TT21/TT22 Minor Change Library

At Trig we have developed a set of EASA approved upgrade instructions that document the process of installing TT21 or  TT22 transponders in a range of aircraft. Trig installers can use these instructions to achieve airworthiness compliance without needing to seek further approval from EASA.

These Minor Change Approvals are free.

First – reference the Applicable Aircraft Model List (bottom of page) to access the relevant Minor Change Approval Certificate.

Next – view the relevant Minor Change Master Instructions, these must be followed as part of the installation. The relevant Master Instruction document name is shown as a heading in the list of aircraft (below) and is titled ‘Applicable Aircraft’ instructions. Access the applicable Instructions in the Minor Change Master Instructions Section.

Finally – some certificates do not contain the full aircraft model list. If this applies then please see the relevant Minor Change Master Instructions. This document will list the full aircraft model list and all applicable variants.

Minor Change Approval Sheets

Each approved aircraft type has a corresponding approval certificate available for download here.  Note that some of these approval certificates include standard text inserted by EASA which says “The installation of this modification by third persons is subject to written permission of the approval holder”.  For the avoidance of doubt, we Trig hereby grant that permission, and this web page may be referred to as evidence of that permission.

If you are installing a TT21 or TT22 transponder on an aircraft type NOT shown here, but for which the minor change instructions would apply, Trig Avionics grant you permission to use the published minor change instructions as the basis for your own application.

Minor Change Master Instructions

The Minor Change master instructions are available for download here.

SUP TT2X 012, issue 1.0 – Fixed Wing (CS-23) TT21/TT22 Instructions (February 2015)

SUP TT2X 011, issue 1.0 – Fixed Wing (CS-23) TT21/TT22 Flight Manual Supplement (February 2015)

SUP/TT2x/009, issue 1.0 – Fixed Wing (CS-23) TT21/TT22 Instructions (Post 2014 Approval)

SUP/TT2x/010, issue 1.0 – Fixed Wing (CS-23) TT21/TT22 Flight Manual Supplement

SUP/TT2x/003, issue 3.0 – Fixed Wing (CS-23) TT21/TT22 Instructions (Pre 2014 Approval)

SUP/TT2x/002, issue 4.0 – Sailplanes (CS-22) TT21/TT22 Instructions (latest revision)

Applicable Aircraft using SUP/TT2x/003 Instructions


BO 207, BO207T, BO 208, BO 208C, BO209, BO209S


C150 A/B/C/D/E/F/G/H/J/K/L/M, A150 K/L/M, C152, A152

Applicable Aircraft using SUP/TT2x/002 Instructions

Diamond Aircraft

H36, HK36, HK36 Super Diamona


All models (Discus, Ventus, Cirrus, Duo Discus, Janus, Mini-Nimbus, Nimbus, SHK, Standard series)

Applicable Aircraft using SUP/TT2x/009 Instructions



Applicable Aircraft using SUP/TT2x/012 Instructions

Robin (Alpha Aviation Concept)

HR200 series / DR400 series