TT31 Service Bulletins for pilots

TT31 Transponder

Software versions run numerically, the higher the number the more recent the release – so the latest software will always include all the features of earlier versions.


01/10/2018          version 0.1

This Hardware Service Bulletin applies to TT31 transponders approved under ETSO authorisation EASA.21O.643 Rev B and EASA.21O.906 Rev A, part number 00220-00-(XX) and part number 00225-00-(XX) which are:

Serial number from 05767 to 09715;

Modification Level 6 or below; Installed in an orientation which is NOT a conventional aft-facing avionics stack mounting.


24.09.2018          version 3.18 – Current software version

TT31 software version 3.18 improves performance of Mode S replies to certain interrogations, correcting software versions 3.14, 3.15, 3.16 and 3.17.

05/12/2017          version 3.17

This software improves the automatic air / ground determination on the TT31.

24/08/2017         version 3.16

This software adds support for the Trig TN72 as a FAR 91.227 compliant ADS-B position source. Adds GPS only air-ground determination algorithm for ADS-B Out.

13/08/2014         version 3.13

This adds compatibility with Garmin’s ADS-B Plus protocol for GNS and GTN navigators. This allows these Garmin units to be used as the GPS source for certified ADS-B Out. Improvements to front panel rotary knob functionality also added.

24/03/2014         version 3.11

Introduces user configurable serial ports, providing greater installation flexibility. Improves automatic dimming of the display backlight. Also adds automatic generation of the transponder Mode S address when a valid aircraft registration is configured (only applicable for ‘N’ registration aircraft). Adds support for the Trig ADS-B protocol which is used by various GPS position sources, including the Avidyne IFD440 and IFD540 for ADS-B.

03/08/2012         version 3.4

Improvements made to ADS-B Extended Squitter function to RTCA DO-260B standard (as required by 14 CFR 91.227). Support added for Garmin 4X0W and 5X0W GPS sources for ADS-B.

21/01/2010         version 2.5

This software adds the ability to receive TIS ‘A’ traffic in relevant US airspace, via RS232 output.

19/12/2008         version 2.3

Adds support for FreeFlight and NextNav GPS sources for ADS-B.

30/10/2008         version 2.2

This improves the timeout behaviour when a new Squawk code has been input.

13/02/2008         version 2.1

Improvements to Bendix King KLN94 GPS receiver support for ADS-B.

18/12/2007         version 2.0

This adds ADS-B Extended Squitter functionality for NMEA 0183 protocol output GPS sources. Also adds support for Squat switches and recall of previous squawk code after powering off.

Come on board for exclusive email updates

Stay in the loop

At Trig Avionics we are passionate about aviation and aim to provide the best avionics for GA pilots. By providing us with your details below we can keep you up to date with product developments, industry information and Trig news.

Trig Avionics will not share your details with any other parties.

Country of Residence

What category of aircraft is it?

What Trig products are you interested in?