FreeFlight Systems RA4XXX Radar Altimeter that measures altitude above ground level User Manual TYPE CERTIFICATION REPORT

FreeFlight Systems Radar Altimeter that measures altitude above ground level TYPE CERTIFICATION REPORT

User Manual

Rhein Tech Laboratories, Inc. Client: FreeFlight Systems 360 Herndon Parkway Model: RA-4000 Series Suite 1400 FCC ID: T7YRA4XXX Herndon, VA 20170 Standards: Part 87 www.rheintech.com Report #: 2008233 Appendix G: User Manual Please refer to the following pages for the manual. 22 of 27
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F EQUIPMENT INSTALLATION MANUAL FOR FREEFLIGHT SYSTEMS RA-4000 SERIES RADAR ALTIMETERS Part Numbers 84560-XX FreeFlight Systems 3700 Interstate 35 South Waco, TX 76706-3756 U.S.A. 1 (254) 662-0000 1 (800) 487-4662
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F REVISION HISTORY REV DESCRIPTION DATE A Initial release 02-Oct-05 B Released per ECN F05032 21-Nov-05 C Released per ECN F06008 11-Sep-06 D Released per SRR #7 20-Sep-07 E Released per ECN F08008 14-Aug-08 F Released per ECN F08030 21-Nov-08
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F i Table of Contents 1 INTRODUCTION.......................................................................................................1-1 1.1 REFERENCE DOCUMENTS.........................................................................................1-2 1.2 TABLE OF ACRONYMS & ABBREVIATIONS...............................................................1-2 2 DESCRIPTION...........................................................................................................2-1 2.1 OPERATIONAL MODES.............................................................................................2-1 2.2 SYSTEM LIMITATIONS..............................................................................................2-2 2.3 SPECIFICATIONS.......................................................................................................2-3 2.4 COMPONENT AND ACCESSORY PART NUMBERS ......................................................2-4 2.5 LICENSE REQUIREMENTS .........................................................................................2-4 3 ELECTRICAL INTERFACE....................................................................................3-1 3.1 GROUND ..................................................................................................................3-1 3.2 POWER IN................................................................................................................3-1 3.3 RESET ......................................................................................................................3-1 3.4 STRUT INPUT............................................................................................................3-2 3.5 NAV TX/RX............................................................................................................3-2 3.6 PGM-EN.................................................................................................................3-2 3.7 NAV-BIAS................................................................................................................3-2 3.8 NAV-COM................................................................................................................3-2 3.9 NAV-TXA/TXB ......................................................................................................3-2 3.10 ARINC-TXA/TXB ...............................................................................................3-2 3.11 ARINC SPEED SELECT ..........................................................................................3-2 4 FUNCTIONAL INTERFACES.................................................................................4-1 4.1 RS-232/422/485 INTERFACE ...................................................................................4-1 4.2 ARINC 429 INTERFACE...........................................................................................4-3 5 MECHANICAL ..........................................................................................................5-1 5.1 RA-4000 MOUNTING...............................................................................................5-1 5.2 CONNECTORS...........................................................................................................5-1 5.3 ANTENNA MOUNTING..............................................................................................5-3 6 INSTALLATION........................................................................................................6-2 6.1 GENERAL INFORMATION..........................................................................................6-2 6.2 UNPACKING AND INSPECTING EQUIPMENT ..............................................................6-2 6.3 EQUIPMENT LIMITATIONS........................................................................................6-2 6.4 ANTENNA INSTALLATION ........................................................................................6-3 6.5 RA-4000 INSTALLATION .........................................................................................6-4 APPENDIX A – ENVIRONMENTAL CATEGORIES.............................................6-1
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F ii List of Figures Figure 1-1: RA-4000 System Block Diagram .................................................................1-1 Figure 5-1: RA-4000 Installation Drawing......................................................................5-2 Figure 5-2: Antenna (P/N 9-1203-115-00) Installation Drawing ....................................5-3 List of Tables Table 2-1: System Technical Characteristics...................................................................2-3 Table 2-2: RA-4000 Physical Characteristics..................................................................2-3 Table 2-3: Antenna (P/N 9-1203-115-00) Physical Characteristics ................................2-3 Table 2-4: RA-4000 Install Kit........................................................................................2-4 Table 2-5: Optional FreeFlight Install Kit and Parts .......................................................2-4 Table 2-6: Other Accessories...........................................................................................2-4 Table 3-1: RA-4000 Interface Pin out .............................................................................3-1 Table 4-1: Data Field Definition......................................................................................4-1 Table 4-2: Status Byte Bit Definition ..............................................................................4-2 Table 4-3: Sample Packet at 1000’..................................................................................4-2 Table 5-1: Connector Descriptions..................................................................................5-1 Table 6-1: Propagation Delay and Attenuation of the Antenna Cable ............................6-3 Table 6-2: Typical Antenna Cable Lengths.....................................................................6-3
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 1-1 1 Introduction This manual contains installation data and specifications for the FreeFlight Systems RA-4000 Series Radar Altimeters (P/N 84560-XX), hereafter referred to as the RA-4000. The RA-4000 meets the requirements for a TSO-C87 Radar Altimeter with Precision Equipment output. The RA-4000 is designed to provide altitude above ground level (AGL) data to an electronic flight instrument system (EFIS), an integrated Flight Management System (FMS), or a navigation management system (NMS). Altitude is calculated by assessing the round trip delay of a signal reflected from the ground. The system consists of three Line Replaceable Units (LRUs): the RA-4000 Receiver/Transmitter (R/T) Unit and two Antenna Units (refer to section 2.4). Refer to Figure 1-1 for a system block diagram. Power InStrut Switch InAltitude out:- Serial RS-485/422- Serial RS-232CI/ORA-4000TransmitReceive Figure 1-1: RA-4000 System Block Diagram
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 1-2 1.1 Reference Documents Document Number Title RTCA/DO-160E Environmental Conditions and Test Procedures for Airborne Equipment; 29-July-97 (incorporating Change 1 dated 14-Dec-00, Change 2 dated 12-June-01, and Change 3 dated 05-Dec-02). RTCA/DO-178B Software Considerations In Airborne Systems And Equipment Certification; 1-Dec-92. TSO-C87 AIRBORNE LOW-RANGE RADIO ALTIMETER; 1-Feb-1966. RTCA/DO-155 Minimum Performance Standards Airborne Low-Range Radar Altimeters; 1-Nov-1974. ARINC 429 Mark 33 Digital Information Transfer System; May 17, 2004 1.2 Table of Acronyms & Abbreviations The following acronyms and abbreviations are used throughout this document. Abbreviation Definition A Ampere AGL Above Ground Level BCD Binary Coded Decimal dB Decibels EFIS Electronic Flight Instrument System FAR Federal Aviation Regulations FFS FreeFlight Systems FMCW Frequency Modulated Continuous Wave FMS Flight Management System Hz Hertz LRU Line Replaceable Unit LSB Least-Significant Bit MHz Mega-Hertz ms Milliseconds NCD No Computed Data NMS Navigation Management System ns Nanoseconds P/N Part Number R/T Receiver / Transmitter RX Receive SDI Source/Destination Indicator SSM Sign/Status Matrix TNC Threaded Neill-Concelman [connector] TSO Technical Standard Order TX Transmit VCO Voltage-Controlled Oscillator VDC Volts Direct Current
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 2-1 2 Description A complete system consists of an RA-4000 R/T unit (P/N 84560-XX) and two antennas (refer to section 2.4). The RA-4000 provides AGL altitude information from -20 feet up to 2000 feet maximum via computer interface. The RA-4000 Radar Altimeter system utilizes a reliable solid-state voltage-controlled oscillator (VCO) to drive its transmitter. Embedded processors precisely measure the signal delay, calculate the altitude, and provide a simple to use computer interface. 2.1 Operational Modes Once the unit has completed a reset, it begins outputting data at a 25 Hz rate. Data consists of the altitude and a status byte on the RS-232/422/485 interface (refer to section 4 for a description of the protocol) and labels 164, 165, and 377 on the ARINC 429 interface. Following is a description of different modes for the unit. 2.1.1 Power On Self-Test At power on, the system initializes operation and performs a self-test for approximately 20 seconds. In the self-test, the lock circuitry is tested and a test signal applied to the receive circuitry. During this time, the unit reports an altitude of 40±3 feet and asserts the “Self-Test” bit in the status byte (see section 4.1.2.1.4). 2.1.2 Altitude Zero Calibration When the Altitude Zero Calibration mode is selected during installation, the unit automatically calibrates the zero altitude point. This automatically compensates for different cable lengths and different antenna installation heights above the ground that would otherwise bias the altitude reading. 2.1.3 On Ground Operation While on the ground, the unit is susceptible to erroneous readings caused by signals returned from nearby buildings or personnel. Utilization of the strut input allows the unit to ignore these erroneous signals and report zero feet. The “Strut” bit of the status byte (see section 4.1.2.1.4) provides an indication of the input signal. 2.1.4 Normal Operation When the unit detects a locked signal and does not have a strut indication (i.e. – aircraft in the air), it reports altitude with the “Signal” bit indicating locked. If unusual terrain, aircraft orientation, or environmental conditions prevent a stable received signal, the “Signal” bit of the status word indicates unlocked.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 2-2 2.2 System Limitations 2.2.1 Terrain At altitudes above 1500 feet, terrain with poor reflectivity may cause the unit to unlock. Examples of unfavorable terrain are dry, loose soil, (e.g. - tilled farmland), or sand. 2.2.2 Excessive Pitch/Roll An excessive pitch or roll attitude may also cause the system to unlock. This sensitivity increases with altitude. In general, below 1500 feet a 30 degree bank is tolerated. Above 1500 feet, the aircraft should be maintained within a 20 degree bank for proper operation. If the unit unlocks due to marginal conditions, it will automatically relock when a signal sufficient for ranging is detected. 2.2.3 Rapid Descent In cases of extremely rapid descent, both the response time of the system and pitch of the aircraft may prevent normal operation. At a descent rate of 1500 feet/minute or less, the RA-4000 system provides normal operation below 2000 feet. 2.2.4 Response Time When flying the RA-4000 system over rapidly changing terrain, e.g., a cliff or ravine, the system is limited by the 100 ms maximum response time of the unit. Note: The RA-4000 system surveys ground directly below the aircraft, and should not be relied on as either a forward looking or warning device.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 2-3 2.3 Specifications Specifications for the RA-4000 system are listed in Tables 2-1 through 2-3. Table 2-1: System Technical Characteristics Parameter Value Type Dual antenna, FMCW Compatible Antennas 1) FreeFlight P/N 9-1203-115-00 2) EDO P/N DM PN19-2-1 Altitude Range -20 to 2000 feet Altitude Accuracy 0 to 100 feet +/- 3 feet 100 to 500 feet +/- 3% 500 to 2000 feet +/- 5% Frequency Range 100 MHz sweep 4.25 - 4.35 GHz Sweep Frequency 100 Hz Input Voltage 20-36 VDC (Internal fuse and reverse polarity protection) Input Current 400 mA Max @ 28 VDC (steady-state) Max. Inrush Current 7 A for 1 ms @ 28 VDC Altitude Output, Rate 25 Hz Altitude Latency less than 100 ms (63% of final value) Operating Temperature -55°C to +70°C Self-Test / Reset On system power-up Environmental DO-160E Certifications TSO-C87, DO-178B Level C Table 2-2: RA-4000 Physical Characteristics Parameter Value Weight 1.9 lb Height 3.06” Length (Including mounting flange) 6.78” Width 3.15” Connectors 2 each TNC antenna connectors 1 each 22 pin circular connector Table 2-3: Antenna (P/N 9-1203-115-00) Physical Characteristics Parameter Value Quantity 2 Weight 0.3 lbs (0.6 lbs total) Dimensions 3.5" W x 3.65" L x .15" H
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 2-4 2.4 Component and Accessory Part Numbers Each RA-4000 unit is shipped individually, as indicated in Table 2-4. Two antennas and associated wiring are also required for installation. An Installation kit is available from FreeFlight, as indicated in Table 2-5. The items listed in Table 2-6 are required, but not supplied by FreeFlight. Table 2-4: RA-4000 Install Kit ITEM FREEFLIGHT P/N QUANTITY RA-4000 R/T Unit 84560-XX 1 required Table 2-5: Optional FreeFlight Install Kit and Parts ITEM FREEFLIGHT P/N QUANTITY Optional Installation Kit 84933-00 1 required Coax Cable RG-142 B/U (30 ft) 0123-0012-00 1 per kit Antennas 9-1203-115-00 2 per kit Connector TNC 0129-0017-00 4 per kit 22 Pin connector RA-4000 Series 84443 1 per kit Connector Backshell Strain Relief 84444 1 per kit Note: EDO Corporation’s Radar Altimeter Antenna (EDO P/N PN19-2-1) is also compatible with FreeFlight Systems RA-4000 Radar Altimeter Unit. These antennas are not sold by FreeFlight Systems and must be purchased from the manufacturer directly or from any EDO antenna dealer. Refer to the manufacturer’s documentation for the specifications for these antennas. Table 2-6: Other Accessories ITEM FREEFLIGHT P/N QUANTITY System Wiring N/A As required Circuit Breaker N/A 1 System Indicator N/A 1 Mounting Tray for altimeter 1900-3121-X2 1 2.5 License Requirements As installed in the aircraft, the radar altimeter does not require an FCC operator’s license. For information, reference FCC 47 CFR Part 87.89 Minimum operator requirements.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 3-1 3 Electrical Interface Electrical interconnection to the RA-4000 is made via 22-pin connector. Refer to Table 3-1 for a description of the pin out. Table 3-1: RA-4000 Interface Pin out Pin Name Function Direction Level 1 Ground Ground - Ground 2 Ground Ground - Ground 3 Power In Aircraft voltage in In 20-36 VDC 4 Power In Aircraft voltage in In 20-36 VDC 5 Reset Reserved In NO CONNECT 6 Reserved 7 Reserved 8 Strut Strut (active low) In Ground or open 9 Reserved 10 429 Speed Select* ARINC 429 Output Speed Select: Low Speed (default, pin open) High Speed (pin to ground) In Ground or open 11 ARINC-TXB* Navigation Port ARINC 429 Out ARINC 429 12 ARINC-TXA* Navigation Port ARINC 429 Out ARINC 429 13 Nav-TX Navigation Port RS-232C Transmit Out RS-232C 14 Nav-RX Navigation Port RS-232C Receive In RS-232C 15 PGM-EN Reserved In NO CONNECT 16 Reserved 17 Reserved 18 Nav-Bias RS-485 100 ohm ground connection - RS-485 Ground 19 Nav-Com Navigation Port Ground - Ground 20 Nav-Com Navigation Port Ground - Ground 21 Nav-TXA Navigation Port Serial RS-485/422 Out RS-485/422 22 Nav-TXB Navigation Port Serial RS-485/422 Out RS-485/422 *Only applicable to part number 84560-02. 3.1 Ground Aircraft ground is connected on two pins. 3.2 Power In Aircraft power of 20-36 VDC is connected on two pins. 3.3 Reset This circuit is reserved for factory test purposes only. Do not connect.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 3-2 3.4 Strut Input The Strut signal is an active low input. That is, the input should be grounded when the aircraft is on the ground. 3.5 Nav TX/RX The Nav-TX/RX lines use RS-232C signal levels. The RS-232C Nav-TX output carries the same data as the RS-485/422 Nav-TXA/TXB pair. The Nav-TX/RX lines are used to initiate the Altitude Zero Calibration function and to reprogram the unit via serial RS-232C protocol. Note that it may be advantageous to route these lines to a point which facilitates shorting them for the Altitude Zero Calibration (see 6.5.1). If this is done, care should be taken that the lines do not accidentally short during normal flight. During normal operation after the Zero Calibration has been accomplished, these lines should not be connected. 3.6 PGM-EN The Program-Enable input is used to reprogram the unit. Do not connect in normal operation. 3.7 Nav-Bias This pin provides a 100 ohm resistive ground connection for the RS-485 communications circuit. 3.8 Nav-Com These connections provide a direct ground reference, if desired. 3.9 Nav-TXA/TXB Used as the primary data interconnect, these pins are driven by an LTC485 device. 3.10 ARINC-TXA/TXB ARINC 429 labels 164, 165, and 377 are transmitted on this interface at a rate of 25 Hz. Cabling should shielded twisted pair with shield grounded to aircraft and radar altimeter chassis. 3.11 ARINC Speed Select This pin is used to configure the unit to output low-speed (12 kbps) or high-speed (100 kbps) ARINC 429 data. If this pin is left open (default) the system will output low-speed ARINC data. If the pin is connected to ground, the system will output high-speed ARINC data.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 4 Functional Interfaces The FreeFlight Systems Radar Altimeter provides serial RS-232/422/485 interfaces and an ARINC 429 interface (Part Number 84560-02 only). The following sections describe the protocols used. 4.1 RS-232/422/485 Interface 4.1.1 Data Rate Data is transmitted in multi-byte packets at 56,000 baud (LSB first, 8 data bits, one start, one stop, no parity). System altitude packets are output at a rate of 25 Hz. 4.1.2 Protocol Definition Note: The information in this section is intended for engineering personnel and is not required for installation. 4.1.2.1 Packet Structure Each packet conforms to the following structure: Field DLE ID LEN DATA CHECKSUM DLE ETX Content 0x10 0xDF 0x03 3 bytes 1 byte 0x10 0x03 4.1.2.1.1 DLE (Data Link Escape Character) Fixed byte = 0x10. 4.1.2.1.2 ID (Identification) Fixed byte = 0xDF. 4.1.2.1.3 Len (Length) Fixed byte = 0x03. 4.1.2.1.4 Data Three data bytes are defined as follows: Table 4-1: Data Field Definition Byte Definition 1 Altitude High byte of a 2-byte binary field. (Units: Feet; Range: -20 to 2500) 2 Altitude Low byte of a 2-byte binary field. 3 Status Byte (See Table 4-2)
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F Table 4-2: Status Byte Bit Definition Bit High (1) Indication Low (0) Indication 0 – Altitude Ascending Descending 1 – Self Test Test in progress Normal operation 2 – Status Unit Failure Normal operation 3 – Invalid Unlocked / Invalid output Locked / Valid output 4 – Strut De-asserted (In air) Asserted (On ground) 5 – Reserved 6 – Reserved 7 – Reserved 4.1.2.1.5 Checksum This is the one-byte 2’s complement of the sum of all the data bytes, including the packet ID and LEN bytes (i.e. 0xDF03). Refer to Table 4-3 for a sample packet with normal status (descending, locked, and good status) and an altitude of 1000 feet. Table 4-3: Sample Packet at 1000’ Byte DLE ID LEN Alt Hi Alt Lo Status Chk DLE ETX Value 0x10 0xDF 0x03 0x03 0xE8 0x00 0x33 0x10 0x03 4.1.2.1.6 DLE (Data Link Escape Character) Fixed byte = 0x10. 4.1.2.1.7 ETX (End Of Text Character) Fixed data byte = 0x03. 4.1.2.2 DLE Stuffing This protocol requires that an occurrence of the DLE (0x10) character in either the data or checksum must be followed by another DLE character. The receiver therefore, should remove, or “unstuff”, the second DLE character when two are received in sequence. Note that the “unstuffing” should occur prior to calculation of the checksum.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 4.2 ARINC 429 Interface This section applies to part number 84560-02 only. 4.2.1 Data Rate All ARINC 429 labels are transmitted at either low or high speed ARINC baud rates as configured at installation time (see section 3.11) and are transmitted at a rate of 25 Hz. 4.2.2 Protocol Definition Note: The information in this section is intended for engineering personnel and is not required for installation. 4.2.2.1 Parity The parity bit of all labels is set to odd parity. 4.2.2.2 Source/Destination Indicator (SDI) The SDI of all labels is set to 00. 4.2.2.3 ARINC 429 Labels The following labels are transmitted: SSM Label (octal) Description Non-Fault Fault 164 Radio Altitude (Binary) NCD/NORM FAIL 165 Radio Altitude (BCD) NCD/NORM N/A* 377 Equipment ID NORM NORM *In case of a failure, label 165 is not transmitted.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 5 Mechanical 5.1 RA-4000 Mounting The mounting requirements for the RA-4000 are illustrated in Figure 5-1. 5.2 Connectors Interfaces to the RA-4000 are provided through three connectors as described below in Table 5-1. Table 5-1: Connector Descriptions Function Description Aircraft interconnections This 22-pin circular connector mates with AMPHENOL P/N 10-565995-231N. TX Antenna This TNC connector mates with AMPHENOL P/N 225554-6 RX Antenna This TNC connector mates with AMPHENOL P/N 225554-6
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F NOTE: NOT TO SCALEFreeFlightRA-4000FRONTINSTALLATION DIMENSIONS Figure 5-1: RA-4000 Installation Drawing
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 5.3 Antenna Mounting Refer to Figure 5-2 for mounting information for antenna P/N 9-1203-115-00. All dimensions are specified in inches. Figure 5-2: Antenna (P/N 9-1203-115-00) Installation Drawing
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 6 Installation 6.1 General Information This chapter contains suggestions and factors to consider before installing an RA-4000 radar altimeter into an aircraft. Adherence to the suggestions will assure satisfactory performance from the system. 6.2 Unpacking and Inspecting Equipment Exercise care when unpacking each unit. Make a visual inspection of each unit for evidence of damage incurred during shipment. If a claim for damage is to be made, save the shipping container to substantiate the claim. When all equipment and the installation kit have been inspected, save the packing material and container in case the unit is to be stored or reshipped. See paragraph 2.4 for equipment and optional parts supplied. 6.3 Equipment Limitations For a compliant installation in accordance with the Technical Standard Order (TSO) and the Federal Aviation Regulations (FAR), the RA-4000 installation must meet the following requirements:  “The conditions and tests required for TSO approval of this article are minimum performance standards. It is the responsibility of those desiring to install this article either on or within a specific type or class of aircraft to determine that the article, when installed, performs in accordance with the design specifications that meet this TSO. The article may be installed only if further evaluation by the applicant documents an acceptable installation and is approved by the Administrator.”  RA-4000 must be connected to a display in a manner that yields no additional inaccuracies and with maximum additional latency of 80 ms (TSO-C87 §2.1). Added display inaccuracies trade with latency at a rate of ±1 ft to 40 ms; i.e., a display introducing ±1 ft of presentation error requires that the permissible installation/display component of latency decreases from 80 ms to 40 ms  The display connected to the RA-4000 must utilize a failure warning indicator plainly discernible under all normal flight conditions (TSO-C87 §2.6b) driven by the status and the invalid bit of the RA-4000 status byte (see Table 4-2: Status Byte Bit Definition).  The antenna installation must comply with the specifications in Section 6.4 Antenna Installation.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 6.4 Antenna Installation 6.4.1 Antenna Cable Selection The antenna cables must have a certain minimum and maximum length for the system to perform accurately and comply with the TSO. The absolute minimum cable length is limited by the required minimum signal propagation delay caused by the cable and the antenna height above the ground when the aircraft is on the ground. The absolute maximum cable length is limited by the maximum allowable attenuation of the signals caused by the cable. Table 6-1: Propagation Delay and Attenuation of the Antenna Cable Min Total Propagation Delay (ns) Max Attenuation (dB) 31 8.5 Table 6-2 shows typical values of propagation velocities, attenuations, and the minimum bend radius for commonly used cable types. Consult the cable manufacturer’s specifications for the exact values for the cables used in the installation. Table 6-2: Typical Antenna Cable Lengths Cable Min Total Length1 (ft) Max Total Length2 (ft) Min Bend Radius3 (in) Propagation Velocity (c) Attenuation/100’ (dB) @ 4.35 GHz RG-142 21.0 28.8 3 69.4 % 29.5 RG-393 21.0 47.8 6 69.4 % 17.8 Note: Total length refers to the combined lengths of the TX and the RX cables. 1 The minimum cable length specified assumes that the antennas are mounted 18” above the ground, resulting in a 3 ns return delay (The propagation delay in air is approximately 1 ns per foot). If the manufacturer’s data indicates a different propagation velocity than the one given in Table 6-2 the minimum cable length must be recomputed by the installer. 2 If the manufacturer’s data indicates a different attenuation than the one given in Table 6-2 the maximum cable length must be recomputed by the installer. 3 The manufacturer specified minimum bend radius may differ. 6.4.2 Antenna Mounting Requirements Refer to Figure 5-2 for mounting instructions. For proper performance and TSO compliance of the RA-4000, the radar altimeter antennas must be installed according to the following rules:
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F  Antennas should be mounted parallel to the ground within a pitch angle of 6° when the aircraft is in level flight.  Antennas should be mounted with the arrows pointing forward. They may be mounted side-by-side or in-line.  If the antennas are mounted in-line, which is the preferred configuration, the transmit antenna should be mounted in front of the receive antenna.  The angle between the pitch of both antennas should not exceed 6°.  The antennas should be mounted such that no protrusion is visible to either antenna within a 60-degree cone below the aircraft.  Antennas should be mounted at least 18" apart and within 40" of each other.  The antenna height above the ground when the aircraft is on the runway should be more than the separation distance between the two antennas.  Antennas should be mounted as close to the aerodynamic center of the aircraft as possible to reduce the effects of aircraft attitude on the altitude measurement.  Antennas should not be mounted closer than 3’ to a DME, transponder, ADF or VHF antenna.  During installation, avoid locations near high heat sources or where fuel, oil or excessive moisture may collect. Bond and shield all parts of the aircraft electrical system such as generators and ignition systems. 6.5 RA-4000 Installation The RA-4000 unit installation layout is shown in Figure 5-1. Route all data and power cables away from circuits carrying high current, pulse-transmitting equipment, 400 Hz circuits and other sources of interference. Do not route with ADF antenna cables. Note: Aircraft which exhibit electrical noise on the airframe or have surfaces or panels which are not properly bonded can cause the altimeter to attempt to "relock" above 2000 feet AGL, thus causing erratic altitude output. Thorough bonding of all control surfaces, gear doors, access panels, etc. should cure the symptom, but in certain extreme circumstances, it may be necessary to install an on/off switch to disable the unit above 2000 feet. This condition is only noticeable above 2000 feet and does not degrade performance below 2000 feet AGL.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F 6.5.1 Altitude Zero Calibration The RA-4000 should be calibrated to account for the antenna height above ground when a zero foot altitude is desired. This procedure should be performed once on initial install of the unit or after servicing the unit. Reflections due to surrounding obstacles may cause inaccurate calibration. It is recommended to Zero the RA-4000 in an open area away from buildings, trees, or other large reflecting surfaces to improve accuracy. Note: If this procedure is not performed on install, after service, or is improperly performed, altitude may not be correct. 1. Remove or disable the Strut input to the system. 2. Clear all obstacles from around aircraft (including personnel). 3. Turn unit on and let run for a minimum of 5 minutes to warm up. 4. Turn off unit and all aircraft power. 5. Short together RS-232C navigation port TX and RX pins. 6. Switch power on for approximately 30 seconds. 7. Switch power off and remove the short from the TX and RX lines. 8. Switch power on. After the self-test is complete, the unit should now output 0' while on ground. 9. Test and repeat as necessary. 10. Restore the Strut input, if necessary. 6.5.2 Pre-Flight Check List 1. Turn on power (after starting engines). 2. Verify the unit self-tests for approximately 20 seconds (during which it displays 40±3 feet and sets the self test flag). 3. After the self-test mode, the unit should output 0 feet while the aircraft is on the ground. 6.5.3 Final Testing 1. During takeoff observe AGL and verify that it is increasing while the aircraft is climbing. 2. After aircraft exceeds 2000 feet AGL verify that unit indicates “unlocked”. 3. With the aircraft above 3000 feet AGL in an open area: a. Put the aircraft into a 500-foot per minute descent. b. The unit should lock and start outputting valid altitude by 2000 feet AGL.
Equipment Installation Manual RA-4000 Series Radar Altimeters P/N 84629, Rev F Appendix A – Environmental Categories Refer to Table A-1 for a summary of RA-4000 Test Categories. Table A-1: DO-160E Test Categories Environmental Test DO-160E Section Category Compliance Method Temperature and Altitude 4 D2 T Temperature Variation 5 B T Humidity 6 B T Shock/Crash Safety 7 B T Vibration 8 S Curve C & U2 T Explosion Proofness 9 n/a X Waterproofness 10 W T Fluids Susceptibility 11 n/a X Sand and Dust 12 n/a X Fungus 13 n/a X Salt Spray 14 n/a X Magnetic Effect 15 Z T Power Input 16 B T Voltage Spike 17 A T Audio Frequency Conducted Susceptibility – Power Inputs 18 B T Induced Signal Susceptibility 19 ZC T Radio Frequency Susceptibility 20 RR T Emission of Radio Frequency Energy 21 M T Lightning, Induced Transient Susceptibility 22 A2XXX T Lightning Direct Effects 23 n/a X Icing 24 n/a X Electrostatic Discharge 25 A T Fire, Flammability 26 C T
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