are located in the underside of the wing between the wing root and tip section. These
openings afford access to aileron bellcranks, flap bellcranks. electrical wiring, strut attach
fittings, control cables and pulleys, and control disconnect points. Beginning with 1981
Models, an optional fuel system installation employs a different wing assembly These
wings are sheet metal constructed, with a single main spar. two fuel spars. formed ribs and
stringers.
The front fuel spar also serves as an auxiliary spar and is the forward wing attaching point.
An inboard section forward of the main spar is sealed to form an integral fuel bay area. The
main spar consists of milled spar caps attaching fittings joined by a web section. The aft fuel
spar is a formed channel. The front fuel spar is a built-up assembly consisting of a formed
channel, doubler, attach strap and support angle. Stressed skin. riveted to the ribs. spars and
stringers, completes the wing structure. Access openings (hand holes with removable cover
plates) are located in the underside of the wing between the wing root and tip section. These
openings afford access to the flap and aileron bellcranks. flap drive pulleys. flap actuator in
left wing, flap and aileron control cable disconnect points, fuel adapter plate, air scoop
connectors and electrical wiring.

18-12.

WING SKIN.

18-13.

NEGLIGIBLE DAMAGE. Any smooth dents in the wing skin that are free from cracks
abrasions and sharp corners, which are not stress wrinkles and do not interfere with any
internal structure or mechanism, may be considered as negligible damage in any area of the
wing. On the optional fuel bay wing, outboard of wing station 65.125 in areas of low stress
intensity, cracks, deep scratches or sharp dents, which after trimming or stop-drilling can
be enclosed by a two-inch circle, can be considered negligible if the damaged area is at least
one diameter of the enclosing circle away from all existing rivet lines and material edges.
The area on the lower surface of the wing between the two stringers adjacent to the main spar
is not considered low stress intensity. Stop-drilling is considered a temporary repair and a
permanent repair must be made as soon as practicable.

18-14.

REPAIRABLE DAMAGE. On a standard wing. Figure 18-4 outlines typical repair to be
employed in patching skin. Before installing a patch. trim the damaged area to form a
retangular pattern. leaving at least one-half inch radius at each corner, and de-burr. The
sides of the hole should lie span-wise or chord-wise. A circular patch may also be used. If the

18-3

MODEL 172 SERIES SERVICE MANUAL
patch is in an area where flush rivets are used. make a flush patch type of repair if in an area
where flush rivets are not used. make an overlapping type of repair. Where optimum
appearance and airflow are desired. the flush patch may be used. Careful workmanship will
eliminate gaps at butt-joints: however. an epoxy type filler may be used at such joints. On the
optional fuel bay wing. repairs must not be made to the upper or lower wing skin inboard of
station 65.125 without factory approval. However, an entire skin may be replaced without
factory approval. Refer to Section 1 for wing station locations. Figure 18-4 outlines typical
repairs to be employed in patching skin. Before installing a patch. trim the damaged area to
form a rectangular pattern. leaving at least one-half inch radius at each corner and de-burr.
The sides of the hole should lie span-wise or chord-wise. A circular patch may also be used. If
the patch is in a area where flush rivets are used. make a flush patch type of repair, if in an
area where flush rivets are not used, make an overlapping type of repair. Where optimum
appearance and airflow are desired, the flush patch may be used. Careful workmanship will
eliminate gaps at butt-joints: however. an opoxy type filler may be used at such joints.
18-15.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If a skin is badly damaged.
repair must be made by replacing an entire skin panel. from one structural member to the
next. Repair seams must be made to lie along structural members and each seam must be
made exactly the same in regard to rivet size, spacing, and pattern as the manufactured
seams at the edges of the original sheet. If the manufactured seams are different, the stronger
must be copied. If the repair ends at a structural member where no seam is used, enough
repair panel must be used to allow an extra row of staggered rivets, with sufficient edge
margin. to be installed.

18-16.

WING STRINGERS.

18-17

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-18.

REPAIRABLE DAMAGE. Figure 18-5 outlines a typical wing stringer repair. Two such
repairs may be used to splice a new section of stringer material in position. without the filler
material.

18-19

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If a stringer is so badly
damaged that more than one section must be spliced. replacement is recommended.

18-20.

WING AUXILIARY SPARS.

18-21.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-22.

REPAIRABLE DAMAGE. Figure 18-8 illustrates a typical auxiliary spar repair.

18-23.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If damage to an auxiliary spar
would require a repair which could not be made between adjacent ribs, the auxiliary spar
must be replaced.

18-24.

WING RIBS.

18-25.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-26.

REPAIRABLE DAMAGE. Figure 18-6 illustrates a typical wing rib repair.

18-27.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. Leading and trailing edge ribs
that are extensively damaged can be replaced. However. due to the necessity of unfastening
an excessive amount of skin in order to replace the rib, they should be repaired if practicable.

18-4

MODEL 172 SERIES SERVICE MANUAL
Center ribs, between the front and rear spar should always be repaired if practicable.
18-28.

WING SPARS.

18-29.

NEGLIGIBLE DAMAGE. Due to the stress which wing spars encounter. very little damage
can be considered negligible. All cracks, stress wrinkles, deep scratches. and sharp dents
must be repaired. Smooth dents, light scratches and abrasions may be considered negligible.

18-30.

REPAIRABLE DAMAGE. Figure 18-7 illustrates typical spar repairs. It is often practical to
cut repair pieces from service parts listed in the Parts Catalog. Service Kits are available for
certain types of spar repairs.

18-31.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. Damage so extensive that
repair is not practicable require replacement of a complete wing spar. Also refer to
paragraph 18-2.

18-32.

AILERONS.

18-33.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-34.

REPAIRABLE DAMAGE. The repair shown in figure 18-9 may be used to repair damage to
aileron leading edge skins. Figure 18-4 may be used to repair damage to flat surfaces
between corrugations; when damage area includes corrugations. see figure 18-3A. It is
recommended that material used for repair be cut from spare parts of the same gauge and
corrugation spacing. Following repair the aileron must be balanced. Refer to paragraph 1836 and figure 18-3 for balancing the aileron. If damage would require a repair which could not
be made between adjacent ribs, see the following paragraph.

18-35.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If the damage would require a
repair which could not be made between adjacent ribs. complete skin panels must be
replaced. Ribs and spars may be repaired, but replacement is generally preferable. Where
extensive damage has occurred, replacement of the aileron assembly is recommended. After
repair and/or replacement, balance aileron in accordance with paragraph 18-36 and figure
18-3.

18-36.

AILERON BALANCING. Following repair, replacement or painting, the aileron must be balanced. A flight control surface balancing fixture kit is available (P/N 5180002-1). See figure
18-3 for procedures pertaining to the use of this kit.

18-37.

WING FLAPS.

18-38.

NEGLIGIBLE DAMAGE.Refer to paragraph 18-13.

18-39.

REPAIRABLE DAMAGE.Flap repairs should be similar to aileron repairs discussed in
paragraph 18-34. A flap leading edge repair is shown in figure 18-10. If an overlapping
patch is to be used, be sure it will not interfere with the wing during flap operation.

18-40.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. Flap repairs which require
replacement of parts should be similar to aileron repairs discussed in paragraph 18-35.
Since the flap is not considered a moveable control surface. no balancing is required.

18-41.

WING LEADING EDGE.

18-42.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-5

MODEL 172 SERIES SERVICE MANUAL
18-43.

REPAIRABLE DAMAGE. A typical leading edge skin repair is shown in figure 18-9. An
epoxy-type filler may be used to fill gaps at butt-joints. To facilitate repair. extra access
holes may be installed in the locations noted in figure 18-11. If the damage would require a
repair which could not be made between adjacent ribs. refer to the following paragraph.

18-44.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. For extensive damage. complete leading edge skin panels must be replaced. To facilitate replacement. extra access
holes may be installed in the locations noted in figure 18-11.

18-45.

ELEVATORS AND RUDDER.

18-46.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13. The exception to negligible damage on
the elevator surfaces is the front spar, where a crack appearing in the web at the hinge
fittings or in the structure which supports the overhanging balance weight is not considered
negligible. Cracks in the overhanging tip rib. in the area at the front spar intersection with
the web of the rib. also cannot be considered negligible.

18-47

REPAIRABLE DAMAGE. Skin patches illustrated in figure 18-4 may be used to repair skin
damage between corrugations. For skin damage which includes corrugations, see figure 183A. Following repair, the elevator/ rudder must be balanced. See figure 18-3 for balancing. If
damage would require a repair which could not be made between adjacent ribs. see the
following paragraph.

18-48.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If the damaged area would
require a repair which could not be made between adjacent ribs, complete skin panels must
be replaced. Ribs and spars may be repaired, but replacement is generally preferable. Where
extensive damage has occurred, replacement of the entire assembly is recommended. After
repair and/ or replacement, balance elevators and rudder in accordance with paragraph 1849 and figure 18-3.

18-49.

ELEVATOR AND RUDDER BALANCING. Following repair, replacement or painting, the
elevators and rudder must be balanced. A flight control surface balancing fixture kit is
available (P/N 5180002-1). See figure 18-3 for procedures pertaining to the use of this kit.

18-50

FIN AND STABILIZER.

18-51

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13.

18-52

REPAIRABLE DAMAGE. Skin patches illustrated in figure 18-4 may be used to repair skin
damage. Access to the dorsal area of the fin may be gained by removing the horizontal
closing rib at the bottom of the fin. Access to the internal fin structure is best gained by
removing skin attaching rivets on one side of the rear spar and ribs. and springing back the
skin. Access to the stabilizer structure may be gained by removing skin attaching rivets on
one side of the rear spar and ribs, and springing back the skin If the damaged area would
require a repair which could not be made between adjacent ribs. or a repairwould be located
in an area with compound curves, see the following paragraph.

18-53.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. If the damaged area would
require a repair which could not be made between adjacent ribs, or the repair would be
located in an area with compound curves, complete skin panels must be replaced. Ribs and
spars may be repaired, but replacement is generally preferable. Where damage is extensive.
replacement of the entire assembly is recommended.

18-54.

FUSELAGE.

18-6

18-33A. CRACKS IN CORRUGATED AILERON SKINS (Continued from page 18-5)
1.

It is permissible to stop drill crack(s) that originate at the trailing edge of the control surface provided the
crack is not more than 2 inches in length.

Stop drill crack using a #30 (.128 inch) drill.

A crack may only be stop drilled once.
NOTE: A crack that passes through a trailing edge rivet and does not extend to the trailing edge of the
skin may be stop drilled at both ends of the crack.

Any control surface that has a crack that progresses past a stop drilled hole shall be repaired. Refer to paragraphs 18-33, -34, and -35 as applicable for repair information.

A control surface that has any of the following conditions shall have a repair made as soon as practicable
A.

A crack that is longer than 2 inches.

B. A crack that does not originate from the trailing edge or a trailing edge rivet.
C. Cracks in more than six trailing edge rivet locations per skin.
Refer to paragraphs 18-33, -34, and -35 as applicable for repair information.
6.

Affected control surfaces with corrugated skins and having a stop drilled crack that does not extend past
the stop drilled hole, may remain in service without additional repair.

18-38A. CRACKS IN CORRUGATED FLAP SKINS (Continued from page 18-5)
1. It is permissible to stop drill crack(s) that originate at the trailing edge of the control surface provided the
crack is not more than 2 inches in length.
2.

Stop drill crack using a #30 (.128 inch) drill.

A crack may only be stop drilled once.
NOTE: A crack that passes through a trailing edge rivet and does not extend to the trailing edge of the
skin may be stop drilled at both ends of the crack.

Any control surface that has a crack that progresses past a stop drilled hole shall be repaired. Refer to
paragraphs 18-38, -39, and -40 as applicable for repair information.

A control surface that has any of the following conditions shall have a repair made as soon as practicable:
A. A crack that is longer than 2 inches.
B.

A crack that does not originate from the trailing edge or a trailing edge rivet.

Cracks in more than six trailing edge rivet locations per skin.

Refer to paragraphs 18-38, -39, and -40 as applicable for repair information.
6. Affected control surfaces with corrugated skins and having a stop drilled crack that does not extend past
the stop drilled hole, may remain in service without additional repair.

Temporary Revision Number 5
7 January 2000

18-6A

MODEL 172 SERIES SERVICE MANUAL

18-46A. CRACKS IN CORRUGATED ELEVATOR SKINS (Continued from page 18-6)
1. It is permissible to stop drill crack(s) that originate at the trailing edge of the control surface provided the
crack is not more than 2 inches in length.
2. Stop drill crack using a #30 (.128 inch) drill.
3. A crack may only be stop drilled once.
NOTE: A crack that passes through a trailing edge rivet and does not extend to the trailing edge of the
skin may be stop drilled at both ends of the crack.
4. Any control surface that has a crack that progresses past a stop drilled hole shall be repaired. Refer to
paragraphs 18-46, -47, and -48 as applicable for repair information.
5. A control surface that has any of the following conditions shall have a repair made as soon as practicable:
A. A crack that is longer than 2 inches.
B. A crack that does not originate from the trailing edge or a trailing edge rivet.
C. Cracks in more than six trailing edge rivet locations per skin.
Refer to paragraphs 18-46, -47, and -48 as applicable for repair information.
6. Affected control surfaces with corrugated skins and having a stop drilled crack that does not extend past
the stop drilled hole, may remain in service without additional repair.

18-6B Temporary

Revision Number 5
7 January 2000

MODEL 172 SERIES SERVICE MANUAL
18-55.

DESCRIPTION. The fuselage is of semimonocoque construction. consisting of formed
bulkheads, longitudinal stringers, reinforcing channels. and skin panels.

18-56.

NEGLIGIBLE DAMAGE. Refer to paragraph 18-13. Mild corrosion appearing upon alclad
surfaces does not necessarily indicate incipient failure of the base metal. However.
corrosion of all types must be carefully considered, and approved remedial action taken.
Small cans appear in the skin structure of all metal aircraft. It is strongly recommended.
however, that wrinkles which appear to have originated from other sources. or which do not
follow the general appearance of the remainder of the skin panels, be thoroughly investigaged. Except in the landing gear bulkhead areas. wrinkles occurring over stringers which
disappear when the rivet pattern is removed. may be considered negligible. However, the
stringer rivet holes may not align perfectly with the skin holes because of a permanent " set"
in the stringer. If this is apparent, replacement of the stringer will usually restore the
original strength characteristics of the area.
NOTE
Wrinkles occurring in the skin of the main landing gear
bulkhead areas must not be considered negligible. The
skin panel must be opened sufficiently to permit a
thorough examination of the lower portion of the landing
gear bulkhead and its tie-in structure.
Wrinkles occurring in open areas which disappear when the rivets at the edge of the sheet
are removed or a wrinkle which is hand removable, may often be repaired by the addition of a
1/2 x 1/2 x .060 inch 2024-T4 extruded angle, riveted over the wrinkle and extended to within
1/16 to 1/8 inch of the nearest structural members. Rivet pattern should be identical to
existing manufactured seam at edge of sheet. Negligible damage to stringers, formed skin
flanges, bulkhead channels, and like parts is similar to that for the wing skin, given in
paragraph 18-13.

18-57.

REPAIRABLE DAMAGE. Fuselage skin repairs may be accomplished in the same manner
as wing skin repairs outlined in paragraph 18-14. Stringers. formed skin flanges. bulkhead
channels and similar parts may be repaired as shown in figure 18-5.

18-58.

DAMAGE NECESSITATING REPLACEMENT OF PARTS. Fuselage skin major repairs may
be accomplished in the same manner as the wing repairs outlined in paragraph 18-15. Damaged fittings must be replaced. Seat rails serve as structural parts of the fuselage and must
be replaced if damaged. Refer to Section 3.

18-58A. BONDED DOORS.
18-58B. REPAIRABLEDAMAGE.Bonded doors may be repaired by the same methods used for
riveted structure. Rivets are a satisfactory substitute for bonded seams on these
assemblies. The strength of the bonded seams in doors may be replaced by a single 3/32.
2117-AD rivet per running inch of bond seam. The standard repair procedures outlined in
AC43.13-1 are also applicable to bonded doors.
18-59.

BULKHEADS.

18-60.

LANDING GEAR BULKHEADS. Since these bulkheads are highly stressed members.
irregularly formed to provide clearance for control cables. fuel lines. etc.. the patch-type
repairs will be, for the most part, impractical. Minor damage. consisting of small nicks or
scratches, may be repaired by dressing out the damaged area. or by replacement of rivets.

18-7

MODEL 172 SERIES SERVICE MANUAL
Any other damage must be repaird by replacing the landing gear support assembly as an
aligned unit.
18-61.

REPAIR AFTER HARD LANDING. Buckled skin or floorboards. and loose or sheared rivets
in the area of the main gear support will give evidence of damage to the structure from an
extrmely hard landing. When such evidence is present. the entire support structure must be
examined, and all support forgings must be checked for cracks, using a dye penetrant and
proper magnification. Bulkheads in the damaged area must be checked for alignment, and
deformation of the bulkhead webs must be determined with the aid of a straightedge.
Damaged support structure, buckled floorboards and skins, and damaged or questionable
forgings must be replaced.

18-62.

FIREW ALL DAMAGE. Firewall sheets may be repaired by removing the damagedmaterial
(MIL-S-5059) corrosion-resistant (18-8) steel. and splicing in a new section. The new portion
must be lapped over the old material, sealed with Pro-Seal #700 (Coast Pro-Seal Co..
Chemical Division. 2235 Beverly Blvd.. Los Angeles. California), compound or equivalent.
and secured with steel (MS20450) rivets. Patches. splices and joints should be repaired with
steel rivets. Angles around the periphery of the firewall are secured with steel rivets, except
where engine shock mount brackets are attached with aluminum (MS20470) rivets. The
diagonal support angles on the upper firewall are secured with steel rivets. Nutplates are
attached with alumunum rivets. The diagonal support angles on the lower firewall are
secured with aluminum rivets.

18-63.

FASTENERS. Fasteners used in the aircraft are generally solid aluminum rivets, blind
rivets, and steel-threaded fasteners. Usage of each is primarily a function of the loads to be
carried, accessibility, and frequency of removal. Rivets used in aircraft construction are usually fabricated from aluminum alloys. In special cases, monel, corrosion-resistant steel and
mild steel, copper. and iron rivets are used.

18-63A. RIVETS. Standard solid-shank MS rivets are those generally used in aircraft construction.
They are fabricated in the following head types: roundhead, flathead, countersunk head, and
brazier head. Flathead rivets are generally used in the aircraft interior where head clearance
is required. MS20426 countersunk head rivets are used on the exterior surfaces of the aircraft to minimize turbulent airflow. MS20470 brazier head rivets are used on the exterior
surfaces of the aircraft where strength requirements necessitate a stronger rivet head than
that of the countersunk head rivet. Both the brazier head and the countersunk head rivets
are used on the exterior of the aircraft where head clearance is required. Hi-shear rivets are
special, patented rivets having a hi-shear strength equivalent to that of standard AN bolts.
They are used in special cases in locations where hi-shear loads are present, such as in
spars, wings, and in heavy bulkhead ribs. This rivet consists of a cadmium-plated pin of
alloy steel. Some have a collar of aluminum alloy. Some of these rivets can be readily identified by the presence of the attached collar in place of the formed head on standard rivets.
Blind rivets are used, where strength requirements permit, where one side of the structure
is inaccessible, making it impossible or impractical to drive standard solid-hank rivets.
18-63B. REPLACEMENT OF HI-SHEAR RIVETS. Replacement of hi-shear rivets with close-tolerance
bolts or other commercial fasteners of equivalent strength properties is permissible. Holes
must not be elongated, and the hi-shear substitute must be a smooth, push-fit. Field replacement of main landing gear forgings on bulkheads may be accomplished by using the following fasteners.
a. NAS464P-* bolt, MS21042-* nut and AN960-* washer in place of Hi-shear rivets for
forgings with machined flat surfaces around attachment holes.

18-8

MODEL 172 SERIES SERVICE MANUAL
b.

NAS464P-* bolt, ESNA2935-* mating base washer and ESNA RM52LH2935-* selfaligning nut for forgings (with draft angle of up to a maximum of 8 ° ) without
machined flat surfaces around attachment holes.

*Dash numbers to be determined according to the size of the holes and the grip lengths re-

quired Bolt grip length should be chosen so that no threads remain in the bearing area.
18-63C.

SUBSTITUTION OF RIVETS.
a. Solid-shank rivets (M20426AD and MS20470AD). When placing rivets in installations which require raised head rivets, it is desirable to use rivets identical to the
type of rivet removed. Countersunk-head rivets (MS20426) are to be replaced by
rivets of the same type and degree of countersink. When rivet holes become enlarged,
deformed, or otherwise damaged, use the next larger size rivet as a replacment. Replacement shall not be made with rivets of lower strength material.
b. Hi-shear Rivets. When hi-ahear rivets are not available, replacement of sizes 3 16inch or greater rivets shall be made with bolts of equal or greater strength than the
rivet being replaced, and with self-locking nuts of the same diameter
c. The following pages contain approved solid-shank and hi-shear rivet substitutions.

18-9

MODEL 172 SERIES SERVICE MANUAL
Replace

In thickness

With

(or thicker)
MS20470AD3

025
.020

NAS1398B4, NAS1398D4
NAS1738B4, NAS1738D4. NAS1768D4,
CR32134, CR3243-4

MS20470AD4

.050
.040

NAS1398B4, NAS139804
NAS1398B5. NAS1398D5, NAS1738B4,
NAS1738E4, NAS1768D4, CR32134
NAS173885, NAS1738E5. NAS1768D5,
CR3213-5, CR3243-4
CR3243-5

.032
.025
MS20470AD5

.063
.050
.040
.032

NAS1398B5. NAS1398D5
NAS139886, NAS1398D6, NAS1398B5
NAS1738E5. CR3213-5
NAS1738B6. NAS1738E6, NAS176805,
CR3213-6, CR3243-5
CR3243-6

.050

NAS1398B6
NAS139806
NAS1738B6, NAS1738D6, NAS1768D6,
CR3213-6
CR3243-6

MS20426AD3
(Countersunk)
(See Note 1)

.063
.040
025

NAS1399B4, NAS1399D4
NAS1769D4, CR3212-4
NAS1769B4, NAS1739E4, CR3242-4

MS20426AD4
Countersunk)

.080
.063
.050
.040

NAS1399B4, NAS1399D4
NAS1739B4, NAS1739D4. CR3212-4
NAS1769D4
CR3242-4

(See Note 1)

.050
.040
.032

CR3212-5
NAS1739B5. NAS1739D5, NAS1769D4
CR3242-5

MS20426AD4
(Dimpled)

.063

NAS1739B4, NAS1739D4

MS20470AD6

18-10

.080
.071
.063

MODEL 172 SERIES SERVICE MANUAL
Replace

In thickness
(or thicker)

With

MS20426AD5
(Countersunk)

.090
.080
.071
.063
.050

NAS1399B5, NAS1399D5
CR3212-5
NAS1739B5, NAS1739E5
NAS1769D5
CR3242-5

(See Note 1)

.063
.040
.032

NAS1739B6, NAS1739D6, NAS1769D6,
CR3212-6
CR3242-6
AN509-10 Screw with MS20365 Nut

MS20426AD5
(Dimpled)

.071

NAS1739B5, NAS1739D5

MS20426AD6
(Countersunk)

.090
.071
.063
.032

NAS1739B6, NAS1739D6, CR3212-6
NAS1769D6
CR3242-6
AN509-10 Screw with MS20365 Nut

MS20426AD6
(Dimpled)

.090
.032

NAS1739B6. NAS1739D6
AN509-10 Screw with MS20365 Nut

NOTE 1: Rework required. Countersink oversize to accommodate oversize rivet.
NOTE 2: Do not use blind rivets in high vibration areas or to pull heavy sheets or extrusions together. High vibration areas include the nacelle or engine compartment including the firewall. Heavy sheets or extrusions include spar caps.

18-11

MODEL 172 SERIES SERVICE MANUAL
REPLACE
Fastener
NAS178

DIAMETER

Collar
NAS179

WITH
Fastener

(See Note 1)
(See Note 1)
(See
(See
(See
(See

Note 1)
Notes 1 and 2)
Note 1)
Note 1)

NAS1054
NAS14XX
NAS529
NAS1446
NAS7034
NAS464
NAS1103

Collar
NAS179, NAS528
NAS1080C, NAS1080E,
NAS 1080G
NAS524A
NAS1080C. NAS1080A6
NAS1080K
AN364. MS20364, MS21042

NAS1303

NAS6203
AN173

NAS1054

NAS179, NAS528
(See Note 2)

NAS14XX

NAS1080C
NAS1080E
NAS1080G

NAS529

NAS524A

(See Note 3)

AN305, MS20305, MS21044.
MS21045

NAS14XX
NAS529
NAS1446
NAS7034
NAS464
NAS1103
NAS1305
NAS6203

NAS1080C, NAS1080E
NAS524A
NAS1080C, NAS1080A6
NAS1080K
AN364. MS20304, MS21042

NAS529
NAS1446
NAS7034
NAS464
NAS1103
NAS1303
NAS6203

NAS524A
NAS1080C, NAS1080A6
NAS1080K
AN364. MS20364, MS21042

NAS1446

NAS1080C. NAS1080A6

NOTE 1 See appropriate tables for nominal diameters available.
NOTE 2: Available in oversize for repair of elongated holes. Ream holes to provide a
.001 inch interference fit.
NOTE 3: NAS1446 oversize only permitted as a replacement for NAS529.
Steel shank fastener designed for drive-on collars.
Steel shank fastener designed for squeeze-on collars. Installation requires sufficient space
for the tool and extended shank of the fastener.
Threaded fastener.

18-12

MODEL 172 SERIES SERVICE MANUAL
18-64.

ENGINE MOUNT.

18-65.

DESCRIPTION.The "dynafocal" type engine mount is constructed of 4130 chromemolybdenum steel tubing. A truss structure, fastened to the firewall at four points.
provides a mount for the nose landing gear as well as the engine. The engine is attached
radially to the four mounting lugs by Lord type. bonded sandwich mounts.

18-66.

GENERAL CONSIDERATIONS. All welding on the engine mount must be of the highest
quality since the tendency of vibration is to accentuate any minor defect present and cause
fatigue cracks. Engine mount members are preferably repaired by using a larger diameter
replacement tube, telescoped over the stub of the original member using fishmouth and
rosette type welds. However, reinforced 30-degree scarf welds in place of the fishmouth
welds are considered satisfactory for engine mount repair work. Refer to Section 19 for
engine mount painting.

18-67.

ENGINE MOUNT RADIAL SUPPORT DAMAGE.Minor damage such as a crack adjacent to
an engine attaching lug may be repaired by rewelding the support tube and extending a
gussett past the damaged area. Extensively damaged parts must be replaced.

18-68.

DAMAGE INVOLVING ENGINE MOUNTING LUGS AND ENGINE MOUNT TO FUSELAGE ATTACHING FITTINGS. Engine mounting lugs and engine mount-to-fuselage
attaching fittings should not be repaired but must be replaced.

18-69.

BAFFLES. Baffles ordinarily require replacement if damaged or cracked. However. small
plate reinforcements riveted to the baffle will often prove satisfactory both to the strength
and cooling requirements of the unit.

18-70.

ENGINE COWLING.

18-71.

REPAIR OF COWLING SKINS. If extensively damaged, complete sections of cowling must
be replaced. Standard insert-type skin patches, however. may be used if repair parts are
formed to fit. Small cracks may be stop-drilled and dents straightened if they are reinforced
on the inner side with a doubler of the same material. Bonded cowling may be repaired by the
same methods used for riveted structure. Rivets are a satisfactory substitute for bonded
seams on these assemblies. The strength of the bonded seams in cowling may be replaced by
a single 3/32,2117-AD rivet per running inch of bond seam. The standard repair procedures
outlined in AC43.13-1 are also applicable to cowling.

18-72.

REPAIR OF REINFORCEMENT ANGLES. Cowl reinforcement angles. if damaged, must be
replaced. Due to their small size, they are easier to replace than to repair.

18-73.

REPAIR OF GLASS-FIBER CONSTRUCTED COMPONENTS. Glass-fiber constructed components on the aircraft may be repaired as stipulated in instructions furnished in Service Kit
SK182-12. Observe the resin manufacturer's recommendations concerning mixing and applcation of the resin. Epoxy resins are preferable for making repairs. since epoxy compounds are usually more stable and predictable than polyester and, in addition, give better
adhesion. In addition, repair kits are also available for the repair of cracks in ABS, PBC.
PVPC, graphite, and fiberglass material. These kits, Part No. 51543 thru 51548, are available from the Cessna Supply Division.

18-74.

CORROSION AND CORROSION CONTROL.
NOTE
For information on corrosion and corrosion control for
aircraft, refer to FAA Advisory Circular AC43-4.

18-13

MODEL 172 SERIES SERVICE MANUAL

WING
12 INCH WIDE
HEAVY CANVAS

1 X 12 X 48
1 X 12 X 11
1 X 12 X 8

30-3/4

2 X 4 X 20

INCH COTTON WEBBING

Figure 18-1.

Wing and Fuselage Support Stands

3/8 INCH DIAMETER
BOLTS

2 X 6

NOTE
ALL DIMENSIONS

ARE IN INCHES

Figure 18-1.

18-14

Wing and Fuselage Support Stands

MODEL 172 SERIES SERVICE MANUAL

GRIND

A
2.00
2. 00
.45

B
1.00
1.00
1.00

WING STATION

29.50
29.50
24.00

39.00
100.50
208.00

ALL WING TWIST OCCURS BETWEEN STA. 100. 50
AND STA. 208. 00.
(Refer to paragraph 18-7 for angle of incidence).

MEASURING WING TWIST
If damage has occurred to a wing, it is advisable to check the twist. The following method can be used with
a minimum of equipment, which includes a straightedge (32" minimum length of angle, or equivalent), three
modified bolts for a specific wing, and a protractor head with level.
1.

Check chart for applicable dimension for bolt length (A or B).

Grind bolt shanks to a rounded point as illustrated, checking length periodically.

Tape two bolts to straightedge according to dimension C.

Locate inboard wing station to be checked and make a pencil mark approximately one-half inch
aft of the lateral row of rivets in the wing leading edge spar flange.

Holding straightedge parallel to wing station (staying as clear as possible from "cans",
longer bolt on pencil mark and set protractor head against lower edge of straightedge

Set bubble in level to center and lock protractor to hold this reading.

Omitting step 6, repeat procedure for each wing station, using dimensions specified in chart. Check
to see that protractor bubble is still centered.

Proper twist is present in wing if protractor readings are the same (parallel).
may be lowered from wing . 10 inch maximum to attain parallelism.
Figure 18-2.

place

Forward or aft bolt

Checking Wing Twist

18-15

MODEL 172 SERIES SERVICE MANUAL

FLIGHT CONTROL SURFACE BALANCING FIXTURE KIT
(PART NUMBER 5180002-1)
5180002-12
WEIGHT ASSEMBLY
WASHER AND BOLT
SLIDING WEIGHT
*5180002-14
MANDRELS
5180002-2
BEAM ASSEMBLY

INCLUDED IN 5180002-1 FLIGHT CONTROL
SURFACE BALANCING FIXTURE KIT.

GENERAL NOTES
1

Balance control surfaces in a draft-free area.

Place hinge bolts through control surface hinges and position on knife edge
balancing mandrels. Be sure hinge bolt shank rests on knife edge.

Make sure all control surfaces are in their approved flight configurations:
painted (if applicable), trim tabs installed, all foreign matter removed from
inside of control surface, elevator trim tab push-pull rod installed and all tips
installed.

Place balancing mandrels on a table or other suitable flat surface.

Adjust trailing edge support to fit control surface being balanced while center of balancing beam is directly over hinge line. Remove balancing beam and
balance the beam itself by moving the adjustable weight (fastened by bolt and
washer). Fine balance may be accomplished by use of washers at long screw
on end of beam.

When positioning balancing beam on control surface. avoid rivets to provide a
smooth surface for the beam and keep the beam 90 ° to the hinge line of the control
surface.

Figure 18-3.
18-16

Control Surface Balancing (Sheet 1 of 5)

MODEL 172 SERIES SERVICE MANUAL

Paint is a considerable weight factor. In order to keep balance weight to a minimum.
it is recommended that existing paint be removed before adding paint to a control
surface. Increase in balance weight will also be limited by the amount of space
available and clearance with adjacent parts. Good workmanship and standard repair
practices should not result in unreasonable balance weight.

The approximate amount of weight needed may be determined by taping loose weight
at the balance weight area.

Lighten balance weight by drilling off part of weight.

10.

Make balance weight heavier by. fusing bar stock solder to weight after removal
from control surface. The ailerons should have balance weight increased by ordering additional weight, listed in applicable Parts Catalog and installing next to
existing inboard weight the minimum length necessary for correct balance.

CENTERLINE ON BEAM MUST
BE ALIGNED WITH CONTROL SURFACE
HINGE CENTERLINE

BEAM ASSEMBLY
HANGAR
ASSEMBLY

HINGE
CENTERLINE

CONTROL SURFACE
CHORD

ADD WASHERS A NECESSARY
TO FINE BALANCE THE BEAM
ASSEMBLY

ADJUSTABLE
WEIGHT

MANDREL
HANGAR ASSEMBLY
(TO BE IN PROPER POSITION)
SLIDING
WEIGHT

READ CONTROL
SURFACE MOMENT
AT CENTER OF WEIGHT
BEAM ASSEMBLY

MANDREL

Figure 18-3.

CHORD LINE

FLAT SURFACE

Control Surface Balancing (Sheet 2 of 5)
18-17

MODEL 172 SERIES SERVICE MANUAL

A balance in this range is "overbalance" .
A balance in this range
is "underbalance".

BALANCING
MANDREL

Detail F

RUDDER

90-

Detail G

SPIRIT-LEVEL

SLIDING

TRAILING EDGE

CENTER LINE

WEIGHT

CHORD
LINE

BALANCING
MANDREL

Detail H

LEVELED SURFACE

Figure 18-3.
18-18

HINGE POINT

Control Surface Balancing (Sheet 3 of 5)

ELEVATOR

MODEL 172 SERIES SERVICE MANUAL

1/16" SLOT: 3/4" DEEP
(To fi t a il er on hi n g e )
KNIFE EDGE

Detail B
MANDREL
Detail

.
SPIRIT-LEVEL
PROTRACTOR

KNIFE EDGES
SUPPORT

aileron is straight in this
area.

BALANCING MANDREL

Detail

Figure 18-3.

Control Surface Balancing (Sheet 4 of 5)
Revision 2

18-19

MODEL 172 SERIES SERVICE MANUAL
CONTROL SURFACE BALANCE REQUIREMENTS
NOTE
Balance limits for control surfaces are expressed for
"Approved Flight" configuration. "Approved Flight"
configuration is that condition of the control surface as
prepared for flight of the airplane whether it be painted or
unpainted.
"Approved Flight" limits must never be exceeded when
the surface is in its final configuration for flight.
DEFINITIONS:
UNDERBALANCE is defined as the condition that exists when surface is trailing edge
heavy and is defined by a symbol (+). If the balance beam sliding weight must be on the
leading edge side of the hinge line (to balance the control surface), the control surface is
considered to be underbalanced.

OVERBALANCE is defined as the condition that exists when surface is leading edge
heavy and is defined by a symbol (-). If the balance beam sliding weight must be on the
trailing edge side of the hinge line (to balance the control surface), the control surface is
considered to be overbalanced.

CONTROL
SURFACE

AILERON

RUDDER

CONFIGURATION
(Inch-Pounds)

0.0 to +11.31

0.0 to + 9.0

RIGHT ELEVATOR

0.0 to + 24. 5

LEFT ELEVATOR

0.0 to + 18. 5

Figure 18-3.
18-20

APPROVED FLIGHT
BALANCE LIMITS

Control Surface Balancing (Sheet 5 of 5)

MODEL 172 SERIES SERVICE MANUAL

PATCH
1/4" MINIMUM EDGE MARGIN
USE EXISTING RIVET PATTERN

ORIGINAL PART
ORIGINAL PART

REPAIR PATCH IN CROSS SECTION

A-A
Figure 18-3A.

Corrugated Skin Repair
18-21

MODEL 172 SERIES SERVICE MANUAL

PATCHES AND DOUBLERS 2024-T3 ALCLAD

MS20470AD4 RIVETS
24 REQD

SKIN
SECTION THRU PATCH
3.00 DIA. HOLE

PATCH REPAIR FOR 3 INCH DIAMETER HOLE
MS20470AD4 RIVETS
16 REQD

22 1/2°
3.00 DIA.

PATCH

DOUDLER

EXISTING
SKIN
SECTION THRU PATCH

2.00 DIA. HOLE

PATCH REPAIR FOR 2 INCH DIAMETER HOLE
2. 50 DIA.
MS20470AD4 RIVETS
8 REQD

EXISTING
SKIN
PATCH

(NO DOUBLER
REQD)

1.00 DIA. HOLE
SECTION THRU PATCH

PATCH REPAIR FOR 1 INCH DIAMETER HOLE
ORIGINAL PARTS
REPAIR PARTS

OVERLAPPIN

REPAIR PARTS IN CROSS SECTION

CIRCULAR PATCH

Figure 18-4.
18-22

Skin Repair (Sheet 1 of 6)

MODEL 172 SERIES SERVICE MANUAL

SECTION THRU ASSEMBLED PATCH

A-A
EDGE MARGIN

2 X RIVET DIA.

PATCH -

2024-T3 ALCLAD

CLEAN OUT

DIAMETER

1/2" RADIUS

RIVET SPACING =
6 X RIVET DIA.

1/2" RADIUS
=
EDGE MARGIN

.- DOUBLER -

2 X RIVET DIA.

2024-T3 ALCLAD

RIVET TABLE
OVERLAPPING RECTANGULAR PATCH

SKIN GAGE
.020

ORIGINAL PARTS

025
.032

REPAIR PARTS

.051

040

RIVET DIA.
1/8
1/8
1/8

1/8
5/32

REPAIR PARTS IN CROSS SECTION

Figure 18-4.

Skin Repair (Sheet 2 of 6)
18-23

MODEL 172 SERIES SERVICE MANUAL

PATCH

EXISTING SKIN
NOTE

SECTION THRU ASSEMBLED PATCH

For optimum appearance and
airflow, use flush rivets, dimpled skin and patch, and countersunk doubler.

A-A
EDGE MARGIN = 2 X RIVET DIA.
PATCH 1/2" RADIUS

REPAIR PARTS IN CROSS SECTION

Figure 18-4.
18-24

Skin Repair (Sheet 3 of 6)

2024-T3 ALCLAD

MODEL 172 SERIES SERVICE MANUAL

NOTE
DOUBLER

dimple skin and patch.

A-A

2024-T4 ALCLAD

EXISTING SKIN

CARRY EXISTING

RIVET PATTERN
THRU PATCH

PITCH 4-8D
TYPICAL

EDGE DISTANCE
2D MIN.

.50 R. MIN.
TYPICAL

RIVET TABLE
SKIN GAGE

RIVET DIA.

.020
.025
.032
.040
.051

1/8
1/8
1/8
1/8
5/32
2024-T3 ALCLAD
FLUSH PATCH AT
STRINGER/BULKHEAD
INTERSECTION
ORIGINAL PARTS
NOTE

REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-4.

This procedure is not recommended in areas where
stringers are riveted to
bulkheads.

Skin Repair (Sheet 4 of 6)
18-25

MODEL 172 SERIES SERVICE MANUAL

DOUBLERS
1/4 B (BUT NOT LESS THAN 4D)

EXISTING

SKIN

RIVET
PATTERN
DOUBLER
-

PATCH

PITCH TYPICAL FOR
PATCH SKIN & DOUBLER

EXISTING SKIN
0. 5" MIN. RADIUS

EDGE DISTANCE

RIVET TABLE
SKIN GAGE

2D MIN

RIVET DIA.

.020
.025
.032

1/8
1/8
1/8

.040
.051

1/8
5/32

SPACER-

2024-T3 ALCLAD

OVERLAPPING PATCH AT
STRINGER/BULKHEAD
INTERSECTION

ORIGINAL PARTS

PATCH 2024-T3 ALCLAD

REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-4.
18-26

Skin Repair (Sheet 5 of 6)

MODEL 172 SERIES SERVICE MANUAL

CLEAN OUT DAMAGED AREA

FUSELAGE SKIN

SKIN RIVET PATTERN

1/4" RADIUS

10 RIVETS
EACH SIDE OF
DAMAGED AREA
FILLER -2024-T4

ALCLAD
DOUBLER -2024-T4

1/4" EDGE MARGIN

ALCLAD

MS20470AD4 RIVETS

ORIGINAL PARTS
REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-4.

Skin Repair (Sheet 6 of 6)
18-27

MODEL 172 SERIES SERVICE MANUAL

DOULBLER
4" EDGE MARGIN.

RIVET SPACING TO MATCH
PATTERN IN SKIN

STRINGER

5 RIVETS EACH SIDE
OF DAMAGED AREA

CLEAN OUT DAMAGED AREA

FILLER -

2024-T4 ALCLAD

A-A

MS20470AD4 RIVETS

SKIN

REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-5.
18-28

Stringer and Channel Repair (Sheet 1 of 4)

MODEL 172 SERIES SERVICE MANUAL

FILLER

2024-T4 ALCLAD

A-A
STRIP -

2024-T3 ALCLAD

5 RIVETS EACH SIDE
OF DAMAGED AREA

STRINGER
PICK UP EXISTING SKIN RIVETS

MS20470AD4 RIVETS

ORIGINAL PARTS

REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-5.

Stringer and Channel Repair (Sheet 2 of 4)
18-29

MODEL 172 SERIES SERVICE MANUAL

STOP DRILL CRACK-

ORIGINAL PARTS
REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-5.
18-30

Stringer and Channel Repair (Sheet 3 of 4)

MODEL 172 SERIES SERVICE MANUAL

FILLER - 2024-T4 ALCLAD
DOUBLER - 2024-T3 ALCLAD

A-A
CLEAN OUT DAMAGED AREA
3/4" RIVET

.--

SPACING

.
-

1/4" RADIUS

2 ROWS RIVETS OUTBOARD
OF LIGHTENING HOLE
1/4" MARGIN
CHANNEL
DOUBLER - 2024-T4 ALCLAD
AN470AD4 RIVETS

ORIGINAL PARTS
,

REPAIR PARTS
REPAIR IN CROSS SECTION

Figure 18-5.

Stringer and Channel Repair (Sheet 4 of 4)
18-31

MODEL 172 SERIES SERVICE MANUAL

STOPDRILL CRACK IF CRACK
DOES NOT EXTEND TO EDGE
OF PART

DOUBLER2024-T3
ALCLAD

1/4" EDGE MARGIN

A-A

MS20470AD4 RIVETS

ORIGINAL PARTS
REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-6.
18-32

Rib Repair (Sheet 1 of 2)

MODEL 172 SERIES SERVICE MANUAL

FILLER - 2024-T4 ALCLAD
DOUBLER - 2024-T3 ALCLAD

RIVET

ORIGINAL PARTS

A-A

REPAIR PARTS

REPAIR PARTS IN
CROSS SECTION
Figure 18-6.

Rib Repair (Sheet 2 of 2)
18-33

MODEL 172 SERIES SERVICE MANUAL

FILLER -

ALCLAD
2024-T4

2024-T4 ALCLAD

DOUBLER-

CLEAN OUT DAMAGED AREA

ANGLE

2024-T4ORIGINAL

PARTS

(TYPICA L)

ORIGINAL PARTS
REPAIR PARTS

MS20470A4

A-A

REPAIR PARTS IN CROSS SECTION

Figure 18-7.
18-34

RIVET

Wing Spar Repair (Sheet 1 of 3)

MODEL 172 SERIES SERVICE MANUAL

NOTE
FILLER -

2024-T4 ALCLAD

This repair applies to either
front or rear spar if the spar
is a single channel.

1/4" EDGE MARGIN (TYP. )

CLEAN OUT DAMAGED AREA

2024-T3 ALCLAD

ANGLE

4 RIVET SPACING
(TYPICAL ALL PARTS)

DOUBLER

EDGE MARGIN
2024-T4 ALCLAD

DAMAGED AREA

1/4" EDGE MARGIN (TYP.)

MS20470AD4 RIVETS

REPAIR PARTS

A-A

REPAIR PARTS IN CROSS SECTION

Figure 18-7.

Wing Spar Repair (Sheet 2 of 3)
18-35

MODEL 172 SERIES SERVICE MANUAL

FILLER ALCLAD

2024-T4

3/4" RIVET
SPACING

CLEAN OUT
DAMAGED A-REA
1/4" EDGE MARGIN

MS20470AD4 RIVETS

ORIGINAL PARTS
.

REPAIR PARTS

REPAIR PARTS IN CROSS SECTION

Figure 18-7.
18-36

Wing Spar Repair (Sheet 3 of 3)

MODEL 172 SERIES SERVICE MANUAL

DOUBLER -

2024-T4 ALCLAD

CLEAN OUT DAMAGED AREA

A-A

REPAIR PARTS IN CROSS SECTION

Figure 18-8.

Auxiliary Spar Repair
18-37

MODEL 172 SERIES SERVICE MANUAL

NOTES:
1.

Dimple leading edge skin and filler material, countersink the doubler.

Use MS20426AD4 rivets to install doubler.

Use MS20426AD4 rivets to install filler, except where bucking is impossible.
Cherry (blind) rivets where regular rivets cannot be bucked.

Contour must be maintained; after repair has been completed, use epoxy filler as necessary
and sand smooth before painting.

Vertical size is limited by ability to install doubler clear of front spar.

Lateral size is limited to seven inches across trimmed out area.

Number of repairs is limited to one in each bay.

Use CR162-4

1" MAXIMUM RIVET
SPACING (TYPICAL)

DOUBLER NEED NOT
BE CUT OUT IF ALL
RIVETS ARE ACCESSIBLE
FOR BUCKING

5/16" MINIMUM EDGE
MARGIN (TYPICAL)

TRIM OUT DAMAGED AREA

REPAIR DOUBLER
2024-T3 ALCLAD
.040"
THICKNESS

FILLER MATERIAL
ORIGINAL PARTS
REPAIR PARTS

SAME THICKNESS
AS SKIN

Figure 18-9.
18-38

Leading Edge Repair

LEADING EDGE SKIN

MODEL 172 SERIES SERVICE MANUAL

1" MAXIMUM RIVET SPACING

1/4" MINIMUM EDGE MARGIN

MINIMUM EDGE MARGIN

DOUBLER -

2024-T3

ORIGINAL PARTS
REPAIR PARTS

Figure 18-10.

Flap Leading Edge Repair
18-39

MODEL 172 SERIES SERVICE MANUAL

S-1443-1 DOUBLER
VIEWED FROM INSIDE
WING LOOKING DOWN
AT TOP OF LOWER

WING SKIN.
#40

(.098) HOLE

(10 REQD)

LOWER WING SKIN (REF)
5.062 DIA

S-225-4F COVER

MS20426AD3

RIVETS

NOTE
PARTS ARE AVAILABLE
FROM THE CESSNA

S-1022Z-8-6 SCREWS

SUPPLY DIVISION

PRECAUTIONS
1. Add the minimum number of access holes necessary.
2. Any circular or rectangular access hole which is used with approved optional equipment
installations may be added in lieu of the access hole illustrated.
3. Do not add access holes at outboard end of wing; remove wing tip instead.
4. Do not add an access hole in the same bay where one is already located.
5. Locate new access holes near the center of a bay (spanwise).
6. Locate new access holes forward of the front spars as close to the front spar as practicable.
.Locate new access holes aft of the front spar between the first and second stringers aft of the
spar. When installing the doubler. rotate it so the two straight edges are closest to the stringers.
8. Alternate bays. with new access holes staggered forward and aft of the front spar, are preferable.
9. A maximum of five new access holes in each wing is permissible: if more are required. contact
the Cessna Service Department.
10. When a complete leading edge skin is being replaced, the wing should be supported in such a
manner so that wing alignment is maintained.
a.

Establish exact location for inspection cover and inscribe centerlines.

Determine position of doubler on wing skin and center over centerlines.
hole locations and drill to size shown.

Cutout access hole. using dimension shown.

Flex doubler and insert through access hole, and rivet in place.

Position cover and secure, using screws as shown.

Figure 18-11.
18-40

Access Hole Installation

Mark the ten rivet

MODEL 172 SERIES SERVICE MANUAL

A-A

CLEAN OUT DAMAGED AREA

ANGLE -

2024-T4 ALCLAD

10 RIVETS EACH SIDE
OF DAMAGED AREA

FIREWALL ANGLE

FILLER -

2024-T4 ALCLAD

MS20470AD4 RIVETS

FIREWALL

FUSELAGE SKIN

ORIGINAL PARTS
REPAIR PARTS
REPAIR PARTS IN CROSS SECTION

Figure 18-12.

Firewall Angle Repair
18-41

MODEL 172 SERIES SERVICE MANUAL

Use rivet pattern at wing station
23. 65 for repair from wing station
23. 65 to wing station 85.87. Use
rivet pattern at wing station 100. 50
for lap splice patterns from wing
station 100. 50 to wing station

190. 00.

See figure 1-2 for wing

stations.
2 Use rivet spacing similar to the
pattern at wing station 100. 50
at leading edge ribs between
lap splices.

Select number of flush rivets to be
used at each wing station leading
edge rib from table.
-

RIBS AND STRINGERS:
Blind rivets may be substituted for
solid rivets in proportionally
increased numbers in accordance
with the table.
SPARS:
Blind rivets may be installed in
wing spars only in those locations
where blind rivets were used during
original manufacture, ie fuel bay
area of front spars on aircraft
with integral fuel bays.

NUMBER OF FLUSH RIVETS IN DIMPLED SKIN REQUIRED IN REPLACEMENT LEADING EDGE SKIN
WING
STATION
RIB

SOLID
MS20426-4

BLIND
CR2248-4

118
136

18
15

22
18

EXISTING
TACK RIVET

PATCH
EXISTING RIVET PATTERN
TYPICAL LEADING EDGE SECTION

Figure 18-13.
18-42

Bonded Leading Edge Repair

MODEL 172 SERIES SERVICE MANUAL
SECTION 19
PAINTING
Page No.
Aerofiche/

TABLE OF CONTENTS

Manual

ACRYLIC LACQUER MATERIALS
Painting of ABS ...........
Interior Parts .............
Exterior Parts .............

3C4/19-2
3C4/19-2
3C5/19-3
3C5/19-3

Clean-Up .................
Prepriming .............
Priming .................
Prepainting ...............

3C7
3C8
3C8
3C9

Refinishing Engine Mounts . ..

3C6/19-4

Painting .................

3C9 19-7

MODIFIED URETHANE
RIALS ...................
Facility ..................

Overall .................
Masking ...............
Touch-Up ...............
Repair of Dents ..........

MATE3C7'19-5
3C7/19-5

19-5
19-6
19-6
19-7

3C9 19-7
3C9 19-7
3C10 19-8
3C10 19-8

NOTE

This section contains standard factory materials
listing and area of application. For paint number
and color, refer to Aircraft Trim Plate and Parts
Catalog. In all cases determine the type of paint
on the aircraft as some types of paint are not compatible. Materials may be obtained from Cessna
Supply Division.
NOTE

Control surfaces, except for wing flaps, must be
balanced after painting. Refer to Section 18,
figure 18-3 for balancing procedures.

Revision 1

19-1

MODEL 172 SERIES SERVICE MANUAL

MATERIAL

PAINT

NO/TYPE

ACRYLIC
LACQUER *

DOMESTIC

LACQUER
CES 1054-215
Heat Resistant
Enamel
PRIMER

THINNER

SOLVENT

FRENCH

AREA OF
APPLICATION

NOTE 1
X

NOTE 6

P60G2 With
R7K44 Reducer

NOTE 2

Ex-Er-7 With
T-Er-4 Reducer

T-8402A

T6094A

NOTE 3

Methyl Ethyl
Ketone (MEK)

NOTE 5

NOTE 4

NOTE
1. Used on aircraft exterior.
2. Used with lacquer or acrylic lacquer on aircraft
exterior.
3. Used to thin lacquer and for burndown.
4. Used to thin acrylic lacquer and for burndown.
5. Used to clean aircraft exterior prior to priming.
6. Used on aircraft engine mount.

* THROUGH SERIALS 17269309,17269311 THRU 17269549.
17269551 THRU 17269556. 17269561
1729557, 17269583,17269584.
19-1.

19-2

THRU 17269566.

PAINTING OF FORMED ABS PLASTIC PARTS. The following procedures outline some
basic steps which are useful during touch up or painting of formed ABS plastic parts.

MODEL 172 SERIES SERVICE MANUAL
19-2.

INTERIOR PARTS (Finish Coat of Lacquer).
a. Painting of Spare Parts.
1. Ensure a clean surface by wiping with Naphtha to remove surface contamination.
CAUTION
Do not use strong solvents such as Xylol. Toluol or
Lacquer Thinner since prolonged exposure can soften or
embrittle ABS.
2.
b.

After the part is thoroughly dry it is ready for the lacquer topcoat. Paint must be
thinned with lacquer thinner and applied as a wet coat to ensure adhesion.
Touch Up of Previously Painted Parts.
1. Light sanding is acceptable to remove scratches and repair the surface but care
must be exercised to maintain the surface texture or grain.
2. Ensure a clean surface by wiping with Naptha to remove surface contamination.
CAUTION
Do not use strong solvents such as Xylol. Toluol or
Lacquer Thinner since prolonged exposure can soften or
embrittle ABS.
3.

After the part is thoroughly dry it is ready for the lacquer topcoat. Paint must be
thinned with lacquer thinner and applied as a wet coat to ensure adhesion.
NOTE
Lacquer paints can be successfully spotted in.

19-3.

EXTERIOR PARTS (Acrylic Topcoat).
a. Painting of Spare Parts.
1. Light scuff sand to remove scratches and improve adhesion.
2. Ensure a clean surface by wiping with Naphtha to remove surface contamination.
CAUTION
Do not use strong solvents such as Xylol. Toluol or
Lacquer Thinner since prolonged exposure can soften or
embrittle ABS.

3. After the part is thoroughly dry it is ready for the topcoat. Paint
must be thinned with appropriate acrylic thinner and applied as a
wet coat to ensure adhesion.
b. Touch Up of Previously Painted Parts.
1. Lightly scuff sand to remove scratches and improve adhestion.
2. Ensure a clean surface by wiping with Naphtha to remove surface
contamination.

19-3

MODEL 172 SERIES SERVICE MANUAL

CAUTION
Do not use strong solvents such as Xylol. Toluol or
lacquer Thinner since prolonged exposure can soften or
embrittle ABS.
3.
4.

Apply a compatible primer - surfacer and sealer.
After the part is thoroughly dry it is ready for the topcoat. Paint must be thinned
and applied as a wet coat to ensure adhesion.

NOTE
Acrylic topcoats can be successfully spotted in.
19-4.

REFINISHING ENGINE MOUNTS. After completing a repair as directed in Section 18.
refinish with Part Number EX2219 (Ameron-Enmar Finished. 16116 E. 13th. Andover.
Kansas 67230) (316) 733-1361 heat-resistant black enamel. Degrease and scuff sand or grit
blast entire area to bare metal Spray enamel to a dry film thickness of 0.001" to 0.0013". and
cure at 250°F for 15 minutes. Part can be handled as soon as cool to touch.
NOTE
BEGINNING SERIAL 17269310. 17269550. 17269557,
17269562 THRU 17269565. 17269568 THRU 17269582. and
17269585.

IMRON MODIFIED URETHANE
MATERIAL
PAINT

NO/TYPE

AREA OF APPLICATION

IMRON ENAMEL

Used as corrosion proof topcoat

IMRON 192S Activator

Catalyst for Imron Enamel

PRIMER

WASH PRIMER P60G2

Used to prime aircraft for Imron Enamel

REDUCER/
THINNER

IMRON Y8485S Reducer

Used to thin Imron Enamel

Catalyst Reducer R7K44

Used to reduce P60G2

NOTE
Do not paint pitot tube, gas caps. or aileron gap seals.
Also do not paint antenna covers which were not painted
at the factory.

19-4

MODEL 172 SERIES SERVICE MANUAL
REQUIRED MATERIALS
NO/TYPE

MATERIAL

AREA OF APPLICATION

STRIPPER

Strypeeze Stripper

Used to strip primer overspray

CLEANER

DX440 Wax and Grease
Remover

Used to clean aircraft exterior

Imperial Cleaner

Used to remove grease, bug stains etc.

Klad Polish

Used to clean aluminum finish

808 Polishing Compound

Used to rub out overspray

Naphtha

Used to clean plexiglass and ABS

Methly Ethyl
Ketone (MEK)

Used to tack aircraft prior to topcoat

CLOTH

HEX Wiping Cloth

Used with solvent to clean aircraft exterior

FILLER

White Streak

Used to fill small dents

MASKING

Class A Solvent Proof
Paper

Used to mask areas not to be painted

Tape Y218

Used for masking small areas

Tape Y231

Used for masking small areas

SOLVENT

19-5.

FACILITY. Painting facilities must include the ability to maintain environmental control to
a minimum temperature of 65°F., and a positive pressure inside to preclude the possibility of
foreign material damage. All paint equipment must be clean, and accurate measuring
containers available for mixing protective coatings. Modified Urethane has a pot life of four
to eight hours, depending on ambient temperature and relative humidity. Use of approved
respirators while painting is a must, for personal safety. All solvent containers should be
grounded to prevent static build-up. Catalyst materials are toxic, therefore. breathing fumes
or allowing contact with skin can cause serious irritation. Material stock should be rotated
to allow use of older materials first, because its useful life is limited. All supplies should be
stored in an area where temperature is higher than 50°F., but lower than 90°F. Storage at
90°F. is allowable for no more than sixty days providing it is returned to room temperature
for mixing and use.
Modified urethane paint requires a minimum of seven days to cure under normal conditions.
if humidity and temperature is lower, curing time will be extended to a maximum of 14 days.
During the curing period, indiscriminate use of masking tape, abrasive polishes, or cleaners
can cause damage to finish. Desirable curing temperature for modified urethane is 60°F. for
a resulting satisfactory finish.

19-6.

CLEAN UP.
a. Inspect airplane for any surface defects, such as dents or unsatisfactory previous
repairs, and correct according to paragraph 19-13.

19-5

MODEL 172 SERIES SERVICE MANUAL
b. Wipe excess sealer from around windows and skin laps with naptha.
Mask windows, ABS parts, and any other areas not to be primed,
with 3M tape and Class A Solvent Proof Paper. Care must be exercised to avoid cuts, scratches or gouges by metal objects to all
plexiglass surfaces, because cuts and scratches may contribute to
crazing and failure of plexiglass windows.
NOTE

Do not use strong solvents such as xytol, toluol,
MEK, or lacquer thinner on plexiglass as crazing
will occur.
c. Methyl Ethyl Ketone (MEK) solvent should be used for final cleaning of
airplanes prior to painting. The wiping cloths shall be contaminant
and lint free HEX. Saturate cloth in the solvent and wring out so it
does not drip. Wipe the airplane surface with the solvent saturated
cloth in one hand, and immediately dry with a clean cloth in the other
hand. It is important to wipe dry solvent before it evaporates.
When an airplane has paint or zinc chromate overspray on the exterior, stripper may be used
to remove the overspray. The stripper may be applied by brush and will require a few
minutes to soften the overspray. Heavy coatings may require more than one application of
the stripper. Use extreme care to prevent stripper from running into faying surfaces on
corrosion proofed airplanes. After removal of the overspray, clean the airplane with Methyl
Ethyl Ketone (MEK) solvent in the prescribed manner.
NOTE
It is imperative that clean solvent be used in cleaning
airplanes. Dispose of contaminated solvent immediately.
Fresh solvent should be used on each airplane.
WARNING
Use explosion proof containers for storing wash solvents
and other flammable materials.
19-7.

19-

PRE-PRIMING.
a. For all standard aircraft. P60G2 primer shall be mixed one part primer to one and one
half parts R7K44 catalyst by volume. Mix only in stainless steel or lined containers.
After mixing, allow primer to set for thirty minutes before spraying. Pot life of the
mixed primer is six hours. All mixed material should be discarded if not used within
this time. Pot pressure during spray operation should be approximately 10 ±1 psi.
Air pressure should be 40 to 50 psi at the gun. Blow loose contaminant off the airplane
with a jet of clean. dry air. Cover the flap tracks, nose gear strut tube, wheels, and
shimmy dampener rod ends. ABS parts and other pre-primed parts do not receive
wash primer.

MODEL 172 SERIES SERVICE MANUAL
WARNING
AIRCRAFT SHOULD BE GROUNDED PRIOR TO
PAINTING TO PREVENT STATIC ELECTRICITY
BUILD-UP AND DISCHARGE.
19-8.

PRIMING.
a. Apply primer in one wet even coat. Dry film thickness to be .0003 to .0005 inches. Do
not topcoat until sufficiently cured. When scratching with firm pressure of the
fingernail does not penetrate the coating, the primer is cured. Primer should be
topcoated within four hours after application.

19-9.

PREPAINTING.
a. On standard aircraft mix the required amount of Imron with Imron 192S Activator in
a 3 to 1 ratio. Mix thoroughly (no induction time required before spraying). Imron
shall be thinned with Y8485S Imron Reducer to obtain a spraying viscosity of 18 to 20
seconds on a No. 2 Zahn Cup. Viscosity should be checked after 4 hours and adjusted if
necessary.
b. When applying modified urethane finishes, the painter should wear an approved
respirator, which has a dust filter and organic vapor cartridge, or an air supplied
respirator. All modified urethane finishes contain some isocyanate. which may
cause irritation to the respiratory tract or an allergic reaction. Individuals may
become sensitized to isocyanates.
c. The pot life of the mixture is approximately 6-8 hours at 75°F. Pot pressure should be
approximately 12 psi during application. Air pressure at the gun should be 40 to 50
psi.
d. Scuff sand the primer only where runs or dirt particles are evident Minor roughness
or grit may be removed by rubbing the surface with brown Kraft paper which has
been thoroughly wrinkled. Unmask ABS and other preprimed parts and check tapes.
Clean surface with a jet of low pressure, dry air.

19-10.

PAINTING ALL-OVER WHITE OR COLOR.
a. Complete painting of the plane should be done with 2 or 3 wet, even coats. Dry coats
will not reflow, and will leave a grainy appearance.
b. Allow 5 minute period for the finish to flash off before moving aircraft to the oven.
c. Move to the force dry oven and dry for approximately 1 1/2 hours at 120°F to 140°F.
d. Dry film thickness of the overall color should be between approximately 2.0 mils.
Films in excess of 3.0 mils are not desirable.

19-11.

MASKING FOR STRIPES.
a. Remove airplane from the oven. Allow airplane to cool to room temperature before
masking.
b. Mask stripe area using 3M Tape Y231 or 3M Tape Y218 and Class A solvent proof
paper. Double tape all skin laps to prevent blow by.
c. Airplanes which will have a stripe only configuration shall be masked. cleaned, and
primed, in stripe area only.
d. If the base coat is not over 72 hours old, the stripe area does not require sanding. If
sanding is necessary because of age or to remove surface defects, use #400 or #600
sandpaper. Course paper will leave sand marks which will decrease gloss and depth
of gloss of the finish. The use of power sanders should be held to a minimum, if used.
exercise care to preclude sanding through the white base coat. Wipe surface to be
striped with a tack cloth and check all tapes.

19-7

MODEL 172 SERIES SERVICE MANUAL
Stripe colors on Imron base coat will be Imron Enamel. Mix as outlined in paragraph
19-9.
f. Painting of the stripe should be done with 2 or 3 wet-even coats. Dry coats will not
reflow, and will leave a grainy appearance. Stripes may be force dried or air dried.
Film thickness of a stripe is approximtely 1.5 mil to 2.0 mils.
g. Do not remove masking tape and paper until the paint has dried to a "dry to touch"
condition. Care should be exercised in removal of the masking to prevent damage to
the finish
h. Modified urethane finishes are sensitive to moisture. therefore. should be stored out
of rain until cured.
e.

19-12.

TOUCH UP.
When necessary to touch up or refinish an area. the defect should be sanded with #400 and
followed by #600 sandpaper. Avoid. if possible, sanding through the primer. If the primer is
penetrated over an area 1/2 inch square or larger. repriming is necessary. Avoid spraying
primer on the adjacent paint as much as possible. Since urethane finishes cannot be "spotted
in" repairs should be in sections extending to skin laps or stripe lines.
a. Dry overspray and rough areas may be compounded out with DuPont #808 rubbing
compound.
b. Grease, bug stains. etc.. may be removed from painted surfaces with DX440 Wax and
Grease Remover or Imperial Cleaner. Klad Polish may be used on bare aluminum to
remove stains, oxides, etc.
c. Rework areas, where paint or primer removal is required. may be stripped with
Strypeeze Paint Remover. All traces of stripper must be removed before refinishing.

19-13.

REPAIR OF DENTS.
NOTE
Refer to Section 18 for repair of damaged area(s). Dent
repair as described in this Section is applicable only to
smooth dents in the skin that are free from cracks, sharp
corners, are not stress wrinkles and do not interfere with
any internal mechanism.
a.
b.

To repair dents use White Streak Filler or equivalent. Mix White Streak in the correct
proportion as recommended by the manufacturer.
Do not apply White Streak Filler over paint. All paint shall be removed in the repair
area and the aluminum surface sanded lightly to increase adhesion. Apply the White
Streak to a level slightly above the surrounding skin. After drying for 10-15 minutes.
sand the filler flush with the skin surface, using care to feather the edges.
NOTE
Application of a top coat thickness in excess of 5.0 mils,
requires a control surface balance check.

19-8

MODEL 172 SERIES SERVICE MANUAL
SECTION 20

WIRING DIAGRAMS
12 VOLT
TABLE OF CONTENTS

Page No.
Aerofiche/
Manual

3C18/20-2
Code Letters ...............
3C19/20-3
Cross Reference Listing ......
D.C. POWER
Ground Service Receptacle ..... 3C20/20-4
Bus Bar. Primary, Alternator
and Electronic ...........
3C21.20-5
Alternator System, 60 Amp . . . 3C23/20-7

...........

3D1320-21

3D14/20-22
3D15/20-23
3D16 20-24

Instrument Panel Post

3D1/20-9

Ammeter .................
Battery Circuit

Clock ...................
LIGHTING
Map/Auxiliary Instrument Light
..........................
Compass/Instrument Light ...
Compass/Instrument Light ....
Instrument Panel Post

Lighting ...............

3D2,20-10

IGNITION
3D3/20-11
Magneto ..
.............
FUEL AND OIL
3D4 20-12
Oil Temperature ...........
ENGINE INSTRUMENTS
3D5 20-13
Fuel Gage Transmitter .......
3D6/20-14
.........
Hourmeter ..
Cylinder Head Temperature . . . 3D7 20-15
Carburetor Air Temperature
. 3D8/20-16
...............
Gage
FLIGHT INSTRUMENTS
.....
3D9.20-17
Turn Coordinator
Turn and Bank Indicator ..... 3D10/20-18
3D11/20-19
Encoding Altimeter ........
Blind Encoder ....
........
3D12 20-20

3D18/20-26

Dome/Courtesy Lights .......
Landing/Taxi Light .........
Landing/Taxi Light .........
Landing/Taxi Light .........
Navigation Lights ..........
Flashing Beacon Light .......
Map Light - Control Wheel ....
Wing Tip Strobe Light .......
HEATING, VENTING/DE-ICING
Cigar Lighter .............
Pitot Heater ...............
CONTROL SURFACE SECTION
Wing Flaps - Electric ........
Wing Flaps - Electric ........

3D19,20-27
3D20/20-28
3D21/20-29
3D22 20-30
3D23 20-31
3D24 20-32
3E1/ 20-33
3E2 20-34
3E3'20-35
3E4 20-36
3E5 20-37
3E6 20-38

24 VOLT
D.C POWER
....
Battery Circuit ......
Ground Service Receptacle ....
Bus Avionics Master Switch . . .
Alternator System .........
Alternator System ..........
....
Ammeter .
Alternator System . .......
Bus Bar Avionics Master Switch
.
. ...
.....
.
Bus Bar Avionics Master Switch
...
.......
...... ....
...
Battery Circuit . .....
........
Ammeter ......
Ground Service Receptacle ....
Ground Service Receptacle . .
Alternator System ..........
IGNITION
Magneto...
...........
Magneto .................

3E7/20-39
3E8 20-40
3E9'20-41
3E10/20-42
3E1120-43
3E12 20-44
3E13/20-45
3E14/20-46
3E16 20-48
3E17'20-49
3E18 20-50
3E19/20-51
3E20 20-52
3E21 20-53
3E22 20-54
3E23 20-55

FUEL AND OIL
Oil Temperature ...........
Oil Temperature ...........
ENGINE INSTRUMENTS
Fuel Pump ...............
Fuel Gage and Transmitter ...
Hourmeter ...............
Hourmeter ...............
Hourmeter ...............
Carburetor Air Temperature
Gage ...................
Instrument Clusters Trans
mitter ..................
Fuel GageTransmitter .......
Hourmeter ...............
Hourmeter ...............
Carburetor Air Temperature
Gage ..................
FLIGHT INSTRUMENTS
Turn Coordinator
Turn and Bank Indicator .....

3E24 20-56
3F1 20-57
3F2
3F3
3F5
3F6
3F7

20-58
20-58A
20-59
20-60
20-61

3F8 20-62
3F9 20-62A
3F11 20-63
3F12 20-64
3F13 20-65
3F14 20-66

3F17 20-67

Revision 1

20-1

MODEL 172 SERIES SERVICE MANUAL
OTHER INSTRUMENTS
Clock ...
.......
3F18 20-68
Digital Clock .........
....
3F19 20-69
Clock ...................
3F20 20-70
LIGHTING
Map Auxiliary Instrument Light 3F21 20-71
Compass. Instrument
Light ..................
3F22/20-72
CompassInstrument Light ....
3F23,20-73
Instrument Panel Post
Lighting ................
3F24/20-74
Instrument Panel Post
Lighting ................
3G1/20-75
Dome/Courtesy Lights .......
3G2/20-76
Landing Taxi Light ........
3G3/20-77
LandingTaxi Light .........
3G4/20-78
Navigation Lights ..........
3G5/20-79
Navigation Lights ..........
3G6/20-80

Flashing Beacon Light ......
Map Light - Control Wheel ....
Wing Tip Strobe Light .......
Landing Taxi Lights ....
...
HEATING. VENTING DE-ICING
Cigar Lighter ............
Pitot Heater ...............
Air Conditioner ............
Circulation Fan ............
Air Conditioner ............
CONTROL SURFACE SECTION
Wing Flaps - Electric ........
Wing Flaps - Electric ........
Wing Flaps - Electric ........
MISCELLANEOUS
Vacuum Out Warning
System .................
Standby Vacuum Pump ......

3G7 20-81
3G8 20-82
3G9 20-83
3G10 20-84
3G11
3G12
3G13
3G14
3G15

3G16 20-90
3G17 20-91
3G18 20-92

3G19 20-93
3G20 20-94

CIRCUIT FUNCTION AND SPECIFIC CIRCUIT CODE LETTERS
A - Armament
B - Photographic
C - Control Surface
CA - Automatic Pilot
CC - Wing Flaps
CD - Elevator Trim
D - Instrument (Other Than Flight or Engine
Instrument)
DA - Ammeter
DB - Flap Position Indicator
DC - Clock
DD - Voltmeter
DE - Outside Air Temperature
DF - Flight Hour Meter
E - Engine Instrument
EA - Carburetor Air Temperature
EB - Fuel Quantity Gage and Transmitter
EC - Cylinder Head Temperature
ED - Oil Pressure
EE - Oil Temperature
EF - Fuel Pressure
EG - Tachometer
EH - Torque Indicator
EJ - Instrument Cluster
EK - Turbine Inlet Temperature
EL - Fuel Flow
F - Flight Instrument
FA - Bank and Turn
FB - Pitot Static Tube Heater and Stall Warning
Heater
FC - Stall Warning
FD - Speed Control System
FE - Indicator Lights
G - Landing Gear
,GA - Actuator
GB - Retraction
GC - Warning Device (Horn)
GD - Limit Switches
GE - Indicator Lights
H - Heating. Air Conditioning. Ventilating
and De-Icing
HA - Anti-Icing
HB - Cabin Heater
HC - Cigar Lighter
20-2

Revision 1

DH HE HF J K L -

M -

P -

Q -

R -

20-85
20-86
20-87
20-88
20-89

De-Ice
Air Conditioners
Cabin Ventilation
Ignition
JA - Magneto
Engine Control
KA - Starter Control
KB - Propeller Synchronizer
Lighting
LA - Cabin
LB - Instrument
LC - Landing
LD - Navigation
LE - Taxi
LF - Rotating Beacon
LG - Radio
LH - De-ice
LJ - Fuel Selector
LK - Tail Flood Light
LL - Recognition Lighting
Miscellaneous
MA - Cowl Flaps
MB - Electrically Operated Seats
MC - Smoke Generator
MD - Spray Equipment
ME - Cabin Pressurization Equipment
MF - Chem O2 - Indicator Light
D. C. Power
PA - Battery Circuit
PB - Generator Circuits
PC - External Power Source
PH - Anti-Ice Power Source
Fuel and Oil
QA - Auxiliary Fuel Pump
QB - Oil Dilution
QC - Engine Primer
QD - Main Fuel Pumps
QE - Fuel Valves
Radio (Navigation and Communication)
RA - Instrument Landing
RB - Command
RC - Radio Direction Finding
RD - VHF
RE - Homing

MODEL 172 SERIES SERVICE MANUAL
RF
RG
RH
RJ
RK
RL
RM
RP
RR
RS

Marker Beacon
Navigation
High Frequency
Interphone
UHF
Low Frequency
Frequency Modulation
Audio System and Audio Amplifier
Distance Measuring Equipment (DME)
Airborne Public Address System

CIRCUITS

FUNCTION

GAUGE

S - Rada
U - Miscellaneous Electronic
US
- Identification - Friend or Foe
W- Warning and Emergency
WA - Flare Release
WB - Chip Detector
WC - Fire Detection System
WD - Low Level Fuel
WE - Vacuum Warning System
X - A. C. Power
BASE COLOR

(or solid)

STRIPE COLOR

Red

None

Red

Black

Red

White

Red

Green

Red

Yellow

Black

None

Black

White

Mike Ground

Black

None

Radio Lights Dim

Yellow

None

Mike Audio

Tan

None

Tan (Shielded)

None

A. Power

Ground

Mike Key

White

Black

Radio Speaker

Green

None

Headphones

Blue

None

Dev

Gray

Red

Dev -

Gray

Green

"Dev."and "Dev- circuits are for use in Nav-o-matic 300 autopilots and any associated
omni indicator circuit to which it connects.
NOTE
All other color-coded wires are for general use in multiconductor radio and autopilot harness assemblies.
CROSS REFERENCE LISTING OF SERIAL REQUEST NUMBERS
LISTED ON DIAGRAMS VS. AIRCRAFT SERIAL NUMBERS.
SR NO
AIRCRAFT SERIAL NO.
SR NO. AIRCRAFT SERIAL NO.
SR NO. AIRCRAFT SERIAL NO.
SR7692 17263459
SR8773 17271035 &F17201750
SR9624 17274010
SR7903 17265685 & F17201385
SR8774 R1722910 &FR17200631
SR9625 R17203400
SR7904 FR17200562
SR9014 17270900& F17201750
SR9742 17274183 & F17202040
SR8133 17265685 & F17201515
SR9104 17272885
SR10034 17275035 & F17202135
SR8134 FR17200591
SR9105 R1723200
SR10056 17275035 & F17202135
SR8146 R1722000
SR9145 17270790
SR10092 17275800 & F17202195
SR8259 17265782 & F17201445
SR9187 17271576
SR10185 17275675
SR8453 17269310 & F17201640
SR9270 17272885. F17201910 &
SR10248 17275361 & F17202136
SR8454 R1722725 &FR17200621
R1723200
SR10412 17276260 & F17202234
SR8490 17267585. F17201515
SR9429 R17272383
SR10523 17276080 & F17202216
R1722000 & FR17200591 SR9435 17271744 & F17201830
SR10581 17275869
SR8552 17268213 & R1722141
SR9583 17273154
SR11072 17276517
SR8596 17269310, R1722825
SR9608 17269310 thru 17272884
F17201640 thru F17201909
Revision 1

20-3

MODEL 172 SERIES SERVICE MANUAL

20-5

MODEL 172 SERIES SERVICE MANUAL

2)
of
2(Sheet
Electronic
& alternator
Primary.
Bar.
Bus

MODEL 172 SERIES SERVICE MANUAL

20-7

MODEL 172 SERIES SERVICE MANUAL

20-9

MODEL 172 SERIES SERVICE MANUAL

::I

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MODEL 172 SERIES SERVICE MANUAL

EQUIPMENT

TABLELE_____-

MODEL 172 SERIES SERVICE MANUAL

20-12

MODEL 172 SERIES SERVICE MANUAL

20-13

MODEL 172 SERIES SERVICE MANUAL

20-14

MODEL 172 SERIES SERVICE MANUAL

20-15

MODEL 172 SERIES SERVICE MANUAL

20-16

MODEL 172 SERIES SERVICE MANUAL

20-18

MODEL 172 SERIES SERVICE MANUAL

20-19

20-20

MODEL 172 SERIES SERVICE MANUAL

OO
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_______

20-22

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WIRING DIAGRAM_

MODEL 172 SERIES SERVICE MANUAL

20-23

MODEL 172 SERIES SERVICE MANUAL

20-25

MODEL 172 SERIES SERVICE MANUAL

MANUAL
SERVICE
SERIES
172

MODEL

20-28

MODEL 172 SERIES SERVICE MANUAL

20-29

MODEL 172 SERIES SERVICE MANUAL

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20-30

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MODEL 172 SERIES SERVICE MANUAL

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20-31

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MODEL 172 SERIES SERVICE MANUAL

20-37

MODEL 172 SERIES SERVICE MANUAL

20-38

MODEL 172 SERIES SERVICE MANUAL

20-39

MODEL 172 SERIES SERVICE MANUAL

^NOTE8.

20-42

SR 845

I54)

A- ZO

MODEL 172 SERIES SERVICE MANUAL

20-45

MODEL 172 SERIES SERVICE MANUAL

Bus Bar & Avionics Master Switch (Sheet 1 of 2)
20-46

MODEL 172 SERIES SERVICE MANUAL

20-48

MODEL 172 SERIES SERVICE MANUAL
NOTE

20-49

MODEL 172 SERIES SERVICE MANUAL

o..ATT..T

BATTE

MODEL 172 SERIES SERVICE MANUAL

20-51

MODEL 172 SERIES SERVICE MANUAL

20-52

MODEL 172 SERIES SERVICE MANUAL
NOTES

057045 I

BuS BAR

P22

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T14r 5R '54

20-53

MODEL 172 SERIES SERVICE MANUAL

20-54

MODEL 172 SERIES SERVICE MANUAL

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20-56

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MODEL 172 SERIES SERVICE MANUAL

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20-57

MODEL 172 SERIES SERVICE MANUAL

20-58

Revision 1

MODEL 172 SERIES SERVICE MANUAL

EE 12

Revision 1 20-58A

MODEL 172 SERIES SERVICE MANUAL

20-58B

Revision 1

MODEL 172 SERIES SERVICE MANUAL

20-59

MODEL 172 SERIES SERVICE MANUAL

20-60

MODEL 172 SERIES SERVICE MANUAL

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20-61

MODEL 172 SERIES SERVICE MANUAL

20-62

MODEL 172 SERIES SERVICE MANUAL

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MODEL 172 SERIES SERVICE MANUAL

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20-63

MODEL 172 SERIES SERVICE MANUAL

20-64
222

MODEL 172 SERIES SERVICE MANUAL

20-65

MODEL 172 SERIES SERVICE MANUAL

EAS

MODEL 172 SERIES SERVICE MANUAL

Revision 1

20-66A/(20-66B blank)

MODEL 172 SERIES SERVICE MANUAL

20-67

MODEL 172 SERIES SERVICE MANUAL

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MODEL 172 SERIES SERVICE MANUAL

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MODEL 172 SERIES SERVICE MANUAL

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20-75

MODEL 172 SERIES SERVICE MANUAL

20-76

MODEL 172 SERIES SERVICE MANUAL

20-77

MODEL 172 SERIES SERVICE MANUAL

20-78

MODEL 172 SERIES SERVICE MANUAL

20-79

MODEL 172 SERIES SERVICE MANUAL

20-80

MODEL 172 SERIES SERVICE MANUAL

20-81

MODEL 172 SERIES SERVICE MANUAL

20-82

MODEL 172 SERIES SERVICE MANUAL

20-83

MODEL 172 SERIES SERVICE MANUAL

20-85

MODEL 172 SERIES SERVICE MANUAL

20-86

MODEL 172 SERIES SERVICE MANUAL

20-89

MODEL 172 SERIES SERVICE MANUAL

20-91

MODEL 172 SERIES SERVICE MANUAL

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MODEL 172 SERIES SERVICE MANUAL

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Source Exif Data:

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File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.4
Linearized                      : No
Encryption                      : Standard V1.2 (40-bit)
User Access                     : Print, Copy, Fill forms, Extract, Assemble, Print high-res
Creator                         : 
Producer                        : Avantext, Inc.
Modify Date                     : 2007:12:06 10:58:15-05:00
Create Date                     : 2001:06:25 08:38:01-04:00
AVTX TGUID                      : cf036fe0-7ced-11d5-b42a-000103c60594
AVTX TID                        : 233
Title                           : D2065-3-13 - MODEL 172 SERIES (1977 THRU 1986)
Subject                         : MODEL 172 SERIES (1977 THRU 1986)
AVTX LLIB                       : MM
AVTX LPROD                      : CS02
Page Count                      : 639
Has XFA                         : No
Mod Date                        : 2007:12:06 10:58:15-05:00
Metadata Date                   : 2007:12:06 10:58:15-05:00
Corruptor                       : http://www.w3.org/1999/02/22-rdf-syntax-ns#li
Author                          : Nobody

EXIF Metadata provided by EXIF.tools

D2065 3 13 172 SERIES (1977 THRU 1986) Cessna_172_1977 1986_MM_D2065 Cessna 1977 1986 MM

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