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Aviation Alerts and Advisories

GTX 3X5(R) main software version 2.54, new GTX 345(R) part numbers and GTX 3X5 NV models, and other misc updates


GTX 335/335R/345/345R (GTX 3X5(R)) units installed using Part 27 AML STC SR02124SE are affected.




Recommended: Garmin recommends the incorporation of this Service Bulletin at the next scheduled service interval.


This STC Service Bulletin provides notification of an update to STC SR02124SE, GTX 3X5(R) Part 27 AML STC, MDL Revision 2.

GTX 3X5(R) main software 2.54 provides the following:

  • Added the ability to accept the magnetic heading from a traffic source to calculate true heading for ADS-B
  • Added automatic enablement of the flight and trip timers whenever the squat switch is inactive for rotorcraft using a squat switch
  • Added ability to connect the GTS via HSDB for GTS 8×0 v4.12, GTS 8×5 v3.12
  • Added text displays NO COMM and EMERGENCY under 7600 and 7700 Squawk codes
  • Added Traffic Audio Cancel/Update and Traffic Audio Mute discretes
  • Fixed an issue that incorrectly decode aircraft length and width values
  • Added GNS format to accept GPS and height above terrain data from a GNS 400W/500W Series device (GTX 335 only)
  • Improved Air/Ground determination logic
  • Improved traffic alerting when on ground or in an airport environment
  • Updated ADS-B out encoding to improve position accuracy
  • Fixed altitude reporting errors when using pressure altitude from a GAE

Other major details of the update include:

  • Updated GTX 3X5 ADS-B software to v3.13
    • Fixes an issue where some ADS-B traffic intruders may not be displayed when over 200 ADS-B intruders are within range

Active TCAS surveillance is not affected by this issue.

  • Updated GTX 3X5 GPS software to v7.0
  • Added new GTX 3X5 NV transponder models
  • Added new GTX 345(R) part numbers
  • Approval of G500H TXi interface
  • Approval of GTS 8XX interface over HSDB
  • Approval of passive GPS splitter interface for VFR only helicopters
  • Added new rotorcraft models to the AML

MDL Revision 2 includes an expansion to the AML.  Under this update, the following models were added to STC SR02124SE.

Rotorcraft Make (TCDS Holder) – Airbus Helicopters Deutschland GmbH
Rotorcraft Model Designation – EC135P3, EC135T3
TCDS number – H88EU

ASDN Service Bulletin 2039 Rev B