Garmin GTR 225 Installation Manual
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Garmin GTR 225 Installation Manual

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GTR 225/GNC 255
TSO Installation Manual
190-01182-02
March 2015
Revision F

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  • Page 1 GTR 225/GNC 255 TSO Installation Manual 190-01182-02 March 2015 Revision F...
  • Page 2 Garmin. Garmin hereby grants permission to download a single copy of this manual and of any revision to this manual onto a hard drive or other electronic storage medium to be viewed and to...
  • Page 3 Added new section, “COM Keypad Input (Display Software Version 2.10 or later). B.2.4.1.13 Added new section, “NAV Keypad Input (Display Software Version 2.10 or later). Added GNS 480 to figure D-15. Appendix D Added figure D-16, “GTR/GNC-GMX 200 Interconnect.” 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B...
  • Page 4 $1,000,000 under Section 2410 of the Export Administration Act of 1979. Include this notice with any reproduced portion of this document. This information in this document is subject to change without notice. Visit Garmin’s website (www.garmin.com) for updates and supplemental information concerning the operation of Garmin products.
  • Page 5 Battery replacement and removal must be performed by professional services. CAUTION To avoid damage to the GTR 225 or GNC 255, take precautions to prevent Electrostatic Discharge (ESD) when handling the GTR, connectors, fan, and associated wiring. ESD damage can be prevented by touching an object of the same electrical potential as the unit before handling the unit itself.

  • Page 6: Table Of Contents

    Configuration Mode Operations ....................6-2 Ground Checks (Configuration Mode) ................6-16 Ground Checks (Normal Mode) ..................6-19 Flight Checks ........................6-22 Software Loading .........................6-23 CONTINUED AIRWORTHINESS ....................7-1 APPENDIX A ENVIRONMENTAL QUALIFICATION FORM ............A-1 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page iii...
  • Page 7 B.1 RS-232 Aviation Format ....................... B-1 B.2 RS-232 NMEA Data Format ....................B-5 APPENDIX C MECHANICAL DRAWINGS ..................C-1 C.1 Drawing List ......................... C-1 APPENDIX D INTERCONNECT DIAGRAMS ................D-1 D.1 Drawing List .........................D-1 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page iv...
  • Page 8 Figure D-10 GNC - King Serial DME - Remote Mount Interconnect ..........D-17 Figure D-11 GNC - Parallel 2 of 5 DME Tuning Interconnect ............D-19 Figure D-12 GNC - Parallel Slip Code DME Tuning Interconnect .............D-21 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page v...
  • Page 9 Figure D-14 GNC - GDU 620 Interconnect ..................D-24 Figure D-15 GTR/GNC - GTN 6XX/7XX, GNS 400W/500W, and GNS 480 Interconnect .....D-25 Figure D-16 GTR/GNC - GMX 200 Interconnect ................D-26 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page vi...
  • Page 10 Table B-1 Aviation Output Sentence Format ..................B-2 Table B-2 Type 2 Aviation Output Sentence Format ................B-4 Table B-3 Input Message Summary ..................... B-21 Table B-4 Output Message Summary ....................B-21 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page vii...
  • Page 11 The table is current at the time of publication of this manual and is subject to change without notice. Authorized Garmin sales and service centers are encouraged to access the most up-to-date bulletin and advisory information at Garmin’s...

  • Page 12: General Description

    011-02719-20 Compatible The GTR 225 and GNC 255 Series units are a family of 6.25" wide, 1.65" tall panel-mounted VHF COM and NAV/COM radios. The GTR 225 Series include an airborne VHF communications transceiver. The GTR 225 Series meet the requirements of the TSOs specified in table 1-10.
  • Page 13 All information depicted in screen shots, including software file names, versions, and part numbers, is subject to change and may not be up to date. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-2...

  • Page 14: General Specifications

    GTR 225 weight (unit only) 2.36 lbs (1.07 kg) GNC 255 weight (unit only) 3.02 lbs (1.37 kg) GTR 225 installed with rack and connectors 3.06 lbs (1.39 kg) GNC 255 installed with rack and connectors 3.96 lbs (1.80 kg) -20C to +55C...

  • Page 15: Com Specifications

    30 seconds time-out, reverts to receive Less than 5% distortion when the transmitter is at 85% modulation Demodulated audio distortion at 350 to 2500 Hz Sidetone 1.4 Vrms into a 500 Ω load 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-4...

  • Page 16: Table 1-5 Com Receiver Specifications

    6 dB BW is greater than ±3.5 kHz for 8.33 kHz channeling 60 dB BW is less than ±7.37 kHz for 8.33 kHz channeling Maximum audio output reduction (offset 11.2 dB carrier operation) 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-5...

  • Page 17: Vor Specifications

    In voice mode, an IDENT tone of 1020 Hz Ident Tone is attenuated at least 20 dB down The distortion in the receiver audio output does not exceed 10% at Audio distortion all levels up to 100 mW 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-6...

  • Page 18: Loc Specifications

    In voice mode, an IDENT tone of 1020 Hz Ident Tone is attenuated at least 20 dB down The distortion in the receiver audio output does not exceed 10% at Audio distortion all levels up to 100 mW 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-7...

  • Page 19: Glideslope Specifications

    50% of the standard deflection Flag • Absence of 150 Hz modulation • Absence of 90 Hz modulation • Absence of both 90 Hz and 150 Hz modulations • Absence of RF signals 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-8...

  • Page 20: Current Draw Specifications

    [2] The specified current draw does not include the superflags. If connected, their current draw must be added to the specified current. The superflags will supply up to 320 mA each regardless of the input voltage. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 1-9...

  • Page 21: License Requirements

    1.4.4. CAUTION The VHF transmitter in this equipment is guaranteed to meet FCC acceptance over the operating temperature range. Modifications not expressly approved by Garmin could invalidate the license and make it unlawful to operate the equipment. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev.

  • Page 22: Certification

    The installer should verify non-Garmin devices, which are to be interfaced with the GTR/GNC, meet the installation requirements identified in this manual to assure the installed system will comply with the Garmin TSO/ETSO authorization.
  • Page 23 3. Garmin was granted a deviation from the TSO to use RTCA/DO-178B instead of an earlier version to demonstrate compliance for the verification and validation of the computer software. 1. Garmin was granted a deviation from the ETSO to have a deflection response of 0.5 to 2.7 ETSO-2C40c seconds.

  • Page 24: Gtr/Gnc Database

    The GTR/GNC database has no safety effect, and does not claim compliance with RTCA/DO-200A Standards for Processing Aeronautical Data. Garmin requests that the flight crew report any observed discrepancies related to database information. These discrepancies could come in the form of an incorrect frequency, incorrectly identified airport, VOR, or other station, or any other displayed item used for navigation or communication in the air or on the ground.

  • Page 25: Aviation Limited Warranty

    (iv) damage caused by service performed by anyone who is not an authorized service provider of Garmin; or (v) damage to a product that has been modified or altered without the written permission of Garmin. In addition, Garmin reserves the right to refuse warranty claims against products or services that are obtained and/or used in contravention of the laws of any country.

  • Page 26: Limitations

    Part 27 aircraft. To meet requirements for Part 23 Class II, Class III and Class IV, and Part 27 aircraft, it may be necessary to install a second VHF communications radio. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 2-1...

  • Page 27: Installation Overview

    In accordance with Canadian Radio Specifications Standard 102 (RSS 102), RF field strength exposure to persons from an antenna connected to this device should be limited to 60V/m for controlled environment and 28 V/m for uncontrolled environment. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 3-1...

  • Page 28: Gtr/Gnc Mounting Considerations

    GTR/GNC unit is not blocked by the glare shield on top, or by the throttles, control yoke, etc., on the bottom. If aircraft has a throw-over yoke, be sure the yoke does not interfere with the GTR/GNC. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 3-2...

  • Page 29: Cabling And Wiring Considerations

    After reconfiguring the avionics in the cockpit panel, if the GTR/GNC unit is mounted less than twelve inches from the compass, recalibrate the compass and make the necessary changes for noting correction data. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 3-3...

  • Page 30: Installation Procedures

    GPS 1.57542 GHz notch filter 330-00067-00 Connector, TNC, male, clamp 031-4452 [1] [1] This part is not available from Garmin. Vendor Contact Information (provided for convenience only): Amphenol RF, Four Old Newtown Road, Danbury, CT 06810 Phone: (800) 627-7100 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev.

  • Page 31: Optional Reference Material

    Push/pull (manually resettable) circuit breakers  Tie wraps or lacing cord  Ring terminals (for grounding)  Coaxial cable (RG-400, RG-142B or equivalent. See table 4.8 for additional information) 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 4-2...

  • Page 32: Special Tools Required

    P2001-P2002 Wire Gauge 22-28 AWG Garmin P/N 336-00021-00 Military P/N M39029/58-360 [1] [1] Non-Garmin part numbers shown are not maintained by Garmin and are subject to change without notice. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 4-3...

  • Page 33: Coaxial Cable Installation

    4. Slide the backplate to the right (viewing from cockpit) until it clicks into place. 5. Secure the backplate by tightening the four #4-40 screws. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 4-4...

  • Page 34: Com Antenna Installation And Connections

    This would be an acceptable place to insert the VSWR. Any problem with the antenna installation is most likely seen as high reflected power. A VSWR of 3:1 may result in up to a 50% loss in transmit power. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 4-5...

  • Page 35: Connector Pinout Information

    LIGHTING LO 1 RESERVED RESERVED RESERVED COM MIC 2 KEY* COM REMOTE TRANSFER* COM REMOTE TUNE UP* COM REMOTE TUNE DOWN* AIRCRAFT POWER RS-232 GND LIGHTING LO 2 RESERVED 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-1...
  • Page 36 An asterisk (*) following a signal name denotes that the signal is an Active-Low, requiring a ground to activate. If there is no asterisk, the signal is an Active-High. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-2...
  • Page 37 VOR/ILS ARINC 429 OUT A VOR OBI CLOCK VOR OBI SYNC VOR OBI DATA VLOC REMOTE TRANSFER ILS ENERGIZE SPARE SPARE GLIDESLOPE +FLAG PAR DME 1 MHZ-D/SERIAL DME ON GLIDESLOPE +UP RESERVED RESERVED 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-3...
  • Page 38 AIRCRAFT GND RESERVED AIRCRAFT POWER AIRCRAFT POWER GLIDESLOPE - FLAG PAR DME 100 kHz-E GLIDESLOPE +DOWN PAR DME 1MHZ-E RESERVED GLIDESLOPE COMPOSITE OUT RESERVED AIRCRAFT GND AIRCRAFT GND AIRCRAFT GND 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-4...

  • Page 39: Power, Lighting, And Antennas

    Pin Name Connector LIGHTING HI 1 P2001 LIGHTING HI 2 P2001 LIGHTING LO 1 P2001 LIGHTING LO 2 P2001 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-5...
  • Page 40 Destination waypoint identifier  Bearing to destination waypoint  Magnetic variation  Navigation and warning status  Waypoint sequence in route  Waypoint position (latitude and longitude) and magnetic variation 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-6...
  • Page 41 Set NAV audio mode (GNC only)  Set omni-bearing select (OBS) value (GNC only)  Set NAV volume level (GNC only)  NAV keypad input (GNC only) (software version 2.10 or later) 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-7...
  • Page 42 COM AUDIO is the summation of the COM receiver audio, COM sidetone audio, and intercom audio. Pin Name Connector Ω COM AUDIO HI P2001 Ω COM AUDIO LO P2001 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-8...
  • Page 43 COM selections only. The pilot may exit this independent mode, restoring COM selection control to the front panel knobs and keys, by again depressing the switch for two seconds. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-9...
  • Page 44 VOR/LOC REMOTE TRANSFER* discrete input may be used to flip-flop between the active and standby NAV frequencies. A momentary low on this pin will load the standby NAV frequency into the active NAV frequency field. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-10...
  • Page 45 +225 ± 75 mVDC. When indicating FROM, output is -225 ± 75 mVDC. When invalid information is present (Flag IN VIEW) the TO/FROM output is 0 ± 10 mVDC. Pin Name Connector VOR/LOC +TO P2002 VOR/LOC +FROM P2002 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-11...
  • Page 46 The driver output voltage is not more than 1.0 V when sinking 20 mA. The maximum off state leakage current with respect to GND is less than 10 A. Pin Name Connector ILS ENERGIZE P2002 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-12...
  • Page 47 The maximum off state leakage current with respect to ground is less than 10 μA. Pin Name Connector VOR OBI CLOCK P2002 VOR OBI SYNC P2002 VOR OBI DATA P2002 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-13...
  • Page 48 PAR DME 50kHz P2002 PAR DME 1MHZ-A P2002 PAR DME 1MHZ-B P2002 PAR DME 1MHZ-C P2002 PAR DME 1MHZ-D/SERIAL DME ON P2002 PAR DME 1MHZ-E P2002 DME COMMON P2002 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-14...
  • Page 49 SERIAL DME - DATA P2002 SERIAL DME - CLOCK P2002 SERIAL DME - RNAV/CH REQ P2002 SERIAL DME - RNAV MODE P2002 DME COMMON P2002 SERIAL DME - DME REQUEST P2002 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 5-15...

  • Page 50: Post Installation Configuration And Checkout Procedures

    The GTR/GNC can be installed after completion of the continuity and power checks. The GTR/GNC should be installed into the rack and secured appropriately, as described in section 4.7.1. The GTR/GNC must be connected to the wiring harness and antennas. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-1...

  • Page 51: Connector Engagement Check

    2. Press and hold the ENT key. 3. Apply power to the GTR/GNC by turning the COM volume knob. 4. When “Garmin” appears on the screen release the ENT key. The first page displayed is the CONFIG MODE page. In configuration mode there are five configuration groups.

  • Page 52: Figure 6-2 Serial Port Page

    No serial data input/output. Serial port will receive “RS-232 Aviation” format input data, as defined in appendix B.1 (for example, as received from Garmin GTN 6XX/7XX and AVN IN/MAPCOM GNS 400W/500W Series navigators). There is no serial data output from the GTR/GNC with this selection.

  • Page 53: Figure 6-4 Intercom Enable Page

    This sets the minimum brightness of the bezel keys or display. The display minimum brightness level has a range from 1 to 100. The default level is 1. The bezel key minimum brightness level has a range from 0 to 100. The default level is 1. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-4...

  • Page 54: Table 6-4 Photocell Page Parameter Description

    0 (zero) to 100, and is set to 50 as a default value. This may also be used to match lighting curves with other equipment in the panel. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-5...

  • Page 55: Figure 6-7 Lighting Bus Page

    The DISPLAY INFORMATION page shows the display software version, software part number, unit serial number, minimum software level, hardware version, boot version, part number, and minimum boot version of the unit. Figure 6-8 Display Information Pages 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-6...

  • Page 56: Figure 6-9 Software Update Page

    Disables all internal OBS functions. Allows use of conventional external CONVERTER converter via the composite output pin. For use with serial Electronic Flight Instrument System (EFIS) conforming SERIAL to the Garmin serial data specification. See appendix B. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-7...

  • Page 57: Figure 6-11 Calibrate Obs Resolver Page

    Number 1 (Pilot) VOR/ILS Receiver VOR/ILS 1 TX: Generates all 429 outputs with SDI = 1 Number 2 (Copilot) VOR/ILS Receiver VOR/ILS 2 TX: Generates all 429 outputs with SDI = 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-8...

  • Page 58: Table 6-9 Dme Settings

    DME is tuned. DIRECT FREQ 1 should be selected if a single-channel ARINC 429 DME is to be tuned. If the GNC is connected to a multi-channel ARINC 429 DME, channel 2 of DIRECTED FREQ 2 that DME is tuned. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-9...

  • Page 59: Figure 6-13 Nav Information Page

    6.4.2.6 NAV Update The NAV update page loads the NAV software to the GNC. See section 6.8 for instructions on loading software to the GNC. Figure 6-14 NAV Software Update Page 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-10...

  • Page 60: Figure 6-15 Mic Gain Page

    COM receiver. See table 6-11 for a description of each setting. Garmin changed the GTR/GNC COM radio factory calibration process to allow the level when the auto squelch opens or closes, to be set at a more sensitive level. The COM RX squelch range (0-100) was remapped as shown in table 6-11.

  • Page 61: Figure 6-17 Com Information Page

    The COM INFORMATION page shows the COM board software version, software part number, hardware version, boot version, boot P/N, FPGA version, and FPGA P/N. Figure 6-17 COM Information Page 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-12...

  • Page 62: Figure 6-18 Com Software Update Page

    However, transmitted audio quality issues may not be noticed by the pilot until notified by air traffic control (ATC). Some pilots prefer the sound quality of the internal sidetone versus the external sidetone. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-13...

  • Page 63: Figure 6-20 Mix Nav Audio Page

    P2001-3 and 19, it may be desirable to enable the hi-fidelity audio. Turn the inner knob to ON or OFF. Press ENT when the appropriate selection is displayed. Figure 6-21 Hi-Fidelity Audio Page 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-14...

  • Page 64: Figure 6-22 Download Log Page

    6.4.5.1 Download Log Page NOTE Garmin recommends the use of a USB 2.0 compatible flash drive for downloading files from the GTR/GNC. The flash drive must be formatted as FAT32. The DOWNLOAD LOG page is where the GTR/GNC keeps an error log to aid in diagnostics and troubleshooting.

  • Page 65: Ground Checks (Configuration Mode)

    8. Verify that the OBS decoded properly from 0 to 360 degrees. If the GNC will not accept the calibration, there may be a problem with the resolver interface. Verify wiring and contact Garmin for assistance, if necessary. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev.

  • Page 66: Figure 6-25 Test Analog Flags Page

    8. Turn the outer knob to T/F. 9. Turn the inner knob to set the T/F flag as FROM, TO, or HIDDEN. 10. Verify the flags on the connected indicator function as configured. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-17...

  • Page 67: Figure 6-26 Test Cdi/Vdi Page

    2. Slowly vary the lighting bus level that is connected to the GTR/GNC. 3. Verify the display brightness tracks the lighting bus setting. 4. Continue to maximum brightness and verify operation. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-18...

  • Page 68: Ground Checks (Normal Mode)

    4. Ensure the Morse code identifier is being received over the crew headsets. 5. Verify the wiring connections to the audio panel, if the audio is not heard., 6. Ensure the audio volume is sufficient for all anticipated cockpit noise conditions. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-19...
  • Page 69 The interfaces to RS-232 equipment such as the G500/G600 or other serial interface should be checked as follows. 1. Operate the connected serial remote tune source and the GTR/GNC in normal mode. 2. Ensure the remote source is able to display data from the GTR/GNC. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-20...
  • Page 70 2. Verify that the DME locks on to the signal and a valid distance is displayed. 3. Tune an invalid VOR station. 4. Verify the DME data is flagged. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-21...

  • Page 71: Flight Checks

    3. Verify the Morse code decoder IDs the station (95% probability). 4. Fly the approach. 5. Verify NAV flag, GS flag, and CDI and VDI are operational. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-22...

  • Page 72: Software Loading

    6.8 Software Loading NOTE Garmin recommends the use of a USB 2.0 compatible flash drive for updating databases and software on the GTR/GNC. The flash drive must be formatted as FAT32. If the software is out of date, go to the Dealer Resource Center on Garmin’s website and download updates...

  • Page 73: Figure 6-27 Usb Update Progress

    2. Turn the inner knob to NAV UPDATE. 3. Press ENT. 4. Press ENT again. 5. Verify the available NAV software update is displayed. 6. Press ENT again to begin the software update process. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-24...

  • Page 74: Figure 6-28 Database Update Page

    8. Press FUNC to verify database information. 9. Turn the outer knob to SYS CONFIGURATION. 10. Turn the inner knob to DATABASE INFO. 11. Press ENT. Figure 6-29 Database Info Page 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page 6-25...

  • Page 75: Continued Airworthiness

    7 CONTINUED AIRWORTHINESS Maintenance of the GTR 225, GTR 225A, GTR 225B, GNC 255A, or GNC 255B is “on condition” only. For regulatory periodic functional checks, refer to approved aircraft maintenance manuals or manual supplements for actual aircraft maintenance requirements.

  • Page 76: Appendix A Environmental Qualification Form

    APPENDIX A ENVIRONMENTAL QUALIFICATION FORM Visit the Garmin Dealer Resource Center for RTCA/DO-160F Environmental Qualification Forms (EQFs). The GTR Series (GTR 225/225A/225B) EQF is P/N 005-00658-02. The GNC Series (GNC 255A/255B) EQF is P/N 005-00658-03. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F...

  • Page 77: Appendix B Gtr/Gnc Data Format

    GTR/GNC (automatic magnetic heading, magnetic variation computed at last known position; true heading, magnetic variation of E00.0°; or user-defined magnetic heading, magnetic variation as entered by user). 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-1...

  • Page 78: Table B-1 Aviation Output Sentence Format

    Distance to destination waypoint in tenths of nautical miles. l (lower case Lima) d d d d d d Note: [1] The altitude is not output if the RS-232 port is configured as “Aviation Output 2.” 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-2...
  • Page 79 - sequence number (1 binary byte; last waypoint flag is set; route sequence number is 1) - ASCII carriage return character (0D hex) - ASCII line feed character (0A hex) 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-3...

  • Page 80: Table B-2 Type 2 Aviation Output Sentence Format

    - hundredths of latitude minutes (unsigned binary) Two's complement binary in 16ths of degrees. mvar Easterly variation is positive. MSB output first. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-4...

  • Page 81: Nmea Data Format

    [1] Encoded hex: each character consists of 4 bits of data placed in the low order nibble +30h. For example, the 8-bit value 5Fh would be encoded as two characters with values of 35h and 3Fh, which map to the ASCII characters “5” and “?”, respectively. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-5...
  • Page 82 ......Message sub-id; set to (ASCII) 1 for Request COM Audio Volume, 0 otherwise. “00”......Reserved. Example messages: $PGRMV2429000<chksm><CR><LF> Request the GNC to send the current NAV Audio configuration. $PGRMC0613000<chksm><CR><LF> Request the GTR/GNC to send the current COM status. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-6...
  • Page 83 8.33 kHz frequency is requested when the GTR/GNC is in 25 kHz channel spacing mode. NOTE The GTR/GNC will ignore this message while transmitting on the active COM frequency. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-7...
  • Page 84 ......Data type: (ASCII) 1 = headphone, 4 = sidetone level, 9 = RF squelch vv ......Volume level: 00-FFh; two encoded hex characters (30h-3Fh). Example message: $PGRMC0211=<chksm><CR><LF> Set the speaker output volume to 1Dh out of FFh (“=“ = 3Dh, -30h = Dh). 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-8...
  • Page 85 “C” ......Message class. This is a GTR/GNC COM message. “19”......Message identifier. p ......Key press: F = Flip/flop key; M = MON key. Example message: $PGRMC19M<chksm><CR><LF> Toggle the standby frequency monitor mode. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-9...
  • Page 86 The kHz portion converts ASCII “4” to 34h, -30h = 4h, x 25 kHz steps = 100 kHz. NOTE The GNC will check input frequencies for validity. An RS-232 serial error message output will be generated if the frequency is invalid. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-10...
  • Page 87 The kHz portion converts ASCII “P” to 50h, -30h yields 20h, x 25 kHz steps = 800 kHz. NOTE The GNC will check input frequencies for validity. An RS-232 serial error message output will be generated if the frequency is invalid. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-11...
  • Page 88 “43”......Message identifier. vv ......Volume level: 00-FFh; two encoded hex characters (30h-3Fh). Example message: $PGRMV431=<chksm><CR><LF> Set the NAV volume to 1Dh out of FFh (“=“ = 3Dh, -30h = Dh). 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-12...
  • Page 89 Message Format: “V” ......Message class. This is a GNC NAV message. “44”......Message identifier. p ......Key press: F = Flip/flop key. Example message: $PGRMV44F<chksm><CR><LF> Flip-flops the NAV active and standby frequencies. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-13...
  • Page 90 8.33 kHz mode. NOTE This message is output at a nominal one second rate, or faster whenever the transceiver function or status changes. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-14...
  • Page 91 ......COM locked out; (ASCII) 0 = OK, 1 = Active frequency locked at 121.500 MHz. Example message: $PGRMC1300100001<chksm><CR><LF> GTR/GNC is running and ready to accept serial input, Push-to-Talk is stuck on, and COM is locked to 121.500 MHz. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-15...
  • Page 92 (ASCII) 0 = OK, 1 = stuck. Example message: $PGRMV4100010<chksm><CR><LF> GNC is running and ready to accept serial input, and glide slope guidance is unavailable. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-16...
  • Page 93 This situation will occur whenever the receiver determines that it is within the “cone of confusion” directly over a VOR, or when no signal is being received. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-17...
  • Page 94 ......Bearing to a resolution of 1/10th of a degree. ddd = three digit bearing in degrees, ranging from “000” to “359.” f = 1/10th of a degree. Example message: $PGRMV23V1654<chksm><CR><LF> A valid bearing of 165.4 degrees FROM the active VOR station. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-18...
  • Page 95 “1” = unknown message. “2” = error or mismatch in message data. Example messages: $PGRMV271<chksm><CR><LF> Received an unknown NAV message. $PGRMC050<chksm><CR><LF> Received a COM message with an invalid checksum. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-19...
  • Page 96 “V” ......Message class. This is a GNC NAV message. 40 ......Message ident. vv ......Volume level: 00-FFh; use encoded hex (30h-3Fh). Example message: $PGRMV4030<chksm><CR><LF> The headphone volume level is 30h out of FFh. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-20...

  • Page 97: Table B-3 Input Message Summary

    / Low Comm Software Version Upon request Length is in bytes and includes the “$” start of message character and the <CR><LF> end of message Notes sequence. 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page B-21...

  • Page 98: Appendix Cmechanical Drawings

    □ Figure C-3 GNC Center of Gravity □ Figure C-4 GTR Center of Gravity □ Figure C-5 GTR/GNC Rear Connector Layout Detail □ Figure C-6 Panel Cutout Detail □ Figure C-7 GTR Mounting Rack 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-1...
  • Page 99 CS'K Ø.300 [7.62] x 100° INSIDE RACK (3 PER SIDE) 1.650 [41.91] 0.650 [16.51] 1.725 [43.82] BEZEL 0.770 [19.56] 0.325 [8.26] 0.437 [11.10] 8.000 [203.20] Figure C-1 GTR/GNC Dimensions 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-2...
  • Page 100 GNC CONNECTOR KIT PART OF GNC CONNECTOR KIT SCREW, 4-40 X .250 BNC CONNECTOR 330-00053-01 (2X) 115-01613-00 211-60234-08 (4X) GTN/GNC MOUNTING RACK SCREW, 4-40 X .250 Figure C-2 GTR/GNC Mounting Rack 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-3...
  • Page 101 6,'( 2) %(=(/  723 2) %(=(/   2876,'( 2) ,167$// 75$< 127(6  ',0(16,216 $5( ,1 ,1&+(6  ',0(16,216 $5( )25 5()(5(1&( 21/< Figure C-3 GNC Center of Gravity 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-4...
  • Page 102 6,'( 2) %(=(/  723 2) %(=(/   2876,'( 2) ,167$// 75$< 127(6  ',0(16,216 $5( ,1 ,1&+(6  ',0(16,216 $5( )25 5()(5(1&( 21/< Figure C-4 GTR Center of Gravity 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-5...
  • Page 103 4.460 REF. P2001 (44 PIN) 1.538 REF. P2002 (62 PIN) REAR VIEW OF CONNECTOR PLATE Figure C-5 GTR/GNC Rear Connector Layout Detail 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-6...
  • Page 104 2. IF THE FRONT LIP OF THE MOUNTING RACK IS BEHIND THE SURFACE OF THE AIRCRAFT INSTRUMENT PANEL, THE UNIT CONNECTORS MAY NOT FULLY ENGAGE. 3. TOLERANCE: +0.03" Figure C-6 Panel Cutout Detail 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-7...
  • Page 105 DURING INSTALLATION OF THE MOUNTING RACK, ENSURE EDGE OF THE TAB (BOTTOM FLANGE OF THE RACK) IS FLUSH WITH THE FACE OF THE INSTURMENT PANEL. Figure C-7 GTR Mounting Rack 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page C-8...

  • Page 106: Appendix D Interconnect Diagrams

    □ Figure D-14 GNC - GDU 620 Interconnect □ Figure D-15 GTR/GNC - GTN 6XX/7XX, GNS 400W/500W, and GNS 480 Interconnect □ Figure D-16 GTR/GNC - GMX 200 Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-1...
  • Page 107 AIRCRAFT POWER & GROUND POWER & GROUND NAV REMOTE TRANSFER NAV REMOTE TRANSFER SWITCH GTR/GNC COM ANTENNA CONNECTOR P2003 NAV ANTENNA CONNECTOR P2004 Figure D-1 GTR/GNC System Interface Diagram 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-2...

  • Page 108: Figure D-2 Gtr/Gnc Typical Installation

    AIRCRAFT POWER AIRCRAFT GND AIRCRAFT AIRCRAFT GND GROUND AIRCRAFT GND COM ANTENNA P2003 COM ANTENNA NAV ANTENNA P2004 NAV ANTENNA Figure D-2 GTR/GNC Typical Installation Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-3...
  • Page 109 TERMINATION LEADS SHOULD BE LESS THAN 3.0". CONNECT OTHER END OF THE SHIELD PER THE REMOTE EQUIPMENT INSTALLATION REQUIREMENTS. SEE FIGURE D-3 FOR POWER AND GROUND WIRING DETAILS. Figure D-2 GTR/GNC Typical Installation Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-4...
  • Page 110 CONNECTOR P2002 IS ONLY APPLICABLE TO THE GNC 255. OPTIONAL CONNECTION. LIGHTING CAN BE CONTROLLED BY THE INTEGRATED PHOTOCELL, A SINGLE LIGHTING BUS, OR DUAL LIGHTING BUSES. Figure D-3 GTR/GNC Power Lighting Configuration Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-5...

  • Page 111: Figure D-4 Gtr/Gnc - Antennas Interconnect

    P2003 COM Antenna DUAL GTR/GNC INSTALLATION GTR/GNC #1 P2003 P2004 VOR/LOC/GS Antenna Splitter COM Antenna GTR/GNC #2 P2004 P2003 Figure D-4 GTR/GNC - Antennas Interconnect Sheet 1 of 4 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-6...
  • Page 112 DUAL GNC/DUAL NAV ANTENNA INSTALLATION COM Antenna G/S Antenna GNC #1 P2003 VOR/LOC Antenna P2004 Splitter Diplexer GNC #2 P2004 COM Antenna P2003 Figure D-4 GTR/GNC - Antennas Interconnect Sheet 2 of 4 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-7...
  • Page 113 G/S Antenna P2004 Splitter Diplexer VOR/LOC Antenna VHF NAV RADIO WITH SEPARATE G/S AND Splitter VOR/LOC ANTENNA PORTS VOR/LOC Figure D-4 GTR/GNC - Antennas Interconnect Sheet 3 of 4 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-8...
  • Page 114 SEE SECTION 3 AND SECTION 4 FOR ANTENNA CABLE SPECIFICATIONS. P2004 NAV ANTENNA PORT IS ONLY APPLICABLE TO THE GNC MODEL. GARMIN P/N 013-00112-00 (MINI-CIRCUITS SPLITTER P/N ZFSC-2-1B+) OR EQUIVALENT SHOULD BE USED. COMANT DIPLEXER P/N CI 507 MAY BE USED.

  • Page 115: Figure D-5 Gtr/Gnc - Audio Panel Interconnect

    NAV 1/(NAV 2) AUDIO HI GND LUG 24/(25) GND LUG GND LUG NAV 1/(NAV 2) AUDIO LO VOR/LOC AUDIO OUT LO Figure D-5 GTR/GNC - Audio Panel Interconnect Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-10...
  • Page 116 SPLICE 500 Ω COM AUDIO LO AND MIC AUDIO IN LO TOGETHER INTO THE SAME PIN ON AUDIO PANEL. THE P2002 NAV CONNECTOR IS ONLY APPLICABLE TO THE GNC MODEL. Figure D-5 GTR/GNC - Audio Panel Interconnect Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-11...
  • Page 117 GROUND. THIS MAY REQUIRE THE USE OF INSULATING WASHERS WHEN MOUNTING THE PHONE PLUGS. ADDITIONALLY, THE SPEAKER RETURN MUST BE ISOLATED FROM GROUND. Figure D-6 GTR/GNC - MIC Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-12...
  • Page 118 VOR OBS STATOR F OBS F (SIN HI) VOR OBS STATOR G (GND) OBS G (SIN LO) GPS ANN NAV ANN Figure D-7 GNC - VOR/ILS Interconnect Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-13...

  • Page 119: Figure D-7 Gnc - Vor/Ils Interconnect

    INSTALLATION REQUIREMENTS. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION. PINOUTS OF OTHER UNITS SHOWN FOR REFERENCE ONLY. Figure D-7 GNC - VOR/ILS Interconnect Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-14...
  • Page 120 VLOC REMOTE TRANSFER CAN BE USED TO TRANSFER THE STANDBY NAV FREQUENCY TO THE ACTIVE NAV FREQUENCY VIA REMOTE MOMENTARY SWITCH. MAY OPTIONALLY USE GRAYHILL SWITCH P/N 30-3. Figure D-8 GTR/GNC Switches Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-15...
  • Page 121 THE REMOTE EQUIPMENT, TERMINATE SHIELDS AS SHORT AS POSSIBLE, NOT TO EXCEED 3.0". REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT/ CONFIGURATION INFORMATION. PINOUTS OF OTHER UNITS SHOWN FOR REFERENCE ONLY. Figure D-9 GNC - RMI OBI Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-16...
  • Page 122 RNAV REQUEST NAV 1 COMMON NAV DME COMMON NAV 2 COMMON 10 BIT/50 BIT SELECT Figure D-10 GNC - King Serial DME - Remote Mount Interconnect Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-17...

  • Page 123: Figure D-10 Gnc - King Serial Dme - Remote Mount Interconnect

    THE DME CHANNEL MODE. SEE SECTION 6.4.2.4 FOR CONFIGURATION SETTINGS. FOR SINGLE GNC INSTALLATIONS, WIRE AS SHOWN FOR GNC #1. Figure D-10 GNC - King Serial DME - Remote Mount Interconnect Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-18...
  • Page 124 10 MHZ-E GROUND 2 X 5 CODE SELECT 48/50 SLIP CODE SELECT BCD CODE SELECT Figure D-11 GNC - Parallel 2 of 5 DME Tuning Interconnect Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-19...

  • Page 125: Figure D-11 Gnc - Parallel 2 Of 5 Dme Tuning Interconnect

    P1-42 ON THE DME AND P3-46 ON THE COLLINS HSI PROCESSOR UNIT HPU-75 NEED TO BE DISCONNECTED FROM GROUND IN ORDER TO ENTER DME HOLD MODE, IF DESIRED. Figure D-11 GNC - Parallel 2 of 5 DME Tuning Interconnect Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-20...

  • Page 126: Figure D-12 Gnc - Parallel Slip Code Dme Tuning Interconnect

    FOR DUAL GNC INTERFACES TO THE DME, IT MAY BE NECESSARY TO INSTALL A TOGGLE SWITCH FOR THE ”DME COMMON” INPUT. INSTALL SWITCH AS SHOWN FOR KING SERIAL PANEL DME INTERCONNECT. Figure D-12 GNC - Parallel Slip Code DME Tuning Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-21...
  • Page 127 SERIAL DME-CLOCK NAV SELECTION SW SERIAL DME-DATA SERIAL DME-RNAV/CH REQ DME COMMON SERIAL DME-REQUEST Figure D-13 GNC - King Serial DME - Panel Mount Interconnect Sheet 1 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-22...

  • Page 128: Figure D-13 Gnc - King Serial Dme - Panel Mount Interconnect

    INSTALLATIONS, WIRE AS SHOWN FOR GNC #1. USE A DOUBLE POLE, DOUBLE THROW, ON-NONE-ON SWITCH. AN ACCEPTABLE SWITCH IS CARLINGSWITCH P/N 316-B-63. LABEL AS SHOWN. Figure D-13 GNC - King Serial DME - Panel Mount Interconnect Sheet 2 of 2 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-23...

  • Page 129: Figure D-14 Gnc - Gdu 620 Interconnect

    CONFIGURE ARINC 429 TX TO LO SPEED AND SDI TO VOR/ILS 1 OR VOR/ILS 2 (TO MATCH NAV 1 OR NAV 2 INPUT ON GDU 620). Figure D-14 GNC - GDU 620 Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-24...

  • Page 130: Figure D-15 Gtr/Gnc - Gtn 6Xx/7Xx, Gns 400W/500W, And Gns 480 Interconnect

    CONFIGURE GTR/GNC SERIAL PORT FOR “AVN IN/MAPCOM.” CONFIGURE RS-232 OUTPUT TO “MAPCOM” FORMAT. RS-232 OUTPUT PORT 1 OR PORT 5 MAY BE USED. Figure D-15 GTR/GNC - GTN 6XX/7XX, GNS 400W/500W, and GNS 480 Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-25...

  • Page 131: Figure D-16 Gtr/Gnc - Gmx 200 Interconnect

    LEADS SHOULD BE LESS THAN 3.0". CONNECT OTHER END OF THE SHIELD PER THE REMOTE EQUIPMENT INSTALLATION REQUIREMENTS. CONFIGURE GNC SERIAL PORT FOR “AVN IN/MAPCOM.” Figure D-16 GTR/GNC - GMX 200 Interconnect 190-01182-02 GTR 225/GNC 255 TSO Installation Manual Rev. F Page D-26...

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