Continental_IO 520 BB_Engine Maintenance_1988 Continental IO BB Engine Maintenance 1988

User Manual: Continental_IO-520-BB_Engine-maintenance_1988

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Permold Series
Maintenance Manual
Engine Models IO-520-B
BA
BB
C
CB
M
MB
Courtesy of Bomar Flying Service
www.bomar.biz
M-11

This Page Intentionally Left Blank

CURRENT STATUS OF PAGES AS OF:
October, 1998
See “Manual Revisions,” in the introduction section for distribution procedure.
THE ORIGINAL DATE OF THIS PUBLICATION IS October,

1998.

INSERT LATEST PAGES, DESTROY SUPERSEDED PAGES.

WARNING
If the user of this manual is uncertain whether all current revisions have been
incorporated into the manual, contact Teledyne Continental Motors. Do not
perform any operation, maintenance, installation or other operation until the
manual is confirmed as current.
MODELS: I0-520-B, -BA, -BB, -C, -CB, -M, -MB
PAGE STATUS

PAGE STATUS

FORM M-11
PAGE STATUS

PAGE STATUS

iii

This Page Intentionally Left Blank

Chapter 1

.............................................................................................................................................................. General

Information

Chapter 2 ............................................................................................................................................................. Tools and Equipment
Chapter 3 ....................................................................................................................................................... Sealants and Lubricants
Chapter 4

................................................................................................................................................ Airworthiness

Limitations

Chapter 5

......................................................... Time

Chapter 6

...................................................................................................... Unpacking/Deinhibiting/Installation

& Test

Chapter 7

.......................................................................................................................................................................Servicing,

Fluids

Chapter 8

................................................................................................................................. Engine

Chapter 9

................................................................................................................................................................... Standard

Limits/Operational Inspection / Engine Troubleshooting

Preservation and Storage
Practices

Chapter 10

........................................................................................................................................................... Engine

Chapter 11

...................................................................................................................................................................... Exhaust

System

Chapter 12

...................................................................................................................................................................... Ignition

System

Maintenance

Chapter 13 ................................................................................................................................................................................ Fuel System
Chapter 14 ................................................................................................................................................................... Induction System
Chapter 15

................................................................................................................................................ Air

Conditioning System

Chapter 16 ........................................................................................................................................... Electrical Charging System
Chapter 17 ................................................................................................................................................. Starter & Starter Adapter
Chapter 18

............................................................................................................................................................. Lubrication

System

Chapter 19 ............................................................................................................................................................... Cylinder Assembly
Chapter 20 .....................................................................................................................................................................................Crankcase
Chapter 21

.............................................................................................................................................................. Engine

Drive Train

Chapter 22 ............................................................................................................... Post Maintenance Adjustment and Test

This Page Intentionally Left Blank

Chapter 1

General Information
Cover Page .......................................................................................................................................................................................................................
Current Status of Pages ..................................................................................................................................................................................... iii
Table of Contents .......................................................................................................................................................................................................v
Replacement Parts .............................................................................................................................................................................................. 1-3
Know Your Supplier ................................................................................................................................................................................... 1-3
Identifying Approved Parts ................................................................................................................................................................... 1-3
Owner/Operator Responsibility ............................................................................................................................................................... 1-4
Notice to all Users .............................................................................................................................................................................................. 1-4
To The Mechanic .................................................................................................................................................................................................. 1-4
Notes, Cautions, and Warnings ................................................................................................................................................................ 1-4
Note ......................................................................................................................................................................................................................... 1-4
Caution ................................................................................................................................................................................................................. 1-4
Warning................................................................................................................................................................................................................ 1-4
About This Manual ............................................................................................................................................................................................. 1-5
Scope ...................................................................................................................................................................................................................... 1-5
Definition of Terms ..................................................................................................................................................................................... 1-5
Manual Revisions ......................................................................................................................................................................................... 1-5
Related Publications ......................................................................................................................................................................................... 1-6
ASTM ............................................................................................................................................................................................................................. 1-6
Slick Ignitions ......................................................................................................................................................................................................... 1-6
Service Documents ............................................................................................................................................................................................. 1-7
Mandatory Service Bulletin (MSB) ................................................................................................................................................ 1-7
Critical Service Bulletin (CSB).......................................................................................................................................................... 1-7
Service Bulletin (SB) .................................................................................................................................................................................. 1-7
Service Information (SID)...................................................................................................................................................................... 1-7
Service Information Leter (SIL) ........................................................................................................................................................ 1-7
Special Service Notice (SSN)............................................................................................................................................................... 1-7
Service Reports and Inquiries............................................................................................................................................................. 1-7
Engine Model Code............................................................................................................................................................................................ 1-8
Engine Design Features .......................................................................................................................................................................... 1-8
Engine Specifications and Operating Limits.................................................................................................................................. 1-9
Accessory Drive Ratios to Crankshaft ............................................................................................................................................. 1-10
Engine Illustrations ......................................................................................................................................................................................... 1-11

1-1

This Page Intentionally Left Blank

1-2

General Information

Replacement Parts
WARNING
Use only parts that meet the engine type
design.
Beware of replacement parts, materials and
accessories that may be sold as aircraft quality but
whose origin and quality are not known. These
parts may be deceptively advertised as “unused,”
“like new,” or “remanufactured,” and purchasers
are often unaware that they are not eligible for use
on certificated aircraft. The hazards involved in
installing these types of parts on your aircraft are
obvious.

Know Your Supplier
Many original parts and components are copied
and the copies are sold at discounted prices for
installation on U.S. certified aircraft. An original
manufacturer's part is often used as a guide to
make duplicates that appear to be as good as the
original, but there are many unknowns about the
quality of design, materials, and workmanship.
Other factors that go into quality parts are the
degree of heat treating and plating, and
inspections, tests, and calibrations. Unfortunately,
a cheaply produced part that looked “as good as
the original” is usually found out too late.
Federal Aviation Regulations FAR 43.13 and FAR
145.57 specify performance rules for replacement
of parts and materials used in the maintenance and
alteration of United States certificated aircraft.
FAR 91.403, FAR 121.363, FAR 123.45, and
FAR 135.143(a) holds the owner/operator responsible for the continued airworthiness of the
aircraft, and that includes the quality of replacement parts.

Identifying Approved Parts
Approved serviceable replacement parts are
identified by:
1. Federal Aviation Administration (FAA) Form
8130-3 Airworthiness Approval Tag. An
Airworthiness Approval Tag identifies a part
or group of parts that have been approved by
an authorized FAA representative.
2. FAA Technical Standard Order (TSO) number
and identification mark indicating that the part
or appliance was manufactured in accordance
with the requirements of FAR 21 Subpart O.
3. FAA Parts Manufacturer Approval (PMA)
symbol with the manufacturer's name, part
number, make and model of the type certified
product on which the part can legally be
installed stamped on the part. An FAA/PMA
is issued under FAR 21.305. Make and model
information may be on a tag attached to the
part.
4. Shipping ticket, invoice, or other document
which verifies that the part was manufactured
by a facility that was holding an FAA
Approved Production Inspection System
Certificate issued under FAR 21 Subpart F, or
by a manufacturer holding an FAA Production
Certificate issued under FAR 21 Subpart G.
5. Certificate of airworthiness for export issued
by governments in countries other than the
United States of America under the provisions
of FAR 21 Subpart N.

1-3

General Information

Owner/Operator Responsibility
The owner/operator is responsible for the
continued airworthiness of the aircraft. In
accordance with FAR, certification of materials,
parts and appliances for return to service for use
on aircraft is the responsibility of the
person/agency who signs the approval. To insure
the continued safe operation of your aircraft, you
must exercise great care when inspecting, testing,
and determining the acceptability of all parts and
materials. A very important part of this is
verifying the origin of all materials, parts, and
accessories that are used on your aircraft .

Notice to all users
This manual does not contain maintenance
information for supplemental type certificated
components or systems. This manual contains
information on engines, components and systems
designed, tested and certified by TCM in
accordance with the pertinent type design data.
This manual contains maintenance information
only. All personnel involved with these functions
must thoroughly read and understand the
information provided. These instructions provide
the procedures necessary to maintain the engine
and they must be carefully followed.
This manual contains no warranties, either
expressed or implied.

WARNING
The Operator and Installation manual,
Maintenance, manual, Overhaul manual,
Service Documents and the Parts Catalog
constitute the instructions for Continued
Airworthiness prepared by TCM as
approved by the FAA, pursuant to FAR
Part 33. As required by FAR § 43.13, each
person performing overhaul, maintenance,
alteration or preventive maintenance on the
engine or accessories must use the methods,

1-4

techniques and practices prescribed in the
Instructions for Continued Airworthiness.
Failure to comply with the Instructions for
Continued Airworthiness may result in
engine malfunction, engine failure, injury
or death.

To The Mechanic
Prior to performing maintenance, alteration,
overhaul or preventive maintenance, the mechanic
must meet requirements of FAR 65 and must
follow FAR Parts 43, 91 and 145 as applicable.
Use this manual in conjunction with Teledyne
Continental Motors (TCM) service documents,
related publications, accessory manufacturer’s
instructions, FAR and FAA Advisory Circulars.

Notes, Cautions and WARNINGS
NOTE...
Special interest information which may facilitate
performance of a procedure or operation of
equipment.

CAUTION...
Used to emphasize certain information or
instructions which if disregarded may result in
damage to engine or accessories.

WARNING
Used to provide warning with respect to
information and/or instructions which if
disregarded will endanger personnel and/or
severely damage the engine resulting in
subsequent engine malfunction or failure.
Notes, cautions and warnings do not impose undue
restrictions. They are provided to obtain maximum
safety, efficiency and performance. Abuse, misuse
or neglect of equipment can cause eventual engine
malfunction or failure.

General Information

About This Manual
This maintenance manual and the publications
listed in “Related Publications,” provide the
information necessary to operate, maintain and
install an aircraft engine. For a list of chapters
contained in this manual refer to the “Table of
Contents” earlier in this chapter. For chapter
contents, refer to the chapter title page at the
beginning of each chapter. The pages, figures and
tables contained in this publication are numbered
consecutively.

Scope
This publication contains the information
necessary to perform scheduled maintenance,
adjustment and testing of the I0-520-B, -BA, -BB,
-C, -CB, -M and -MB engines.

Definition Of Terms
In this manual, front, rear, left and right refer to
the engine as viewed from the accessory end. The
accessory end is the rear and the propeller flange
is the front of the engine. Cylinders are numbered
starting from the rear, with odd numbers on the
right and even numbers on the left.

Manual Revisions
Teledyne Continental Motors’ manuals are revised
as necessary. Revisions to this manual will be
furnished to purchasers who fill out and return the
registration post card located in the front of this
manual.
Page iii, “Current Status Of Pages,” is updated at
each revision. Remove and discard the old page iii.
Insert the new page iii as a record of which
revisions have been incorporated into the manual.

If for any reason, you are uncertain
whether all current revisions have been
incorporated into the manual, contact
Teledyne Continental Motors or a TCM
Distributor to confirm the manual is the
most current revision. Do not use the
manual and do not perform any operation,
maintenance or installation procedures or
other operations upon the engine or
accessories until the manual has been
confirmed to be current.
This manual is current and correct to the
best of Teledyne Continental Motors’
knowledge at the time of publication.
Teledyne Continental Motors solicits and
encourages users comments regarding
suggested changes to this manual (a post
card is provided at the front of the manual
for this purpose.) Routine recommended
changes or questions should be sent to:
Teledyne Continental Motors
P.O. Box 90
Mobile, Alabama 36601
ATTN:
Technical Publications Department
If the user observes incorrect information
or mistakes in this publication that may
affect safety in any manner, immediately
contact the Technical Publications Department at (334) 438-3411 of Continental
Motors at (334) 438-3411, or contact a
Teledyne Continental Motors Distributor
or the Federal Aviation Administration.

1-5

General Information

Related Publications
The following is a listing of related manuals:
1. Overhaul Manual for I0-520 Permold series
engine models -B, -BA, -BB, -C, -CB, -M, and
-MB Engines, Form OH-11.

ASTM
American Society for Testing and Materials
(ASTM). Order through:
ASTM
1916 Race Street, Philadelphia, PA.
19103-1187 USA
Ph: (215) 299-5400

2. Illustrated Parts Catalog for for I0-520
Permold series engine models -B, -BA, -BB, C, -CB, -M and -MB Permold Series Aircraft
Engine, Form X30624A.

Slick Ignitions

3. Operator and Installation Manual, Form OI11.

Order Slick Ignition Systems Master Service
Manual Index and Order Form through:

4. Teledyne Continental Motors Aircraft Engine
Service Documents (including service
bulletins).

Slick Aircraft Products, Unison Industries
530 Blackhawk Park Avenue
Rockford, Illinois 61104
ATT: Subscription Department
Telephone: (815) 965-4700

5. Fuel Injection Manual, Form X30593A.
6. Starter Service Instructions, Form X30592.
7. TCM Ignition Systems Master Service
Manual, Form X40000
The above publications can be ordered through
your Teledyne Continental Motors Distributor or
ordered directly, if prepaid, from:
Teledyne Continental Motors
P. 0. Box 90
Mobile, Alabama 36601
ATTN: Publication Sales Department
Telephone: (334) 438-3411
For price information on the above publications
request TCM Publications Pricing Index of
Current Publications and Optional Publications.

1-6

General Information

Service Documents
Teledyne Continental Motors service documents
are:
(1) Mandatory Service Bulletin
(2) Critical Service Bulletin
(3) Service Bulletin
(4) Service Information Directive
(5) Service Information Letter
Special Service Notice (SSN)
See “Related Publications,” for service document
ordering information. Following are definitions of
the above service document categories:
CATEGORY 1: “Mandatory Service Bulletin”
(MSB)
Service documents relating to known or suspected
hazards to safety that have been incorporated in
whole or in part in an Airworthiness Directive
(AD) issued by the FAA or have been issued, at
the direction of FAA, by the manufacturer in order
to require compliance with an already issued AD
(or an equivalent issued by another country's
airworthiness authority).
CATEGORY 2: “Critical Service Bulletin”
(CSB)
Service documents (not included in Category 1)
that have been determined by the product
manufacturer to constitute a threat to continued
safe operation of an aircraft or to persons or
property on the ground unless some specific action
(inspection, repair, replacement, etc.) is taken by
the product owner or operator. Documents in this
category may be incorporated in an Airworthiness
Directive issued by the FAA.

includes updates of instructions for continued
airworthiness.
CATEGORY
4:
“Service
Information
Directive” (SID)
Service documents (not included in Categories 1, 2
or 3) that have been determined by the
manufacturer to be of value to an owner/operator
in the use of a product by enhancing safety,
maintenance or economy.
CATEGORY 5: “Service Information Letter”
(SIL)
This category includes all information (not
included in Categories 1 through 4) that may be of
use to the owner/operator or maintainer of the
aircraft.

Special Service Notice (SSN)
TCM may issue a Special Service Notice when a
product condition can be rectified by direct contact
with each customer to whom the product was
delivered. Special service notices will be upgraded
to Service Bulletins if confirmation of compliance
with the Special Service Notice cannot be verified
by TCM.

Service Reports And Inquiries
If for any reason you have an inquiry or require
technical assistance, contact your local TCM
distributor or TCM field representative. Requests
for copies of Teledyne Continental Aircraft Engine
service publications should be made through your
distributor or Teledyne Continental Motors, P. 0.
Box 90, Mobile, AL 36601, ATTN: Publications
Sales Department.

CATEGORY 3: “Service Bulletin” (SB)
Service documents (not included in Categories 1
and 2) considered by the product manufacturer to
constitute a substantial improvement to the
inherent safety of an aircraft or component of an
aircraft. This "Service Bulletin" category also

1-7

General Information

Engine Model Code
This is how a typical IO-520 engine model code is
interpreted:
Engine Displacement
in Cubic Inches
Engine Specification Number
Refer to the Engine Parts
Catalog for Information

Fuel Injection

IO-520-X (x)
Horizontally
Opposed
Cylinders

Engine Model
Number

Engine Design Features
The I0-520 Permold series engines have six air
cooled, horizontally opposed cylinders with
overhead valves. The 5.25 inch bore and 4.00 inch
stroke provides 520 cubic inches displacement.
The engines are fuel injected and feature up-draft
induction systems. The crankshaft is equipped
with pendulum type counterweight dampers that
suppress torsional vibrations.
A gear-driven alternator is installed on the rightfront side of the crankcase forward of the number
5 cylinder. The engine is equipped with two geardriven magnetos and two accessory drive pads.
The exhaust system is supplied by the airframe
manufacturer.
The I0-520 Permold Series engines have a
doweled six bolt hole configuration propeller
flange. A mounting pad is provided for a hydraulic
controlled governor for a constant speed propeller.
A wet sump and positive displacement oil pump
are installed on the lower rear of the crankcase.
When properly adjusted under normal operating
conditions, the desired oil pressure is maintained
by a pressure relief valve located in the oil pump
housing.
A geared, right-angle drive starter adapter with a
direct current starter motor provides engine
cranking.

1-8

General Information

Engine Specifications
and Operating Limits
The operating limits and specifications listed in
this section are applicable to the I0-520 Permold
Series aircraft engines. Consult the I0-520
Operator And Installation Manual, Form OI-11 for
additional operating procedures.
For time between overhaul (TB0) for I0-520
Permold Series engines see section 5-3 and the
latest TBO Service Bulletin (Revised Overhaul
Periods For All Teledyne Continental Aircraft
Engines). Accessories supplied with the engine by
TCM have the same TBO with criteria for service
and longevity outlined in current TCM TBO
Service Bulletins, unless otherwise specified.

Engine Specifications

Operating Limits
NOTE...
The following specifications apply to all I0-520
Permold Series engines unless otherwise specified.
Crankshaft Speed - RPM
Rated Maximum Continuous Operation 2700
600 min.
Idle
Intake Manifold Pressure At Idle (In. Hg.)
18.5 max.
Fuel Control System
Continental Continuous Flow Injection
See Chapter 7, “Servicing Fluids”
Fuel
See Chapter 7, “Servicing Fluids”
Oil
Oil Pressure
10
Idle, Minimum, psi
30 to 60
Normal Operation, psi @ 200° F
Oil Sump Capacity (U.S. Quarts) I0-520-B, -BA, BB, -C, -CB, -M, -MB
12
Oil Consumption (LB /BHP/Hr. Max.)
.006 X % Power
100
Oil Temperature Limits
24°C/75°F
Minimum for Take-Off
115.6°C/240°F
Maximum Allowable
..........

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

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

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

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

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

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

Manufacturer: Teledyne Continental Motors
Models: I0-520-B, -BA, -BB, -C, -CB, -M, -MB
Cylinders
Individual cylinders
Arrangement
horizontally opposed
8.5:1
Compression Ratio
1-6-3-2-5-4
Firing Order
6
Number of cylinders
5.25
Bore (Inches)
4.00
Stroke (Inches)
520
Piston Displacement (cu in )
...........................................................

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

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

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

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

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

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

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

Ignition Timing (Compression stroke, breaker
opens)
22° ± 1°
Right Magneto, degrees BTC
22° ± 1°
Left Magneto, degrees BTC
..........................................

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

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

Brake Horsepower
Rated Maximum Continuous Operation

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

285

The following spark plugs are approved for use in
engine models according to the following listing:
I0-520 Permold Series:

TCM
Champion

634675
RHB32E

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

Spark Plug Gap:
Use spark plug manufacturer's specified gap
................................

1-9

General Information

Accessory Drive Ratios to Crankshaft
Accessory

Direction of Rotation

Drive Ratio

Tachometer

CCW

.5:1

Magneto

CCW

1.5:1

Starter

CCW

48:1

Alternator (Gear Dr.)

CCW

3:1

**Propeller Governor

1:1

Fuel Pump (Injection)

1:1

Accessory Drives (2)

1.5:1

“CW”- Clockwise and “CCW” - Counterclockwise (facing drive pad).
** This drive is a modified AND 20010 and is supplied with cover plate only.

WARNING
Oil pressure is applied to the face of
accessory drive pads. If a gasket, accessory
or cover is not properly installed or
hardware is not properly torqued, oil
leakage will occur.
DO NOT operate the engine without a
propeller governor or internally grooved
cover plate installed. Failure to do so will
cause damage to the crankshaft and oil
transfer collar.

1-10

General Information

#1
Starter Motor

Alternator

Starter Adapter

Fuel Pump

Oil Filter

Fuel
Manifold
Valve
Induction
Balance Tube

Induction Tube
Oil Cooler
1200 Series Magneto
#6

Oil Filler and Crankcase
Breather

Figure 1-1
IO-520-B, -BA and -BB Engine Models - Top View

1-11

General Information

Magnetos
Oil Filler
Fuel Manifold Valve

Oil Cooler

Spark Plug
Oil
Filter

C ontinental

Propeller
Governor Pad
Induction
Balance
Tube

Tachometer
Drive
Oil Pressure
Connection

Engine
Mount

Oil Temperature
Connection

Oil Sump

Induction Tubes

Fuel Metering Unit

Figure 1-2
IO-520-B,-BA and -BB Engine Models - Side View

1-12

General Information

Retard
Connection

Magneto Switch
Connection
Cylinder Barrel

Alternator

Cylinder Head

Head Temperature
Port 6 Cylinders

Rocker
Cover
Induction
Balance Tube
Manifold
Drain

Pushrod
Housing
Engine
Mount
Oil Sump

Figure 1-3
IO-520-B, -BA and -BB Engine Models - Front View

1-13

General Information

Vacuum Pump Return
Fuel Inlet From Fuel Tank

AND 20000
Drive Pad
Fuel Pump
Vapor Return To Tank

Fuel Outlet To Fuel Control

Fuel Return From Fuel Control
Oil Filter

Starter Motor

Starter
Adapter
Oil Temperature
Control Valve
(Vernatherm)

Tach Drive
Seal Drain

Manifold Pressure
Reference

Oil Pump
Throttle

Fuel Control
Unit

Figure 1-4
IO-520-B, -BA and -BB Engine Models - Rear View

1-14

Intake Manifold
Drain

General Information

Fuel Injectors
#3

Magnetos
Starter Motor

Alternator

Engine Mount

Crankshaft

Throttle &
Fuel
Control

Prop
Flange

Fuel Manifold Valve

Crankcase
Oil Filter

Induction System
Balance Tube
Cylinder
Assembly

Engine Mount

Oil Cooler
Oil Filler and
Crankcase Breather

Valve Covers

Figure 1-5
IO-520-C, -CB Engine Models - Top View

1-15

General Information

Magnetos
Oil Filler
Fuel Manifold Valve

Oil Cooler

Spark Plug

Engine Mount
Oil Filter
Fuel Pump

Continental

Prop
Governor
Pad
Induction
Balance
Tube

Engine
Mount
Oil Sump

Induction Tube

Oil Pressure Port

Oil Sump Drain
Oil Temperature Port

Figure 1-6
IO-520-C, -CB Engine Models - Side View

1-16

Fuel
Metering
Unit

General Information

Courtesy of Bomar Flying Service
www.bomar.biz

Retard
Connection

Magneto Switch
Connection
Cylinder Barrel

Alternator

Cylinder Head
Rocker
Cover

Pushrod
Housing

Induction manifold
Balance Tube
Intake Manifold
Drain

Oil Sump Drain

Figure 1-7
IO-520-C, -CB Engine Models - Front View

1-17

General Information

Oil Filter
Oil Cooler
Cylinder
Head

Rocker
Cover

Pushrod
Housing
Engine
Mount

Starter Adapter

Inlet From Fuel Pump
Throttle

Figure 1-8
IO-520-C, -CB Engine Models - Rear View

1-18

General Information

Starter Motor

Alternator
Starter Adapter
Fuel Pump

Fuel
Manifold
Valve

Oil Filter
Induction Tube
Oil Cooler

Induction
Balance Tube

1200 Series Magneto
#6

Oil Filler & Crankcase
Breather

Figure 1-9
IO-520-M, -MB Engine Models - Top View

1-19

General Information

Magnetos
Oil Filler
Fuel Manifold Valve

Oil Cooler

Spark Plug
Oil Filter
Fuel Pump

Continental

Fuel
Metering
Oil Pressure Unit
Connection

Propeller
Governor
Pad
Induction
Balance Tube

Engine
Mount

Oil Sump
Oil Sump
Drain

Figure 1-10
IO-520-M, -MB Engine Models - Side View

1-20

Oil Temperature
Connection
Induction Tube

General Information

Retard
Connection

Magneto Switch
Connection
Cylinder Barrel

Alternator

Cylinder Head

Rocker
Cover

Head Temperature
Port 6 Cylinders
Induction Manifold
Balance Tube
Pushrod Housing

Intake Manifold
Drain
Oil Sump Drain

Figure 1-11
IO-520-M, -MB Engine Models - Front View

1-21

General Information

Vacuum Pump Return

AND 20000
Drive Pads

Fuel Pump

Fuel Inlet
From Fuel Tank

Vapor Return To Tank

Fuel Pump Outlet
To Fuel Control

Fuel Return From
Metering Unit

Oil Filter

Starter Adapter

Starter Motor
Oil Cooler
Manifold Pressure
Reference

Intake Mainifold Drain
Oil Temperature Control Valve
(Vernatherm)
Electrical Tachometer
Drive AND 20005

Figure 1-12
IO-520-M, -MB Engine Models - Rear View

1-22

Intake Manifold
Drain
Engine Mount
4 Places

Chapter 2

Tools and Equipment

Necessary Tools .................................................................................................................................................................................................... 2-3
Possible Special Tool Procurement Sources.................................................................................................................................. 2-4
Special Tools ........................................................................................................................................................................................................... 2-5
General Engine Reciprocating .......................................................................................................................................................... 2-5
Ignition System ............................................................................................................................................................................................... 2-5
Fuel Injection................................................................................................................................................................................................... 2-5
Charging System ........................................................................................................................................................................................... 2-5
Starting System ............................................................................................................................................................................................... 2-5
Lubrication System ...................................................................................................................................................................................... 2-5
Cylinders ............................................................................................................................................................................................................. 2-5
Crankcase ........................................................................................................................................................................................................... 2-7
Engine Drive Train ..................................................................................................................................................................................... 2-7
Operational Inspection ............................................................................................................................................................................ 2-7

2-1

This Page Intentionally Left Blank

2-2

Tools and Equipment

Necessary Tools
The mechanic should be equipped with a complete set of tools that include the following:
1. Wrenches - 1/4” through 1 1/4"
2. Common and Philips Head Screwdrivers
3. Pliers - Common, Diagonal Cutters, Needle Nose, Duck Bill, Snap Ring, Safety Wire
4. Ratchets 1/4", 3/8", 1/2" Drive
5. Sockets - 1/4”' Drive 5/32" through 1/2",- 3/8" Drive 3/8" through 1" - 1/2" Drive 7/16" through 1-1/ 4"
6. Sockets (Deepwell) -1/2" Drive, 7/6" through 1"
7. Feeler Gauges
8. Leather or Soft Plastic Mallet
9. Torque Wrenches* 0-500 In. Lbs. and 0-100 Ft. Lbs.
10. Micrometers*
11. Slide Hammer
12. Pullers
13. Thickness Gauges
14. Vernier Calipers*
15. Small Hole Gauges
* Must be currently calibrated, and the calibration must be traceable to the National Bureau of Standards.

2-3

Tools and Equipment

Possible Special Tool Procurement Sources
Note: All tools in the "Special Tool" list are for reference only, and not for the purpose of promoting or
suggesting tools to be purchased from the indicated sources.
ALCOR
Box 32516 10130 Jones Maltsberger Rd.
San Antonio, TX 78284 Ph.512/349-3771

Instruments for Light Powered Aircraft
Special Tools

KENT- MOORE
29784 Little Mack
Roseville, Ml 48066-2298 Ph. 800/253-0138

Precision Instruments
Measuring Instruments
Precision Tools, Special Tools

CHAMPION SPARK PLUG, CO.
Box 910, 900 Upton Ave.
Toledo, OH 43661 Ph. 419/535-2461

Spark Plugs, lgnitors, Oil Filters
Special Tools

EASTERN ELECTRONICS, INC.
180 Roberts St.
East Hartford, CT 06108 Ph. 203/528-9821

Fuel Pressure Test Equipment
Measuring Instruments
Precision Tools, Piston Position Indicators

FEDERAL TOOL SUPPLY CO., INC.
1144 Eddy St.
Providence, Rhode Island 02940 Ph. 800/343-2050

Precision Inspection Instruments
Special Tools

AIRCRAFT TOOL SUPPLY
P.O. Box 4525, 2840 Breard St.
Monroe, LA 71201 Ph. 507/451 -5310

Precision Tools
Special Tools

McMASTER-CARR SUPPLY CO.
P.O. Box 4355
Chicago, Illinois 60680 Ph. 312/833-0300

Precision Tools
Special Tools

SNAP ON TOOLS
2611 Commerce Blvd.
Birmingham, Alabama 35210 Ph. 205/956-1722

Precision Tools
Special Tools

KELL-STROM TOOL COMPANY, INC.
214 Church St.
Wethersfield, CT 06109

Ignition Test Equipment

FAX CORPORATION
210 South King St.
Danbury, Connecticut 06813 Ph. 203/748-6117

Ultrasonic Test Equipment

MERRIT PRODUCTS
201 W. Manville, Compote, Cal. 90224 Ph. 310/639-4242

Special Tools

AERO TEST, INC.
29300 Goddard Rd, Romulus, Mi. 48174 Ph. 313/946-547

Model 20 ATM-C Porta-Test Unit

PARKER RESEARCH CORPORATION
P.O. Box 1406 Dunedin Fl. 34697 Ph. 1-800-525-3935

Model DA-200 Contour Probe
Fax. 813-797-3941

2-4

Tools and Equipment

Special Tools
Specific tools listed below, or equivalent tools marketed by other manufacturers, are necessary for overhaul and
maintenance.

General Engine Reciprocating
1. Master Orifice Tool for cylinder compression test available from Kent - Moore.
2.

Differential Pressure Cylinder Checker available from Kent - Moore.

Ignition System
1.
2.
3.

Borrough's 3608A Protractor/Timing Indicator Disc or equivalent for setting engine timing.
Model E25 Timing Indicator available from Eastern Electronics, Inc.
11-9110-1 Magneto Timing Light available from KELL-STROM Tool Company Inc.

Fuel Injection
1.

Borrough's 8165 Injector Nozzle Remover and Installer or equivalent.

Charging System
1.
2.
3.
4.
5.
6.
7.
8.

Borrough's 7726 Tork Band Tension Adjuster or equivalent for Gen./Alt. Belt Tensioning.
BT-33-73F Belt Tension Gauge available from Kent - Moore.
Borrough's 4973 Generator Drive Holders or equivalent.
Borrough's 61-5 Pulley Puller or equivalent for gen./alt. sheave removal
Borrough's 8091 GEN./ALT. Output Tester or equivalent.
647 Alternator Analyzer Voltage Regulator Tester from Eastern Electronics, Inc.
E100 Alternator/Regulator/Battery Tester available from Eastern Electronics, Inc.
Model 29 Voltage & Circuit Tester available from Eastern Electronics, Inc.

Starting System
1.
2.

Borrough's 8093C Bearing Puller or equivalent for needle bearing removal.
Borroughs 23-1 Needle Bearing Installer or equivalent.

Lubrication System
1.

Oil Pressure Relief Spot Facer available from Kent - Moore.

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

Push Rod Spring Compressor available from Kent - Moore.
5204 & 8158A Cylinder Base Nut Wrenches available from Kent - Moore.
Borrough's 8079 Cylinder Base Nut Wrenches or equivalent.
3882, 3882-2 Cylinder Base Nut Wrenches available from Kent - Moore.
Borrough's 5221A Holding Fixture Adapters or equivalent
Borrough's 5221 13A Cylinder Holding Fixture or equivalent.
Borrough's 8156 Cylinder Heating Stand or equivalent.

2-5

Tools and Equipment

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.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.

2-6

Borrough's 8086 Valve Seat Insert Remover & Replacer or equivalent.
Borrough's 4910 Installer Valve Seat Insert or equivalent.
Borrough's 4956 Installer Valve Seat Insert or equivalent.
Borrough's 8116 Common Parts Kit or equivalent.
Borrough's 8116-1 B through 15B Boring Bars or equivalent.
Borrough's 8116-1 R through 15R Reamers or equivalent.
Borrough's 8116-1 through 16 Expanding Guide Bodies or equivalent.
4909 Valve Seat (Straight Side) Insert Cutters available from Kent - Moore.
4954 Valve Seat (Straight Side) Insert Cutters available from Kent - Moore.
4985 Valve Seat (Straight Side) Insert Cutters available from Kent - Moore.
5224 Valve Seat (Straight Side) Insert Cutters available from Kent - Moore.
5225 Valve Seat (Straight Side) Insert Cutters available from Kent - Moore.
8135 Valve Seat (Step Side) Insert Cutters available from Kent - Moore.
8136 Valve Seat (Step Side) Insert Cutters available from Kent - Moore.
8138 Valve Seat (Step Side) Insert Cutters available from Kent - Moore.
Borrough's 8122A Common Drive Handle or equivalent.
122 Valve Guide Cleaner available from Kent - Moore.
4981 Valve Guide Remover available from Kent - Moore.
2842 Valve Guide Replacer available from Kent - Moore.
Borrough's 3170 Floating Holder or equivalent.
4981 Valve Guide Remover available from Kent - Moore.
Borrough's 8116-24 through 29 Valve Stem Hole Reamers or equivalent.
2847-2CP Reamer (Carbide Tipped) available from Kent - Moore.
2847-1CP Reamer (Carbide Tipped) available from Kent - Moore.
2847-1HP Reamer (High Speed Steel) available from Kent - Moore
2847-2HP Reamer (High Speed Steel) available from Kent - Moore
Plug Gauge for valve guide inspection available from Kent - Moore.
4943-1 HS through 5HS Reamers, Valve Guide Boss available from Kent - Moore.
Borrough's 4918 Spark Plug Insert Replacer or equivalent.
Borrough's 4919 Spark Plug Insert Remover or equivalent.
Borrough's 445, 18mm Spark Plug Tap or equivalent for straightening out damaged
2769A13 Rosan® Stud Remover available from McMASTER-CARR Supply Co.
Rosan® is a registered trademark of Fairchild Aerospace Fastener Division.
8074 Rosan® Lock Ring Installer available from Kent - Moore.
Rocker Arm Bushing Remover/lnstaller available from Kent - Moore.
7232 Reamer Rocker Arm Bushing available from Kent- Moore.
DA-200 Contour Probe available from Parker Research Corporation.

Tools and Equipment

Crankcase
1. Borrough's 8114 Crankcase Through Bolt Removers or equivalent.
2. L423 Crankcase Splitter available from Kent - Moore.
3. Borrough's 505 Stud Drivers or equivalent.

Engine Drive Train
1. Borrough's 8117A Runout Block Set or equivalent for crankshaft inspection.
2. Wheel Fax Jr. Mark IV Model O for Crankshaft Ultrasonic Testing available from Fax Corporation.
Operator must be certified in accordance with TCM standards.

3.
4.
5.
6.
7.

Borrough's 8087A Polishing Tools for Crankshaft Bearings or equivalent.
4965A Crankshaft Blade and Damper Bushing Remover/Replacer available from Kent- Moore.
Borrough's 8077A Bushing Remover & Replacer, Counterweight or equivalent.
Borrough's 8111A Connecting Rod Fixture or equivalent.

Borrough's 8042C Adapter Kit or equivalent for connecting rod inspection.
8. 5008 Reamers for connecting rod bushing available from Kent - Moore.
9. D-4000 Federal Dimension Air Gauge for connecting rod bushing inspection available from Federal Tool Supply
Co., Inc.
10. 1.1268 Setting Ring for checking 1.1267 to 1.1269 tolerance available from Federal Tool Supply Co., Inc.
11. 1.1268 Air Plug for checking 1.1267 to 1.1269 tolerance available from Federal Tool Supply Co., Inc.
12. Propeller Shaft Oil Seal Installer available from Kent - Moore

Operational Inspection
1
2
3

Alcor Portable Digital EGT Unit available from Alcor, Inc.
Alcor Portable Digital CHT available from Alcor, Inc.
Model 20 ATM-C Porta-Test Unit available from Aero Test, Inc.©

NOTE...
The rights to manufacture Borrough's Tools have been acquired by Kent-Moore.

2-7

This Page Intentionally Left Blank

2-8

Chapter 3

Sealants and Lubricants

Sealants and Lubricants ................................................................................................................................................................................. 3-3
Aviation Engine Oil Ashless Dispersant .................................................................................................................................... 3-3
Aviation Break-in Oil ................................................................................................................................................................................ 3-4
Aviation Preservative Oil ....................................................................................................................................................................... 3-4
Lubricants .................................................................................................................................................................................................................. 3-4
Sealants........................................................................................................................................................................................................................ 3-6
Adhesives .................................................................................................................................................................................................................... 3-8
Miscellaneous ......................................................................................................................................................................................................... 3-8

3-1

This Page Intentionally Left Blank

3-2

Sealants and Lubricants

Sealants And Lubricants
Aviation Engine Oil Ashless Dispersant
Recommended Grade:
Above 40'F ambient air, sea level:
Below 40'F ambient air, sea level:

SAE 50 or 15W50
SAE 30 or 20W60

Manufacturer

Brand Name

BP Oil Corporation
Castrol
Castrol Limited (Australia)
Chevron U.S.A., Inc.
Continental Oil
Delta Petroleum Company
Exxon Company, U.S.A.
Gulf Oil Company
Mobil Oil Company
NYCO S.A.
Pennzoil Company
Phillips Petroleum Company
Phillips Petroleum Company

BP Aero Oil
Castrol Aero AD Oil
Castrol Aero AD Oil
Chevron Aero Oil
Conco Aero S
Delta Avoil Oil
Exxon Aviation Oil EE
Gulfpride Aviation AD
Mobil Aero Oil
TURBONYCOIL 3570
Pennzoil Aircraft Engine Oil
Phillips 66 Aviation Oil, Type A
X/C Aviation Multiviscosity Oil
SAE 2OW50, SAE 2OW60
Quaker State AD Aviation Engine Oil
Red Ram X/C Aviation Oil 2OW50
Aeroshell (R) W
Aeroshell Oil W, Aeroshell Oil W 15W50
Anti-Wear Formulation Aeroshell Oil W 15W50
Aeroshell Oil W, Aeroshell Oil W 15W50
Anti-Wear Formulation Aeroshell Oil W 15W15
Sinclair Avoil
Texaco Aircraft Engine Oil - Premium AD
Total Aero DM 15W50
Union Aircraft Engine Oil HD

Quaker State Oil & Refining Company
Red Ram Limited (Canada)
Shell Australia
Shell Canada Limited
Shell Oil Company
Sinclair Oil Company
Texaco Inc.
Total France
Union Oil Company of California

3-3

Sealants and Lubricants

Aviation Break-in Oil
MIL-C-6529 Type 11 Corrosion preventive mineral oil.
NOTE... Mineral oil conforming with MIL-C-6529 Type 11 contains a corrosion preventive additive and must not
be used for more than 25 hours or six months, whichever occurs first. If oil consumption has not stabilized in this
time, drain and replenish the oil and replace the oil filter.

Aviation Preservative Oil
Type

Suggested Sources

Application

MIL-C-6529 Type 11

(Aeroshell Fluid 2F or equivalent)

For Temporary storage (up to 90
days)

MIL-P-46002, Grade 1 oil

(NOX RUST VCI-105 or equivalent)
May be purchased through: Rock Island
Lubricant & Chemical Co. P.O. Box
5015 1320 1st Street Rock Island,
Illinois 61204 Phone: 1 -800-522-1150

For Indefinite storage

Lubricants
Type
Molyshield Grease

Suggested Sources
May be purchased through: American
Lubricants
1227 Deeds
Dayton, Ohio 45401
Phone: (513) 222 - 2851

Application
Needle bearings and ball bearings
Valve stems
All ACC. drive splines and couplings
Idler gear and pin
Fuel injection controls, o-rings,
springs, shafts and bushings
Magneto rubber drive bushings
Oil pump and scavenge pump
gear shafts, ends and teeth. Oil
pump and scavenge pump housing and cover gear contact areas.
Starter worm gear drive teeth and
bevel gear teeth

Dow Corning® G-N Paste. Dow
Corning G-N Paste is a registered
trademark of Dow Corning Corp.

Type
Continued
3-4

For Distributor information call
1-800-248-2481, have state & city
information available

Suggested Sources

Camshaft lobes and lifter faces

Application

Sealants and Lubricants

Alvania (Shell #2)
For Distributor information

Shell Product Information Center,
Phone: 1-800-231-6950

Front crankshaft oil seal. Apply
light
coat at point of contact
between nutseat and ferrule on
ignition lead

MIL-S-3545C Grease (Shell #5)

Shell Product Information Center,
Phone: 1-800-231-6950

Fuel injection linkage pivot points,
throttle shaft bushings, lever
bushings

Permatex Maintain® Lubricant

For Distributor information call:
Permatex Customer Service @
Phone: 1-800-641-7376

Fuel injection linkage pivot points,
throttle shaft bushings, lever
bushings

646943 - Antiseize Lubricant
or
Loctite Anti-Seize Lubricant 767

May be purchased through your local
TCM Distributor. For Distributor
information , call Loctite Customer
Service at
1-800-243-4874

Approved, Clean, 50 Weight
Ashless Dispersant Oil

See Aviation Engine Oil Ashless
Dispersant Table

Approved Clean Break-In Oil

See Break-In Oil Table

CHAMPION® - Spark Plug
Thread Lubricant No. 2612
[CHAMPION® is a registered
trademark of Cooper Industries.]

For Champion Products Distributor
information:
Phone: 803-843-5400

Lubricants

All .3125 and larger studs unless
otherwise specified.
All mechanical tach drive housing
threads not through to an oil
source
Air reference fittings on all throtle
bodies
Cylinder stud and through bolt
threads, crankcase stud threads,
connecting rod bolt and nut threads
and engine accessory stud threads
Crankshaft bearings, connecting rod
bearings,
camshaft
bearings,
tachom-eter gears and adapters,
accessory spur gear teeth, starter
cone, bushing and nut, starter
adapter clutch spring (ID and OD),
sealing surface of valve guide seals,
pistons, piston pins, piston rings,
rocker arms, pivots, valves and
tappets, thrust washers and o-rings,
prop governor transfer collar and
sleeve, oil filter adapter seals
Spark plugs

(Continued)

3-5

Sealants and Lubricants

WD-40 or Chesterton No. 4

Chesterton Technical Product
Information

Induction system hose
connections

Phone: (508) 469-6783
Dow Corning® No. 4

For Distributor information call 1-800248-2481, have state & city information
available

Spin-on oil filter rubber seals
Magneto adapter gaskets (both
sides)
Gasket, governor pad (both
sides)

Sealants
Type

Suggested Sources

Application

LUBRIPLATE® 930 AA
(P/N L0096-035)

For Distributor information Call
LUBRIPLATE®
@ Phone: 1-800-733-4755

Apply to the outside diameter of valve
guides at installation

TCM P/N 654514 CRC 336 Rust
Preventative Compound

May be purchased through
your local TCM Distributor

Spray exhaust end of turbocharger for
engine preservation

Permatex Aviation Grade 3D
and
#641543 Silk Thread
and
#646942 Gasket Maker
or
Loctite Gasket Eliminator
515 Sealant

For Distributor information call:
Permatex Customer Service @
Phone: 1-800-641-7376

Crankcase parting face, oil pump
covers, scavenge pump covers

May be purchased through
your local TCM Distributor
May be purchased through
your local TCM Distributor
For Distributor information call:
Loctite Customer Service @
Phone: 1-800-243-4874

Continued...

3-6

Sealants and Lubricants

Sealants (Continued)
653692 - Primer
or
Loctite LocQuic Primer 7649

May be purchased through
your local TCM Distributor

#646942- Gasket Maker

May be purchased through your
local TCM Distributor

or
Loctite Gasket Eliminator
515 Sealant

Crankcase crankshaft nose oil seal
area

For Distributor information:
Loctite Customer Service @
Phone: 1-800-243-4874

Engine nose seal, outside diameter of
all uncoated oil seals except fuel pump
adapter seal, between oil sump and oil
sump gaskets

#642188 - Gasket Sealant
(TCM) 1.5 oz. tube

May be purchased through your
local TCM Distributor or
K & W Copper Coat
For Distributor information r-all:
K & W Products Customer
Phone: 1-800423-9446

Cam bore cover gasket (except beaded
gaskets), idler pin gasket, oil filler
neck gasket, pressed in plugs, 2 bolt
suction tube gasket

Loctite Pipe Sealant with Teflon
PS/T 592

For Distributor information:
Loctite Customer Service @
Phone: 1-800-243-4874

Pipe threads (except fuel system
fittings), pressure relief valve housing
threads, stud holes that are exposed to
oil.

#646940 - F/I Sealant
or
Loctite Hydraulic Sealant 569

May be purchased through
your local TCM Distributor

All pipe thread fittings in fuel
injection system (use sparingly on
male threads only)

Miller Stephenson
MS 122/CO2 Spray

For Distributor information:
Miller-Stephenson Customer
Service,
Phone: 1-800-992-2424

For Distributor information:
Loctite Customer Service,
Phone: 1-800-243-4874

Ignition harness terminals at magneto
block end

3-7

Sealants and Lubricants

Adhesives
Type

Suggested Sources

Application

646941 High Strength Adhesive
Sealant or Loctite 271

May be purchased through your
local TCM Distributor

Cylinder deck studs, squirt nozzles, fuel
manifold valve diaphragm and plunger
assembly, crankshaft nose seal retainer
bolts, studs on coolant manifold

653696 Primer or Loctite
LocQuic Primer 7471

For Distributor information:
Loctite Customer Service,
Phone: 1-800-243-4874

649306 Sealant (optional
646940) or Loctite Adhesive
Sealant 222 (optional Loctite
Hydraulic Sealant 569)

For Distributor information:
Loctite Customer Service,
Phone: 1-800-243-4874

Through stud holes on accessory end of
crankcase, manifold valve to bracket
screws

3M Brand EC1252 White Spot
Putty

Cylinder deck stud nuts, through bolt
nuts, magneto flanges, throttle body and
fuel metering unit

Miscellaneous
Type

Suggested Sources

Application

TCM P/N 626531-1
Enamel - Gold (1 qt)
TCM P/N 626531-2
Enamel - Gold (1 gal)

May be purchased through
your local TCM Distributor

High temp. paint for cosmetic and
corrosion protection

TCM P/N 535001S
Lockwire -.032 inch dia. Steel,
Corrosion Resistant

May be purchased through
your local TCM Distributor

Where applicable for lockwiring

"ACCELAGOLD"
Turco® Products
Tucker, GA 30084
[Accelagold is manufactured by
Turco® Products, Inc.]

For sales and service: Elf Atochem
N.A. Turco® Products Div. P.O.
Box 195 State Route 95
West Marion, Ohio, 43302
215-419-5376

Corrosion protection interior and
exterior aluminum parts

Engine Preservation Kit
• Dehydrator plugs
• Desiccant bags
• Streamers, warning sign
• Preservative oils

May be purchased through:
TANAIR
P.O. BOX 117
Glenwood, MN 56334
(US & CAN) 1-800-4432136
(MN) 1-800-862-2443

Engine Preservation

3-8

Chapter 4

Airworthiness Limitations

Airworthiness Limitations ............................................................................................................................................................................. 4-3

4-1

Airworthiness Limitations

This Page Intentionally Left Blank

4-2

Airworthiness Limitations

Airworthiness Limitations
This Airworthiness Limitations section has been
FAA approved and specifies maintenance required
under §§ 43.16 and 91.403 of the Federal Aviation
Regulations unless an alternative program has
been FAA approved. Federal Aviation Regulations §§ 43.16 and 91.403 require owner/operator
compliance with all maintenance limitations in this
section concerning mandatory replacement times,
inspection intervals and other related procedures
that are specific to this engine. Any such
limitations listed below are part of the design
limits of the engine and the engine was type
certificated based upon required owner/operator
compliance with the limitations.

Mandatory Replacement Times
Subject to additional information contained in
FAA Airworthiness Directives (AD) issued after
the date of certification, the engines covered in
this manual do not contain any components having
mandatory replacement times required by type
certification.

Mandatory Inspection Intervals

Distribution of Changes to
Airworthiness Limitations.
Changes to the Airworthiness Limitations section
constitute changes to the type design of this engine
and require FAA approval. Such changes will be
published in FAA Airworthiness Directives (AD).

Note
The limitations in this section apply only to
specific limitations which are part of the engine
design. Under the Federal Aviation Regulations
numerous other additional limitations are
applicable to this engine and it's accessories. For
example Federal Aviation Regulation Parts 91 and
43, among other parts, define inspection criteria,
maintenance requirements and procedures that are
applicable to this engine. It is the responsibility of
the owner / operator to maintain the engine in an
airworthy condition by complying with all
applicable Federal Aviation Regulations and by
performing maintenance in accordance with TCM
Instructions for Continued Airworthiness, which
consist of TCM publications and service
documents.

Subject to additional information contained in
FAA Airworthiness Directives (AD) issued after
the date of certification, the engine does not
require specific intervals of inspection pursuant to
type certification.

Other Related Procedures
Subject to additional information contained in the
Airworthiness Directives (AD) issued after the
date of certification, there are no other related
procedures required pursuant to the type
certification for this engine.

4-3

Airworthiness Limitations

This Page Intentionally Left Blank

4-4

Chapter 5

Time Limits,
Operational Inspection,
Engine Troubleshooting
General ........................................................................................................................................................................................................................ 5-3
Overhaul Period ................................................................................................................................................................................................... 5-3
Operational Inspection.................................................................................................................................................................................... 5-4
Starting......................................................................................................................................................................................................................... 5-4
Operational Checklist ...................................................................................................................................................................................... 5-4
Test Operating Limits ....................................................................................................................................................................................... 5-4
Time Interval Inspections .............................................................................................................................................................................. 5-6
25-Hour Inspection ............................................................................................................................................................................................ 5-6
50-Hour Inspection ............................................................................................................................................................................................ 5-6
100-Hour Inspection ......................................................................................................................................................................................... 5-8
300-Hour Inspection ...................................................................................................................................................................................... 5-10
500-Hour Inspection ...................................................................................................................................................................................... 5-10
Annual Inspection ............................................................................................................................................................................................. 5-10
Unscheduled Maintenance ........................................................................................................................................................................ 5-10
Propeller Strikes......................................................................................................................................................................................... 5-10
Hydraulic Lock ................................................................................................................................................................................................... 5-11
General Information ............................................................................................................................................................................... 5-11
Engine Overspeed Inspection .................................................................................................................................................................. 5-11
Lightning Strike .................................................................................................................................................................................................. 5-12
Contaminated Fuel or Incorrect Fuel Grade ............................................................................................................................. 5-12
General Troubleshooting Information ............................................................................................................................................. 5-13

5-1

This Page Intentionally Left Blank

5-2

Time Limits, Operational Inspection, Engine Troubleshooting

General
The scheduled inspection and maintenance
described in this section must be complied with in
addition to all aircraft manufacturer and accessory
manufacturer
inspection
and
maintenance
requirements. This manual does not contain
inspection or maintenance requirements for
supplemental type certificated engines, components
or systems. Such information must be obtained from
the supplemental type certificate holder.
Safety, efficiency and engine service life is
predicated on compliance with the aircraft and
engine manufacturer's required instructions,
inspections and maintenance schedule. The
owner/operator is primarily responsible for
maintaining the engine in an airworthy condition,
including compliance with applicable Airworthiness
Directives as specified in Part 39 of the Federal
Aviation Regulations (FAR); reference FAR
91.163. The owner/operator is responsible for
assuring the engine meets the conformity
requirements as specified by the original Type
Certificate (TC) or any Supplemental Type
Certificate (STC) that may apply to modifications or
alterations accomplished after the issuance of the
original TC.

When performing any inspection or
maintenance, always treat the engine as if
the ignition switch was on. Do not stand or
allow anyone else to stand within the arc of
the propeller. A loose or broken wire or a
component malfunction could cause the
engine and propeller to rotate and/or start.
Engines operated in extremely humid locations or in
exceptionally cold, damp climates or coastal areas
may require more frequent inspections. If the engine
is operated in excess of 100 hours per year, the
engine should be inspected at each 100-hour
interval in addition to an annual inspection.

Overhaul Period
Engine Models
I0-520-B, -BA, -BB, -C, -CB, -M, and
1700 HOURS
-MB Permold Series
......................................................................................

NOTE
Overhaul periods for the engine include all
engine accessories unless otherwise specified by
the accessory manufacturer.

NOTE
Engine operational inspection must be performed before and after any 50 or 100-hour
inspections or maintenance in accordance with
"Operational Inspection" requirements described in this Chapter.
During engine 50 and 100-hour inspections, if
engine components must be replaced or repaired,
refer to the applicable system maintenance chapter.
Corrections and adjustments will be found in the
individual system chapters.

WARNING
5-3

Time Limits, Operational Inspection, Engine Troubleshooting

Operational Inspection
An operational inspection must be performed prior
to and after 50/100-hour inspections.

Starting
Start engine using the starting procedure given in
the airframe manufacturers Airplane Flight Manual
(AFM).
Oil Pressure - Check, If no oil pressure within 30
seconds, shut engine down and investigate.

Operational Checklist

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

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

Check and record the following system data :
__________
Starter
*Record RPM Drop for each magneto at 1700
(150 RPM MAXIMUM AND 50 RPM SPREAD
__________
MAXIMUM)
__________
*Propeller Operation at 1700
*Or as specified in aircraft manufacturer's
instructions.
Increase engine to full power and record:
__________
Manifold Pressure
__________
RPM
__________
Fuel Flow
__________
Oil Pressure
__________
Oil Temperature
__________
Cylinder Head Temperature
__________
Alternator Output
Reduce engine to idle and record:
__________
Manifold Pressure
__________
RPM
__________
Oil Pressure
__________
Oil Temperature
__________
Cylinder Head Temperature
__________
Magneto System Grounding Check
................................................................................................................................................................

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

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

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

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

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

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

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

CAUTION…
The magneto system grounding check must be
performed at idle RPM only. Damage to the
engine may result at engine speeds above idle
RPM.

5-4

With engine speed at idle rpm, quickly turn both
magnetos off then back on. The engine should
cease running momentarily indicating both
magnetos are properly grounded. If engine
continues to run, one or both magneto ground
circuits is faulty and must be repaired prior to
further operation.
Slowly move mixture control to IDLE CUT OFF
and record:
Mixture RPM Rise ( 25 to 50 RPM ) __________
__________
Positive Fuel Cutoff
When propeller stops rotating, place ignition switch,
master switch and fuel selector in off position.

Test Operating Limits
IO-520-M and -MB
Recommended Minimum for Idle
Recommended Maximum for Cruising

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

600 RPM

225 @ 2500
Rated Maximum Continuous Operation
300 BHP @ 2700 RPM
IO-520-B, -BA, -BB
600 RPM
Recommended Minimum for Idle
Recommended Maximum for Cruising
235 @ 2500
Rated Maximum Continuous Operation
300 BHP @ 2700 RPM
IO-520-C, -CB
600 RPM
Recommended Minimum for Idle
Recommended Maximum for Cruising
235 HP @ 2500
Rated Maximum Continuous Operation
300 BHP @ 2700 RPM
.................................................................................................................................................................................................

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

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

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

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

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

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

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

NOTE:
May not be obtainable with aircraft static.
Manifold Air Pressure at Idle (Inches Hg) Max.
18.5
...........................................................................................................................................................................................................

Time Limits, Operational Inspection, Engine Troubleshooting

Fuel - Aviation Gasoline - minimum grade
100LL (Blue) or 100 (Green)
...............................................................................................

Fuel Flow at Full Throttle (Lbs./hr.)
Model

Pounds Per Hour

Model

At Idle

24.9-26.6
24.9-26.6
24.9-26.6
24.2-25.6
24.2-25.6
25.9-27.3
25.9-27.3
At Full Throttle

I0-520-B
3.9-4.5
I0-520-BB
3.9-4.5
I0-520-C
3.9-4.5
Unmetered Fuel Pressure
Model

At Idle

I0-520-A
I0-520-B
I0-520-C

8.0-10.0
8.0-10.0
8.0-10.0

Idle, minimum psi
Normal Operation psi
Maximum (oil cold)

10
30 - 60
100

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

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

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

GPH

I0-520-B
146-156
I0-520-BA
146-156
I0-520-BB
146-156
IO-520-M
142-150
IO-520-MB 142-150
IO-520-C
152-160
IO-520-CB
152-160
Metered Fuel Pressure

Oil Pressure

17.7-20.0
16.5-18.4
17.6-19.6

Oil Sump Capacity (Quarts)
IO-520-M, -MB, -B, -BA, -BB, -C, -CB
...................................................................................................................................................................................

12 Quarts

Magnetos
Magneto Drop (Max.)

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

Magneto Spread (Max.)

150 RPM

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

50 RPM

Cylinder Head Temperatures
Cylinder Head Temperature with Bayonet
Thermocouple (Limit)

460° F

Recommended Operating Maximum

420° F

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

Mixture Rise at Idle Cutoff-RPM

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

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

25-50

At Full Throttle

32.0-36.0
29.2-36.2
31.6-37.8

Mixture Rise At Idle Cutoff - RPM

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

25 - 50

Oil Temperature
Minimum for Takeoff

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

Limit
Recommended Flight Operation

75° F.

240° F.
170° F.

5-5

Time Limits, Operational Inspection, Engine Troubleshooting

Time Interval Inspections
Engine mounted accessories not supplied by TCM
may require servicing at specific intervals; some of
these are alternators, pneumatic pumps, air/oil
separators and stand-by generators. Refer to the
instructions provided by the aircraft manufacturer,
accessory manufacturer or STC holder for detailed
information.

CAUTION…

Approved Oil Grade: All Temperatures
TCM Approved Multiviscosity

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

Below 40° F. Ambient Air (Sea Level )
TCM Approved SAE 30 or Multiviscosity

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

New, rebuilt and overhauled engines or engines
that have had overhauled or new cylinders and
new piston rings installed must be given a
100-hour inspection after 25 hours of operation.
50 hours
Oil Change Interval
Or six months, whichever comes first.
...................................................................................................................

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

CAUTION...
Use only TCM approved oils. See TCM approved
oils in chapter 3, “Table of Sealants and
Lubricants.”

25-Hour Inspection
NOTE
Research and comply with all applicable Service
Publications and Airworthiness Directives.
1. After the first 25 hours of operation on new,
rebuilt or overhauled engines, perform a
complete 100-hour inspection. Drain the oil
used for engine break-in. If engine oil
consumption has stabilized, service the engine
with TCM approved oil. If oil consumption has
not stabilized, service engine with a mineral oil
conforming to MIL-C-6529 Type II.

NOTE…
Mineral oil conforming to MIL-C-6529 Type II
is a straight mineral oil with a corrosion
preventive additive. This oil must not be
operated in excess of 25 hours or 6 months,

5-6

whichever occurs first. If oil consumption has
not stabilized within the first 25 hours of engine
operation, drain and replenish the oil and
replace the filter.

Above 40° F. Ambient Air (Sea Level )
TCM Approved SAE 50 or Multiviscosity
.............................

2. Visually inspect the engine and nacelle for fuel,
oil leaks and other discrepancies.
3. Correct any discrepancies noted during this
inspection prior to returning the engine to
service.

50-Hour Inspection
NOTE
Research and comply with any applicable Service
Publications and Airworthiness Directives.
1. Thoroughly inspect the engine for any signs of
leakage. Clean engine exterior by spraying or
brushing with a flame resistant solvent used for
general cleaning of engine parts.

NOTE
Any environmentally hazardous materials used
in cleaning must be caught and disposed of in
accordance with Environmental Protection
Agency regulations.

CAUTION…
Do not use any alkaline cleaning solutions for
external engine cleaning, these solutions will
remove the “alodized" finish of aluminum
parts.

CAUTION…
Do not use kerosene or gasoline for cleaning.

Time Limits, Operational Inspection, Engine Troubleshooting

2. A preinspection operational run-up must be
performed. See "Operational Inspection" of this
chapter.
(a) Record the engine operating parameters.
(b) Verify the recorded parameters meet the
published specifications for the engine as
provided in the aircraft or engine
manufacturer's Maintenance, Operator's and
Overhaul Manuals.
After the operational inspection, inspect, isolate
and repair any leaks found.
3. Reference the applicable Airplane Flight
Manual for operational values.
4. Remove and inspect induction air filter. Clean
or replace as instructed by the filter
manufacturer. Inspect induction system ducts,
seals and gaskets for condition, deterioration
and obstructions in accordance with the aircraft
manufacturer's instructions. With induction air
filter installed:
(a) Verify the induction air filter retainer is
properly installed and the attaching
hardware is secure in accordance with the
aircraft manufacturer's instructions.
(b) Replace any questionable components as
required in accordance with the aircraft
manufacturer's instructions.

(c) Inspect all engine controls for proper travel,
freedom of movement, wear, correct
rigging and correct attachment in
accordance with the aircraft manufacturer's
instructions.

CAUTION…
Failure to properly install the induction air filter
will result in unfiltered air being ingested into the

engine which will accelerate engine wear and
reduce engine service life.
5. Inspect induction air box for security and
deterioration in accordance with the aircraft
manufacturer's instructions.
6. Inspect the aftercooler core and associated air
passages for obstructions.

WARNING
Insure that the fuel selector is in the off
position prior to servicing fuel filters.
7. Drain the fuel filter and if sediment was noted,
remove it. Service as required and reinstall in
accordance with the aircraft manufacturer's
instructions.
8. Visually inspect engine and nacelle for fuel, oil
leaks and other discrepancies.
9. Drain engine oil. During engine oil change, oil
must be drained into an appropriate container
and disposed of properly. Reinstall oil drain
plug with new gasket, torque and safety.
10. Remove oil filter. Inspect filter element. See
“Oil Filter Element Inspection, Oil Analysis
and Spectrographic Oil Analysis” in Chapter 7,
“Servicing Fluids.”
11. Place a thin film of Dow Corning® DC-4
compound on new oil filter gasket. Install new
oil filter. Torque filter to values as directed by
filter manufacturer and safety wire.
12. Inspect all induction system or cylinder drain(s)
for clogging or restriction.
13. Inspect ignition leads for chafing, deterioration
and proper routing.
14. Visually inspect magnetos for condition.
Inspect, repair and adjust as required if magneto
drop or spread was not within published limits.

5-7

Time Limits, Operational Inspection, Engine Troubleshooting

15. Correct all discrepancies noted.

WARNING
Operation of a malfunctioning engine can
result in additional engine damage, bodily
injury or death.
16. At the completion of any maintenance event the
engine must be given a complete and thorough
operational run-up. A test flight will be
required if any engine adjustments have been
made which affect flight characteristics or
operation; this test flight is required by FAR
91.167.
(a) Record all engine parameters.
(b) Verify recorded parameters are within the
specifications published for the engine and
aircraft.

WARNING
Failure to identify and correct fuel or oil
leaks can result in engine/nacelle fire, loss of
engine power, engine failure, bodily injury
or death.
17. Correct any discrepancies noted during
operational run-up prior to returning engine to
service.

100-Hour Inspection
NOTE…
Research and comply with the Service Publications
and Airworthiness Directives.
In addition to the items listed in 50 Hour the
following inspections and maintenance must be
performed.

5-8

1. Drain engine oil. Reinstall oil drain plug with
new gasket, torque and safety.
2. Inspect the cylinder barrels and cylinder heads
for cracks, leaks rust and pitting. Inspect
cylinder head and barrel cooling fins for any
restriction of cooling airflow.
3. Inspect all inner cylinder and peripheral
baffling for correct installation, proper
positioning, deterioration and missing or broken
sections.
4. Perform a cylinder compression test in
accordance with chapter 19
5. Inspect the entire engine, accessory section and
nacelle for indications of fuel or oil leaks.
Inspect all wiring, fluid lines, hoses and
electrical connections for proper routing,
support and evidence of deterioration.
6. Visually inspect all cylinder and accessory to
engine attaching hardware for security.
Visually inspect airframe to engine
connections for security and corrosion.
7. Inspect the induction and exhaust system for
leaks, cracks, deterioration, broken, missing or
loose brackets, clamps and hardware.
8. Insure magneto to engine timing is within
specifications in accordance with chapter 12 .

CAUTION…
Magnetos using riveted type impulse coupling
require repetitive 100-hour inspection in
accordance
with
the
manufacturer’s
instructions.
9. Clean, inspect, gap, test and rotate all spark
plugs. See chapter 12 for spark plug wear
determination and spark plug rotation.

WARNING
Worn spark plugs that are continued in
service may cause internal arcing in the
magnetos.

Time Limits, Operational Inspection, Engine Troubleshooting

10. Check all engine controls, control cables,
control rod ends and levers for security, wear,
proper assembly, routing and freedom of
movement throughout the entire range of travel.
See chapter 13 for fuel system component
replacement and throttle/mixture control lever
lubrication.

WARNING
Insure fuel selector is in the off position
prior to removing the fuel metering unit
inlet screen.
11. Inspect fuel nozzles, upper deck and fuel
injection nozzle reference lines, hoses,
manifolds and fittings for proper routing,
support and signs of fuel stains. Inspect
manifold valve for security of installation,
proper venting and signs of fuel stains.

14. Inspect engine mount legs for cracks. Check
engine mount isolators for signs of
deterioration, proper assembly and security.
15. Verify operation and accuracy of exhaust gas
temperature (EGT) system. Note: The aircraft
manufacturer may require the EGT system to be
operational for all categories of flight. Check
the limitations section of the Airplane Flight
Manual for specific requirements.
16. Correct any discrepancies noted.
17. Perform post inspection operational run-up.
Visually inspect engine and nacelle for fuel and
oil leaks.
18. Correct any discrepancies noted during this
inspection prior to returning engine to service.

CAUTION…
Never clean nozzles with wire or other similar
object. If nozzle jet is plugged and obstruction
cannot be removed by solvent action,
REPLACE THE NOZZLE.
12. At the first 100-hour inspection on new, rebuilt
or overhauled engines, remove and clean all
fuel injection nozzles. See 300 Hour Inspection.
NOTE…
Any environmentally hazardous materials used
in cleaning must be collected and disposed of in
accordance with Environmental Protection
Agency regulations.
13. Inspect all accessories for condition, security of
mounting and proper operation. Refer to aircraft
or component manufacturer's Maintenance
Manual for specifics.

5-9

Time Limits, Operational Inspection, Engine Troubleshooting

300-Hour Inspection
Remove and clean all fuel nozzles by soaking in
lacquer thinner, acetone or methyl ethyl ketone
(MEK). Fuel nozzles must be cleaned every
300-hours and annual inspection.

500-Hour Inspection
In addition to the items listed for 100-hour
inspections, perform the following inspections and
maintenance every 500 hours of engine operation.
1. Magnetos require a thorough, detailed
inspection. Refer to the applicable service and
overhaul information published by the
manufacturer of the magneto. Magnetos must
be overhauled or replaced at the same intervals
as the engine. TCM magnetos must be
overhauled or replaced every four years
regardless of total operating hours since last
overhaul or replacement.
2. Engine mounted accessories not supplied by
TCM such as alternators, stand-by generators,
etc., may require servicing at specific intervals.
Refer to the instructions provided by the aircraft
manufacturer, accessory manufacturer or STC
holder for detailed information.
3. TCM gear-driven alternators require inspection
and testing at 500-hour intervals. Refer to the
applicable
alternator
manufacturer's
instructions. See "Related Publications" in the
Introduction section of this manual.

Annual Inspection
Perform all requirements of 25, 50, 100, 200, 300
hour and any calendar inspections due. Comply
with any 500 hour inspections that will come due
before the next regularly scheduled maintenance
event.

Unscheduled Maintenance

5-10

Unscheduled maintenance events include but are
not limited to:

Propeller Strikes
A propeller strike is any incident, whether or not the
engine is operating, that requires repair to the
propeller or any incident while the engine is
operating in which the propeller makes contact with
any object that results in a loss of engine RPM.
Propeller strikes against the ground or any object,
can cause engine and component damage even
though the propeller may continue to rotate. This
damage can result in engine failure.
When the propeller is damaged by a small object
during operation, such as a small stone, inspection
and repair must be accomplished in accordance with
the propeller manufacturer's published instructions.
Any time damage from an object strike requires
propeller removal for repairs the incident is
considered a propeller strike.
Following any propeller strike a complete engine
disassembly and inspection is mandatory and must
be accomplished prior to further operation. Inspect
all engine accessories in accordance with the
manufacturer's instructions.

Time Limits, Operational Inspection, Engine Troubleshooting

Hydraulic Lock
General Information
Hydraulic lock is defined as a condition in which a
volume of liquid, equal to or greater than the
clearance volume of the combustion chamber is
present in the cylinder during starting.
Incompressible liquid restricts piston travel during
the compression stroke. Damage occurs after the
preceding cylinder or cylinders in the firing order
have fired providing the required force to drive the
piston of the fluid filled cylinder through the
compression stroke.
Hydraulic locks in horizontally opposed aircraft
engines are due to excess fuel accumulation in the
induction system and/or cylinder assembly or
failure to properly drain preservation oil.
Damage from a hydraulic lock can be extensive.
Engine components such as connecting rods,
cylinder assemblies, pistons, piston pins, crankcase
and crankshaft can be damaged due to overstress.
In the event the operator starts an over-primed or
flooded engine, hydraulic lock may result.
Indications of hydraulic lock are difficult to detect
since the engine will not normally exhibit any
unusual operation once the fuel-air mixture
stabilizes.
Therefore, the operator must be
cognizant of the fact that a hydraulic lock can occur
during an attempt to start an over-primed/flooded
engine.
In the event of a hydraulic lock perform the
following inspection:
1. Remove all cylinders and connecting rods in
accordance with the current TCM Overhaul
Manual. Inspect the connecting rods in
accordance with the current TCM Overhaul
Manual.

2. If all connecting rods meet the criteria specified
by TCM, reassemble the engine in accordance
with the current TCM Overhaul Manual.
3. If any connecting rod does not meet TCM
specifications, remove and disassemble the
engine to allow inspection of the crankcase and
crankshaft in accordance with the current TCM
Overhaul Manual. Replace any part that does
not meet TCM specifications. Replace each
non-conforming connecting rod and its
associated piston, piston pin and cylinder
assembly.

CAUTION…
Any parts that require replacement must be
destroyed to prevent future installation.
4. Clean, inspect, repair, reassemble and test the
engine in accordance with the current TCM
Overhaul Manual.

Engine Overspeed Inspection
Engine operation at engine speeds in excess of rated
RPM limitations can cause damage to the engine
and can result in subsequent engine failure.
If an engine overspeed occurs determine the cause
for overspeed and correct it. The airframe
manufacturer's instructions on engine and propeller
overspeed must also be referenced and followed.
If an engine overspeed occurs use the following
procedures:
RPM To 3000
1. Less than one minute - No action required
2. More than one minute - Proceed as follows:
a. Drain oil through a fine mesh screen and
inspect for debris.
b. Remove oil filter and inspect filter element
for debris.

5-11

Time Limits, Operational Inspection, Engine Troubleshooting

c. Remove and inspect inside of rocker covers
for debris. Inspect valve stem (keeper
grooves) and valve keepers for condition,
security and proper installation. Inspect
valve springs, rocker arms, spring retainers,
rotocoils, pushrods, etc.
d. Perform a borescope inspection on all
cylinders.
e. If no discrepancies are noted, re-service
engine, perform operational inspection and
correct any discrepancies noted prior to
returning the engine to service.
f.

If discrepancies are found a decision must
be made, based on the evidence, as to the
extent of the corrective action required.

RPM To 3300
In addition to action required for above, proceed as
follows:
1. Remove all cylinder assemblies including rods
and pistons.
Clean, inspect, repair or replace all components
removed from the engine in accordance with
the manufacturer's current overhaul manual.
Using new connecting rod bolts and nuts,
reassemble, service and test the engine in
accordance with the current overhaul manual.
2. After five and ten hours of engine operation
remove oil filter and inspect filter element for
debris.
RPM Exceeding 3300
1. Remove engine and clearly identify "Removal
For Overspeed".
2. Engine and accessories must be completely
overhauled in accordance with the respective
manufacturer's current overhaul instructions or
replaced with certified airworthy components.

5-12

Lightning Strike
It is impossible to assess internal damage that may
result from a lightning strike. A complete
disassembly and inspection of the engine must be
accomplished in accordance with the current
overhaul manual.

Contaminated Fuel or
Incorrect Fuel Grade
If the aircraft is inadvertently serviced with the
wrong grade of fuel or jet fuel the fuel must be
completely drained and the tank properly serviced.
Any engine operated on fuel of lower grade than
approved for the engine or jet fuel must be
completely disassembled, cleaned, inspected,
repaired, reassembled and tested in accordance with
the manufacturer's current overhaul manual.

Time Limits, Operational Inspection, Engine Troubleshooting

General Troubleshooting Information
The troubleshooting chart which follows discusses symptoms which can be diagnosed and interprets the
probable causes and the appropriate corrective actions to be taken.
Troubleshooting for individual systems follow the engine troubleshooting chart. Any attempt by unqualified
personnel to adjust, repair or replace any parts, may result in engine malfunction or failure.

WARNING
Operation of a malfunctioning engine can cause further damage to a disabled component and
possible injury to personnel.
Engine Troubleshooting
TROUBLE
Engine Will Not Start

PROBABLE CAUSE
No fuel to engine
Improper starting procedure

Cylinder overprimed. Engine
flooded

Induction system leak

Engine Will Not Run
At Idling Speed

Rough Idling

Excessive Starter slippage
Fuel system malfunction
Ignition system malfunction
Fuel injection system improperly
adjusted
Air leak in intake manifold
Fuel injection system improperly
adjusted
Mixture levers set for improper
mixture

CORRECTION
Service aircraft fuel system in
accordance
with
the
airframe
manufacturer's instructions
Refer to the airframe manufacturer's
Airplane Flight Manual (AFM) for
engine starting procedures. Check for
performance of each item
Allow fuel to drain from intake
system. WARNING…Starting an
engine with a flooded intake system
may result in hydrostatic lock and
subsequent engine malfunction.
Torque or replace loose or damaged
hose connection
Replace starter adapter
Isolate cause and correct
See "Ignition Troubleshooting
See "Fuel Injection System
Troubleshooting
Torque loose connection or replace
malfunctioning part
Adjust fuel system in accordance with
chapter 22 "Fuel System Adjustment."
Adjust the manual mixture control in
accordance with the airframe manufacturer's Airplane Flight Manual .

5-13

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
TROUBLE

PROBABLE CAUSE
Fouled Spark Plugs

Rough Idling (continued)

Hydraulic tappets fouled
Burned or warped exhaust valves
worn seat, scored valve guides

Engine Runs Too Lean
At Cruising Power

Manifold valve vent obstruction
Improper manual leaning procedure
Fuel injection system maladjusted

Engine Runs Too Rich
At Cruising Power

Restrictions in air intake passages
Improper manual leaning of
fuel/Air mixture

Engine Runs Too Lean Or Too
Rich At Throttle Setting Other Than
Cruise
Continuous Fouling Of
Spark Plugs

Engine Runs Rough At
High Speed

Fuel injection system maladjusted
Piston rings excessively worn or
broken
Piston rings are not seated

Loose mounting bolts or damaged
mount pads
Plugged fuel nozzle jet

Propeller out of balance
Ignition system malfunction

5-14

CORRECTION
Remove, clean and adjust gaps in
accordance with the spark plug
manufacturer's instructions
Replace fouled tappets. Inspect and
clean oil filter at more frequent
intervals
Inspect, repair or replace cylinder.
Replace any burned, warped or worn
exhaust valves
Repair or replace manifold valve
Refer to the airframe manufacturer's
Airplane Flight Manual (AFM) for
engine operating instructions
Adjust fuel system in accordance with
chapter 22, "Fuel System Adjustment
Check passages and remove restrictions
See the airframe manufacturer's
Airplane Flight Manual (AFM) for
correct leaning procedure
See "Fuel Injection System
Troubleshooting”
Replace rings. Replace cylinder if
damaged
Hone cylinder walls, replace rings
NOTE…Cylinder grinding and honing
must be done by a qualified FAA
approved rework facility
Torque mounting bolts. Replace mount
pads
Clean. Replace nozzle if obstruction
cannot be cleared by solvent action.
Never use wire or any other object to
clear nozzle jet
Remove and repair in accordance with
airframe manufacturer's instructions
See "Ignition Troubleshooting"

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
Continuous Missing At
High Speed

Broken valve spring
Plugged fuel nozzle jet

Burned or warped valve

Sluggish Operation And
Low Power

Hydraulic tappet dirty or worn
Throttle not full open

Restrictions in air intake passages
Ignition system malfunction
Fuel injection system maladjusted
High Cylinder Head
Temperature

Lean fuel/air mixture
Debris between cylinder fins
Incorrect engine timing
Exhaust system gas leakage
Exhaust valve leaking

Inspect, repair or replace cylinder.
Replace valve springs
Clean. Replace nozzle if obstruction
cannot be cleared by solvent action.
Never use wire or any other object
to clear nozzle jet
Inspect, repair or replace cylinder.
Replace any burned, warped or
worn exhaust valves
Remove and replace
Check and adjust linkage. See
Rigging of Mixture and Throttle
Controls in the applicable airframe
manufacturer's instructions
Inspect air intake and remove
restrictions
See "Ignition Troubleshooting”
See "Fuel Injection System
Troubleshooting”
See the airframe manufacturer's
Airplane Flight Manual (AFM) for
correct leaning procedure
Clean thoroughly
Adjust engine timing in accordance
with chapter 12
Locate and correct in accordance
with the airframe manufacturer’s
instructions
Repair cylinder. See chapter 19,
“Cylinder assembly Maintenance.”

5-15

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
TROUBLE
Oil Leaks

Low Compression

PROBABLE CAUSE
At front of engine, damaged
crankshaft oil seal
Around plugs, fittings and gaskets
due to looseness or damage
Piston rings excessively worn
Valve faces and seats worn

Engine Will Not Stop At
Idle Cutoff
Climbing to Altitude,
Fuel Flow Fluctuates
Low Fuel Pressure

High Fuel Pressure

Fluctuating Fuel
Pressure

Excessively worn cylinder walls
Fuel manifold valve not seating
properly
Fuel Vaporization

Incorrect fuel pump adjustment
Malfunctioning fuel pump relief
valve
Malfunctioning relief valve
operation in fuel pump
Restricted recirculation passage in
fuel pump
Incorrect fuel pump adjustment
Fuel gauge line leak or air in gauge
line
Vapor in fuel system, excessive
fuel temperature

Engine Has
Poor Acceleration

5-16

Idle mixture too lean

CORRECTION
Replace crankshaft oil seal
Torque or replace
Inspect, repair or replace cylinder.
Replace piston rings
Inspect, repair or replace cylinder.
Replace any worn parts
Replace cylinder & piston rings
Repair or replace fuel manifold
valve
Operate fuel boost pump in
accordance with the airframe
manufacturer's Airplane Flight
Manual (AFM)
Check and adjust in accordance with
chapter 22, "Fuel System
Adjustment
Replace fuel pump
Replace fuel pump
Replace fuel pump
Check and adjust per Chapter 22,
"Fuel System Adjustment
Drain gauge line and torque
connections in accordance with the
airframe manufacturer's instructions
Normally, operating the auxiliary
pump will clear system. Operate
boost pump in accordance with the
airframe manufacturer's Airplane
Flight Manual (AFM)
(Check RPM Rise, Idle Cutoff).,
Adjust idle mixture in accordance
with Chapter 22, "Fuel System
Adjustment"

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
TROUBLE
Engine Has
Poor Acceleration (continued)

PROBABLE CAUSE
Incorrect fuel/air mixture, worn
control linkage, or restricted air
cleaner
Malfunctioning ignition system

Engine Runs Rough At
Speeds Above Idle

Improper fuel/air mixture

Restricted fuel nozzle jet

Ignition system and spark
plugs malfunctioning

Engine Lacks Power,
Reduction in Maximum
Manifold Pressure

Incorrectly adjusted throttle control
linkage or dirty air filter

CORRECTION
Replace worn elements of linkage.
Service air cleaner in accordance
with airframe manufacturer's
instructions
Check ignition cables and
connections in accordance with the
ignition manufacturer's instructions
Replace malfunctioning spark plugs
Check fuel manifold connections
for leaks. Torque loose connections.
Check fuel control/metering unit
and linkage for setting and
adjustment in accordance with
chapter
22,
"Fuel
System
Adjustment ." Check fuel filters and
screens for debris. Check for proper
fuel pump pressure.
Clean. Replace nozzle if obstruction
cannot be cleared by solvent action.
Never use wire or any other object
to clear nozzle jet
Clean, regap and test spark plugs.
Inspect, test and repair ignition
system in accordance with the
ignition system manufacturer's
instructions. Replace components as
required
Check movement of linkage by
moving control from idle to full
throttle. Make proper adjustments
in accordance with chapter 22,
"Fuel System Adjustment." Replace
worn components. Service air
cleaner in accordance with the
airframe manufacturer's instructions

5-17

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
TROUBLE
Engine Lacks Power,
Reduction in Maximum
Manifold Pressure (continued)

PROBABLE CAUSE
Malfunctioning ignition system
component

Loose or damaged intake manifold

Fuel nozzles restricted

Low Oil Pressure
Indication On
Engine Gauge

Insufficient oil in oil sump, oil
dilution or using improper grade oil
for prevailing ambient temperature
High oil temperature

Restricted oil filter. Leaking,
damaged or loose oil line
connections
Oil pressure gauge malfunction
Engine oil pressure maladjusted

5-18

CORRECTION
Inspect spark plugs for fouled
electrodes, heavy carbon deposits,
erosion of electrodes, improperly
adjusted electrode gaps, and cracked
porcelains. Test plugs for regular firing
under pressure. Replace damaged or
misfiring plugs. Gap spark plugs to
spark
plug
manufacturer's
specifications.
Inspect entire manifold system for
possible leakage at connections.
Replace damaged components, torque
all connections and clamps to
specifications
Clean nozzles. Replace nozzle if
obstruction cannot be cleared by
solvent action. Never use wire or any
other object to clear nozzle jet
Add oil, or change oil to proper
viscosity. Inspect for possible oil
dilution, repair as required
Malfunctioning oil temperature control
valve in oil cooler; oil cooler
restriction. Replace valve and clean oil
cooler
Check for restricted lines, loose
connections, and for partially plugged
oil filter. Replace oil filter. Clean parts,
torque connections, and replace
malfunctioning parts
Check oil pressure gauge calibration in
accordance with the airframe
manufacturer's instructions
Adjust oil pressure in accordance with
chapter 22, "Oil Pressure Adjustment”

Time Limits, Operational Inspection, Engine Troubleshooting

Engine Troubleshooting (continued)
TROUBLE
Low Oil Pressure Indication On
Engine Gauge (continued)

PROBABLE CAUSE
Low oil supply. Oil viscosity too
low
Malfunctioning oil pump
Weak or broken oil pressure relief
valve spring

CORRECTION
Replenish. Drain and refill with
correct viscosity
Repair or replace oil pump
Replace spring. Adjust oil pressure
in accordance with chapter 22, "Oil
Pressure Adjustment."

High Oil Temperature Indication

Prolonged ground operation

Limit ground operation to a
minimum
Check wiring. Check bulb unit.
Check
gauge.
Replace
malfunctioning parts in accordance
with the airframe manufacturer's
instructions

Malfunctioning gauge or bulb unit

Fuel Injection
TROUBLE
Fluctuating Fuel Flow
Indications

PROBABLE CAUSE
Fuel vapor as a result of high
ambient temperatures

Poor Idle Cutoff

Air in fuel flow gauge line. Leak at
gauge connection
Engine getting fuel

Unmetered Fuel Pressure To High

Internal orifices plugged

Unmetered Fuel Pressure Drop
Very High Idle And Full Throttle
Fuel Pressure Present

Relief valve stuck open
Relief valve stuck closed

CORRECTION
If not cleared with auxiliary pump,
check for clogged vent in fuel pump
vapor separator cover. Clean only
with solvent, no wires. Refer to
airframe manufacturer's instruction
Repair leak and purge line. Refer to
airframe manufacturer's instruction
Check mixture control is in full idle
cutoff. Check auxiliary pump is
OFF. If neither, replace manifold
valve.
Clean internal orifices injector
pump. Refer to Fuel Injection
Service Manual, Form X30593A
Repair or replace fuel pump
Repair or replace fuel pump

No Fuel Pressure

Check valve stuck open

Repair or replace fuel pump

5-19

Time Limits, Operational Inspection, Engine Troubleshooting

Fuel Injection (continued)
TROUBLE

PROBABLE CAUSE

CORRECTION

Engine Will Not Start And No
Fuel Flow Gauge Indication

No fuel to engine

Check tank fuel level

Mixture control improperly rigged

Check mixture control for proper
rigging. Refer to airframe
manufacturer's instruction

Engine not primed

Check auxiliary pump switch
position. Refer to airframe
manufacturer's instruction

Selector valve in wrong position

Position selector valve to MAIN
TANK position. Refer to airframe
manufacturer's instruction

Engine flooded

Allow all fuel to drain from intake
system.
WARNING…Starting an engine
with a flooded intake system may
result in hydrostatic lock and
subsequent engine malfunction

No fuel to engine

Loosen one line at nozzle. If no
fuel shows, with fuel flow on
gauge, replace fuel manifold valve

Engine Will Not Start With
Fuel Flow Gauge Indication

5-20

Time Limits, Operational Inspection, Engine Troubleshooting

Fuel Injection (continued)
TROUBLE

PROBABLE CAUSE

CORRECTION

Rough Idle (continued)

Improper idle mixture

Adjust fuel mixture in accordance
with chapter 22, "Fuel System
Adjustment”

Poor Acceleration

Idle mixture incorrect

Adjust fuel mixture in accordance
with chapter 22, "Fuel System
Adjustment”

Unmetered fuel pressure too high

Lower unmetered fuel pressure.
Adjust in accordance with chapter
22, "Fuel System Adjustment."

Worn linkage

Replace worn elements of linkage.
in accordance with the airframe
manufacturer's instruction

Restricted nozzle

Clean. Replace nozzle if obstruction
cannot be cleared by solvent action.
Never use wire or any other object
to clear nozzle jet.
Adjust fuel mixture in accordance
with chapter 22, "Fuel System
Adjustment
Check for restriction between fuel
pump and fuel metering unit

Engine Runs Rough

Improper mixture
Low Fuel Flow Gauge Indication

Restricted flow to metering unit
Inadequate flow from fuel pump

High Fuel Flow Gauge Indication

Restricted flow beyond metering
valve
Restricted recirculation passage in

Adjust engine-driven fuel pump in
accordance with chapter 22, "Fuel
System Adjustment”
Check for restricted nozzles or fuel
manifold valve. Clean or replace as
required
Replace engine driven fuel pump

5-21

Time Limits, Operational Inspection, Engine Troubleshooting

Induction
TROUBLE
Engine Will Not Start
Engine Will Not Run At Idling
Speed
Engine Runs Too Rich At Cruise
Power
Sluggish Operation And Low
Power

PROBABLE CAUSE
Induction system intake obstructed
Induction system leakage

CORRECTION
Locate and remove obstruction
See chapter 14

Restrictions in air intake passages

Check air passages remove
restriction
Check and adjust control
connections in accordance with the
airframe manufacturer’s
instructions.

Throttle not opening wide

Ignition
TROUBLE
Engine Fails To Start

PROBABLE CAUSE
Ignition switch OFF or grounded
switch wires
Spark plugs fouled, improperly
gapped, or loose

Magnetos improperly timed to
engine
Shorted condenser

Rough Idling

Magneto internal timing incorrect
or timed for opposite rotation
Spark plugs fouled or improperly
gapped
Weak condenser

Rough At Speeds Above Idle

5-22

Loose or improperly gapped spark
plugs

CORRECTION
Turn switch On. Check for
grounded wires
Remove and clean. Adjust to proper
gap in accordance with spark plug
manufacturer's
specifications.
Torque spark plugs in accordance
with chapter 12
Refer to chapter 12, Ignition Timing
for timing procedures
Replace condenser in accordance
with
magneto
manufacturer's
instructions
Install correctly timed magneto
Clean spark plugs. Adjust to proper
gap in accordance with spark plug
manufacturer's specifications
Replace condenser in accordance
with
magneto
manufacturer's
instructions
Adjust to proper gap in accordance
with spark plug manufacturer's
specifications. Torque spark plugs
in accordance with chapter 12

Time Limits, Operational Inspection, Engine Troubleshooting

Ignition (continued)
TROUBLE
Rough At Speeds Above Idle
(continued)

Sluggish Operation And/Or
Excessive RPM Drop

Sluggish Operation And/Or
Excessive RPM Drop (continued)

PROBABLE CAUSE
High tension leak in ignition
harness

CORRECTION
Inspect ignition harness in
accordance with harness
manufacturer's instructions
Weak or burned out condenser as Replace points and condenser in
evidenced by burned or pitted accordance with magneto
breaker points
manufacturer's instructions
Fouled or dead spark plugs
Clean spark plugs. Discard faulty
plugs. Adjust to proper gap in
accordance with spark plug
manufacturer's specifications
Improperly gapped spark plugs
Adjust to proper gap in accordance
with spark plug manufacturer's
specifications
Magnetos out of time
Refer to Installation of Magnetos
and Ignition Timing for proper
timing procedure chapter 12. Refer
to the magneto manufacturer's
instructions for magneto internal
timing
Damaged magneto breaker points or Replace points and condenser in
condenser
accordance
with
magneto
manufacturer's instructions

Starting
TROUBLE
Starter Will Not Operate

PROBABLE CAUSE
Master switch circuit continuity
Master circuit continuity
Starter motor malfunctioning

Starter Motor Runs But Does Not
Turn Crankshaft
Starter Motor Dragging

Starter adapter drive train or clutch
malfunctioning
Improperly charged battery
Starter switch contacts burned or
dirty
Malfunctioning Starter

CORRECTION
Refer to the airframe manufacturer's
instructions
Refer to the airframe manufacturer's
instructions
See chapter 17, "Starter
Maintenance"
See chapter 17, "Starter adapter
Maintenance"
Refer to airframe manufacturer's
instructions
Refer to airframe manufacturer's
instructions
Chapter 17, "Starter Maintenance

5-23

Time Limits, Operational Inspection, Engine Troubleshooting

Lubrication
TROUBLE
Excessive Oil Consumption

PROBABLE CAUSE
Oil leakage
Gasket or seal leakage
Improper seasonal weight or grade
oil
Worn piston rings or valve guides
Excessive crankcase pressure

High Oil Temperature Indication

Low oil supply
Cooler air passages clogged
Cooler core plugged
Thermostat damaged or held open
by solid matter
Oil Viscosity too high
Prolonged ground operation
Malfunctioning gauge or bulb unit
Exhaust leak

Low Oil Pressure Indication

Low oil supply. Oil viscosity too
low
Malfunctioning oil pump
Malfunctioning pressure gauge
Weak or broken oil pressure relief
valve spring
Clogged oil filter

5-24

CORRECTION
Replace leaking oil lines, torque
loose connections
Replace gasket or oil seals
Service engine with proper oil, see
chapter 7
Inspect, repair or replace cylinder.
Replace piston rings
See the most current revision of
TCM service bulletin 89-9,
“Excessive Crankcase Pressures.”
Replenish, see chapter 7
Clean thoroughly
Remove cooler and flush
thoroughly
Remove clean valve and seat. If still
inoperative, replace
Drain and refill with correct
viscosity. See chapter 7
Limit ground operation to a minimum. Refer to the airframe manufacturer's operating instructions
Check wiring. Check bulb unit.
Check gauge. Refer to the Airframe Manufacturer's Instructions
Replace malfunctioning component, insure exhaust system is installed properly, replace leaking gaskets
Replenish. Drain and refill with
correct seasonal weight. See chapter
7
Replace pump
Check gauge. Clean plumbing.
Replace if required in accordance
with AFM Instructions
Replace spring. Adjust pressure to
30-60 psi. in accordance with
chapter 22
Replace oil filter

Time Limits, Operational Inspection, Engine Troubleshooting

Cylinders
TROUBLE
Rough Idling

High Cylinder Head Temperature

Low Compression

PROBABLE CAUSE
Hydraulic tappets fouled
Burned or warped exhaust valves,
worn valve seats. Scored valve
guides
Valve seats worn and leaking,
piston rings worn or stuck in ring
lands
Exhaust valve leaking, cylinder
baffles loose or bent. Cooling area
between cylinder fins obstructed
Exhaust gasket leaking
Valve seats worn and leaking,
piston rings worn or stuck in ring
lands
Piston rings excessively worn
Valve faces and seats worn
Excessively worn cylinder walls

Continuous Fouling Of Spark Plugs

Valve seats worn and leaking,
piston rings worn or stuck in ring
lands
Piston rings excessively worn or
broken
Piston rings not seated
Cylinder has been overheated
Cylinder bore out of round

Sluggish operation and low power
output

Valve seats worn and leaking,
piston rings worn or stuck in ring
lands
Valve seats worn and leaking,
piston rings worn or stuck in ring
lands

CORRECTION
See chapter 19, Cylinder Assembly
Maintenance "Hydraulic Tappets"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
Replace gasket
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"
See chapter 19, Cylinder Assembly
Maintenance "Cylinders"

5-25

Time Limits, Operational Inspection, Engine Troubleshooting

Crankcase
TROUBLE
Oil Loss

PROBABLE CAUSE
Loose accessories or deteriorated
gaskets
Cracked crankcase
Insufficient torque

Loose accessories

Loose or stripped studs
Insufficient torque

Engine Runs Rough

Cracked engine mount

Excessive Crankcase Pressure

Cylinder blow-by

CORRECTION
See chapter 20, "Crankcase
Maintenance
See chapter 20, "Crankcase
Maintenance
Tighten hardware to proper torque
in accordance with the applicable
Overhaul Manual
Replace studs in accordance with
the applicable Overhaul Manual
Tighten accessory hardware to
proper torque in accordance with
the applicable Overhaul Manual
Replace engine mount in
accordance with the applicable
Overhaul Manual
Perform cylinder compression test

Crankshaft
Prop Control "RPM"

PROBABLE CAUSE
Malfunctioning prop governor
Incorrect oil control collar to
crankshaft clearance

Oil Loss

5-26

Worn crankshaft nose seal

CORRECTION
See the airframe manufacturer's
instructions
Replace oil control collar and/or
repair crankshaft in accordance with
the applicable overhaul manual
Replace crankshaft nose oil seal in
accordance with the applicable
Overhaul Manual

Chapter 6

Unpacking, Deinhibiting,
Installation and Testing

Engine Unpacking, Deinhibiting, Installation and Testing ................................................................................................ 6-3

6-1

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6-2

Unpacking, Deinhibiting, Installation and Testing

Engine Unpacking, Deinhibiting,
Installation and Testing
Engine unpacking, deinhibiting, installation and
testing must be performed in accordance with the
instructions in the IO-520-B, BA, BB, C, CB, M &
MB Permold Series Operation and Installation
Manual, Form OI-11 and the airframe manufacturer’s instructions.

6-3

This Page Intentionally Left Blank

6-4

Chapter 7

Servicing Fluids

Servicing Oil ............................................................................................................................................................................................................ 7-3
Oil Filter Element Inspection ..................................................................................................................................................................... 7-4
Material Identification ............................................................................................................................................................................. 7-4
Oil Analysis ....................................................................................................................................................................................................... 7-4
Spectrographic Oil Analysis ....................................................................................................................................................................... 7-5
Limitations ......................................................................................................................................................................................................... 7-5
General Procedures.................................................................................................................................................................................... 7-5
Servicing Fuel......................................................................................................................................................................................................... 7-6

7-1

This Page Intentionally Left Blank

7-2

Servicing Fluids

Servicing Oil
CAUTION…
Some funnel-type quart containers incorporate a
styrofoam or aluminum seal. Remove this seal
from the container and discard it before adding
oil to the engine. If the seal becomes unattached
and falls into the engine, engine damage and
possible failure can result.
The oil system must be serviced to capacity with
the oil grades specified in Chapter 3.
A certain amount of oil consumption is normal. If
excessive consumption or any abrupt change in
rate of consumption is detected, this condition
must be corrected before further flight.

Maintain the engine compartment, nacelle and the
fuselage adjacent to the nacelle in a clean
condition in order that an oil leak can be detected
and corrected before further flight.

WARNING
Engine operation with no oil or severely
reduced oil levels will cause engine
malfunction or failure.
Oil sump capacity in U.S. quarts:
IO-520-B, -BA, -BB, -C, -CB, -M, -MB ...................12

Oil
Sump

Oil Sump
Drain (2)
Oil Filter

Oil
Filter

Oil Filler
and Gauge

Engine Top View

Engine Rear View

Figure 7-1
General Oil Servicing Points
7-3

Servicing Fluids

NOTE...
Engines which have a complete set of new or
overhauled cylinders and new piston rings must
be serviced with clean, approved Engine BreakIn and Preservation oil until oil consumption
has stabilized (approximately 25 hours of
operation). Thereafter, service the engine with
clean ashless dispersant oil that is TCM
approved.

CAUTION...

• Bronze or Copper—will turn bright green when
placed in nitric acid.
• Carbon—will disintegrate when
between index finger and thumb.

rubbed

• Sand—will not disintegrate when rubbed
between two hard surfaces and will scratch glass
when pressure is applied.
• Nickel—will not be magnetically attracted but
looks similar to ferrous material.

Petroleum base aviation engine oil is flammable
and must be stored in a well ventilated area away
from any heat source.

• Tin—will not be attracted magnetically. It looks
similar to nickel but is soft and malleable.

Oil Filter Element Inspection

Oil Analysis

Oil filter element inspection is recommended at
each oil and filter change even if oil analysis is
being used. Filter element inspection may identify
Internal engine wear that will not be identified
through oil analysis.
New, rebuilt, overhauled engines or engines that
have had cylinders replaced will generally exhibit
noticeable amounts of normal wear material at the
first and second oil and filter change. The amount
of material present should significantly decrease
between the first and second oil and filter change
if the engine and or cylinders have been properly
operated during the break-in period.
As with oil analysis, oil filter element inspection
provides maintenance personnel with additional
information on the wear characteristics of a
specific engine. Sudden, unexplained increases in
concentration of wear material in a filter element
should alert maintenance personnel to investigate
the source and cause of the material.

Material Identification

• Ferrous attracts to magnet.
• Aluminum—will “sizz” or bubble when placed
in a 50 % solution of muriatic acid.

7-4

Spectrographic oil analysis has become popular
with the owners and operators of general aviation
piston powered aircraft. This process was
developed more than 35 years ago by the railroads
as a method of identifying wear characteristics in
large diesel engines. Eventually oil analysis was
adopted by the military and then by commercial
and general aviation.
Engines are designed and manufactured using
various materials and alloys. The engine
lubrication system is designed to provide either
pressure or splash oil to areas of the engine
subjected to frictional loading. During normal
operation these areas undergo minute, continuous
wear; sub microscopic material is released from
these contact surfaces and are suspended in the
lubricating oil. Spectrographic oil analysis
identifies these materials and their level of
concentration in parts per million (PPM).
There are two accepted methods of performing oil
analysis: atomic absorption and atomic emissions.
Atomic absorption will identify suspended wear
material that is five micron in size or smaller,
while atomic emissions will identify suspended
wear material that is ten micron in size or smaller.
Since engine oil analysis is used as a tool to

Servicing Fluids

establish engine wear trends and deviations from
the established norm, either method is acceptable;
however, it is important to realize the oil analysis
program must utilize the same laboratory for all
sample analysis. Comparing an oil analysis report
from a separate laboratory will have little meaning
if each laboratory uses a different analysis method.

Limitations

Spectrographic Oil Analysis

General Procedures

A proper spectrographic oil analysis program
should begin with the first engine oil change.
Establishing a wear trend data base for an engine
will require analysis of at least three oil samples.
As the engine accumulates operating time and
additional oil samples are analyzed, a definitive
wear trend can be identified. Unexplained
deviations from normal wear trend patterns should
be investigated using accepted, conventional
inspection methods.
Spectrographic oil analysis must be accomplished
according to a set protocol to provide any useful
information. Even if done properly, spectrographic
oil analysis will rarely provide any prior indication
of a fatigue type failure. A single spectrographic
oil sample will usually not provide a high level of
useful information since there is no established
wear breed data on that specific engine for
comparison.

Variations in operation, use and maintenance may
be reflected in the parts per million content
reported. Deviations from standard or previously
used sampling procedures may result in variations
to the parts per million content in the sample
report.
To establish a data base for comparison and
analysis, oil samples must be taken on a regular
schedule using the same sampling techniques and
laboratory. The engine must have been operated
long enough to obtain normal operational
temperatures and the oil sample taken within 30
minutes after engine shut down. The tube or
funnels used to drain the oil from the sump must
be clean and free of any debris or residue. If the oil
sample is taken from the oil as it drains from the
sump, allow approximately 1/3 of the oil drain
prior to taking the sample. If the sample is taken
via the oil filler or other location using a sampling
tube, it is critical the sample be taken from two or
three inches above the bottom of the oil sump, not
from the bottom. Do not take an oil sample from
the oil filter canister.

Spectrographic oil analysis will assist in the
identification of an internal engine problem. If
samples are properly taken at regular intervals, it
should provide the owner / operator and oil
analysis technician with information relative to
normal or abnormal wear that occurs during the
course of engine operation. Deviations from an
established wear trend pattern should alert the
owner/operator and oil analysis technician to
further investigate.

7-5

Servicing Fluids

Servicing Fuel
Aviation Min. Grade
..................................................................................................

100LL (Blue) or 100(Green)

Refer to the airframe manufacturer’s instructions
for aircraft Fueling Procedure and Fueling Points.

WARNING
The use of lower octane rated fuel or jet
fuel will result in damage or destruction of
an engine the first time high power is
applied. This would most likely occur on
takeoff. If the aircraft is inadvertently
serviced with the wrong grade of fuel or jet
fuel the fuel must be completely drained
and the tank properly serviced.
Any engine operated on fuel of lower grade than
approved for the engine or jet fuel must be
completely disassembled, cleaned, inspected,
repaired, reassembled and tested in accordance with
the current overhaul manual.

7-6

Chapter 8

Engine Preservation
and Storage

Engine Preservation and Storage ........................................................................................................................................................... 8-3

8-1

This Page Intentionally Left Blank

8-2

Engine Preservation and Storage

Engine Preservation
and Storage
Engine engine preservation and storage must be
performed in accordance with the instructions in
the I0-520-B, -BA, -BB, -C, -CB, -M and -MB
Operation and Installation Manual, Form OI-11.

8-3

This Page Intentionally Left Blank

8-4

Chapter 9

Standard Practices

General Practices ........................................................................................................................................................................................... 9-3
Lockwire Procedure .............................................................................................................................................................................. 9-4
Tab Washer Installation ..................................................................................................................................................................... 9-6
Cotter Pin Installation ......................................................................................................................................................................... 9-6
Adhesives ............................................................................................................................................................................................................... 9-7
Gasket Installation ......................................................................................................................................................................................... 9-7

9-1

This Page Intentionally Left Blank

9-2

Standard Practices

General Practices
1. To facilitate and insure proper reinstallation,
tag or mark all parts and hardware as they are
removed or disassembled.
2. Tag any unserviceable parts or units for
investigation and possible repair. Take
extreme care to prevent lockwire, nuts,
washers, dirt, etc., from entering the engine on
or off the aircraft. Make use of protective caps,
plugs and covers to insure openings are
unexposed.

CAUTION…
Dust caps used to protect open lines must be
installed OVER the tube ends and NOT IN
the tube ends. Flow through the lines will be
blocked if lines are inadvertently installed
with the dust caps in the tube ends.
3. If anything is dropped into the engine work
must be stopped immediately and the item
removed.
4. Insure that all parts are thoroughly clean and
lubricated as specified before assembling.

cotter pin head must fit into a recess of the nut
with the other end bent such that one leg is
back over the stud and the other is down flat
against the nut in accordance with Figure 9-4.
Use only manufacturer specified corrosion
resistant steel cotter pins. All lockwire used on
TCM engines must conform to MS20995
Condition A.
7. When replacing gaskets, packing, or rubber
parts use the type or composition specified by
the manufacturer.
8. Make sure replacement nonmetallic and
metallic parts show no sign of storage
deterioration. Parts exceeding specified shelf
life limitations must not be used.
9. When a hammer is required to come in direct
contact with an engine part during assembly or
disassembly, use a mallet made of plastic or
rawhide material only.
10. Parts removed from the engine must be
cleaned and inspected in accordance with the
specified instructions located in the applicable
system chapter.

5. Insure all parts are thoroughly clean and
lubricated as specified before assembling.
6. All lockwire and cotter pins must fit snugly in
holes drilled in specific hardware. On
castellated nuts, unless otherwise specified, the

9-3

Standard Practices

Lockwire Procedure
Lockwiring is the securing together of two or more
parts with lockwire installed in such a manner that
any tendency for a part to loosen will be
counteracted by additional tightening of the
lockwire.
All lockwire utilized on TCM engines must
conform to MS20995 Condition A. Most bolts
utilized in TCM engines that require lockwiring will
use .032 lockwire and require twisting at a rate of 7

Figure 9-1
General Lockwire Procedure
9-4

to 10 twists per inch. Smaller lockwire (when
specified or required) will require twisting at a rate
of 9 to 12 twists per inch. Lockwire must be new at
each application.
Lockwire must be pulled taut while being twisted
and caution must be exercised during the twisting
operation to keep the lockwire tight without
overstressing. See Figure 9-1, “General Lockwire
Procedure,” for steps in applying lockwire.

Standard Practices

Various examples of lockwiring are shown in
Figure 9-2, “General Lockwire Patterns.”
1. Check the units to be lockwired to insure they
have been correctly torqued. Applying
torquethat is above or below specified limits to
obtain alignment of the holes is not permitted.
2. It is desirable to have the holes parallel, but this
is not a necessity. For right hand threads, the
lockwire shall be installed in such a manner that
3. Insert half of the required length of lockwire
through the first unit and bend around the head
of the unit. The direction of wraps and twist of
strands shall be such that the loop around the
unit comes under the strand protruding from the
hole so that the loop will stay down and will not
tend to slip up and leave a slack loop.

Twist the strands while taut until the twisted
part is just short of a hole in the next unit. The
twisted portion should be within one-eighth
(1/8) inch from the hole in either unit.
5. Insert the uppermost strand through the hole in
the second unit and follow the rules in
Paragraph three.
6. After lockwiring the last unit continue twisting
the lockwire to form a pigtail, providing
sufficient twists (four minimum) to assure that
the pigtail will not unravel. Cut off the excess
lockwire and bend the pigtail toward the part
and against the bolt head flats. Do not allow
the pigtail to extend above the bolt head.

Figure 9-2
General Lockwire Patterns
9-5

Standard Practices

Figure 9-3
Tab Washer Installation Procedure

Figure 9-4
Cotter Pin Installation Procedure

Tab Washer Installation

Cotter Pin Installation

Tab washers are installed by fitting a tab in a tab
slot and bending the remaining tabs firmly against
the bolt or nut flat. Tab washers are used in various
locations in TCM engines and must not be re-used
after removal.
Tabs that are provided to be bent up against the
head flats must be seated firmly with no scarring of
the tabs. This provides proper locking of the unit
and prevents tabs from breaking off.
1. Make certain the holding tab is located in the
tab hole or slot.
2. Check the units to be secured and verify they
are correctly torqued in accordance with the
specified instructions of the applicable system
section.
3. Bend tabs against the head flats firmly by
tapping them into place with a soft drift. See
Figure 9-3, “Tab Washer Installation
Procedure.”

Cotter pins are installed by inserting the cotter pin
through a hole in one part, slots in the other part and
spreading the exposed ends.
Cotter pins are not reusable and must be replaced
with a new cotter pin after removal.
1. Torque the nut to the lower limit of the torque
specification. If the slots in the nut do not line
up with one of the holes in the bolt continue
torquing until one does. Do not exceed the
upper limit of the torque specification. Change
the nut if necessary.
2. Insert the cotter pin with the head seated firmly
in the slot of the nut. Bend the ends over the flat
on the nut and the end of the bolt. Trim the
prong lengths as necessary.
3. Seat the prongs firmly against the bolt and nut.
See Figure 9-4, “Cotter Pin Installation
Procedure.”

CAUTION…
Do not use side-cutting type pliers to bend the
ends over since the resulting nick could weaken
the pin and allow a portion to become detached.

9-6

Standard Practices

Adhesives

Gasket Installation

Adhesives and sealants will be used only in specific
applications outlined in Chapter 3, “Table Of
Sealants and Lubricants.”

All gaskets must be new, of the proper material and
visually inspected prior to installation.

WARNING
The improper use of sealants and lubricants
will cause engine malfunction or failure.
Gasket Maker P/N 646942 - Surfaces must be clean
and free of nicks, burrs, oil and grit. Apply a thin
even coat of Gasket Maker between .010 and .020
inch thick to the surface specified in Chapter 3,
“Table Of Sealants and Lubricants.”
Gasket Maker is an easily workable tacky gel which
can be extruded onto one side of a flange surface
from a tube and evenly spread. Small parts can be
covered adequately by pressing them into a
saturated polyester urethane sponge or by roll
coating them with a short nap roller. Once Gasket
Maker has been applied evenly torque assembly
into place. Excess material can be cleaned by
wiping with chlorinated solvent. Material on hands
can be cleaned with waterless mechanics hand soap
followed by soap and water.

Following visual inspection, if the gasket shows any
indication of gouges, nicks, cuts or bend and fatigue
marks replace with a new manufacturer specified
gasket.
Gasket surfaces must be clean and free of nicks,
burrs, oil and grit. Apply a thin coat of TCM Gasket
Sealant P/N #642188-1 to both sides of gasket
unless otherwise specified. See Chapter 3, “Table
Of Sealants and Lubricants,” for application of
gasket sealant. Once TCM Gasket Sealant has been
applied install gasket. Install assembly and evenly
torque hardware to specified value. This will
prevent over stressing gasket.

WARNING
Gaskets and components must be properly
positioned, hardware torqued and safetied
as required during assembly to prevent oil
loss.

NOTE…
TCM general purpose primer P/N 653160 must
be used for surface preparation before applying
Gasket Maker at the engine nose seal area.

9-7

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9-8

Chapter 10

Engine Maintenance

General ..................................................................................................................................................................................................................... 10-3

10-1

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10-2

Engine Maintenance

General
During engine 50 and 100 hour inspections, if
engine components must be removed and replaced,
refer to the applicable disassembly/-reassembly
instructions found in the IO-520 Permold Series
Overhaul Manual, Form X30568A as outlined in
the Maintenance section of each system.
Note...
Engine operational inspection must be performed
prior to any 50 or 100 hour static inspections.
Refer to Chapter 5, “Operational Inspection.”
Corrections and adjustments will be found in the
individual system chapters of this manual under
“Maintenance,” and in Chapter 22, “Post
Maintenance Adjustment and Test.”
At the completion of all 50/100 hour inspection
procedures, refer to Chapter 22 and perform the
post maintenance operational test.

10-3

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10-4

Chapter 11

Exhaust System

Exhaust System ................................................................................................................................................................................................... 11-3

11-1

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11-2

Exhaust System

Exhaust System
This chapter is reserved for engines utilizing
an exhaust system and components supplied
on some engine models by Teledyne
Continental Motors.
For I0-520-B, BA, BB, C, CB, M & MB
exhaust system maintenance, refer to the
airframe manufacturer's instructions.

11-3

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11-4

Chapter 12

Ignition System

TCM Ignition System...................................................................................................................................................................................... 12-3
Ignition System Component Description ........................................................................................................................................ 12-5
Magneto Accessory Drive Adapter .............................................................................................................................................. 12-5
Spark Plugs............................................................................................................................................................................................................ 12-5
Magneto to Engine Timing ........................................................................................................................................................................ 12-7
Operational Tests ............................................................................................................................................................................................. 12-7
Magneto Impulse Coupling Test .................................................................................................................................................... 12-7
Timing Steps .................................................................................................................................................................................................. 12-8
Ignition System Maintenance ............................................................................................................................................................... 12-13
Magneto Drive Adapter Removal and Replacement ................................................................................................... 12-13
Service Limits ............................................................................................................................................................................................ 12-14
Magneto Removal and Replacement ....................................................................................................................................... 12-15
Ignition Harness Removal and Replacement .................................................................................................................... 12-15

12-1

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12-2

Ignition System

TCM Ignition System
Dual ignition is provided by two magnetos. The left
magneto fires 1-3-5 lower and 2-4-6 upper spark
plugs, while the right magneto fires the 1-3-5 upper
and 2-4-6 lower spark plugs.
The TCM S6RN-201, -205, 1201, 1205 series
magnetos are designed to provide ignition for six
cylinder aircraft engines. The magnetos generate
and distribute high tension current through high
tension leads to the spark plugs. Because of the one
piece housing design, these high tension magnetos
are comparatively easy to maintain between
overhauls. The magnetos must be overhauled at
engine overhaul or four calendar year interval in
accordance with the applicable Magneto Service
Manual.

To obtain the retard spark necessary for starting, the
S-20 series magnetos and some S-1200 series
magnetos employ an impulse coupling. The purpose
of the impulse coupling is to: (1) rotate the magneto
between impulse trips faster than the engine
cranking speed thus generating a better spark for
starting the engine, (2) automatically retard the
spark during engine cranking, and (3) act as a drive
coupling for the magneto. S-200 series magnetos
and some S-1200 series magnetos employ the
"shower of sparks" ignition system, including a
starter vibrator. The purpose of the "shower of
sparks" is to: (1) boost ignition energy by feeding
pulsating battery voltage to the magneto primary
circuit during starting and (2) automatically retard
the spark during engine cranking.
The following chart explains the various letters and
numbers appearing in the type designations:

S 6 R N - 1201
Magneto Configuration
S = Single Type Magneto:
one drive, one output distributor
D = Dual Type Magneto:
one drive, two output distributors

Cylinders Fired
4 = Four Cylinders
6 = Six Cylinders
8 = Eight Cylinders

Rotation As Viewed
Looking At Drive End
L = Left (counterclockwise)
R = Right (clockwise)

Designator
N = Scintilla Design
SC = Short Cover

Model Number
S-20 Series
20: Dog-Ear Mount, No Impulse Coupling
21: Dog-Ear Mount, Impulse Coupled
23: Dog-Ear Mount, Impulse Coupled, Military
Shielding
25: Deep Flange Mount, Impulse Coupled
25P:Deep Flange Mount, Impulse Coupled,
Pressurized
S-200 Series
200: Dog Ear Mount, With Retard Breaker
201: Deep Flange Mount, With Retard Breaker
204: Dog Ear Mount, Without Retard Breaker
205: Deep Flange Mount, Without Retard Breaker
S-1200 Series
1201: Deep Flange Mount, With Retard Breaker
1205: Deep Flange Mount, Without Retard Breaker
1208: Short Flange Mount, With Retard Breaker
1209: Short Flange Mount, Without Retard Breaker
1225: Deep Flange Mount, Impulse Couple
1227: Short Flange Mount, Impulse Coupled
1251: Pressurized Version of 1201
1255: Pressurized Version of 1205
1258: Pressurized Version of 1208
1259: Pressurized Version of 1209

The following detailed explanation gives the meaning of the variousD-3000
lettersSeries
and numbers appearing in the TCM
3000: Impulse Coupled
magneto serial number (Manufacturing Number). Example: B138901FR
3200: With Retard Breaker

12-3

Ignition System

A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.

Month

Day of
Month

Year
(1989)

Sequential Number
for unit begins with
"01" each day

Product
Code:

Factory
Rebuilt
(No letter
for new)

January
February
March
April
May
June
July
August
September
October
November
December

D: S-20
E: S200
F: S1200
G: D3000

Ignition System Components
Conventional dual ignition is provided by two magnetos. The left magneto fires the 1-3-5- lower and the 2-4-6
upper spark plugs, while the right magneto fires the 1-3-5 upper and 2-4-6 lower spark plugs.
The Slick 6210 Series Magnetos, manufactured by Slick Electro Incorporated, 530 Blackhawk Park Avenue,
Rockford, Illinois 61101, are designed to provide ignition for six cylinder light aircraft engines. The magnetos
generate and distribute high tension current through high tension leads to the spark plugs.
To obtain the retard spark necessary for starting, the magnetos employ an impulse coupling. The purpose of the
impulse coupling is to: (1) rotate the magneto between impulse trips faster than engine cranking speed, thus
generating a better spark for starting the engine; (2) automatically retard the spark during engine cranking, and
(3) act as a drive coupling for the magneto.
Slick serial number explanation:

EG-2 03 132
The year of manufacture
(2=1982)

The number of a
particular model
manufactured in the
month specified

The month of manufacture
(03=March)

12-4

Ignition System

Ignition System
Component Description

Spark Plugs
Remove spark plugs for cleaning or replacement in
accordance with the applicable disassembly/reassembly instructions in the IO-520-B, BA, BB,
C, CB M & MB Overhaul Manual, Form OH-11.
After spark plugs are removed:
1. Clean and gap or replace in accordance with the
spark plug manufacturer’s specifications.
2. Test spark firing under pressure using a
Champion® cleaner/tester or equivalent.
3. Replace any spark plug that does not fire
properly. Insure that each spark plug is free of
residue from the cleaning process.
1. Apply Champion® thread lubricant to all spark
plugs in accordance with the manufacturer’s
instructions and reinstall spark plugs in the
reverse spark plug installation order. Do not
torque spark plugs at this time.

For a detailed description of magnetos and harness,
see TCM Ignition System Master Service Manual
Form X40000 or Slick Ignition Systems Master
Service Manual Form F-1100 as applicable. See
“Related Publications” for ordering information.

Magneto Accessory Drive Adapter - Each
magneto is driven by a magneto drive shaft, retainer
and bushings housed inside a magneto and
accessory drive adapter. The adapters are attached
to the upper rear portion of the crankcase and secured by four studs, washers and nuts. The magneto
drive shafts are installed in the front of the adapter
and meshed in the proper position with the idler
gear. Two rubber bushings (per magneto) are
installed within a retainer on the drive shaft. The
rubber bushings provide a shock absorbing engagement between magneto and engine drive train.

5
T

3
B

CAUTION...
Never install a spark plug that has been
dropped: discard it.

Spark Plug Rotation

CYLINDER
NUMBER

FROM

2
COAT

1 TOP

6 BOTTOM

1 BOTTOM

6 TOP

2 TOP

5 BOTTOM

2 BOTTOM

5 TOP

3 TOP

4 BOTTOM

3 BOTTOM

4 TOP

3 BOTTOM

4 BOTTOM

3 TOP

5 TOP

2 BOTTOM

5 BOTTOM

2 TOP

6 TOP

1 BOTTOM

6 BOTTOM

1 TOP

Figure 12-1
Spark Plug Rotation
12-5

Ignition System

Use Figure 12-2 to help you make an informed
decision whether to clean, regap, and reuse a spark
plug or discard it.

NORMAL ELECTRODE CONDITION
Insulator tip gray, tan or light brown. Few combustion
deposits. Electrodes not burned or eroded. Proper
type heat range plug for engine and service. Spark
plug should be cleaned regapped and tested before
reinstallation.

NORMAL WORN-OUT CONDITION
Electrodes eroded by high-voltage sparking and by
corrosive gases formed during combustion to less
than 1/2 original thickness. More voltage needed to
fire spark plugs - often more than ignition system can
produce. Discard and replace with new spark plugs.

SEVERE WORN-OUT CONDITION
Excessively eroded center and ground electrodes
plus extensive necking of fine wire ground electrodes
indicate abnormal engine power or plugs long overdue for replacement. Check fuel metering and magneto
timing. Discard spark plugs and check heat range
before installing new ones.

ELECTRODE WEAR PATTERNS
Constant polarity occurs with even-numbered cylinder
magnetos. One plugs fires with positive polarity, causing
excessive ground-electrode wear, while the next plug fires
negatively, causing excessive center electrode wear. To
equalize this, rotate as indicated in Figure 10-4.

Figure 12-2
Spark Plug Wear

12-6

Ignition System

Magneto to Engine Timing
WARNING
To prevent possibility of serious bodily
injury or death, before moving the
propeller accomplish the following:
a. Disconnect all spark plug leads.
b. Verify magneto switches are connected
to magnetos, that they are in the "OFF"
Position and "P" leads are grounded.
c. Throttle position "CLOSED."
d. Mixture control "IDLE-CUT-OFF."
e. Set brakes and block aircraft wheels.
Insure that aircraft tie-downs are
installed and verify that the cabin door
latch is open.
f. Do not stand within the arc of the
propeller blades while turning the
propeller.

Operational Tests
Perform the following operational tests at the
specified intervals to insure that these systems are
functioning properly:

Magneto Impulse Coupling Test
WARNING
Failure to properly ground magnetos will
result in engine ignition and possible injury
to personnel.
1. Insure that both magnetos are properly
grounded and that all spark plugs are installed
in all cylinders. Remove all spark plug harness
lead ends from the spark plugs and ground them
to the engine to prevent ignition.
2. Before cranking engine perform the following:
a. Magneto switch, if separate from starter
Off
switch
Idle Cut Off
b. Mixture
Closed
c. Throttle
Off
d. Fuel selector
On
e. Master switch
3. Crank engine several revolutions.
...................................................................................................................................................................
...............................................................................................................

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

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

WARNING
Magneto-to-engine timing does not insure
magneto, harness, and spark plug performance. Failure to properly maintain the
magneto, harness, and spark plugs will lead
to internal engine damage and failure.
Magneto, ignition harness, and spark plugs
must be maintained in accordance with the
manufacturer’s instructions.
CAUTION...
A single severe kickback while cranking the
engine can cause failure of components in the
cranking system. Kickback can be caused by
intermittent operation of the impulse couplings.

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

WARNING
Use extreme caution in the area of the
propeller while performing this test. Do
not stand or allow anyone else to stand in
the propeller arc area.
a. Impulse coupling operation is audible and
can be felt through the magneto housings.
The impulse couplings should consistently
click together while the engine is being
cranked.
b. If no clicking or if only intermittent
clicking is heard, remove the magnetos and
service them in accordance with the
magneto manufacturer's instructions.

12-7

Ignition System

c. When performing a magneto timing check, use
the following tools:
• Top dead center locator
• Protractor and Pointer
The Eastern Electronics Model E25 Timing
Indicator kit or equivalent is recommended.
Use the following timing procedure to insure correct
engine timing.

NOTE...
Whenever setting or checking timing, always
turn the crankshaft steadily in the direction of
rotation to eliminate backlash error.

Timing Steps
1. Remove all top spark plugs.
2. Rotate the crankshaft in the direction of normal
rotation until the number one piston is
approximately at top dead center on the
compression stroke.
3. Rotate the crankshaft in the opposite direction
of normal rotation until the piston is far enough
down the barrel to allow the TDC locator to be
installed.
4. Install the Top Dead Center locator into number
1 cylinder top spark plug hole.
5. Slowly rotate the crankshaft in the direction of
normal rotation until the piston lightly touches
the TDC locator.
6. Install timing indicator disc on the crankshaft
flange, propeller spinner or center hub of
propeller blades.
7. Rotate disc of timing indicator until the 0
degree mark aligns with the pointer as shown in
Figure 12-3.

Figure 12-3
Timing Procedure Step 1
12-8

Ignition System

Figure 12-4
Timing Procedure Step 2

2. Slowly turn crankshaft in opposite direction of
normal rotation until the piston lightly touches
the TDC locator.
3. Observe the reading on the disc under the
pointer and move the disc exactly one half of
the number of degrees observed toward the top
center mark. This will be one half the number
of degrees remaining of 360 degrees of
crankshaft rotation. You have now located top
dead center.

12-9

Ignition System

Figure 12-5
Timing Procedure Step 3
10. Remove the TDC locator from the cylinder and
find the compression stroke on the No. 1
cylinder by placing a finger over the spark plug
hole (or by any other adequate method). As you
come up on compression, stop the pointer at the
TDC location determined in step 3. For engines
equipped with impulse couplings, continue
turning the propeller in the normal direction of
rotation until each impulse coupling trips.
Couplings may trip a few degrees on either side
of TDC. If one or both couplings trip after
TDC, turn the propeller back to a few degrees
before TDC and approach the TDC position
from the normal direction of rotation.

12-10

Ignition System

Figure 12-6
Timing Procedure Step 4

4. To check either the magneto timing or to time
the magneto to the engine, move the propeller
in the opposite direction of normal rotation past
the specified magneto timing setting and then
back in the direction of normal rotation until the
desired setting before top dead center is under
the pointer. (This removes gear backlash.)

12-11

Ignition System

Figure 12-7
Timing Procedure Step 5

6. The breaker points should be just starting to
open at this setting. Breaker point opening
must be checked with a timing light.

12-12

Ignition System

Ignition System
Maintenance
Magneto Drive Adapter Removal and
Replacement
Remove magneto drive adapter assemblies for
repair or replacement in accordance with the
applicable portion of the “Magneto And Accessory
Drive” disassembly instructions in the IO-520
Permold Series Overhaul Manual, Form OH-11.
When performing magneto drive adapter repairs
prior to engine TBO, the dimensional limits on page
12-12 may be used.

Caution...
When performing dimensional inspection, the
following “Service Limits” may be used.
However, they are intended only as a guide
for reuse when performing engine
maintenance prior to major overhaul. Parts
with dimen-sions or fits that exceed service
limits must not be reused. Parts with values up
to and including service limits may be reused.
However, consideration should be given to
how close the engine is to its next
recommended overhaul. Service limits must
NOT be used when overhauling an engine.

12-13

Ignition System

Service Limits
Refer to Figure 12-8 for locations of the following magneto components:
Ref.
No.
1.
2.
3.
4.
5.

Diameter:
Diameter:
Diameter:
Diameter:

Service
Limits
0.0040T
0.0050L
0.0070T
0.0040T

Diameter:
End Clearance:

0.0550L
0.0770L

Side Clearance:

0.040L

Side Clearance:
Diameter:

0.0140L
0.0050L

Description
Bushing in magneto and accessory drive adapter
Magneto and accessory drive gear in adapter bushing
Oil seal in adapter
Sleeve in magneto and accessory drive gear
Magneto coupling retainer on magneto and
accessory drive gear sleeve
Magneto and accessory drive gear
Magneto coupling retainer in
magneto drive gear slot
Magneto coupling rubber bushings on
magneto drive lugs
Magneto pilot in crankcase

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

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

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

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

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

6.
7.

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

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

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

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

1
2
6
8
3
Figure 12-8
Service Limits

12-14

Ignition System

Magneto Removal and
Replacement

Ignition Harness Removal
and Replacement

Remove the magnetos for repair or replacement in
accordance with “Ignition System Disassembly/Reassembly” in the IO-520 Permold Series Overhaul Manual, Form OH-11.

Remove the harness assemblies for repair or
replacement in accordance with the applicable
“Ignition System Disassembly/Reassembly instructions” in the IO-520 Permold Series Overhaul
Manual, Form OH-11.

Magneto maintenance such as point replacement,
condenser replacement, impulse coupling replacement or internal magneto timing must be performed
in accordance with the magneto manufacturer's
instructions.

Any harness assembly maintenance such as single
lead replacement must be performed in accordance
with the harness manufacturer’s instructions.

UPPER
SPARK PLUGS

ENGINE FIRING ORDER
1 6 3 2 5 4
MAGNETO FIRING ORDER 1 2 3 4 5 6

4
3
2
1

3
2
1

6
4

1
2
3

RIGHT MAG

LEFT MAG

1
4
3
6
5

Figure 12-9
Ignition Wiring Diagram
12-15

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12-16

Chapter 13

Fuel System

Engine Fuel System Description ........................................................................................................................................................... 13-3
Fuel Pump ....................................................................................................................................................................................................... 13-4
Fuel Pump Replacement................................................................................................................................................................................................................... 13-5
Service Limits .......................................................................................................................................................................................................................................... 13-6
Throttle and Fuel Control Unit ...................................................................................................................................................... 13-7
Fuel Control Unit ...................................................................................................................................................................................... 13-8
Fuel Manifold Valve................................................................................................................................................................................ 13-9
Fuel Manifold Valve Replacement ............................................................................................................................................................................................. 13-9
Fuel Nozzle .................................................................................................................................................................................................. 13-10
Fuel Nozzle Removal, Cleaning and Replacement ........................................................................................................................................ 13-11
Fuel System Maintenance ....................................................................................................................................................................... 13-12
Throttle, Fuel Control Unit and Mixture Levers Maintenance .......................................................................... 13-13
Throttle and Fuel Control Unit/Throttle and Fuel Metering Unit Replacement .................................... 13-17
Fuel Line Replacement ............................................................................................................................................................... 13-19
Fuel Hose Replacement.............................................................................................................................................................. 13-19
Table 1 - Torque Specifications for Fittings ..................................................................................................................... 13-20
Table 2 - Torque Specifications for Hose Fittings ....................................................................................................... 13-20

13-1

This Page Intentionally Left Blank

13-2

Fuel System

There are four basic elements in the fuel injection
system: the fuel pump, fuel control unit, fuel
manifold valve and fuel nozzles. Fuel flows from
the fuel pump to the fuel control unit. The fuel then
flows from the fuel control unit to the fuel manifold
valve where it is distributed to the six fuel injector
nozzles.

Engine Fuel System
Description
IO-520-B, BA, BB, C, CB, M, MB fuel system.
The fuel injection system is a low pressure,
multinozzle, continuous flow system that supplies
fuel to the intake valve port in the cylinder head.

4
2

6
8
10

FUEL
PRESSURE
P.S.I.

12
14

20
18

Metered
Fuel
Pressure

Inlet Fuel From Aircraft

Return Fuel From Fuel Control

Unmetered Fuel Pressure

Nozzle Pressure

Metered Fuel Pressure

Vapor Return

Vapor Vent Return
To Fuel Tank
m

Fuel Inlet
From Fuel
Tank

Fuel Pump Assembly

n
m

Fuel Manifold
Valve

Fuel Control Unit

Fuel Return From Fuel Control
r

Low Pressure
Relief Valve

Fuel Injectors

Adjustable Orifice
u

u
u

Idle Mixture
Adjust

Bypass
4

Idle Speed
Stop Screw

Drain

6
8
10

FUEL
PRESSURE
P.S.I.

12
14

20
18

Throttle Body

Figure 13-1
Fuel System

13-3

Fuel System

Fuel Pump
IO-520-B, BA, BB, C, CB, M, MB
Fuel enters the fuel pump at the swirl well of the
vapor separator. Here, vapor is separated by a
swirling motion so that only liquid fuel is fed to the
pump. The vapor is drawn from the top center of the
swirl well by a small pressure-jet of fuel and is fed
into the vapor return line. This line carries the vapor
back to the fuel tank. There are no moving parts in
the vapor separator, and the only restrictive passage
is used in connection with vapor removal. Thus,
there is no restriction of main fuel flow.
Ignoring the effect of altitude or ambient air
conditions for the moment, the use of a positive
displacement, engine-driven pump means that
changes in engine speed affect total pump flow
proportionally. The fuel pump provides greater
capacity than is required by the engine. Thus, a
recirculation path is provided.
By arranging a variable orifice and relief valve in
the recirculation path, the pump delivery pressure is
maintained proportional to engine speed and
ambient air pressure. This insures proper pump
pressure and delivery at all engine operating speeds
and altitudes.

The IO-520-B, BA, BB, C, CB, M and MB type
fuel pumps utilize an aneroid and rod assembly that
assist in controlling fuel flow. The aneroid housing
is referenced to ambient air pressure. The aneroid
bellows expands when the air pressure surrounding
it decreases. As the aneroid expands it moves the
rod increasing the size of the orifice opening. An
increased amount of fuel flows through the orifice
to a recirculation path. This decreases fuel flow
from the fuel pump to the fuel control unit.
A check valve is provided so that boost pressure to
the system can bypass the engine-driven fuel pump
during starting. This feature also aids in the
suppression of vapor formation during high ambient temperature conditions. The check valve permits
use of the auxiliary airframe fuel boost pump in the
unlikely event of an engine driven fuel pump
malfunction.

Vapor Ejector

Pump
Assembly

Fuel Inlet
Vapor Separator

Drive
Coupling

Figure 13-2
Fuel Pump
IO-520-B, BA, BB, C, CB, M, MB

13-4

Relief Valve
Assembly

Fuel Outlet

Check
Valve

Adjustable
Orifice

Fuel System

Fuel Pump Replacement
The fuel pump can be replaced or it can be
repaired and calibrated in accordance with the
applicable instructions in the Fuel Injection
System Parts And Overhaul Manual, Form
X30593A, latest revision.

NOTE...Appropriate test calibration equipment
must be used when overhauling TCM fuel
injection system component.
Whenever the fuel pump is removed from the
engine, both the fuel pump drive coupling to
crankshaft gear clearance of 0.0095L to 0.0155L
and the fuel pump drive coupling to fuel pump
clearance 0.0030L to 0.0090L must be checked.

CAUTION...
When performing dimensional inspections, the
following Fits and Limits may be used. However,
they are intended only as a guide, when
performing engine maintenance prior to major
overhaul, in determining whether a part can be
reused. Parts which have dimensions or fits that
exceed service limits must not be reused. Parts
which have dimensions or fits up to and including service limits may be reused. However, use
sound judgment and take into consideration the
engine’s proximity to recommended overhaul.
1. Remove any airframe components required to
gain access to the fuel pump in accordance
with the airframe manufacturer’s instructions.
Remove the following hoses from their fittings
on the fuel pump and install protective covers
on the hose ends. Identify fuel line location for
proper reinstallation:
a. Airframe to engine fuel connections in
accordance with the airframe manufacturer’s instructions.
b. Vapor return hose
c. Fuel outlet (unmetered pressure) hose.

2. Remove mixture control cable connection in
accordance with the airframe manufacturer’s
instructions.
3. Remove the nuts and washers that hold the
fuel pump on the crankcase:
a. 2 plain nuts
b. 2 lock washers
c. 2 hold down washers
Discard lock washers.

CAUTION...
Do not allow the coupling to fall into the
crankcase. If it does, you must retrieve it
before proceeding.
4. Carefully remove the fuel pump, coupling, and
gasket.
5. Discard gasket.
6. Inspect hoses for condition. Replace any hose
that exhibits wear or deterioration.
7. Discard worn or damaged parts.
8. The fuel pump can be replaced or repaired and
calibrated in accordance with the applicable
instructions in the Fuel Injection System Parts
And Overhaul Manual, Form X30593A, latest
revision.
9. Fittings from the original fuel pump may be
installed and oriented to the same position in
the replacement pump.

CAUTION...
Never use Teflon tape on fuel injection system
fittings.
10. The fittings must be clean and free of damage
and debris prior to installation. Apply F/I
sealant to tapered male threads in accordance
with Figure 13-9. Install fittings in fuel pump
and orient to the original positions.
11. Apply a small amount of Gasket Maker to the
crankcase split lines above and below the fuel
pump bore.

13-5

Fuel System

12. Apply Molyshield Grease to the coupling
receptacle on the fuel pump.

2. Torque the fuel pump nuts to 180 - 220 inch
pounds.

13. Insert the fuel pump coupling into the
coupling receptacle on the fuel pump. Insure
that the coupling is fully seated .

3. Install fuel hoses on fuel pump. Torque fuel
pump hose connections in accordance with
Table 2, “Torque Specifications for Hose
Fittings.”
4. Reinstall cowling and airframe accessories in
accordance with the airframe manufacturer’s
instructions.
5. After all requirements of scheduled maintenance have been performed and prior to any
engine operation, a complete fuel system leak
check must be performed in accordance with
the aircraft manufacturer or STC holder’s
information.

14. Install the new gasket on the crankcase fuel
pump bore studs.
15. Install the fuel pump on the crankcase by
sliding the fuel pump on the fuel pump
mounting studs while carefully guiding the
fuel pump coupling into the square hole in the
crankshaft gear.
1. Install hold-down washers, new lock-washers,
and nuts on each stud.

Service Limits

Ref.
Description
1.
Fuel pump drive coupling to crankshaft gear
2.

13-6

Fuel pump drive coupling to fuel pump

Service Limit
Clearance:
Clearance:

0.0155L
0.0090L

Fuel System

Throttle And Fuel
Control Unit
IO-520-B, BA, BB, C, CB, M, MB
The throttle and fuel control unit controls engine air
intake and sets the metered fuel pressure for proper
fuel/air ratio. The air throttle is mounted at the air
manifold inlet. The throttle valve controls the flow
of air to the engine as positioned by the cockpit
throttle control lever.

Fuel enters the fuel control unit through a strainer
and passes to the metering valve. The rotary
metering valve has a cam-shaped edge across the
fuel delivery port. The position of the cam at the
port controls fuel flow to the fuel manifold valve
and fuel nozzles. The fuel mixture is controlled by
the manual mixture control lever in the cockpit that
is connected to the fuel control unit mixture control
valve.

INLET SCREEN
IDLE SPEED STOP SCREW
CW = INCREASE

THROTTLE
LEVER

FUEL INLET FITTING
(U NMETERED PRESSURE)

IDLE MIXTURE
ADJUSTMENT
CW = ENRIC H

MIXTURE
LEVER
FUEL OUTLET
(M ETERED
PRESSURE)
FUEL RETU RN
(TO FUEL PUM P)

Figure 13-3
Air Throttle and Fuel Control Unit for IO-520-B, BA, BB, C, CB, M, and MB

13-7

Fuel System

Fuel Control Unit
IO-520-B, BA, BB, C, CB, M & MB
(Figure 13-4)
The fuel control body is made of bronze. The fuel
metering shaft and mixture control shaft are made
of stainless steel. The metering valve is located at
one end and the mixture control valve is located at
the other end of the control valve central bore. The
valves ride in bushings and are sealed against
leakage by o-rings. Loading springs force the valve
ends against a fixed plug installed in the center of
the central bore. This bronze plug has one passage
that mates with the fuel return port and one passage
that connects the mixture control valve chamber
with the metering valve chamber. O-rings seal this
plug in the central bore. Each valve includes a
groove which forms a fuel chamber.

The contoured end face of the mixture control valve
aligns with the passages in the metering plug to
regulate the fuel flow from the fuel chamber. A
control lever is installed on the mixture control
valve shaft for connection to the cockpit mixture
control. In the metering valve, a cam shaped cut is
made on the outer part of the end face. A control
lever on the metering valve shaft is connected to the
air throttle valve shaft with linkage. The fuel return
port in the control body connects to the return
passage of the metering plug and alignment of the
mixture control valve face with this passage
determines the amount of fuel returned to the fuel
pump. A removable plug at the fuel inlet port
includes a filter screen to prevent admittance of
debris.

Fuel Inlet From
Fuel Pump

Fuel Return To
Fuel Pump

Figure 13-4
Fuel Control Unit for IO-520-B, BA, BB, C, CB, M, and MB
13-8

To Fuel Manifold
Valve

Fuel System

VENT TO
ATMOSPHERE

TO METERED
PRESSURE GAUGE

TO FUEL INJECTOR
NOZZLE

FROM FUEL
CONTROL UNIT

TO FUEL
INJECTOR
NOZZLE

Figure 13-5
Fuel Manifold Valve

Fuel Manifold Valve
The fuel manifold valve body contains a fuel inlet, a
diaphragm chamber and outlet ports for fuel lines to
the individual nozzles. The spring loaded
diaphragm carries a plunger in the central bore of
the manifold body. The diaphragm is enclosed by a
vented cover which retains the diaphragm loading
spring. When the plunger is down in the body bore,
fuel passages to the nozzles are closed off. The
plunger is drilled for passage of fuel from the
diaphragm chamber to its base and the valve within
the plunger. As fuel flow increases pressure
overcomes diaphragm spring tension causing the
plunger to move to the open position and fuel flows
from manifold valve outlets through fuel lines to the
fuel nozzle assemblies.

Fuel Manifold Valve
Replacement
The fuel manifold valve can be replaced with a
new valve, or it can be repaired and calibrated in
accordance with the applicable instructions in the

Fuel Injection System Parts And Overhaul
Manual, Form X30593A, latest revision.
Use the following procedure to remove and
replace the fuel manifold valve:
1. In accordance with manufacturer’s instructions, remove cowling and any airframe
accessories that may obstruct access to the
manifold valve.
2. Disconnect the 6 fuel lines from the fuel
manifold valve.
3. Disconnect the fuel hose from the elbow on
the manifold valve.
4. Install protective covers on all open lines and
hoses.
5. Remove crankcase backbone hardware at
manifold bracket.
6. Remove the fuel manifold valve and mounting
bracket from engine.

CAUTION...
Never use Teflon tape on fuel injection
system fittings.

13-9

Fuel System

Fuel Nozzle
The fuel discharge nozzle is located in the cylinder
head. The nozzle outlet is screwed into the tapped
fuel nozzle hole in the cylinder head. The nozzle
body has a drilled central passage with a
counterbore at each end. The lower end is the fuel
outlet. The upper bore contains a removable jet for
calibrating the nozzles. Near the top, radial holes
connect the upper counterbore with the outside of
the nozzle body for air admission. These holes enter
the counterbore above the orifice and draw outside

air through a cylindrical screen fitted over the
nozzle body which keeps dirt and foreign material
out of the interior of the nozzle. A press-fitted shield
is mounted on the nozzle body and extends over the
greater part of the filter screen, leaving an opening
near the bottom. This provides both mechanical
protection and an air path .
Nozzles are calibrated in several ranges and all
nozzles furnished for one engine are of the same
range identified by a letter stamped on the hex of
the nozzle body.

Fuel Inlet

Calibrated
Orifice

Screen

Shield

Air Inlet

Injection Mixture
Outlet

Figure 13-6
Fuel Nozzle

13-10

Fuel System

Fuel Nozzle Removal,
Cleaning and Replacement
1. Remove cowling and any airframe accessories
that may obstruct access to the fuel nozzles in
accordance with the airframe manufacturer’s
instructions
2. Loosen and remove the fuel line from the fuel
injector nozzle assembly.
3. Loosen and remove the fuel nozzle.
4. Clean nozzle by soaking in lacquer thinner,
methyl ethyl keytone or acetone for several
hours.
5. If a nozzle is obstructed and cannot be cleaned
by solvent action, it must be replaced with a
new nozzle.

6. Apply TCM 646943 antiseize lubricant to
cylinder end of nozzle threads in accordance
with Figure 13-14. Reinstall the nozzle and
torque to 55 - 65 inch pounds.
7. Install fuel line on nozzle.
8. Torque the fuel line “B” nut to 40 - 45 inch
pounds.
9. Reinstall all airframe supplied accessories and
cowling in accordance with the airframe
manufacturer’s instructions.
After all requirements of scheduled maintenance
have been performed and prior to any engine
operation, a complete fuel system leak check must
be performed in accordance with the aircraft
manufacturer or STC holder’s information.

CAUTION...
Do not attempt to clear nozzle obstruction with
wire.

13-11

Fuel System

Fuel System Maintenance
Compare recorded findings of operational inspection with the following data:
ENGINE

{IO-520-M
& MB
{IO-520-B,
BA, BB
{IO-520-C,
CB

RPM
Propeller

Unmetered or
Pump Pressure
(PSI)

Metered
Pressure
(PSI)

600

8.0 - 10.0
32.0 - 36.0

2700
600
2700
600
2700

Fuel Flow
Lbs./Hr.

Fuel Flow
Gal./Hr.
(APPROX.)

3.9 - 4.5
18.0 - 19.8

142 - 150

24.2 - 25.6

8.0 - 10.0
29.2 - 36.2

3.9 - 4.5
16.5 -18.4

146 -156

24.9 -26.6

8.0 - 10.0
31.6 - 37.8

3.9 - 4.5
17.6 -19.6

152 -160

25.9 -27.3

NOTE…Unmetered or pump pressure values and metered or nozzle pressure values are taken using a gauge
vented to atmosphere. All readings are predicated on properly calibrated gauges.
{ Flight test required to verify fuel flow vs. pressure altitude values are within the limits specified. See the
Altitude Leaning Charts in chapter 22.
If the fuel injection system is found to be in good physical condition and operational inspection readings
conform with the specified flows and pressures, the engine fuel system can be approved for return to service.
If the fuel system is not functioning properly, see troubleshooting in chapter 5 to determine the cause and
procedure for correcting it.

13-12

Fuel System

Throttle, Fuel Control Unit
and Mixture Levers
Maintenance
To insure proper operation and to prevent
accelerated wear of I0-520-B, BA, BB, C, CB, M,
MB model engines, the fuel control to throttle
linkage must be inspected for excessive play which
can cause lost motion and breakage of parts due to
vibration. Inspect the pivot points of levers and
linkages on all I0-520 engine models for debris, old
grease and oil. Clean pivot point areas thoroughly
using clean Stoddard solvent. After cleaning, dry
each area using compressed air.

WARNING
Whenever fuel control to throttle linkage,
attaching hardware, levers or lever bushings
have been replaced or reassembled, the fuel
system must be checked and adjusted in
accordance with the “Fuel System Adjustment” chapter and tested in accordance with
chapter 22, “Post Maintenance Operational
Test.” This test is MANDATORY.
NOTE…
Linkage connections between the throttle and
fuel control unit are the same on the I0-520-B,
BA, BB, C, CB, M, MB engine models; however,
the throttle bodies, throttle levers and fuel
control unit levers used on the different engine
models are physically different.

lubrication must be accomplished using Shell #5
Grease or Lubriplate #630AA or equivalent.
Lubrication of levers, link rods, or bushings must be
performed in accordance with Figure 13-7 on the
following page.
Consult the airframe manufacturer and/or their most
current published instructions concerning aircraft
engine control cable attach point inspection,
cleaning, repair, installation and lubrication.
After the above procedures have been accomplished, verify that each control has full limit of
travel, that required safeties are in place, that no
binding of levers or linkages is occurring and that
control movement is not restricted by contact with
other parts or components that are located in close
proximity.

WARNING
Whenever the fuel pump, fuel control unit,
fuel manifold valve or fuel injection nozzles
are removed and replaced, the fuel system
must be checked and adjusted in accordance
with the “Fuel System Adjustment” chapter
and tested in accordance with chapter 22,
“Post Maintenance Operational Test” of this
manual.

Worn or corroded linkage, attaching hardware,
levers or lever bushings must be replaced in
accordance with the Permold Series Overhaul
Manual, Form OH-11. After cleaning, inspection
and repair has been accomplished as required, each
pivot point must be lubricated using LPS 2, Permatex “Maintain®” Lubricant. If levers, link rods or
bushings have been replaced or reassembled, initial

13-13

Fuel System

Clean, inspect and lubricate in accordance
with the procedure specified under
“Throttle, Fuel Control and Mixture Levers.”

Clean, inspect and
lubricate in accordance
with the Airframe
Manufacturer’s Instructions

Clean, inspect and
lubricate in accordance
with the procedure
specified in “Throttle,
Fuel Control and
Mixture Levers”

Clean, inspect and lubricate
in accordance with the airframe
manufacturer’s instructions

Figure 13-7
Throttle and Fuel Control Unit Lubrication for IO-520-B, -BA, -BB, -C, -CB, -M and -MB

13-14

Fuel System

Clean, inspect and lubricate in
accordance with the airframe
manufacturer’s instructions

Figure 13-8
Throttle and Fuel Control Unit Lubrication for IO-520-B, -BA, -BB, -C, -CB, -M and -MB

13-15

Fuel System

1. Fittings from the original manifold valve may
be installed and oriented to the same position
in the replacement manifold valve. The fittings
must be clean and free of damage and debris
prior to installation. Apply F/I sealant to
tapered male threads in accordance with
Figure 13-9. Install fittings in fuel manifold
valve and orient to the original positions.
Torque fittings in accordance with Table 2,
“Torque Specifications For Hose Fittings.”
2. If the replacement manifold valve does not
include a mounting bracket, remove the
existing bracket from the old manifold valve
as follows:
a. Cut, remove and discard lockwire.
b. Remove 4 screws and 4 lock washers.
Discard lock washers.
c. Remove bracket and 4 plain washers from
old manifold valve.
d. Clean manifold valve bracket and
hardware with mineral spirits solvents and
dry. Inspect all screw threads and insure
that none are damaged.
e. Orient manifold valve bracket on new
manifold valve using 4 plain washers and
secure with 4 new lock washers and 4
screws.
Torque screws to 20 ± 1 inch pounds and
lockwire in accordance with “Typical
Lockwire Procedure” in Chapter 9.
g. Position manifold and bracket assembly
over crankcase backbone mounting holes.
Install manifold/bracket assembly to backbone with 2 screws, washers, and nuts.
Torque to 180-220 inch pounds.
h. Remove all protective covers from fuel
lines and hoses and reinstall fuel lines to
the manifold valve. Insure that B-nut
threads are clean and free of damage.
f.

13-16

WARNING
While installing the bracket, do not
displace or tear manifold valve diaphragm.
9. Torque fuel line to nozzle nuts to 40 - 45 inch
pounds. Torque fuel line to manifold valve
nuts to 55 - 60 inch pounds.
10. Torque fuel inlet hose to manifold valve elbow
nut in accordance with Table 2, “Torque
Specifications For Hose Fittings.”
11. Reinstall removed airframe components in
accordance with airframe manufacturer’s
instructions.
12. After all requirements of scheduled maintenance have been performed and prior to any
engine operation, a complete fuel system leak
check must be performed in accordance with
the aircraft manufacturer or STC holder’s
information.

Fuel System

Throttle and Fuel Control Unit/
Throttle and Fuel Metering Unit
Replacement
1. I0-520-M and MB throttle and fuel control
units must be replaced in accordance with the
airframe manufacturer’s instructions.
2. On I0-520-B, BA, BB, C, CB, M & MB
model engines, remove any airframe
components required to gain access to the
throttle and fuel control unit/throttle and fuel
metering unit in accordance with the airframe
manufacturer’s instructions. Remove
the
following hoses from their fittings.
a. Fuel hose from fuel control unit/fuel
metering unit to manifold valve.
b. Fuel hose(s) from fuel pump to fuel
control unit/fuel metering unit.
3. Install protective covers on all loose hose
ends.
4. On I0-520-B, BA & BB model engines,
remove the throttle to induction manifold
clamp and hose. Remove two bolts and
washers and remove throttle and fuel control
as a unit. On I0-520-C & CB model engines,
remove the throttle to induction elbow clamps
and hoses. Loosen and remove upper throttle
support brackets and hardware in accordance
with the airframe manufacturer’s instructions.
Remove nut from lower throttle body support
bracket and remove throttle and fuel control as
a unit.

8. The throttle and fuel metering unit can be
repaired and calibrated in accordance with the
applicable instructions in the Fuel Injection
System Parts And Overhaul Manual, Form
X30593, latest revision .
9. Fittings from the original fuel control unit/fuel
metering unit may be installed and oriented to
the same positions in the new or replacement
fuel assembly. The fittings must be clean and
free of damage and debris prior to installation.
Apply F/I sealant to tapered male threads in
accordance with Figure 13-9. Install fittings
and orient to the original positions. Torque
fittings in accordance with Table 2, “Torque
Specifications For Hose Fittings.”

CAUTION...
Never use Teflon tape on fuel injection system
fittings.
1. Install I0-520-M & MB model engine throttle
and control assemblies in accordance with the
airframe manufacturer’s instructions.
2. On I0-520-B, BA, BB, C, and CB model
engines, using serviceable hoses and clamp
assemblies, install the throttle and fuel control
unit/throttle and metering unit on the intake
manifold. Tighten hose clamps sufficiently to
insure complete engagement and security of
hose. Do not over tighten clamps to the point
of cold flow.

5. Inspect hoses for condition. Replace any hose
that exhibits wear, damage, or deterioration.
6. Remove and inspect all fittings for cleanliness
and damaged threads. Replace fittings that are
damaged.
7. TCM offers rebuilt fuel injection system
components as an alternative to field repair of
components.

13-17

Fuel System

CAUTION...
Torque all hose connections and fittings in
accordance with Table 2, “Torque Specifications For Hose Fittings” later in this
chapter.
5. Install the following hoses:
a. Remove protective cover and install fuel
hose from throttle and fuel control
unit/throttle and fuel metering unit to
manifold valve.
b. Remove protective cover and install fuel
hose(s) from fuel pump to throttle and
metering unit.

Apply Fuel Injection
Sealant Sparingly Here
DO NOT Apply Fuel
Injection Sealant To
The First Two Threads

Figure 13-9
F/I Sealant Application
3. On I0-520-B, BA and BB engines, install
serviceable throttle and control unit on oil
sump and secure with two washers and bolts.
Torque bolts to 155-175 inch pounds. Install
lock wire on bolts in accordance with Chapter
9.
10. On I0-520-C and CB model engines, align
throttle stud with lower support bracket and
install nut. Torque nut to 90-110 inch pounds.
Install upper throttle support brackets and
hardware in accordance with the airframe
manufacturer’s instructions.

13-18

6. Reinstall cowling and airframe accessories in
accordance with the airframe manufacturer’s
instructions.
7. After all requirements of scheduled maintenance have been performed and prior to any
engine operation, a complete fuel system leak
check must be performed in accordance with
the aircraft manufacturer or STC holder’s
information.

Fuel System

Fuel Line Replacement

Fuel Hose Replacement

Use the following procedure to remove and
replace an existing manifold valve to nozzle fuel
line:

1. Remove any airframe supplied support hardware
from fuel hose in accordance with the airframe
manufacturer’s instructions. Remove fuel hose
from its elbows. Drain fuel into a suitable
container.

1. Separate fuel line from fuel line support
bracket and clamp.
2. Disconnect the fuel line at the manifold valve.
3. Disconnect the fuel line at the fuel nozzle and
remove fuel line.
4. Position a new or existing serviceable fuel line
on the engine and connect it to the fuel
manifold valve. Torque to 55 - 60 inch
pounds.

2. Inspect elbow threads for damage. Remove and
replace elbow in accordance with the preceding
component fitting installation instructions if
damaged or worn.

5. Install the fuel line on the fuel nozzle. Torque
B-nut to 40 - 45 inch pounds.

3. Install new, clean fuel hose on elbows. The fuel
hose must be routed in it’s original position away
from any heat source and any airframe support
hardware that was removed must be reinstalled in
accordance with the airframe manufacturer’s
instructions.

6. Install the fuel line into the fuel line support
bracket and clamp.

4. Torque hose fittings in accordance with Table 2,
“Torque Specifications For Hose Fittings

7. If the rubber fuel line protector is damaged,
replace it with a new protector.

5. After all requirements of scheduled maintenance
have been performed and prior to any engine
operation, a complete fuel system leak check must
be performed in accordance with the aircraft
manufacturer or STC holder’s information.

8. After all requirements of scheduled maintenance
have been performed and prior to any engine
operation, a complete fuel system leak check must
be performed in accordance with the aircraft
manufacturer or STC holder’s information .

13-19

Fuel System

SIZE
5/16-24
5/16-24
3/8-24
3/8-24
7/16-20
7/16-20
7/16-24
9/16-18
9/16-18
3/4-16
3/4-16
7/8-14
7/8-14

TABLE 1 - TORQUE SPECIFICATIONS FOR FITTINGS
FITTING AND MATERIAL
TUBE O.D.
INCH POUNDS
#2 (Brass/Aluminum)
.125
15-30
#2 (Steel)
.125
15-50
#3 (Brass/Aluminum)
.188
40-65
#3 (Steel)
.188
50-90
#4 (Brass/Aluminum)
.250
60-80
(Steel)
.250
70-120
#4 (Steel)
.190
60-80
#6 (Brass/Aluminum)
.375
75-125
#6 (Steel)
.375
90-150
#8 (Brass/Aluminum)
.500
150-250
#8 (Steel)
.500
135-250
#10 (Brass/Aluminum)
.625
200-350
#10 (Steel)
.625
300-400
TABLE 2 - TORQUE SPECIFICATIONS FOR HOSE FITTINGS

HOSE SIZE

THREAD SIZE

(5/16-24)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

50-80
75-120

(3/8-24)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

70-105
95-140

(7/16-20)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

100-140
135-190

(1/2-20)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

130-180
170-240

(9/16-18)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

150-195
215-280

(3/4-16)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

270-350
470-550

# 10

(7/8-14)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

360-430
620-745

# 12

(1-1/16-12)

Hose End Fitting To Brass/Allum. Fitting
Hose End Fitting To Steel Fitting

460-550
855-1055

13-20

FITTING MATERIAL

INCH POUNDS

Chapter 14

Induction System

Induction System Description ................................................................................................................................................................. 14-3
Air Throttle Assembly .................................................................................................................................................................................... 14-4
Induction System Maintenance .............................................................................................................................................................. 14-5

14-1

This Page Intentionally Left Blank

14-2

Induction System

Induction System Description
Engine components through which air flows
following the aircraft air inlet filter/alternate air
door are: throttle assembly, manifold, induction
tubes and cylinder intake ports. Air flows through
these components in the order they are listed.
Refer to the aircraft manufacturer's Airplane Flight
Manual (AFM) for alternate air door operations.

The intake manifold is an air distribution system
mounted below the engine cylinders. It serves to
carry induction air to the individual cylinder intake
ports.
The cylinder intake ports are cast into the cylinder
head assembly. Air from the manifold is carried into
the intake ports, mixed with fuel from the injector
nozzles where it enters the cylinder as a
combustible mixture when the intake valve opens.

Bottom View Of Engine
With Induction Manifold
Installed

Balance Tube

Riser
Cylinder No.
6
Riser
Cylinder No.
5
Throttle
Butterfly

Riser
Cylinder No.
4

Riser
Cylinder No.
3

Riser
Cylinder No.
1

Clamps
and Hoses

Riser
Cylinder No.
2

Figure 14-1
Induction System

14-3

Induction System

The shaft bosses contain bushings in which the shaft
rides. Wave washers provide protection against
vibration. An idle speed adjusting screw is provided
in one of the throttle valve shaft levers and bears
against a stop pin installed in the throttle body.

Air Throttle Assembly
Air Throttle Assembly I0-520-B, BA, BB, C, CB,
M & MB - The air throttle assembly is an aluminum
casting that contains the shaft and throttle valve
assembly. The throttle bore area is tailored to the
engine size. No venturi or other restriction is used.

STOP PIN

PLAIN
WASHER

WAVE
WASHER
PLAIN
WASHER

Figure 14-2
Air Throttle Assembly

14-4

LEVER
THROTTLE BUSHING
THROTTLE PLATE

COLLAR
THROTTLE
SHAFT

Induction System

Induction System
Maintenance
Induction system maintenance is limited to removal
and replacement of malfunctioning components and
tightening loose connections in accordance with the
applicable portions of the IO-520 Permold Overhaul
Manual, Form OH-11 Induction System disassembly and reassembly procedures.

14-5

Induction System

This Page Intentionally Left Blank

14-6

Chapter 15

Optional Air Conditioning
Equipment

Air Conditioning System Description ............................................................................................................................................... 15-3
Air Conditioning System Components.............................................................................................................................................. 15-3
Compressor Mounting Kit .................................................................................................................................................................. 15-3
Maintenance ......................................................................................................................................................................................................... 15-4

15-1

This Page Intentionally Left Blank

15-2

Optional Equipment

Air Conditioning
System Description
Teledyne Continental Motors supplies an optional
compressor mounting bracket for the addition of a
customer supplied belt driven compressor and air
conditioning system. For a description of the
complete air conditioning system refer to the
airframe manufacturer's information.

Air Conditioning
System Components
Compressor Mounting Kit
The compressor mounting bracket assembly is
bolted to the 1-3-5 side rear crankcase half with one
crankcase through bolt, two plain bolts and two lock
washers. The bracket utilizes an adjustable block
and idler sheave for tensioning the compressor belt.

Figure 15-1
Optional Compressor Drive

15-3

Optional Equipment

Maintenance
Remove and replace worn or malfunctioning
components in accordance with applicable portions
of disassembly, reassembly in the IO-520 Permold
Series Overhaul Manual, Form OH-11, Chapter 11
and the following:
Premature belt replacement can usually be
attributed to improper alignment of the sheaves
and/or improper belt tensioning. Use the following
instructions to correct this problem.
The alignment of compressor, starter adapter and
idler sheaves must be checked using Borroughs
Tool Number 8082 alignment tool. Check tool
flatness (calibration) by laying it on a surface table.
Place the alignment tool around the drive sheave
with the extended end overlaying the upper portion
of the compressor sheave. When the alignment is

Figure 15-2
Checking Sheave Alignment

15-4

correct the alignment tool extended end (bar center)
will fall within 0.020 inch of the center of the
sheave. Use this same procedure to check the idler
sheave, except the extended end of alignment tool
will overlay the lower portion of the compressor
sheave. See Figure 15-2, "Checking Sheave
Alignment."
If drive sheave or idler are not in alignment, remove
sheaves and install up to but do not exceed five
0.020 shims [P/N 643956-20] to achieve the correct
alignment. See Figure 15-3, "Sheave Alignment."
When idler sheave is properly adjusted torque
sheave screw to 300-350 inch pounds torque. When
drive sheave is properly adjusted, torque sheave
12-point, self- locking nut to 450-500 inch pounds.
Nuts must be lubricated with clean aviation engine
oil. All threads of sheave nut must be engaged.

Optional Equipment

CAUTION…
Prevent engine from turning when torquing nut.
Refer to Figure 15-4, "Belt Tensioning," on the next
page. Loosen the jam nut, adjusting bolt and slide
nut. The slide nut should be loosened only enough
to allow the slide to move freely and the adjusting
bolt should be turned out far enough to allow
installation of the belt.
Install the drive belt. Slide the idler pulley snugly
against the belt and tighten the adjusting bolt finger
tight into its socket. In this position the idler sheave
should be rotatable by hand under the belt. Tighten
the adjusting bolt two full turns. Torque the
adjusting bolt jam nut to 275-375 inch pounds
torque. Torque the idler sheave screw to 300-350
inch pounds.

Confirm belt tension is 50-70 pounds by one of the
following methods:
1. Use a direct reading belt tension gage such as
Borroughs Tool Number BT-33-73F.
2. Measure belt deflection under a five pound load
at the center of the longest belt span. Correct
deflection is 0.30- 0.40 inch.
If belt tension is not within the above tolerance,
loosen jam nut and slide nut, readjust belt tension.
One full turn of adjusting screw will give
approximately ten pounds change in belt tension.
CAUTION…Do not over tighten drive belt.
After approximately five hours of operation,
recheck belt tension and adjust as required to
maintain 50-70 pounds belt tension.

Figure 15-3
Sheave Alignment

15-5

Optional Equipment

Figure 15-4
Belt Tensioning

15-6

Chapter 16

Electrical Charging System

Electrical Charging System ...................................................................................................................................................................... 16-3
Electrical Charging System Components ............................................................................................................................... 16-3
Maintenance and Repair...................................................................................................................................................................... 16-4
Direct Drive Alternator Removal and Replacement ............................................................................................... 16-4
Alternator Drive Hub ...................................................................................................................................................................... 16-4
Slippage Inspection ................................................................................................................................................................... 16-4
Repair/Replacement .................................................................................................................................................................. 16-4
Installation ....................................................................................................................................................................................... 16-4

16-1

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16-2

Electrical Charging System

Electrical Charging System
Components

Electrical Charging
System
The IO-520-B, BA, BB, C, CB, M and MB model
engines have a direct drive alternator mounted on
the right front crankcase half. The alternator
generates electrical current for powering the
aircraft electrical system and for recharging
aircraft batteries.

For detailed information about TCM alternators,
refer to “Alternator Service Instructions,” Form
X30531-3.

For a description of the aircraft electrical and
charging system, refer to the airframe
manufacturer’s documentation.
For alternator location on the engine, refer to
Figure 16-1, “Alternator Location.”

ALTERNATOR

FOWARD

Figure 16-1
General Alternator Location

16-3

Electrical Charging System

Maintenance and Repair

Alternator Drive Hub

For maintenance or repair of TCM alternators,
refer to TCM Form X30531-3, “Alternator Service
Instructions.” The alternators may be removed for
repair or replacement in accordance with the
following removal and replacement instructions.

Slippage Inspection

CAUTION...
When an alternator is removed that has a
grounding strap, the strap must be reinstalled with
the new or rebuilt alternator.

Direct Drive Alternator
Removal and Replacement
Removal
1. Disconnect electrical connections from
alternator in accordance with airframe
manufacturer’s instructions.
2. Remove plain washer, lock washer, and nut
from the four mounting studs.
3. Discard lockwashers.
4. Remove the alternator from the mounting
studs.
5. Remove gasket from mounting studs

Whenever the alternator is removed, perform the
following drive gear hub slippage inspection:
1. The torque required to slip the elastomer
coupling when new must be 180 inch pounds
(15 foot pounds) torque minimum measured
after 45° of revolution at a rate of 1 to 2
degrees per second.
2. Slippage must occur at the outside diameter of
elastomer with no damage to the elastomer.
3. On couplings which have been in service for
more than 25 hours, slippage torque must not
be less than 140 inch pounds (11.7 foot
pounds) torque.
4. Drive hubs that do not conform with the above
specifications must be discarded.

Repair/Replacement
1. Alternator repair/replacement must be
performed in accordance with TCM Alternator
Maintenance and Parts Catalog, Form
X30531A.

Installation
1. Install new gasket on new or rebuilt alternator.
2. Install alternator assembly on mounting studs
with four plain washers, four new lock
washers, and four plain nuts.
3. Torque nuts to 180 - 220 inch pounds.
4. Install all electrical connections in accordance
with airframe manufacturer’s instructions.

16-4

Chapter 17

Starting System

Starter and Starter Adapter ...................................................................................................................................................................... 17-3
Starting System Components ................................................................................................................................................................... 17-4
Starter ................................................................................................................................................................................................................. 17-4
Starter Adapter ............................................................................................................................................................................................ 17-4
Starting System Maintenance .................................................................................................................................................................. 17-5
Starter Motor Replacement ............................................................................................................................................................... 17-9
Starter Adapter Replacement ........................................................................................................................................................... 17-9

17-1

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17-2

Starting System

Starter and Starter Adapter
The I0-520 Permold Series engines utilize a
starting system that employs an electric starter
motor mounted on a right angle starter drive
adapter. The right angle drive adapter serves to
shorten engine overall length. As the starter motor
is electrically energized, the adapter worm shaft

and gear engage the starter shaftgear by means of a
spring and clutch assembly. As the shaftgear
rotates, it in turn rotates the crankshaft gear and
crankshaft. When the engine starts and accelerates,
the gripping action of the clutch spring is relieved,
disengaging the shaftgear from the worm shaft and
electric starter motor.

Figure 17-1
Starter and Starter Adapter

17-3

Starting System

Starting System Components
Starter
For a detailed description of TCM electric starter
motors See TCM Form X30592, Starter Service
Instructions.

Starter Adapter
The starter adapter assembly uses a worm drive
gear shaft and worm gear to transfer torque from
the starter motor to the clutch assembly. The shaft
is supported in the housing at the starter end by a

Figure 17-2
Starter Adapter

17-4

ball bearing and retaining ring, the opposite end is
supported by a needle bearing pressed into the
adapter housing. As the worm gear rotates the
worm wheel and clutch spring, the clutch spring is
tightened around the drum of the starter shaftgear.
As the shaftgear turns, its torque is transmitted
directly to the crankshaft gear. The starter
shaftgear is supported at the adapter cover by a
pressed in ball bearing, and is supported at the
opposite end by a needle bearing pressed into the
1-3-5 crankcase half.

Starting System

CAUTION...

Starting System
Maintenance
The starter motor may be removed for repair or
maintenance in accordance with applicable
portions of starter and starter adapter disassembly/
reassembly instructions in the I0-520 Permold
Series Overhaul Manual, Form OH-11.
Disassembly, maintenance and reassembly of the
starter motor must be performed in accordance
with the Starter Service Instructions, Form
X30592.
When performing starter adapter repairs prior to
engine TBO the following dimensional limits may
be used.

When performing dimensional inspection the
following "Service Limits" may be used.
However, they are only intended as a guide for
reuse when performing maintenance of the
engine prior to major overhaul. Parts with
dimensions or fits that exceed service limits must
not be reused. Parts with values up to and
including service limits may be reused, however,
judgment should be exercised considering the
PROXIMITY of the engine to its recommended
overhaul time.

SERVICE LIMITS
REF.

DESCRIPTION

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
1.

Starter shaftgear needle bearing hole crankcase
Diameter:
Starter shaft gear front (bearing) journal
Diameter:
Starter shaftgear in clutch drum bearing
Diameter:
Clutch spring sleeve in starter adapter
Diameter:
Starter shaft gear in ball bearing
Diameter:
Bearing in starter adapter cover
Diameter:
Worm wheel gear
End Clearance:
Worm wheel drum
Diameter:
Starter Shaft gear drum
Diameter:
Clutch spring in clutch spring sleeve
Diameter:
From center line of wormgear shaft to starter adapter thrust pads:
Needle bearing hole starter adapter
Diameter:
Ball bearing in starter adapter
Diameter:
Worm gear shaft in needle bearing area
Diameter:
Worm gear shaft in ball bearing
Diameter:
Starter worm gear on shaft
Diameter:
Starter spring on worm drive shaft
Diameter:
Starter pilot to starter drive adapter
Diameter:
Starter drive tongue to worm shaft drive slot
Side Clearance:
Starter worm wheel gear and worm gear
Backlash:
Starter adapter Cover Pilot In Adapter Housing
Diameter:

SERVICE
LIMIT
1.0005
0.7480
1.0000L
0.0050T
0.0005L
0.0010L
0.0250
Figure 17-6
Figure 17-5
0.0030T
0.2520
0.7495
0.0010L
0.5600
0.0007L
0.0040L
0.0250L
0.0070L
0.0340L
0.0200
0.0040L

When sand blasted diameter finish is smoother than 75 RMS, replace sleeve.

17-5

Starting System

Figure 17-3
Starter Adapter Fits and Limits

17-6

Starting System

SERVICE LIMITS
REF.

DESCRIPTION

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

Starter shaftgear needle bearing hole crankcase
Starter shaftgear front (bearing) journal
Starter shaftgear in clutch drum bearing area
Clutch spring sleeve in starter adapter
Starter shaftgear in ball bearing
Bearing in starter adapter cover
Worm wheel gear
Worm wheel drum

Starter Shaftgear Drum

10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
End Clearance:
Diameter:
Diameter:

Clutch spring in clutch spring sleeve
Diameter:
From center line of worm gearshaft to starter adapter thrust pads:
Needle bearing hole starter adapter
Diameter:
Ball bearing in starter adapter
Diameter:
Worm gearshaft in needle bearing area
Diameter:
Worm gearshaft in ball bearing
Diameter:
Starter worm gear on shaft
Diameter:
Starter spring on worm drive shaft
Diameter:
Starter pilot to starter drive adapter
Diameter:
Starter drive tongue to worm shaft drive slot
Side Clearance:
Scavenge pump driver gear on starter gear shaft
Diameter:
Scavenge pump driver gear in body
End Clearance:
Scavenge pump driver gear in body
Diameter:
Starter gearshaft in scavenge pump body
Diameter:
Ball bearing in scavenge pump body
Diameter:
Starter worm wheel gear and worm gear
Backlash:

SERVICE
LIMIT
1.0005
0 7480
1.0000
0.0050T
0.0007L
0.0010L
0.0250
See Figure
17-6
See Figure
17-5
0.0030T
0.2520
0.7495
0.0010L
0.5600
0.0007L
0.0040L
0.0250L
0.0070L
0.0340L
0.0030L
0.0060L
0.0160L
0.0040L
0.0011L
0.0200

When sand blasted diameter finish is smoother than 75 RMS, replace sleeve.

17-7

Starting System

Figure 17-4
Customer Specification Starter Adapter Fits and Limits

17-8

Starting System

Starter Motor Replacement

Starter Adapter Replacement

Removal

1. Disconnect electrical cable from starter motor
in accordance with airframe manufacturer’s
instructions.

1. Remove starter motor in accordance with
“Starter Motor Removal And Replacement.”
2. Remove four sets of attaching parts (two on
outside of crankcase between cylinder No. 1
and starter, and two on cover assembly.)
remove starter adapter assembly from crankcase. Discard lock washers.
The starter adapter must be repaired in accordance
with the I0-520-Permold Series Overhaul Manual,
Form OH-11.

2. Remove the two nuts and plain washers from
the starter motor mounting studs.
3. Carefully remove the starter motor assembly
without damaging mounting stud threads.
4. Remove and discard O-ring.
Starter motor repair/replacement must be performed in accordance with TCM Starter Service
Instructions, Form No. X30592.

Installation
1. Lubricate new o-ring with clean 50 wt. aviation
engine oil and install on starter pilot.
2. Install starter motor on mounting studs and
insure that drive lug aligns with slot. Secure
starter motor with two plain washers and 2
nuts.
3. Torque nuts to 200 - 220 inch pounds.
Reconnect electrical cable in accordance with
airframe manufacturer’s instructions.

Replacement
1. Using the following, install new, rebuilt or
serviceable starter adapter.
2. Apply a thin coat of TCM Gasket Maker
646942 to the starter adapter gasket crankcase
mating surface only.
3. Apply TCM gasket maker to silk thread and
split line of crankcase at oil pump bore. Place
silk thread ends into split line of oil pump bore.
4. Install new gasket on crankcase.

CAUTION…
Sealant must be applied sparingly to prevent
contamination of the engine oil system.
5. Lubricate teeth on starter shaftgear and mesh
with crankshaft gear as starter adapter is placed
in position. Seat adapter against gasket. Secure
adapter assembly to crankcase with washers,
new lock washers and nuts. Torque 5/16-24
nuts to 180-220 inch pounds. Torque 3/8 16
nuts to 200-220 inch pounds.
6. Replace starter motor in accordance with
“Starter Motor Removal And Replacement.”

17-9

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17-10

Chapter 18

Lubrication System

Lubrication System .......................................................................................................................................................................................... 18-3
Oil Pump .................................................................................................................................................................................................................. 18-5
Oil Cooler and Oil Temperature Control Valve....................................................................................................................... 18-6
Oil Sump .................................................................................................................................................................................................................. 18-7
Oil Suction Tube ......................................................................................................................................................................................... 18-7
Lubrication System Maintenance ......................................................................................................................................................... 18-8
Oil Filter Adapter Stud ........................................................................................................................................................................ 18-8
Oil Pump ......................................................................................................................................................................................................... 18-9
Oil Filter Adaptor ................................................................................................................................................................................. 18-10
Oil Sump ....................................................................................................................................................................................................... 18-10
Oil Suction Tube .................................................................................................................................................................................... 18-10
Oil Cooler ................................................................................................................................................................................................... 18-10
Oil Pressure Relief Valve ............................................................................................................................................................... 18-10
Oil Temperature Control Valve................................................................................................................................................... 18-11
Tach Drive Assembly ................................................................................................................................................................................. 18-12
Lubrication System Lubrication Dimensional Limits ........................................................................................................ 18-12

18-1

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18-2

Lubrication System

Lubrication System
The engine oil supply is contained in the oil sump.
The oil is drawn from the sump through the oil
suction tube to the intake side of the engine
driven, gear type, oil pump. From the outlet side of
the pump, oil is directed to the full flow,
replaceable oil filter. A bypass valve is incorporated in the oil filter. An oil pressure relief valve
is incorporated in the oil pump housing. The valve
opens when the pump pressures exceed the
adjusted limit and oil is directed back to the intake
side of the oil pump gears.
From the oil filter discharge port, oil is directed
through a crankcase passage to the oil cooler. In
addition to facilities for oil cooling, the oil cooler
incorporates an oil temperature control valve. Oil
passing by the oil temperature control valve cavity
directs oil either through the oil cooler core and or
through the oil cooler bypass to the crankcase
passage at the rear depending on the oil
temperature. If engine oil temperature is above
180°F, all oil is directed through the oil cooler.
Oil entering the engine is directed to the hollow
camshaft which serves as the engine main oil
gallery. Grooves and drilled holes in the camshaft
are located so as to afford proper lubrication
through a system of orifices to the main bearings,
hydraulic valve tappets, idler gear bushing,
accessory drive gear bushings and the starter drive
gear bearing.
Oil leaving the camshaft interior at the front of the
crankcase is directed to the left main crankcase
gallery, from there it is directed upward through
crankcase oil passages to the main thrust bearing
and to the governor drive gear.

WARNING
Oil pressure is applied to the face of the
accessory drive pads. If gaskets, accessory
or covers are not properly installed and
hardware is not properly torqued oil
leakage will occur.
From the governor drive gear lubricating oil is
directed from the left main gallery through drilled
crankcase passages and oil transfer collar to the
crankshaft. Oil then travels through a transfer plug
installed in the inside diameter of the crankshaft
and is routed to the variable pitch propeller.
Hydraulic valve tappets transfer oil from the main
oil galleries to the cylinder overhead through the
hollow pushrods to a drilled oil passage in the
rocker arms. Oil exiting the rocker arms lubricates
the valve stems, springs and rotocoils. The oil then
falls to the lower rocker cavity and returns to the
crankcase and sump through the pushrod housings.
Oil from the left main crankcase gallery is also
directed upward through crankcase oil passages to
the crankshaft main bearings and idler gear
bushing. Oil is directed upward from the idler gear
bushing to both accessory drive bushings. Oil
lubricating the crankshaft mains is directed
through the upper main bearing oil holes, through
crankcase passages to oil squirt nozzles that spray
oil onto the underside of the pistons for heat
dissipation and lubrication. Oil falls from the
pistons through the crankcase cavity back to the
oil sump.

18-3

Lubrication System

OIL TRANSFER COLLAR
CAMSHAFT

CRANKSHAFT
ACCESSORY DRIVES

GOVERNOR
PAD
IDLER
STARTER

HYDRAULIC
LIFTERS

SCAVENGE PUMP
TURBOCHARGER
SYSTEM RETURN
FULL FLOW OIL FILTER
WITH BY-PASS VALVE

OIL COOLER

SUMP OIL PICK-UP
OIL PRESSURE AND
TEMPERATURE CONNECTION
OIL TEMPERATURE
CONTROL VALVE

Figure 18-1
Lubrication System Schematic

18-4

OIL PRESSURE
RELIEFVALVE
TO TURBOCHARGER
SYSTEM (if equipped)

Lubrication System

Oil Pump
The positive displacement oil pump consists of
two meshed gears that revolve inside the pump
housing cavity. The clearance between the oil
pump cavity and oil pump gear teeth is small.
The camshaft drives the oil pump drive gear,
which drives the oil pump driven gear. The oil
pump driven gear is supported by a shaft pressed
into the oil pump housing.
The oil pump drive gear shaft is supported by the
tach drive housing on one end and the oil pump
housing at the opposite end. The oil pump drive
gear has a tachometer drive gear attached to its end
which drives a tachometer shaftgear inside the tach
drive housing for either electrical or mechanical
tachometers.
As the engine starts rotating, the oil pump drive
gear turns (looking from the rear of the engine
forward) counterclockwise, this drives the driven
gear in a clockwise direction. The two gears
turning creates a suction that draws oil from the
sump, through the oil suction tube to the pump
gears.

The oil is then forced around the outside of the
gears and through a gallery to the oil filter adapter
and pressure relief valve. Oil that flows past the
pressure relief valve is directed through a passage
back to the inlet side of the pump gears.
The adjustable oil pressure relief valve maintains
oil pressure at a preset value to insure adequate
lubrication to the engine and its accessories at high
engine RPM. Oil pressure is adjusted by turning
the oil pressure relief valve adjusting screw.
During normal operation, oil flows from the bypass to an area between the oil filter housing and
filter element. The oil is then directed through the
element, down to a gallery in the filter adapter,
through a passage in the oil pump housing and out
to the engine. The oil filter bypass allows the oil to
continue to circulate through the engine if the filter
element becomes clogged.

Oil Filter
Element

Oil Filter Housing

Oil Pump Housing

Oil Pump Drive Gear

Oil Filter
Adapter

Oil Pump Driven Gear

Oil Flow
To Engine

Figure 18-2
Oil Pump

Oil Suction
Tube Plug
Recirculation
Back To Inlet Side
Of Pump Gears

Oil Pressure
Relief Valve

Oil From Oil Sump

18-5

Lubrication System

Oil Cooler And Oil
Temperature Control Valve

pass flows past the oil temperature control valve
and out to the crankcase main oil galleries and the
camshaft.
When oil temperature reaches 180°F the oil
temperature control valve closes, forcing the oil to
flow through the oil cooler. As the oil flows
through the cooler core, cooling air fins between
the core oil passages dissipate excess heat from the
oil, maintaining normal operating tempera-tures.

Oil flowing from the oil pump enters the oil cooler
inlet where it is directed upward through the
cooler core by the oil gallery. When the oil is
below normal operating temperature, the oil
temperature control valve (vernatherm) opens
allowing oil to flow through the center bypass
portion of the cooler. Oil flowing through the by-

Static Oil

Oil Flow-Thru
Bypass
(Cold Oil)

Oil Out
To Engine

Cooling Core

Valve Open
(Oil Cold)

Oil In From
Oil Pump

Static Oil
(Oil Hot)

Limited Oil
Flow (Oil Cold)

Oil Out
To Engine

Valve Closed
(Oil Hot)

Cooling Fins

Oil In From Oil Pump
Static Oil

Oil Out To Engine

Oil Flow
(Oil Hot)

Figure 18-3
Oil Cooler
18-6

Lubrication System

Oil Sump
The oil sump used on I0-520-A and C model
engines is a stamp-pressed aluminum alloy
assembly. The oil sump used on the I0-520-B
model engines is cast aluminum with provisions
for attaching engine mount legs. The sump is held
to the crankcase sump mount flange with 32 bolts,
washers and lock washers. The oil sump assembly
incorporates a tapped drain plug boss, a plug, and
a crush washer to facilitate draining engine oil.
The drain plug boss has provisions for safety
wiring of the oil drain plug.

Oil Suction Tube
The oil suction tube extends from the oil sump to
the oil pump inlet providing oil pickup and flow
path. The pickup tube entrance is screened. The oil
screen on I0-520-B engines has .06" diameter
holes. The oil screens on I0-520-A and C engines
have .085" diameter holes. On I0-520-A and -C
engines, the pickup end is supported by welded
brackets bolted to the crankcase spine below the
camshaft. On I0-520-B engines, the pickup end is
supported by welded brackets bolted to two
crankcase bolt bosses. The opposite end with a
crush washer installed protrudes through the
crankcase into the oil pump inlet. The threaded
tube end is held and sealed to the oil pump
housing by a crush washer and a plug.

Figure 18-4
Oil Sump and Suction Tube

18-7

Lubrication System

Lubrication System
Maintenance
Oil filter Adapter Stud Replacement
A new stud P/N 653490 must be installed if :
1. The old stud is a plain steel color with a length
of 1.440" inch.
2. If the old stud is found to be loose or installed
beyond the stud setting height specified in
Figure 18-6, “Oil Filter Adapter Stud
Inspection.” Install new stud in accordance
with the following procedure:
a. Remove old stud P/N 632373 and inspect
the threads in the adapter housing for
damage. Replace the adapter housing if
any thread damage is evident.
NOTE...
Oil filter adapters that incorporate this
modification from the factory can be
determined by the letter "S" stamped into
the adapter housing, See Figure 18-5
"Stud Identification."

Figure 18-5
Stud Identification

18-8

b. Clean the adapter housing threads
thoroughly to remove any remaining
thread adhesive and oil.
c. Install the applicable new stud (P/N
653490) and confirm that the incomplete
thread on the stud stops at the first thread
in the adapter housing and does not
continue into the housing below the
minimum .500" extension. See Figure 185, "Oil Filter Adapter Stud Inspection."
Replace the adapter housing if the
extension is less than the specified .500"
minimum.
d. After extension height inspection, remove
the stud from the adapter. Clean the
threads of the adapter housing and stud
with Loctite "Primer T" (TCM P/N
646944) and allow to dry.
e. Apply a line of Loctite 271 (TCM P/N
646941) along the large threads (.8125-16
end) of the stud and install into the adapter
finger tight to 30 inch pounds torque.
Check for proper stud extension height in
accordance with Figure 18-6," Oil Filter

Lubrication System

Figure 18-6
Oil Filter Adapter Stud Inspection
Adapter Stud Inspection."
f. Allow the parts to cure for a minimum
of thirty minutes prior to installation
of the oil filter.
CAUTION...
Curing times may vary depending on
ambient temperature. Consult Loctite
instructions .
g. After installation of a new oil filter
adapter stud, stamp a .125" high letter
"s" in the location shown in Figure 185 Stud Identification

Oil Pump
Malfunctioning oil pumps or oil pump components must be removed and discarded.
The oil pump may be removed in accordance with
oil pump disassembly/reassembly instructions in
the IO-520 Permold Series Overhaul Manual,
Form No. OH-11.
Repairs other than smoothing nicks on parting
surfaces, replacing studs and worn parts, and
refacing the oil pressure relief valve seat on the oil
pump housing are not possible.
The pump driven gear shaft is pressed into the
pump housing and is not field replaceable. The
pump gear chamber must not be enlarged. If it
becomes scored, the pump housing must be
discarded. Scoring on the gear contact area of the
oil pump cover renders it unserviceable unless the
parting surfaces can be lapped smooth and
perfectly flat.
If required, replace oil pump housing studs in
accordance with the IO-520 Permold Series
Overhaul Manual, Form OH-11.

18-9

Lubrication System

Oil Filter Adapter
Discard oil filter adapters that are cracked or that
are worn beyond specified limits. Smooth small
nicks on parting surface. No other repairs are
possible.

Oil Sump
If the oil sump must be removed for repair or
replacement, see the I0-520 Permold Series
Overhaul Manual, Form OH-11. Any airframe
components that obstruct removal must be
removed in accordance with the airframe
manufacturer’s instructions.
Whenever the oil sump is removed, the oil suction
tube screen must be cleaned and all lower internal
hardware must be inspected for secure installation
and safetying.
Discard any oil sump that is warped or cracked.

Oil Suction Tube
The outer suction tube to oil pump housing plug
gasket can be removed and replaced.
To gain access to the oil suction tube assembly,
the oil sump assembly must be removed.

Oil Cooler
The oil cooler or its components may be removed
for replacement and repair in accordance with
applicable portions of oil cooler disassembly/reassembly instructions in the I0520 Permold
Series Overhaul Manual, OH-11.

Oil Pressure Relief Valve
Cut safety wire, remove oil pressure relief valve,
and inspect the plunger for scoring, nicks, and the
conical face for roughening. Oil pressure relief
valves with scoring, nicks, roughening of the
conical face or that exceed the specified limits
must be discarded and replaced with new. Inspect
the oil pressure relief valve seat for scoring, nicks

18-10

or roughening. Seats with these indications must
be refaced. Using the specified oil pressure relief
spot facer, reface the pressure relief valve seat in
the oil pump housing.
CAUTION...
Reface pressure relief valve seat using light
finger pressure when turning refacing tool.
After the refacing procedure, the depth from the
top of the oil pump housing to the seat face must
not exceed the specified limit item (2) in Figure
18-7,” Lubrication System Service Limits. “Oil
pump housings exceeding specified limits must be
discarded.
CAUTION...
Thoroughly clean oil pressure relief valve cavity
after refacing procedure. All debris from the
refacing procedure must be removed.
1. Reassemble serviceable or new relief valve
housing and adjusting screw. Turn adjusting
screw into housing about halfway.
2. Install new copper washer and nut.
3. Assemble plunger, spring, washer and slide
into housing. Coat housing threads with TCM
anti-seize lubricant.
4. Insure relief valve components are aligned and
install in oil pump housing.
5. Torque housing to 240-260 inch pounds.
6. Safety wire oil pressure relief valve housing in
accordance with chapter 9," Lockwire
Procedure."
7. The engine oil pressure must be adjusted prior
to release for return to service in accordance
with Chapter 22, "Oil Pressure Adjustment."

Lubrication System

Oil Temperature Control Valve
Remove the oil temperature control valve and
inspect the valve seat for scoring, nicks, roughness
or deterioration. Oil temperature control valves
exhibiting any of these indications or that exceed
specified limits must be discarded and replaced
with new.
1. Reinstall serviceable or new oil temperature
control valve using new gasket and torque to
440-460 inch pounds.
2. Safety wire oil temperature control valve
housing in accordance with Chapter 9,
“Lockwire Procedure.”

18-11

Lubrication System

Tach Drive Assembly
Repairs other than stud replacement, worn parts
replacement, and stoning nicks on parting flanges
are not possible. Discard tach drive assemblies that
are cracked or worn beyond the specified limits.
Replace studs in accordance with the I0520
Permold Series Overhaul Manual, Form OH-11.
When performing lubrication system component
repairs prior to engine TBO, the following
dimensional limits may be used.

CAUTION...
When performing dimensional inspection, the
following "Service Limits" may be used.
However, they are intended only as a guide for
reuse during engine maintenance prior to major
overhaul. Parts with dimensions or fits that
exceed service limits must not be reused. Parts
with values up to and including service limits
may be reused. However, the PROXIMITY of the
engine to its recommended overhaul time should
be considered.

SERVICE LIMITS
REF.

SERVICE
LIMIT

DESCRIPTION
OIL PRESSURE RELIEF VALVE ASSEMBLY

1.
2.

Oil Pressure Relief Valve Adjusting Screw In Plunger
Oil Pressure Relief Valve Seat In Housing

Diameter:
Depth:

0.0070L
1.060

Diameter:
Diameter:
Diameter:
End Clearance:
End Clearance:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:

0.0070L
0.0045L
0.0040L
0.0050
0.0050
0.0045L
0.0045L
0.0040L
0.0040L
0.0080L
0.0045L
0.0045L
0.003L
0.0065T

OIL PRESSURE PUMP ASSEMBLY

3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.

Oil Pump Drive Gear In Pump Housing
Oil Pump Drive Gear Shaft In Pump Housing
Oil Pump Driven Gear To Driven Gearshaft
Oil Pump Drive Gear In Pump Housing
Oil Pump Driven Gear In Pump Housing
Oil Pump Drive Gear Shaft In Tach Drive Housing
Oil Pump Drive Gear Shaft In Tach Drive Housing
Oil Pump Drive Gear Shaft Pin In Bevel Gear
Oil Pump Drive Gear Shaft Pin In Bevel Gear
Oil Pump Driven Gear In Pump Housing
Tach Drive Shaft In Tach Drive Housing
Tach Drive Shaft In Tach Drive Housing
Oil Seal In Tach Drive Housing
Oil Seal In Tach Drive Housing
GEAR BACKLASH

17.
18.
19.

Oil Pump Drive and Driven Gears
Tach Drive and Driven Bevel Gears
Tach Drive and Driven Bevel Gears

Backlash:
Backlash:
Backlash:

0.0160
0.0120
0.0120

SPRING TEST DATA

20.
21.

Oil Pressure Relief Valve Spring Compressed To 1.25 Inch Length
Load:
Oil temperature control valve 0.090 inches min. travel at Oil Temperature:
Oil temperature control valve must close between
Oil Temperature:
I0-520-B

18-12

30 Lbs.
120°-170°
168°-172°
I0-520-A and C

Lubrication System

Figure 18-7
Lubrication System Service Limits

18-13

This Page Intentionally Left Blank

18-14

Chapter 19

Cylinder Assembly

Cylinder Cooling ............................................................................................................................................................................................... 19-3
Cylinders, Pistons and Overhead Drive Train .......................................................................................................................... 19-4
Cylinder Assembly Description IO-520-B, -BA, -BB, -C, -CB, -M, -MB .............................................................. 19-5
Piston.......................................................................................................................................................................................................................... 19-6
Valve Rockers, Shafts, Pushrods, and Housings (Overhead Drive Train) .......................................................... 19-7
Hydraulic Tappet .............................................................................................................................................................................................. 19-8
Cylinder Assembly Maintenance .......................................................................................................................................................... 19-9
Cylinder Compression Test ............................................................................................................................................................... 19-9
Leakage Checks ................................................................................................................................................................................... 19-9
Static Seal.......................................................................................................................................................................................... 19-9
Dynamic Seal ................................................................................................................................................................................. 19-9
Equipment ................................................................................................................................................................................................ 19-9
Master Orifice Tool ................................................................................................................................................................ 19-10
Performing the Check .................................................................................................................................................................. 19-10
Compression Test Troubleshooting.......................................................................................................................................... 19-14
Single Cylinder Removal ........................................................................................................................................................... 19-15
Pistons .............................................................................................................................................................................................. 19-15
Rings................................................................................................................................................................................................... 19-15
Connecting Rods ....................................................................................................................................................................... 19-15
Single Cylinder Reassembly.................................................................................................................................................... 19-15
Single Cylinder Reinstallation .............................................................................................................................................. 19-16
Cylinder Torque Procedures .................................................................................................................................................. 19-16
Hydraulic Valve Tappets .................................................................................................................................................................. 19-17
Cylinder Assembly Service Limits IO-520-B, -BA, -BB, -C, -CB, -M, -MB.............................................. 19-21

19-1

This Page Intentionally Left Blank

19-2

Cylinder Assembly

Cylinder Cooling
Cylinder cooling is accomplished by transferring
heat from the cylinder barrel and head cooling fins
to the surrounding airflow. Airframe engine
cowling and engine/airframe supplied baffles and
baffle seals direct cooling airflow close and evenly
around the cylinders. Controlling airflow in this
manner contributes to uniform cylinder tempera-

tures. Cooling airflow is generated by air from the
propeller and ram air induced by the aircraft's
forward movement. This airflow is regulated by the
size of the cooling air inlets and outlets. Increasing
or decreasing outlet size with the use of airframe
cowl flaps changes airflow and is used as an aid in
controlling engine operating temperatures. Below is
a general illustration showing engine cooling
airflow.

Aircraft-Supplied
Cooling Baffles

High Pressure
Area

Ram
Air

Continental

Ram
Air

Low Pressure
Area

Cowl Flaps

Cooling
Air
Exit

Figure 19-1
Engine Cooling Airflow
19-3

Cylinder Assembly

Cylinders, Pistons and
Overhead Drive Train
The cylinders, pistons and overhead drive train are
the portion of the engine that develop power. The
cylinder combustion chamber provides a controlled
area for burning fuel/air mixture and converting that
heat energy into mechanical energy. Aviation fuel
and air is drawn into a cylinder during the intake
stroke, compressed by the piston during the
compression stroke and then ignited by a high
intensity spark produced across the spark plug
electrode air gap during the power stroke. As the
mixture is ignited, the expanding gases force the
piston to move inward toward the crankshaft.
This inward motion acting on the connecting rod
and crankshaft throw is converted into circular or

rotary motion by the crankshaft. As the crankshaft
throw rotates past half of one revolution, the
connecting rod and piston start moving outward on
the exhaust stroke toward the cylinder head. During
this movement, the exhaust valve begins to open
allowing the burned mixture (exhaust) to escape.
Momentum from the crankshaft forces the piston
toward the cylinder head in preparation of the next
intake stroke event.
Proper mechanical timing between the crankshaft
and camshaft allows the intake and exhaust valves
to open and close in synchronization with piston
position in all six cylinders.
Proper magneto internal timing and magneto to
engine mechanical timing allow precise spark plug
ignition, 22°±1° before top dead center, during the
piston's compression stroke.

Figure 19-2
Cylinder, Piston, and Overhead Drive Train IO-520-B, -BA, -BB, -C, -CB, -M, -MB
19-4

Cylinder Assembly

Cylinder Assembly Description
Cylinder, Valve Guides, Valves, Rotocoil And
Retainer - The externally finned aluminum alloy
head castings are heated and valve seat inserts
installed before the head is screwed and shrunk onto
an externally finned steel alloy barrel to make the
permanent head and barrel assembly. The cylinder
barrel is nitrided for wear resistance. Intake and
exhaust valve guides are pressed into the heated
cylinder assembly. Special helical coil thread inserts
are installed in upper and lower spark plug holes.
The cylinder intake and exhaust ports are located

below the cylinder as installed. Exhaust valve faces
are Stellite and stem tips are hardened. Valve stems
are solid. A rotocoil assembly retains the two
concentric springs surrounding the exhaust valve
and is locked to the exhaust valve stem by tapered,
semicircular keys which engage grooves around the
stem. The controlled rotating action of this type
retainer helps to prevent burning and eroding the
valve and valve seat. A retainer retains the two concentric springs surrounding the intake valve and is
locked to the intake valve stem by tapered, semicircular keys which engage grooves around the
stem. Valve rocker covers are painted diecast
aluminum.
Rocker Shafts

Rocker Arm
Valve Retainer
Keys

Retainer

Rotocoil
Inner Spring
Outer Spring
Valve Guide

Valve Guide Seal
(Intake Valve Only)

Valve Guide

Exhaust
Valve

Cooling Fins

Valve Seat
Insert

Cooling
Fins
Valve Seat
Insert

Cylinder
Head
Intake Valve

Cylinder
Barrel

Cylinder Base
Flange
Cylinder
Skirt

Figure 19-3
Cylinder Assembly Description IO-520-B, -BA, -BB, -C, -CB, -M, -MB
19-5

Cylinder Assembly

Piston
Pistons are aluminum alloy castings with a steel
insert cast into the top ring groove. The skirts are
solid and have cylindrical relief cuts at the bottom.
Pistons have three ring grooves above the pin hole
and one ring groove below. Compression rings are
installed in the top, and second grooves. The groove

Piston

Steel
Insert
Piston
Pin

Top
Compression
Ring
2nd
Compression
Ring

Plug

Oil
Control
Ring

Oil
Scraper

Piston Skirt

Figure 19-4
Piston Assembly

19-6

below the pin hole contains an oil scraper. A center
grooved and slotted oil control ring is installed in
the third groove which has six oil drain holes to the
interior. Weight differences are limited to 1/2 ounce
or 14.175 grams in opposing bays. Piston pins are
full floating with permanently pressed-in aluminum
end plugs.

Cylinder Assembly

Valve Rockers, Shafts, Pushrods
And Housings (Overhead Drive
Train)
Valve rockers are steel forgings with hardened
sockets, rocker faces and pressed in bronze
bushings. They have a drilled oil passage for
lubrication. The rocker shafts are held in place in

the rocker bosses by bolts and washers. Pushrods
are constructed of steel tubes and pressed-in,
hardened, forged steel ball ends, which are center
drilled for oil passages. The pushrod housings are
beaded steel tubes. The bead at the cylinder end
retains washer, gasket and a second washer. The
bead at the crankcase end retains a heavy spring,
washer, packing ring and second washer.

Cylinder
Barrel
Cylinder Head
Piston

Rocker
Arm

Connecting
Rod

Crankcase

Rocker
Shaft

Washer

Pushrod

Pressed-In
Steel Ball

Pressed
Bead
O-Ring

Spring
Lubrication
Passage

Pressed
Bead

Packing
Hydraulic
Tappet

Camshaft
Lobe

Figure 19-5
Overhead Drive Train IO-520-B, -BA, -BB, -C, -CB, -M, -MB
19-7

Cylinder Assembly

Hydraulic Tappet
See Figure 19-8. The barrel type hydraulic valve
tappet consists of a steel body (1), an expanding
spring (2), a check valve assembly (3, 4 and 5), a
plunger (6), a socket (7) for pushrod end, and a
retaining ring (8). A groove (9), around outside of
the body picks up oil from the crankcase supply
hole. From the exterior groove oil is directed to the
interior body groove (11) through hole (10) and
from the interior groove through the hole to the
reservoir (12). Oil is withheld from reservoir (14)
by check valve ball (5) which is supported by a

spring (4) in the housing (1). The check valve is
opened by outward motion of the plunger under
pressure of the expanding spring whenever a
clearance occurs in the valve train. Thus the body
reservoir is kept full of oil which transmits lifting
force from the body of the plunger. The plunger and
socket are selectively fitted to the body to permit a
calibrated leakage so the lifter will readjust its
effective length after each cycle while the cylinder
valve is closed to return "lash" in valve train to zero.
The barrel type hydraulic tappets may be removed
and replaced without complete disassembly of the
engine.

Retaining Ring

Socket

Interior Oil Groove
Exterior Oil Groove

Body Oil Inlet
Plunger
Tappet Body
Oil Reservoir
Plunger
Check Ball
Oil Discharge Hole

Plunger Spring

Oil Reservoir Body
Check Ball Spring
Oil Outlet Hole
Check Ball Retainer

Figure 19-6
Hydraulic Tappet

19-8

Cylinder Assembly

Cylinder Assembly
Maintenance
Cylinder Compression Test
The differential pressure test is an accepted
method of determining cylinder condition by
measuring air pressure loss past the pistons, rings
and valves. The operation of the equipment is
based on the principle that, for any given airflow
through a fixed orifice, a constant pressure drop
across that orifice will result.
The compression testing equipment must be
calibrated and used in the proper manner to insure
accurate results.
To accurately accomplish a leakage check, use the
following information on leakage and use the
Master Orifice tool to calibrate the leakage
checking equipment used on Teledyne Continental
engines.

Leakage Checks
Cylinder leakage is broken down into two areas of
concern the "Static Seal" and the "Dynamic Seal."

Static Seal
The static seal consists of the valve to valve seat
seals, spark plug to spark plug port seals and
cylinder head to barrel seal. No leakage of the
static seal is permissible.

Equipment
Testing equipment must be kept clean and checked
periodically for accuracy as follows: using a line
pressure of 100 to 120 pounds per square inch,
close the cylinder pressure valve, then set the
regulator pressure valve to 80 pounds per square
inch. The pressure in both gauges should stabilize
with no leakage.
The restrictor orifice dimension in the Master
Orifice Tool for Teledyne Continental aircraft
engines must be 0.040 inch orifice diameter, 0.250
inch long with 60° approach angle, and must flow
120±5 cubic feet per hour at 30 pounds per square
inch differential pressure.
FACTORY CALIBRATED ORIFICE
(CLEAN With Soft Brush. Do Not Alter Size)
DUST CAP

DUST CAP

SPARK PLUG
THREADS (18mm)

Figure 19-7
Master Orifice Tool

Dynamic Seal
The dynamic seal consists of the piston rings to
the cylinder wall seal. This seal leakage can vary
from cylinder to cylinder, ring gap position, wear
or the amount of engine oil on the cylinder wall.

19-9

Cylinder Assembly

Master Orifice Tool

Performing The Check

For conformity in testing equipment a Master
Orifice Tool, Part Number 646953, is available to
calibrate equipment and determine the low
indicated leakage limit prior to the engine leakage
check. Connect compressed air at 100 - 120
pounds per square inch to the tester with cylinder
pressure valve closed. Turn the regulator pressure
valve on, adjusting pressure to indicate 80 pounds
per square inch. Remove the dust caps from both
ends of the Master Orifice Tool and install onto a
cylinder spark plug adapter. Turn the cylinder
pressure valve on and readjust regulator pressure
gauge to read 80 pounds per square inch. At this
time the cylinder pressure gauge indication will be
the low allowable limit for cylinder leak checks.
The low allowable limit is referred to as the master
orifice calibrated pressure reading. After the
master orifice calibrated pressure reading has been
recorded, close regulator pressure valve and
remove Master Orifice Tool from the cylinder
adapter. See the schematic diagram of a typical
differential pressure tester shown below.

The following procedures are listed to outline the
principles involved, and are intended to
supplement the manufacturer's instructions for the
particular tester being utilized.

Figure 19-8
Static Seal
19-10

WARNING
To prevent possibility of serious bodily
injury or death, before moving the
propeller accomplish the following:
a. Disconnect all spark plug leads.
b. Verify magneto switches are connected
to magnetos, that they are in the "OFF"
Position and "P" leads are grounded.
c. Throttle position "CLOSED."
d. Mixture control "IDLE-CUT-OFF."
e. Set brakes and block aircraft wheels.

Figure 19-9
Dynamic Seal

Cylinder Assembly

f. Insure that aircraft tie-downs are
installed and verify that the cabin door
latch is open.
g. Do not stand within the arc of the
propeller blades while turning the
propeller.
1. Perform the test as soon as possible after the
engine is shut down to insure that the piston
rings, cylinder walls, and other engine parts
are well lubricated and at operating conditions.
2. Turn the crankshaft by hand in the direction of
rotation until the piston, in the cylinder being
checked, is coming up on its compression
stroke.

11. Install an adapter in the spark plug hole and
connect the calibrated differential pressure
tester to the adapter. (NOTE: Cylinder
pressure valve is in the closed position.)
Slowly open the cylinder pressure valve and
pressurize the cylinder, not to exceed 20 psi.
Continue rotating the engine against this
pressure until the piston reaches top dead
center. Reaching top dead center is indicated
by a flat spot or sudden decrease in force
required to turn the crankshaft. If the
crankshaft is rotated too far, back up at least
one-half revolution and start over again to
eliminate the effect of backlash in the valve
operating mechanism and to keep the piston
rings seated on the lower ring lands. This is
critical because the slightest movement breaks
this piston ring sealing and allows the pressure
to drop.

Figure 19-10
Differential Pressure Tester Calibration
19-11

Cylinder Assembly

WARNING
Care must be exercised in opening the
cylinder pressure valve, since sufficient air
pressure will be built up in the cylinder
causing it to rotate the crankshaft if the
piston is not at top dead center. The
propeller must be secured during check to
prevent rotation.
4. Open the cylinder pressure valve completely.
Check the regulator pressure gauge and adjust,
if necessary to 80 pounds per square inch.
5. Observe the pressure indication on the
cylinder pressure gauge. The difference
between this pressure and the pressure shown
by the regulator pressure gauge is the amount
of leakage through the cylinder. If the cylinder
pressure gauge reading is higher than the
previously determined master orifice calibrated pressure reading, proceed to the next
cylinder and perform leak check. If the
cylinder pressure gauge reading is lower,
proceed with the following:

NOTE...
Document cylinder compression pressure.
6. Check the static seal for leakage (See Figure
19-8, "Static Seal"). Positive identification of
static seal leakage is possible by listening for
air flow sound at the exhaust or induction
system port. When checking for cylinder head
to barrel leakage, use a soapy solution at the
cooling jacket to barrel junction and watch for
bubbles. Use a soapy solution around both
spark plug seals for leakage. NO LEAKAGE
IS ALLOWED IN STATIC SEALS.
7. If leakage is occurring in the intake or exhaust
valve areas, try staking the valves. Remove
rocker covers from applicable cylinder. Place
a fiber drift on the rocker arm directly over the
valve stem and tap the drift several times with
a hammer to dislodge any debris that may be

19-12

between the valve face and seat. If leakage by
the valves cannot be corrected by, "staking,"
the cylinder must be removed for repair or
replacement.
CAUTION…
When correcting a low reading in this
manner, rotate the propeller so the piston will
not be at top dead center. This is necessary to
prevent the valve from striking the top of the
piston in some engines. Rotate the propeller
again before rechecking leakage to reset the
valves in the normal manner. Do not allow
the fiber drift to contact the valve spring
retainer or rotocoil.
8. If leakage is noted between the cylinder head
and barrel, REPLACE THE CYLINDER,
(See Figure 19-9, "Dynamic Seal.")
9. To check the dynamic seal of a cylinder,
proceed with the leakage test and observe the
pressure indication of the cylinder pressure
gauge. The difference between this pressure
and the pressure shown by the regulator gauge
is the amount of leakage at the dynamic seal.

WARNING
To prevent possibility of serious bodily
injury or death, before moving the
propeller accomplish the following:
a. Disconnect all spark plug leads.
b. Verify magneto switches are
connected to magnetos, that they are
in the "OFF" Position and "P" leads
are grounded .
c. Throttle position "CLOSED."
d. Mixture control "IDLE-CUT-OFF."
Continued...
e. Set brakes and block aircraft
wheels. Insure that aircraft tie-

Cylinder Assembly

downs are installed and verify that
the cabin door latch is open.
f. Do not stand within the arc of the
propeller blades while turning the
propeller.
10. If the leakage is below the previously
determined low cylinder gauge reading, loss
past the dynamic seal may be due to piston
ring end gap alignment or by the piston and
piston rings angular direction in the cylinder
bore See Figure 19-13, "Ring Positioning."
First insure that the piston and piston rings are
centered. This can be accomplished by
reducing regulator pressure to 20 pounds per
square inch and working piston through top
dead center several times bringing the piston
to top dead center in the normal direction of
engine rotation. Adjust regulated pressure to
80 pounds per square inch and determine
amount of loss. If the gauge reading is higher
than the previously determined master orifice
calibrated reading, proceed to next cylinder to
be tested.

NOTE:
Piston ring rotation within the ring land is a
normal design characteristic. As illustrated in
Figure 19-13, "Ring Positioning," the
compression ring location may have a direct
bearing on the dynamic seal pressure check.
Therefore, complete the test in the opposite
direction if readings are below prescribed
limits.
11. If recheck of cylinder pressure gauge reading
indication remains below allowable loss,
engine may be run up to operating temperature and rechecked prior to cylinder being
removed and repaired. Rework of cylinders
must be accomplished in accordance with
"Cylinder Assembly Repair And Replacement" in the I0-520 Permold Series Overhaul
Manual, Form OH-11.
After cylinder compression test, if all
cylinders are within specifications reinstall
spark plugs and torque to 300-360 inch
pounds.

T.D.C
.
Direction
of
Movement

Top Compression
Ring Gap

T.D.C
.

Direction
of
Movement

Top Compression
Ring Gap

Figure 19-11
Ring Positioning
19-13

Cylinder Assembly

Compression Test Troubleshooting
Use the following troubleshooting chart as a guide. Review the probable causes and other listings of problems
that have similar symptoms. The probable causes are listed in order of “easiest to find” which is not
necessarily in order of probability of occurrence.
cCorrective

First Check
Static seal
(No leakage
Permissible)

Check For

Method

Discrepancy

Intake valve to seat seal

Listen to air flow
in intake port

Carbon
Cracked cylinder
Seat worn or burned
Valve worn or burned

Stake valve
Replace cylinder
Reface or replace
Reface or replace

Exhaust valve to seat seal

Listen for air flow
in exhaust port

Carbon
Cracked cylinder
Seat worn or burned

Stake valve
Replace cylinder
Reface or replace
Replace

Valve worn or burned
Spark plug (2) to port seal

Apply soapy solution
around spark plug

Loose helical coil
Cracked cylinder

Replace helical coil
Replace cylinder

Cylinder head to barrel
seal

Apply soapy solution
between head and
barrel

Bubbles

Replace cylinder

Cylinder head cracks

Apply soapy solution
around cylinder head area

Bubbles

Replace cylinder

Second Check
Dynamic seal

Action

Check For
Leakage by piston rings
remove oil filler cap,

Method
Test gauge below
tolerance

listen

Test gauge above
tolerance

Discrepancy

Corrective Action

Piston cracked or out
of limits

Replace piston

Worn rings

Replace rings

Cylinder wall dimensions
out of limits

Replace cylinder

None

c Perform all corrective actions in accordance with “Cylinder Assembly Maintenance” in this chapter.

19-14

Cylinder Assembly

WARNING
Fuel injection lines must not be
deformed. The fuel injection lines
securely clamped to the fuel line
brackets. Do not assemble in a
configuration.

bent or
must be
support
binding

Single Cylinder Removal
Disconnect battery in accordance with the airframe
manufacturer's instructions. Tag the propeller with
the warning “DO NOT TURN PROPELLER.”
Remove cowling and any airframe supplied
accessories in accordance with the airframe
manufacturer's instructions. Remove cylinder
using cylinder and piston removal instructions in
the I0-520 Permold Series Overhaul Manual, Form
OH-11.

NOTE...
When the cylinder is removed with the spark plugs
installed, inspection can be accomplished by
filling the inverted cylinder bore with
nonflammable solvent and then inspected for leaks
at the static seal areas.
When a cylinder is removed, use the following
information below under “Pistons” to clean pistons
prior to dimensional inspection.

Pistons
Do not use wire brushes or scrapers of any kind.
Soft or hard carbon deposits may yield to solvent
action. If deposits remain, install tight fitting skirt
protector and blast the piston head with soft grit or
by the vapor grit method. Do not use sand shot,
metal grit or glass beads. Ring grooves must be
cleaned by pulling lengths of binder twine or very
narrow strips of crocus cloth through them. Do not
use automotive ring grooves scrapers, since the
corner radii at the bottoms of the grooves and side
clearances must not be altered. Abrasive cloth
must not be used on the piston skirts because the
diameters and cam-ground contour must not be

altered. Scored or burned pistons must be
discarded. After cleaning, thoroughly rinse pistons
using a Stoddard solvent to remove all debris.

Rings
Piston rings must be replaced 100%.
Before any repair procedures are performed after
cleaning, the cylinder and related components
must be visually, fluorescent penetrant, and
magnetic particle inspected as applicable in
accordance with the I0-520 Overhaul Manual,
Form OH-11.

Connecting Rods
Cylinders removed which have indications of:
• Burnt paint
• Pistons with four point scoring
• Erosion of the piston crown
1. Remove piston, piston pin and connecting rod
in accordance with the IO-520 Permold Series
Overhaul Manual, Form OH-11
2. Remove piston pin bushing and inspect
connecting rod in accordance with the IO-520
Permold Series Overhaul Manual, Form OH11.
3. Magnaflux all components in accordance with
the IO-520 Permold Series Overhaul Manual,
Form OH-11. Replace any part that does not
conform with the inspection requirements of
the overhaul manual.
4. Replace piston pin bushing in accordance with
the IO-520 Permold Series Overhaul Manual,
Form OH-11.
5. Install connecting rod in accordance with the
IO-520 Permold Series Overhaul Manual,
Form OH-11.
6. Install new piston rings and piston pin in
accordance with the IO-520 Permold Series
Overhaul Manual, Form OH-11.

19-15

Cylinder Assembly

Single Cylinder Reassembly
After all cylinder components have been cleaned,
inspected and repaired in accordance with TCM
specifications, reassemble cylinder in accordance
with “Cylinder and Piston Subassembly” of the I0520 Permold Series Overhaul Manual, Form OH11.

Single Cylinder Reinstallation
Reinstall repaired or new cylinder in accordance
with the IO-520 Permold Series Overhaul Manual,
Form OH-11. Loosely install spark plugs and
gaskets in cylinder. Have an assistant hold nuts on
opposite end of cylinder through bolts when
torquing cylinder attaching hardware.

WARNING
Lubricate all cylinder deck stud and
through bolt threads with clean 50-weight
aviation oil. Failure to lubricate threads
will result in incorrect fastener preloading
and loss of main bearing crush, engine
damage and possible failure.

Form OH-11. Torque to the maximum value
rated for the cylinder base nuts.
1. Torque the through bolt nuts to their
maximum rated values in the applicable
engine overhaul manual. Torque the 7th stud
nut last as applicable.
Position numbers 1, 4
790-810 (12 Point Nut)
690-710 (6 Point Nut)
Position numbers
490-510
2,3,5,6,7,8,9,10
1/2 inch through bolts at
615-635
cadmium plated washers
NOTE…
When replacing less than a full set of six point
nuts prior to overhaul the twelve point nut may
be used and torqued to 690-710 inch pounds
torque.
...................................................................................................

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

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

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

Cylinder Torque Procedures
Cylinder torquing must be accomplished by two
people to install and tighten cylinder attaching
hardware.
The proper torque sequence for all cylinder
applications requires a three-step torque process:
1. Torque cylinder base nuts to 50% of the rated
value using the sequence shown in the
applicable engine overhaul manual. Do not
torque the cylinder through bolt nuts during
this initial torque sequence.
2. Torque the cylinder through bolt nuts and
cylinder base nuts in the sequence shown in
the IO-520 Permold Series Overhaul Manual,

Figure 19-14
Single Cylinder Torque Sequence
19-16

Cylinder Assembly

Hydraulic Valve Tappets
Malfunctioning hydraulic valve tappets must be
removed, discarded and replaced with new.
Remove and replace tappets in accordance with
the applicable instructions in the I0-520 Permold
Series Overhaul Manual, Form OH-11.
Reinstall all valve train components that were
removed using new o-rings, seals and gaskets in
accordance with in the I0-520 Permold Series
Overhaul Manual, Form OH-11. Rocker cover
screws must be torqued to 45-55 inch pounds and
safetied as required.

CAUTION...
When performing dimensional inspection the
following "Service Limits" may be used.
However, they are only intended as a guide for
reuse when performing engine maintenance
prior to major overhaul. Parts with dimensions or
fits that exceed service limits must not be reused.
Parts with values up to and including service
limits may be re-used, however, judgment should
be exercised considering the PROXIMI-TY of the
engine to its recommended overhaul time.
When performing cylinder assembly repairs prior
to engine TBO the following dimensional limits
may be used.

19-17

Cylinder Assembly

CYLINDER ASSEMBLY SERVICE LIMITS IO-520-B, -BA, -BB, -C, -CB, -M, -MB
REF.

SERVICE
LIMIT

DESCRIPTION

CYLINDER ASSEMBLY
Cylinder bore (lower 4-1/4" of barrel)

Cylinder bore choke (at 5.75" from open end of barrel)

3.
4.

Cylinder bore out-of-round
Cylinder bore

5.
6.
7.
8.
9.
10.
11.

Cylinder bore surface roughness (Nitride Barrels)
using 180 grit stone, cross hatch
Finish (in micro inches)
Cylinder barrel in crankcase
Intake valve seat insert in cylinder head
Intake valve guide in cylinder head
Exhaust valve guide in cylinder head
Exhaust valve seat insert in cylinder head
Intake valve seat

12.

Exhaust valve seat

13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.

Exhaust valve seat-to-valve guide axis
Angle:
Intake valve seat-to-valve guide axis
Angle:
ROCKER ARMS AND SHAFTS
Rocker shaft in cylinder head bosses
Diameter:
Rocker shaft in rocker arm bearing
Diameter:
Rocker arm bushing (inside)
Finish Bore Diameter:
Rocker Arm
Side Clearance:
Intake valve in guide
Diameter:
Exhaust valve in guide
Diameter:
Intake valve face (to stem axis)
Angle:
Exhaust valve face (to stem axis)
Angle:
Intake valve face (gauge line) to stem
Length:
Exhaust valve
Length:
Intake and exhaust valve seat-to-stem (full indicator reading)
Run-out:
Rocker arm foot-to-valve stem (dry valve gear lash)
:

Diameter:

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

Taper:
:

Allowable Oversize:

Angle:
Ra:
Diameter:
Diameter:
Diameter:
Diameter:
Diameter:
Width:

22° - 32°
30-50
0.0100L
0.012T
0.0025T
0.0030T
0.0100T
See Figure

Width:

See Figure

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

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

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

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

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

19-18

See Figure
19-16
See Figure
19-16
0.0020
See Figure
19-16

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

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

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

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

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

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

45°-00'
60°-15'
0.003L
0.0040L
0.7515
0.0350L
0.0050L
0.0062L
60°-15'
45°-30'
4.714
Replace 100%
0.0040
0.2000

Cylinder Assembly

REF.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.

DESCRIPTION
PISTONS, RINGS AND PINS
Piston (bottom of skirt) in cylinder
Diameter:
Top piston ring in groove
Side Clearance:
Side Clearance;
Second piston ring in groove
Side Clearance:
Third piston ring in groove
Side Clearance:
Fourth piston ring in groove
Top ring gap at 1.00 ± .50 depth (in cylinder barrel)
Gap:
Second ring gap at 1.00 ± .50 depth (in cylinder barrel)
Gap:
Third ring gap at 1.00 ± .50 depth (in cylinder barrel)
Gap:
Fourth ring gap at 1.00 ± .50 depth (in cylinder barrel)
Gap:
Piston pin in piston (standard or 0.005' oversize)
Diameter:
Piston pin
Diameter:
Piston pin (0.005 oversize)
Diameter:
Piston pin in cylinder
End Clearance:
Piston pin in connecting rod bushing
Diameter:
Bushing in connecting rod
Diameter:
Bolt in connecting rod
Diameter:
Connecting rod bearing on crankpin
Diameter:
Connecting rod on crankpin
End Clearance:
Connecting bearing and bushing twist or convergence per inch of length:
Hydraulic tappet in crankcase
Diameter:
SPRING TEST DATA
Inner valve spring 631521 compressed to 1.230 in. length
Load:
Inner valve spring 631521 compressed to 1.746 in. length
Load:
Outer valve spring 637837 compressed to 1.275 in. length
Load:
Outer valve spring 637837 compressed to 1.791 in. length
Load:
Installed outer valve spring
Height:
...................................................................................................................................................................................

SERVICE
LIMIT
0.0110L
0.006L
0.006L
0.0075L
0.0100L
0.044
0.050
0.036
0.031
0.0015L
1.1245
1.1295
0.090L
0.0040L
0.0050T
0.0018L
0.0060L
0.0160
0.0010
0.0035L
82 Lbs.
29 Lbs.
118 Lbs.
46 Lbs.
1.791

NOTES: T=Tight L=Loose
Use .005" oversize rings.
Gap for second ring must be at least .006 larger than gap for top ring.
(See illustration on next page)

19-19

Cylinder Assembly

Figure 19-15
Cylinder Assembly Service Limits for IO-520-B, -BA, -C, -CB, -M, -MB
19-20

Cylinder Assembly

SIZE
STD.
.005
.010
.015

“D” DIAMETER
SERVICE LIMITS
MIN.
5.254
5.259
5.264
5.269

MAX.
5.256
5.261
5.266
5.271

“X” DIAMETER
SERVICE LIMITS
MIN.
5.255
5.260
5.265
5.270

MAX.
5.257
5.262
5.267
5.272

Note:
Dimensions shown are finish size after honing.
Cylinder bore out of round not to exceed (new) 0.002 (service) 0.003

Figure 19-16
Cylinder Assembly Service Limits for IO-520-B, -BA, -BB, -C, -CB, -M, -MB
19-21

This Page Intentionally Left Blank

19-22

Chapter 20

Crankcase

Crankcase Description ................................................................................................................................................................................. 20-3
Crankcase Maintenance .............................................................................................................................................................................. 20-4
Crankcase Cracks ...................................................................................................................................................................................... 20-4
Reasons For Crankcase Replacement ....................................................................................................................................... 20-4
Crankcase Gaskets ................................................................................................................................................................................... 20-5
Crankcase Studs ......................................................................................................................................................................................... 20-5
Engine Mounts ............................................................................................................................................................................................. 20-6
Crankcase Separation ............................................................................................................................................................................ 20-6
Crankcase/Starter Needle Bearing Installation ................................................................................................................ 20-6

20-1

This Page Intentionally Left Blank

20-2

Crankcase

Crankcase Description
The crankcase is the foundation of the engine. It
supports the crankshaft, camshaft, various gears
accessories, cylinders and various brackets. The
crankcase provides a tight enclosure and oil
galleries for lubrication. The crankcase is sufficiently rigid and strong to prevent misalignment of
the crankshaft, camshaft and bearings. The
crankcase is made of aluminum alloy.
Two aluminum alloy castings are joined along the
vertical center plane to form the complete
crankcase. The individual castings (with studs and
inserts) will be referred to as the “left crankcase”
and “right crankcase” throughout this chapter.
Bosses molded in the crankcase castings are line
bored in the assembled castings to form bearings

for the camshaft and saddles for precision
crankshaft main bearing inserts. Guides are bored
through lateral bosses for hydraulic tappets and on
the left crankcase half for the governor drive gear
shaft. A needle bearing bore is located on the right
crankcase half at the rear main bearing saddle for
the starter adapter needle bearing.
Cylinder mounting pads on the left crankcase are
farther forward than the corresponding pads on the
right crankcase to permit each connecting rod to
work on a separate crankpin. There are seven studs
and two through bolts for attaching cylinder base
flanges. The propeller governor mount pad is
located on the left hand lower front corner of the
left case half. On the right Permold crankcase an
alternator pad is located at the front ahead of the
#5 cylinder mount pad.

1-3-5
Crankcase
Intermediate Crankshaft
Half
Bearing Bores
Alternator
Backbone
Access
Crankshaft Nose
Seal Land

Idler Gear
Pilot
Starter Shaftgear
Needle Bearing

CYL # 5

CYL # 3

CYL # 1

Rear Crankshaft
Bearing Bore

Oil Pump
Pilot
Camshaft
Bearing Bore
Front Crankshaft
Bearing Bore

Hydraulic
Lifter Guides

Oil Sump
Mounting Flange

Hydraulic
Lifter Guides

Camshaft Bearing
Bore

Hydraulic Lifter
Guides

Camshaft Bearing
Bore

Figure 20-1
Crankcase
20-3

Crankcase

Crankcase Maintenance
Crankcase Cracks
Critical (white) and noncritical (shaded) areas are
illustrated in Figure 20-3. If a crack is observed in
any of the noncritical (shaded) areas that is less
than two (2) inches in length, the crack should be
scribe-marked at its extremities and reinspected
for crack progression at the next 50 hours of
operation. If no progression is observed and no
additional cracks are found, continue to inspect at
regular intervals not to exceed 100 hours of
operation.

Figure 20-2
Inspection of Crankcase Noncritical Area

20-4

Critical Areas
If a crack is observed in any non-critical (shaded)
area that is more than two (2) inches in length , or
if a previously observed crack has progressed to
two (2) or more inches in length, repair or replace
the crankcase prior to further flight.
If any crack is observed in a critical (white) area,
repair or replace the crankcase or engine prior to
further flight.

Reasons for Crankcase Replacement
1. Any crack in the critical (white) areas.
2. Any crack two (2) inches or more in length in
the noncritical (shaded) area.
3. Any crack that is leaking oil (not seeping) .

Crankcase

Figure 20-3
Critical (Clear) Areas and Noncritical (Shaded) Areas of the Crankcase
CAUTION...
Repair of the crankcase must be performed
by repair facilities certified to perform
specialized crankcase repairs.

WARNING
Weld repairs must not be performed in the
critical (clear) areas of the crankcase as
shown in Figure 20-3.
TCM has established that welding of the crankcase
is an acceptable repair process. The weld
procedure must conform with approved TCM
repair standards and the dimensional integrity of
the crankcase must be maintained.

Crankcase Gaskets
Leaking gaskets must be replaced. Remove
component, install new gasket and reinstall
component in accordance with applicable system
or component section in the I0-520 Permold Series
Overhaul Manual, Form OH-11. Exercise
judgment as to the extent of disassembly required.
During reassembly, insure that all reinstalled
components are properly torqued and safetied.

Crankcase Studs
The replacement of crankcase studs or helical coils
require component removal and replacement in
accordance with the applicable component sys-tem
section in the I0-520 Permold Series Overhaul
Manual, Form OH-11. During reassembly, insure

20-5

Crankcase

that all reinstalled components are properly
torqued and safetied .

fluorescent penetrant, magnetic particle or
ultrasonic inspection requirements.

Engine Mounts

All crankcase repairs must be performed in
accordance with the I0-520 Permold Series
Overhaul Manual, Form OH-11. Any accessory
not supplied by TCM that was disassembled for
maintenance must be reassembled in accordance
with the applicable accessory manufacturer's
instructions.
Any
maintenance
involving
crankcase separation will require an acceptance
test, oil consumption determination, reinstallation
in airframe and test flight in accordance with the
I0-520 Permold Series Overhaul Manual, Form
OH-11.

Replace engine shock mounts in accordance with
the airframe manufacturer's instructions. Replace
any cracked or broken engine mounts in
accordance with in the I0-520 Permold Series
Overhaul Manual, Form OH-11.

CAUTION...
When relieving engine weight from the
airframe, the engine hoist must be attached
to the engine lifting eyes only.
NOTE...
Place a support at the load bearing area of aircraft
tail to prevent damage to the airframe.

Crankcase/Starter Needle
Bearing Installation

Crankcase Separation

If a new crankcase needle bearing has to be
installed in the engine prior to overhaul, use a
modified needle bearing tool and fixture shown in
Figures 20-4 and 20-5 on the following page.
Replace the needle bearing in accordance with the
I0-520 Permold Series Overhaul Manual, Form
OH-11.

If the crankcase halves must be separated, remove
the engine from airframe in accordance with the
I0-520 Permold Series Overhaul Manual, Form
OH-11 and the airframe manufacturer's instructions. Engine disassembly, cleaning, inspection,
repair, replacement and assembly must be accomplished in accordance with the I0-520 Permold
Series Overhaul Manual, Form OH-11.

NOTE...
Exercise judgment in determining how far systems
and components should be disassembled.
Any maintenance of engine systems and components removed from engine must be performed in
accordance with that particular system or
component chapter of this manual.

CAUTION...
Dimensional inspection of the crankcase and
crankcase internal components must be
performed in accordance with the I0-520
Permold Series Overhaul Manual, Form
OH-11. Prior to dimensional inspection,
insure that the part conforms with all visual,

20-6

Crankcase

Figure 20-4
Crankcase Needle Bearing Installer

Figure 20-5
Modified Crankcase Needle Bearing Tool

20-7

This Page Intentionally Left Blank

20-8

Chapter 21

Engine Drive Train

Engine Drive Train.......................................................................................................................................................................................... 21-3
Crankshaft .............................................................................................................................................................................................................. 21-5
Connecting Rod .................................................................................................................................................................................................. 21-6
Camshaft .................................................................................................................................................................................................................. 21-7
Idler Gear ............................................................................................................................................................................................................... 21-8
Engine Drive Train Maintenance ........................................................................................................................................................ 21-9
Crankshaft Nose Oil Seal .................................................................................................................................................................... 21-9
Preparation ............................................................................................................................................................................................. 21-9
Oil Seal Installation ...................................................................................................................................................................... 21-10
Engine Drive Train Component Removal ........................................................................................................................... 21-11

21-1

This Page Intentionally Left Blank

21-2

Engine Drive Train

Engine Drive Train
When starting engine, torque is transmitted from
the starter (13) through starter adapter components
(14 through 19) to crankshaft gear (1). As wormwheel (17) is turned, the spring mounted on its
hub, is tightened to grip the shaftgear (18) drum.
After engine is started the spring returns to its
normal position releasing the shaftgear and
disengaging the starter. Torque is transmitted to
the alternator by a face gear (21) mounted on the
crankshaft. Torque from the crankshaft (2) is
transmitted by the crankshaft gear (1) directly to
the idler gear (10) and the camshaft gear (3).

ITEM
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.

The idler gear, rotating in a counterclockwise
direction, drives the magneto drive gears (11, 12 ).
Optional accessories mounted on the crankcase
upper rear are driven by internal splines of
magneto drive gears.
The fuel pump coupling is driven directly from the
crankshaft gear (1). The splined end of the oil
pump drive gear (8) mates with the internal splines
of the camshaft gear and transmits torque to the oil
pump driven gear (9). The governor drive bevel
gear (6) is keyed to the camshaft (4) and meshes
with and drives the governor drive bevel gear (7).
Shown below are the accessory gear to crankshaft
gear drive ratios. The item numbers correspond
with those shown in Figure 21-1, “Engine Drive
Train”

DESCRIPTION
Crankshafts Gears .................................................................................
Crankshaft .................................................................................................
Camshaft Gear ........................................................................................
Camshaft.....................................................................................................
Hydraulic Tappet...................................................................................
Governor Drive Bevel Gear ............................................................
Governor Driven Bevel Gear .........................................................
Oil Pump Drive Shaftgear................................................................
Oil Pump Driven Gear .......................................................................
Idler Gear Assembly............................................................................
Right Magneto Drive Gear ..............................................................
Left Magneto Drive Gear .................................................................
Starter ...........................................................................................................
Starter Coupling .....................................................................................
Worm Drive Shaft ................................................................................
Starter Worm Gear ...............................................................................
Starter Worm Wheel............................................................................
Starter Shaftgear ....................................................................................
Alternator ...................................................................................................
Alternator Driven Gear ......................................................................
Alternator Drive Gear .........................................................................

GEAR RATIO
1:1
1
1:0.5
1:0.5
—
1:0.5
1:1
1:0.5
1:0.5
1:0.652
1:1.5
1:1.5
48:1
—
48:1
48:1
3:1
3:1
3:1
3:1
1:1

21-3

Engine Drive Train

Figure 21-1
Engine Drive Train

21-4

Engine Drive Train

Crankshaft
The crankshaft is made of aircraft quality steel.
The crankshaft has five, machined, main journals
which rotate on the bearings in the crankcase. Six,
machined, rod journals provide for attachment of
the connecting rod assemblies.
The following shows the method of numbering the
crankshaft main journals, connecting rod journals
and crankshaft cheeks which are identified by
letters and location numbers.
The method of numbering the crankshaft journals
and cheeks is illustrated in Figure 21-2. Main
journals, rod journals, and crankshaft cheeks are
identified by letters and location numbers.

The counterweight order number designates the
vibration order the counterweight is absorbing. If a
vibration occurs six times per revolution, the
counterweight which has been tuned to counteract
this frequency of vibration is a 6th order
counterweight. Similarly, if a vibration occurs five
times per revolution, the counteracting counterweight is a 5th order counterweight.

(a) Main Journal - M.J.
(b) Rod Journal - R.J.
(c) Crankshaft Cheek - C.C.

On IO-520 Permold engine crankshafts (except
IO-520-BA) two sixth order counterweights are
installed on the #2 cheek hangers. The #5 cheek
hangers support one fifth and one fourth order
counterweight. On the IO-520-BA engine
crankshaft, two sixth order counterweights are
installed on the #2 cheek hangers. The #5 cheek
hangers support one sixth and one 4th order
counterweight. It does not matter on which side of
a cheek a particular counterweight is installed.

Counterweights are supplied in matched pairs with
the bushings installed. This is necessary to insure
that their weight difference does not exceed 2
grams.

The crankshaft gear is heated prior to installation
to obtain a shrink fit. The gear is positioned on the
crankshaft by a dowel pin The crankshaft gear
incorporates a square drive hole that accepts the

#5 Crankcheek

Alternator Drive “Face” Gear

#6 Crankcheek

Counterweight Hanger Blade
#4 Crankcheek

#1 Crankcheek

Propeller
Flange

Oil Slinger

#7 Crankcheek

Crankcheek #9
Crankcheek #8

#3 Crankcheek

#2 Crankcheek

Counterweight Hanger Blade

Figure 21-2
Crankshaft
21-5

Engine Drive Train

square drive fuel pump coupling providing a direct
drive for the fuel pump. The gear also has a timing
mark to provide a means of insuring correct
crankshaft to camshaft timing.

Connecting Rod
Connecting rods are made of aircraft quality steel.
The plain type connecting rod large diameter end,
which attaches to the crankshaft crankpin or rod
journal, is fitted with a cap and two-piece bearing.
The bearing cap is held to the main rod by two
bolts and either spiral lock nuts or pinned
castellated nuts.

The alternator drive gear, is attached to the flange
just behind the #5 main journal location at the
front of the crankshaft and is secured by four bolts
and lockplates.
A neoprene oil seal, which is stretched over the
crankshaft flange, and a split retainer ring are
seated between the crankcase castings in the front
shaft exit area and is sealed to the crankshaft by a
helical spring inside the seal's cavity.
Pin
Width

Split
Bushing

Pin Bore
Chamfer

Spread
(C/C Dimension)

Pin Bore

Piston Pin End

I-Beam
or
Shank

Rod

Mate Marks

Crank Bore

Split Line

Crank Bore
Chamfer

Cap
Crank
Width

Figure 21-3
Connecting Rod Description
21-6

Engine Drive Train

tappet movement inward and outward in their
bores is caused by the eccentric shape of the cam
lobes. The lobes and journals are ground and
hardened. Movement of the tappets open and close
the intake and exhaust valves within the cylinder
head by mechanical linkage of the pushrods and
rocker arms. The valves opening and closing is
synchronized with piston position due to timing of
the camshaft and crankshaft gears. Four unequally
spaced bolts retaining the gear to the camshaft
insure proper positioning, locating the gear’s
timing mark in relation to the cam lobes. The
camshaft gear incorporates a splined drive for
driving the engine oil pump. A front mounted
bevel gear drives the prop governor bevel gear.

The portion of the rod between the crankpin and
piston pin ends is called the “I beam.” A split steel
backed bronze bushing is pressed into the piston
pin end and machined for a precision pin to
bushing fit. Weight variation of connecting rods
between opposing bays. Example: #5 and #6
connecting rods, is limited to 1/2 ounce or 14.175
grams.

Camshaft
The camshaft is made of aircraft quality steel. The
forging is machined on four (4) main journals,
nine cam lobes and the gear mount flange at the
rear of the camshaft. The main journals ride within
the crankcase camshaft bores. The hydraulic

Oil Pump Drive
Shaft Provision

Governor
Drive Gear
#6
EXH

#5 INT
#6 INT

#5
EXH

#4
EXH

MJ
CL

#3 INT
#4 INT

#3
EXH

#2
EXH

#2 INT
#1 INT

#1
EXH

MJ
CL

Camshaft
Gear

Figure 21-4
Camshaft

21-7

Engine Drive Train

Idler Gear
The idler gear support pin supports the idler gear.
The bushing in the crankcase supports the forward
part of the idler gear support pin shaft. The idler
gear is driven directly by the crankshaft. The idler
gear drives the left and right magneto accessory
drive gears.

Engine Drive Train
Maintenance
Crankshaft Nose Oil Seal
The crankshaft nose oil seal may be replaced
according to the following instructions:

WARNING

Figure 21-5
Idler Gear

To prevent starting of engine before
moving the crankshaft, accomplish the
following:
a. Disconnect all spark plug leads.
b. Verify magneto switches are connected
to magnetos, that they are in the “OFF”
Position and “P” leads are grounded.
c. Throttle position “CLOSED.”
d. Mixture control “IDLE-CUT-OFF.”
e. Set brakes and block aircraft wheels.
f. Insure that aircraft tie-downs are
installed and verify that the cabin door
latch is open.
g. Do not stand within the arc of the
propeller blades while turning the
propeller.

Preparation
1. Remove oil seal.
2. Clean surfaces thoroughly making certain that
no debris remains on the shaft or in the seal
counterbore. Wash seal area with solvent.
3. Remove any plating in the one inch area
shown in Figure 21-6, “Helix Pattern Application.” Remove plating by working a piece of
very fine emery cloth back and forth around
the shaft. This should blend the finish uniformly without leaving any lines (scratches).

21-12

Engine Drive Train
1”

Direction of 30 Degree
Pattern Marks

Propeller End of Crankshaft
Figure 21-6
Helix Pattern Location
1. See Figure 21-6, “Helix Pattern Application.”
Apply helix using a strip of 180 grit emery
cloth approximately one half inch wide. Do
approximately one quarter of the surface
indicated at a time, stroking the cloth outward
toward the propeller flange in the direction of
rotation (CCW) towards you using maximum
hand pressure. Reverse direction for left hand
rotating engines. This should result in a 30°
pattern similar to that illustrated in Figure 216, “Helix Pattern Application.” After doing the
first portion rotate crankshaft by hand to make
next portion available. Apply the same pattern
again and continue completely around the
crankshaft in this manner.

2. Repeat cleaning operation.

21-11

Engine Drive Train

Oil Seal Installation
1. Use the specified oil seal assembly only.
Check the spring length. It should be 7 53/64”+0” -1/32” in length. See Figure 21-7,
“Crankshaft Oil Seal.”
2. Remove spring and reinforcing ring from oil
seal. Unhook spring ends using an unwinding
motion. Place spring around crankshaft in oil
seal area and turn spring ends in an unwinding
direction the join and allow one end to wind
into the other end.
1. Apply Alvania ™ (Shell #2) to lip of oil seal
and prop flange only. Squeeze oil seal until egg
shaped and start over flange. A special tool
P/N5209 is available from Kent Moore to assist
in oil seal installation. After oil seal is on shaft
wipe all grease from oil seal and shaft. The oil
seal outside diameter must be clean and dry
before installation in the crankcase. Press the

reinforcing spring into the oil seal recess by
moving fingers in both directions from split.
Insure spring is in deepest part of recess all the
way around.
2. Apply a thin coat of Permatex to outside
diameter of seal.
3. Using thumb pressure,
crankcase counterbore.

work

seal

into

4. After seal is in place, wipe oil from seal and
shaft.
5. Spray exposed portion, from which plating has
been removed, with aluminum primer.
6. Apply Loctite 271 to oil seal retainer screws.
Apply Loctite Primer 7471 to crankcase oil seal
retainer screw holes. Install crankshaft oil seal
retainer plates and secure with screws. Torque
screws to 21-25 inch pounds.

Figure 21-7
Crankshaft Oil Seal

21-12

Engine Drive Train

Engine Drive Train
Component Removal

accomplished in accordance with the I0-520
Permold Series Overhaul Manual, Form OH-11.

If all other probabilities have been evaluated and it
is determined that a malfunction is occurring with
internal engine components, remove the engine
from the airframe and disassemble it in accordance
with the I0-520 Permold Series Overhaul Manual,
Form OH-11 and the airframe manufacturer's
instructions.

CAUTION...
When relieving engine weight from the airframe,
attach the engine hoist only to the engine lifting
eyes.

NOTE...
Place a support at the load bearing area of airframe
tail to prevent damage to the airframe.

NOTE...
Exercise judgment in determining the extent of
disassembly.
Maintenance of removed engine systems and
components must be performed in accordance with
that particular system or component section of this
manual.

CAUTlON...
Dimensional inspection of the crankcase and
crankcase internal components must be
performed in accordance with the I0-520
Permold Series Overhaul Manual, Form OH-11.
Prior to dimensional inspection, insure that the
part conforms with all visual, fluorescent
penetrant, magnetic particle or ultrasonic
inspection requirements.

NOTE...
When the engine has been disassembled a
complete visual, dimensional and non destructive
test inspection must be performed on all
components prior to reassembly.
Engine disassembly, cleaning, inspection, repair,
replacement, assembly and test must be

21-11

Engine Drive Train

21-12

Chapter 22

Postmaintenance
Adjustment and Test
Post Maintenance Operational Test .....................................................................................................22-3
Servicing With Fluids ................................................................................................................................22-3
Operational Test............................................................................................................................................22-3
Oil Pressure Adjustment .........................................................................................................................22-3
Fuel System Adjustment ..................................................................................................................................22-4
Adjustment Tools and Equipment Required.............................................................................22-4
Presetup Procedures ..................................................................................................................................22-5
Setup Procedures ..........................................................................................................................................22-6
Postsetup Procedures .............................................................................................................................22-10
Test Flight ...............................................................................................................................................................22-18

22-1

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22-2

Post Maintenance Adjustment and Test

Post Maintenance
Operational Test

2. After the operational inspection is completed,
make any required engine system adjustments
as follows:

An operational test must be performed after each:

Oil Pressure Adjustment

• 50-hour inspection

1. Prepare the aircraft for ground run up and start
the engine in accordance with the aircraft
manufacturer's instructions.
2. Turn the oil pressure adjusting screw clockwise to increase oil pressure and counterclockwise to decrease oil pressure. With engine
oil at normal operating temperature, adjust the
oil pressure to 10 psi idle minimum and 30-60
psi normal operation. Torque locknut and safety
as required.

• 100-hour inspection
• Annual inspection.

Servicing With Fluids
Refer to Chapter 7 and insure that:
1. The engine has been properly serviced with the
specified oil.
2. The aircraft has been serviced with the specified fuel in accordance with the airframe manufacturer’s instructions. See chapter 7 for fuel
specifications.

Operational Test
After engine maintenance is completed, an engine
operational inspection must performed in accordance with Chapter 5.
NOTE...
If a new cylinder or cylinders and piston rings have
been installed:
1. Start the engine in accordance with the airframe
manufacturer's Airplane Flight Manual (AFM)
2. Operate the engine at 750 RPM for one minute,
gradually increasing RPM to 1000 RPM in
three minutes.
3. Check the magneto circuit for proper grounding
prior to a normal shutdown.
4. Allow the engine to cool adequately and
visually inspect for any irregularities.
1. If the engine exhibits any irregularities, refer to
the applicable chapter and correct all discrepancies. All discrepancies must be corrected
prior to operational test and engine adjustment.

Oil Pressure
Adjustment

Figure 22-1
Oil Pressure Adjustment on Oil Pump

22-3

Post Maintenance Adjustment and Test

Fuel System Adjustment
The procedures and values provided apply
to TCM fuel injected engines that have not
been modified from their type design. Refer
to supplemental type certificate (STC)
holder information and instructions for
aircraft and engines that have been
modified from their type design.
Aircraft and engines that have been modified from
their type design must have the fuel injection
system maintained in accordance with the
Supplemental Type Certificate Holders FAA
approved instructions.

CAUTION...
Engine performance, service life and reliability
will be compromised if the engine fuel injection
system is neglected.
The following adjustment procedures are
presented in a sequential format that must be
followed to insure proper fuel system adjustment.
Reference the applicable Aircraft Maintenance
Manual for detailed fuel system adjustment and
maintenance procedures.
Any fuel system that cannot be adjusted to meet
the specified values will require repair or
replacement of the affected components prior to
further engine operation.
CAUTION...
Refer to Chapter 13, Tables 1 and 2, for specified
values when torquing all hose connections and
fittings.

22-4

Adjustment Tools And Equipment
Required
A complete set of tools and test equipment is
essential for correct setup of TCM fuel injection
systems. Various combinations of these tools and
equipment will be used, depending on the engine
model. A proper inventory of tools and equipment
for fuel system adjustment will include the
following:
1. TCM recommends the Model 20 ATM - C
Porta Test Unit P/N 630045-20 ATM-C or
equivalent to insure the fuel injection system
meets all pressure and flow specifications. An
alternative procedure would be to use
calibrated gauges. You may acquire a Model
20 ATM-C Porta Test Unit by contacting the
following company:
AERO TEST, Inc.
29300 Goddard Road
Romulus, Michigan 48174
(313) 946-9000
a. One (1) calibrated 0-60 PSI gauge,
graduated in 1 PSI increments. This
gauge will be used for unmetered pressure
measurement.
b. One (1) calibrated 0-30 PSI gauge,
graduated in 1 PSI (maximum) increments. This gauge will be used for
metered pressure measurements and
verification of aircraft fuel flow gauge
indications.
2. Two (2) P/N MS51523-B4 swivel tees. These
fittings will be used to tee into fuel lines for
unmetered and metered pressure reference.
3. Hoses of appropriate diameters and sufficient
lengths to keep personnel and equipment away
from propeller arc area.
4. Common hand tools including: 7/8”, 11/16”,
9/16”, 1/2”, 3/8”, 7/16”, 11/32”, and 5/16”
wrenches. A 1/4” drive: ratchet and sockets,
universal swivel, extension and a 5/32” allen
wrench, common screw driver, a calibrated
.

Post Maintenance Adjustment and Test

torque wrench, an oil can, mirror and
flashlight. Safety equipment including hearing and eye protection.
5. Tachometer verification instrument - various
types are available. Verify aircraft tachometer
accuracy prior to fuel system adjustment.

Presetup Procedures
1. Prior to fuel system adjustments, flush the
aircraft fuel system by first removing the
engine-driven fuel pump inlet hose and
terminating the end into a large, clean
container. Operate the aircraft boost pump
and allow a minimum of one gallon of fuel to
flow through the system. Take necessary
precautions to prevent a fire hazard. If
contamination is present, locate and correct
the source, and repeat this step prior to
proceeding.
2. Prior to any checks or adjustments, verify the
accuracy of the tachometer, manifold pressure
gauge and fuel flow gauge. Any gauge found
to be inaccurate must be repaired or replaced
prior to adjusting the fuel system.

WARNING
Use of inaccurate gauge(s) will result in
incorrect adjustment of the engine fuel
system, possible cylinder wear due to
lean operation, preignition, detonation,
loss of power and severe engine damage.

10.

component that is not operating properly in
accordance with the airframe manufacturer's
instructions.
Inspect the aircraft vapor return system for
proper operation in accordance with the
manufacturers’ instructions. Correct any
discrepancies noted.
Insure the fuel manifold valve vent and fuel
pump drain lines are properly installed, open
and free of obstruction. Correct any
discrepancies noted.
Inspect all engine control rod ends for wear,
freedom of movement, proper installation and
security in accordance with the test stand or
aircraft manufacturer's instructions. Correct
any discrepancies noted.
Insure all engine controls operate freely
throughout their full range of travel and are
properly adjusted in accordance with the
aircraft manufacturer's instructions.
Lubricate all control rod ends and fuel system
components in accordance with Chapter 13 of
this manual and the aircraft manufacturer’s
instructions.

WARNING
Failure to correctly install and maintain
engine controls can result in loss of
system control and subsequent engine
power.

3. Insure that all fuel system components are of
the correct part number and installed properly.
Correct any discrepancies noted.
4. Remove, inspect, clean, and reinstall the
aircraft and engine fuel screens in accordance
with the manufacturer's instructions.
5. Inspect the aircraft induction air filter and
alternate air system for condition, operation
and cleanliness.
Repair or replace any

22-5

Post Maintenance Adjustment and Test
Inlet Screen

Idle Speed Stop Screw
CW = Increase
Throttle Lever

Fuel Inlet Fitting
(Unmetered Pressure)

Idle Mixture Adjustment
CW = Enrich

Heat Shield

Cutaway To Reveal
Fittings

Mixture
Lever
Fuel Return
(To Fuel Pump)

Fuel Outlet
(Metered
Pressure)

Figure 22-2
Throttle, Fuel Control and Metering Unit Adjustments

Setup Procedures
1. Locate the IDLE speed stop screw on the
throttle body and turn it counter-clockwise
two complete turns. See Figure 22-2. During
fuel system adjustment, IDLE RPM will be
controlled manually using the cockpit throttle
control.

WARNING
During removal and installation of fuel
lines and hoses, failure to properly
support component fittings can result in
fitting and/or component damage and
loss of system pressure. Refer to
Chapter 9, “Standard Practices.”
2. Loosen and remove the unmetered fuel supply
hose from either the fuel pump outlet fitting or
the fuel metering unit inlet fitting, whichever
is most accessible

22-6

3. Install and torque the MS51523-B4 swivel tee
directly to the fuel pump outlet fitting or to the
fuel metering unit inlet fitting as applicable.

NOTE...
Installation may require combinations of
different fittings and hoses to facilitate
installation of unmetered and metered test
equipment connections.
4. Attach the unmetered fuel supply hose to the
straight end of the tee connector and torque.
5. Connect the unmetered test hose from the
Porta Test Unit to the tee fitting and torque. If
using the alternative procedure, connect the 060 PSI gauge to the swivel tee using a length
of hose which will provide proper clearance
from the engine cowling and propeller arc.
Torque all connections.
6. Loosen and remove the metered fuel supply
hose from the manifold valve inlet fitting.

Post Maintenance Adjustment and Test

7. Install and torque the second MS51523-B4
swivel tee directly to the fuel manifold valve
inlet fitting.
8. Attach the metered fuel supply hose to the
straight end of the tee connector and torque.
9. Connect the metered pressure test hose from
the Porta Test Unit to this second tee connector and torque. If using the alternative procedure, connect the 0-30 PSI gauge to the
swivel tee using a hose long enough to provide
proper clearance from the engine cowling and
propeller arc. Torque all connections.

10. Position the throttle control in the FULL
OPEN position and the mixture control to
FULL RICH. Operate the aircraft boost pump
in accordance with the aircraft manufacturer’s
instructions. Following the instructions provided with the Porta Test Unit, bleed all air
from the test unit and hoses. If using the
alternative calibrated test gauges, loosen the
test connections at each gauge to bleed the
lines of any air. Operate the boost pump only
long enough to allow purging of air from the
installed test equipment. Verify that all fuel
lines, hoses and fittings are secured and
torqued and that no fuel leaks exist before
proceeding. Insure test hoses have been routed
clear of the exhaust system and are supported
their entire length to preclude inaccurate
gauge readings.

Low Pressure
Relief Valve

Adjustable Orifice

Figure 22-3
Fuel Pump Adjustments

22-7

Post Maintenance Adjustment and Test

WARNING
11. Inspect the exhaust and induction systems for
proper installation, security and leaks. Correct
any discrepancies noted.
12. Inspect all lines, hoses and wire bundles for
chafing, loose connections, leaks and stains.
Correct any discrepancies noted.
13. Loosen and remove the metered fuel supply
hose from the manifold valve inlet fitting.
14. Install and torque the second MS51523-B4
swivel tee directly to the fuel manifold valve
inlet fitting.
15. Attach the metered fuel supply hose to the
straight end of the tee connector and torque.
Connect the metered pressure test hose from the
Porta Test Unit to this second tee connector
and torque. If using the alternative procedure,
connect the 0-30 PSI gauge to the swivel tee
using a hose long enough to provide proper
clearance from the engine cowling and
propeller arc. Torque all connections.
16. Position the throttle control in the FULL
OPEN position and the mixture control to
FULL RICH. Operate the aircraft boost pump
in accordance with the aircraft manufacturer's
instructions.
Following the instructions
provided with the Porta Test Unit, bleed all air
from the test unit and hoses. If using the
alternative calibrated test gauges, loosen the
test connections at each gauge to bleed the
lines of any air. Operate the boost pump only
long enough to allow purging of air from the
installed test equipment. Verify that all fuel
lines, hoses and fittings are secured and
torqued and that no fuel leaks exist before
proceeding. Insure test hoses have been
routed clear of the exhaust system and are
supported their entire length to preclude
inaccurate gauge readings.
17. Install the engine cowling or cooling shroud
during ground operation.

22-8

Make certain all fuel has drained from
the induction system prior to
attempting engine start. Failure to do
so could cause hydraulic lock and
subsequent engine failure .
18. The Operational Test Form on page at the end
of this chapter may be reproduced for use in
recording adjustments and test indications.
Record the applicable IDLE and FULL
POWER adjustment points: RPM, fuel
pressure, fuel flows, manifold pressure and
fuel/air mixture rise from “Test Operating
Limits” in Chapter 5 and Aircraft Maintenance
Manual on the operational test form. See the
end of this chapter for:
•
•
•

Constant Speed Sea Level Performance
Curve
Fuel Flow Vs. Brake Horsepower
Performance Curve
Fuel Flow Vs. Metered Pressure Performance Curve

NOTE...
To insure optimum cooling during FULL
POWER operations, the FULL POWER
fuel flow should be set to the maximum
specification limit.

WARNING
Before starting the engine, insure that
the aircraft wheels are chocked and
brakes are set.
19. Prepare the aircraft for ground run and start
the engine in accordance with the aircraft
manufacturer's instructions.
20. Advance the throttle to 1500 to 1800 RPM.
While monitoring all engine gauges, operate
the engine at this speed until the engine

Post Maintenance Adjustment and Test

temperatures and pressures have stabilized in
the operational range. Use the operational test
form to record the gauge indications.
21. With the mixture control in the FULL RICH
position, reduce the throttle to the specified
IDLE RPM. Record the unmetered pressure
indicated on the gauge. Slowly move the
mixture control toward the IDLE CUT-OFF
position and record the maximum RPM rise.
Return the mixture control to FULL RICH.
22. Monitoring all engine gauges, slowly advance
the throttle control to full rated power for the
engine and allow the engine to stabilize for 15
seconds. Record all engine and test gauge
indications. DO NOT ALLOW ENGINE
TEMPERATURES TO EXCEED 420°F
CYLINDER HEAD TEMPERATURE
AND 210°F OIL TEMP. Retard throttle
control to 800 to 1000 RPM.

NOTE…
Engine driven fuel pump output pressures
vary with engine RPM. If the engine will
not achieve full power rpm during static
ground operational test run use Table 22-1
to correct the metered fuel pressure
specification for the actual rpm achieved.

NOTE…
Insure that all engine and engine-related
aircraft systems are adjusted and functioning properly before making any adjustment
to the fuel system.
23. Compare the recorded IDLE fuel pressure,
IDLE RPM fuel/air mixture rise and full
power RPM, manifold pressure (as applicable), unmetered fuel pressure, metered fuel
pressure and fuel flow indications with the
specified values recorded on the operational
test form. If all recorded values are within
specifications, proceed to paragraph 22.

24. If any of the recorded readings are not within
specifications, the fuel system will require
complete adjustment.

Caution...
All readings must be taken with mixture
control in the full rich position.
25. Install the engine cowling or cooling shroud
during all ground operation.

NOTE...
Insure that the manifold pressure is
adjusted in accordance with the aircraft
manufacturer’s instructions.

WARNING
Make all adjustments with the engine
stopped and the ignition and master
switches in the off position.
26. To adjust the IDLE RPM unmetered pump
pressure, loosen the lock nut on the low pressure relief valve. See Figure 22-3. Turning
the adjustment clockwise (CW) will increase
pressure and counterclockwise (CCW) will
decrease pressure. Operate the engine at 1500
- 1800 RPM for 15 seconds after each
adjustment, then retard the throttle to the
specified IDLE RPM. Repeat this step until
pressure is within specified limits.

NOTE...
It is desirable to set IDLE RPM unmetered
pump pressure to the minimum limit. With
properly adjusted fuel/air mixture, this will
provide a slight fuel enrichment during
part throttle operations.
27. With engine operating at the specified IDLE
RPM and unmetered fuel pressure, slowly
move the mixture control from the FULL
RICH position toward IDLE CUT-OFF to

22-9

Post Maintenance Adjustment and Test

check fuel/air mixture. A rise of 25 to 50
RPM should be obtained. An RPM change
greater than 50 indicates the mixture is too
rich and a change that is less than 25 indicates
the mixture is too lean.
Any mixture
conditions that are too rich or too lean will be
adjusted as follows:
a. Adjust idle mixture in accordance with
Figure 22-2, “Throttle and Fuel Metering
Adjustments.”
b. Perform an IDLE fuel/air mixture check
and observe RPM rise. If the RPM rise is
not within specifications, advance the
throttle control to 1500 - 1800 RPM for 15
seconds after each adjustment to clear the
engine. Retard the throttle control to
IDLE RPM and repeat mixture check.
Make the necessary adjustment. Repeat
this procedure until the specified RPM rise
is achieved.
c. Recheck IDLE RPM unmetered pump
pressure. If pressure in not within limits,
repeat Steps 18, 19, 19-a and 19-b before
continuing.
28. See chapter 5 “Test Operating Limits.” Adjust
the full power fuel flow to the specified value
by turning the adjustable orifice screw
clockwise to increase fuel flow and
counterclockwise to decrease fuel flow. See
Figure 22-3 for fuel pump adjustments.
29. When full power fuel flow has been adjusted
to the specified values, recheck the IDLE
RPM unmetered fuel pressure and fuel/air
mixture. If any values are not within specified limits, repeat the adjustment procedures.
30. With the fuel system set to the specified
pressure and flow values, set the IDLE RPM
to the specified value by turning the Idle
Speed Stop screw clockwise to increase RPM
and counterclockwise to decrease RPM. See

22-10

Figure 22-2 and chapter 5, “Test Operating
Limits.”

Postsetup Procedures
1. Insure that the master switch, ignition switch
and fuel selector are in the off position.
2. Remove the engine cowling or cooling shroud
in accordance with the aircraft manufacturer's
instructions. Remove all test gauges, fittings
and hoses that were installed for fuel system
setup. Reconnect all fuel hoses to their
original locations, support and torque all
fittings to the specified value.
3. Perform a complete fuel system leak check in
accordance with the aircraft manufacturer’s
instructions. Correct any discrepancies noted.
4. Install engine cowling or cooling shroud in
accordance with the aircraft manufacturer's
instructions.
5. Perform a complete operational ground run-up
and verify that all fuel system performance
specifications are achieved .
6. Repeat the setup and adjustments as required
until the fuel injection system is performing
within the published specification for the
aircraft and engine.

Post Maintenance Adjustment and Test

Metered Pressure Vs. RPM @ 70°F Fuel Temperature
Static Engine RPM

Correction Factor

Corrected Metered Pressure
(Metered Pressure x Correction Factor)

Rated RPM

-20

.991

-40

.982

-60

.973

-80

.964

-100

.955

-120

.946

NOTE: All values are approximate. Variations may be noticed due to engine and installation
specific influences.

Example:

I0-520-B, -BA, -BB: Maximum Rated RPM = 2700
Metered Fuel Pressure Limits = 16.5 - 18.4

If maximum static engine RPM = 2640, (-60 RPM) use Correction Factor .973
Metered Fuel Pressure Limits x Correction Factor = Corrected Metered Pressure Limits
16.5 x .973 = 16.0545 (Minimum Metered Pressure Limit) @ 2640 RPM
18.4 x .973 = 17.9032 (Maximum Metered Pressure Limit) @ 2640 RPM

Table 22-1
Compensation Table for Static Ground Setup

22-11

Post Maintenance Adjustment and Test

Chart 22-1
IO-520-B, -BA, -BB Metered Fuel Pressure vs. Fuel Flow
22-12

Post Maintenance Adjustment and Test

Figure 22-2
IO-520-B, -BA, -BB Brake Horsepower vs. Fuel Flow
22-13

Post Maintenance Adjustment and Test

Figure 22-3
IO-520-C, -CB Metered Fuel Pressure vs. Fuel Flow
22-14

Post Maintenance Adjustment and Test

Figure 22-4
IO-520-C, -CB Fuel Flow vs. Brake Horsepower

22-15

Post Maintenance Adjustment and Test

Figure 22-5
IO-520-M, -MB Metered Fuel Pressure vs. Fuel Flow
22-16

Post Maintenance Adjustment and Test

Figure 22-6
IO-520-M, -MB Fuel Flow vs. Brake Horsepower

22-17

Test Flight
Refer to the aircraft manufacturer’s or Supplemental Type Certificate (STC) holders POH/AFM
for specific operational information.
NOTE…
I0-520-M, -MB, -B, -BA, -BB, -C, -CB engines
require the auto lean operation inspection below
during test flight.
Ambient air and engine operating temperatures are
of major concern during this test flight. Do a normal
preflight run-up in accordance with the Airplane
Flight Manual. Conduct a normal take-off with full
power and monitor the fuel flow, RPM, oil pressure,
coolant temperatures and oil temperatures. Reduce
to climb power in accordance with the Airplane
Flight Manual. The manual mixture control should
be set in the full rich position for all operations
except leaning for field elevation and leaning to
maintain smoothness during climb and leaning for
cruise economy. Leaning operations must be
performed in accordance with the Airplane Flight
Manual.

NOTE…
New, rebuilt and overhauled engines or engines
that have had new or repaired cylinders installed
must be flown in accordance with the following
procedure for the first two hours of operation.
Level flight cruise should be at 75% power with
best power or richer mixture for the first hour of
operation. The second hour power settings should

22-18

alternate between 65% and 75% power with the
appropriate best power mixture settings. The best
power mixture setting is 100° to 125° rich of peak
turbine inlet temperature. Engine controls or aircraft
attitude should be adjusted as required to maintain
engine temperatures and pressures within
specifications.
Descent from high altitude should be accomplished
at low cruise power settings. During descent, engine
pressures and temperatures must be care-fully
monitored. Avoid long descents with cruise RPM
and manifold pressure below 18” Hg.

CAUTION…
Avoid rapid descents at high RPM and low
manifold pressure.
During descent monitor coolant and oil
temperatures maintaining above the minimum
recommended operating range .

NOTE…
Avoid long descents at low manifold pressure,
which can result in excessive engine cooling.
Satisfactory engine acceleration may not occur
when power is applied.
Any discrepancies detected during test flight must
be corrected and the aircraft again test flown prior
to approval of engine for return to service. The
appropriate logbook entries must be made in
accordance with Part 43 of the Federal Aviation
Regulations (FAR) before the engine can be
returned to service.

Post Maintenance Adjustment and Test

22-19

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22-20

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