Any recommendations for a TRIG installer ?

[Hugh_Jarse]

Has anyone had a TRIG TT31 fitted to a "CofA" aircraft (or whatever we call them these days!) ? If so, any positive/negative feedback on your installation experiences (and indeed on the kit itself after install) ?

Thanks,

Hugh

PS : any installers reading who would like to quote to fit one, feel free to PM !

[flyingfemme]

I had one fitted to my Comanche at the last annual - it was a plug-n-play replacement. No drama but it is N reg. Speak to Gary at International WasteofSpace.

[KeesM]

I have one to replace my old KT76A. It was just plag and play. The rack and pin-layout are the same as the KT. Check their website for approvals on aircraft/ Mode-C replacements, that will save paperwork issues.

Compared to the KT it works nicer when you have to enter a new squack. There are some timer functions and I believe an altitude alarm function. Never used those.

-Kees

[Ultranomad]

Compared to the KT it works nicer when you have to enter a new squack.
Looking at the photo of a TT31, I imagined just the opposite, and for this very reason was thinking of a Garmin 328 instead. Has anyone tried both of these? Please share your opinions!

[Rod1]

I am sure the regulars are expecting me to post about now…

Avoid the Garmin 328. It is the only mode S transponder that does not support ES, so cannot be used for ADS-B. ADS-B forms part of the CAA aircraft interoperability plan (phase 3). If you fit a 328 you are very likely to have to replace, or upgrade in the not too distant future. Any of the other units do not have this risk attached.

Rod1

[Shoestring Flyer]

As Rod points out the Garmin 328 is not comparable with the TT31 being not ADS-B compliant. So you might be throwing it away within 5years.

The comparable Garmin unit to the TT31 is the Garmin 330 which at the thick end of a grand more money made it a no-brainer in favour of the TRIG to me.

The TRIG TT31 does what it says on the tin. It is easy to use and best of all it is British!!

[Kolibear]

We've just fitted a TRIG 31, its good. I doubt if we'll ever use all the features on it though, like the timer/stopwatch.

I do like the 'one-push-7000' feature though.

Phoenix charged us £350 to fit it though. :ooh:

[KeesM]

The TRIG TT31 does what it says on the tin. It is easy to use and best of all it is British!!

Nope, it is Scottish :E

[Fitter2]

Ah Kees, you don't understand the nuances of nationality. Anything good from North of the Tweed is British (as well as Scottish). (Hence the TRIG is British). Anything disliked is Scottish.

If anything other than a KT76A is fitted, then the rewiring/tray change at £350 is good value. If a KT76A is fitted, anything over £50 for the signature in the logbook is grossly excessive.

PM sent to HughJarse.

[Rod1]

Fitter2

You are a professional and I am just an amateur bodger but;

The TRIG is plug compatible with the KT76A, so it will not need any rewiring/tray change? If on a C of A it would obviously need mod paperwork, but having helped a permit owner friend fit one it took 10 min to get the KT out and 2 min to get the TRIG in. The flight test showed all to be working fine.

Rod1

[Fitter2]

Hi Rod

Exactly, no rewiring/tray change IF a KT76A is fitted, but needed if anything else is. I thought I had said that, and rereading my post can't see how to say it any more clearly. Kolibear doesn't say what was there before in his case.

A CAA/EASA CofA Aircraft, even for something so trivial, needs a qualified engineer to do the box change according to the generic TRIG SEP mod.

A LAA permit aircraft has somewhat different rules, which it would take too long to go into, but a chat to ones LAA inspector will reveal all.

[A and C]

So just how long would it take for a guy to fit a Trig in a KT76 slot, do the tests & do the paperwork on a C of A aircraft?

Also what is the cost of the test kit needed to do the job?

[ea200]

Two minor points to consider: The TRIG is a direct replacement for a KT76A but it draws slightly more power. The KT76A may have a 3 amp C/B the TRIG needs a 5 amp. The other point which affected me in a tight installation is that the TRIG knobs are longer than the KT76 and fowled the stick at full forward travel. Had to move the rack slightly.

[Fitter2]

Two minor points to consider: The TRIG is a direct replacement for a KT76A but it draws slightly more power. The KT76A may have a 3 amp C/B the TRIG needs a 5 amp.

From the TT31 EASA Generic Modification document (SEP):

3.6 Electrical Load Analysis

Existing Mode A/C transponders draw typically 1.1 Amp from the DC power supply, with currents of up to 1.9 Amp during high activity.

The TT31 draws typically 0.25 Amp from a 14V DC power supply on standby, with currents of around 0.45 Amp during high activity. On 28V supplies the currents are lower.

Since the current taken by the TT31 is less than half that of the transponder it is replacing, any systems that were properly sized to support an existing transponder will be adequate to support the TT31.
On the same basis, it can be concluded that the 30 minute battery requirement of CAP747 GR6 will also be satisfied.

and

4.4.1 Verify Circuit Breaker Status

Trace and identify the existing transponder circuit breaker. Verify that the circuit breaker is in satisfactory condition and is of the correct type and rating. The circuit breaker for the TT31 should rated between 3 Amps and 5 Amps.

[david viewing]

I installed the Trig TT31 in place of a KT76a in my Warrior. The results are extremely pleasing: no more complaints from ATC, 'identified' within seconds, no more staring into the tx light hole to see if it is blinking or just reflecting sunlight. It's been in place for over a year and no complaints

-But-

I also fly a Cessna with the KT-76C push button transponder. There's no doubt that on a normal day it is easier to push the number buttons almost as quickly as the controller gives them to you. The Trig with its turn and push knob is slightly awkward. The situation is less clear cut on a very bumpy day when it's hard to stab the correct button on the KT76C as it dances all over the panel, while with the Trig in the same conditions you can hold on to the knob with thumb and forefinger whilst simultaneously pressing the enter button.

So on cost/benefit grounds, the Trig is an unbeatable winner. But with unlimited funds the push button type comes out slightly in front. In my view.

Mine was purchased from Harry and installed and signed off by David Jones at Derby 01283 733803

[AN2 Driver]

Hi guys,

I understand from several avionic services in Switzerland that any direct replacement will still need major installation work, as a air/ground switch is needed for any and all Mode S installations. Any comments on that, how does EASA generally handle this?

And btw, what is the retail price of one of those TT31's?

Best regards

AN2 Driver

[KeesM]

If you have a retract, yes otherwise I can not think where that switch should go.

I paid 1800,- euro incl VAT early this year for just the transponder.
I'm not sure what the installation did cost because it was done during the annual and I also had a 406 Mhz ELT installed.

There are less expensive mode-s transponders on the market(the small Filser for example) but the important thing is the bottom line.
The Trig came with all the paper work to have it replace a KT76A in a C150. And that saves money.
Here is a link for the minor changes: TT31 Minor Change Library (http://www.trig-avionics.com/minormod.html)

If you prepare all paperwork yourself, put staples in the appropiate corners, then the installer only have to install the thing, test it and sign.
Or you can just hand over the aircraft keys to the installer and tell him/her to put a new transponder in. The bill will look a bit different that way.

Not sure what registration your plane has but maybe you have to update the radio license.(On a D-reg you have to.)


-Kees

[Fitter2]

I understand from several avionic services in Switzerland that any direct replacement will still need major installation work, as a air/ground switch is needed for any and all Mode S installations. Any comments on that, how does EASA generally handle this?

If the generic EASA approval (see the TRIG website) applies to your aircraft, then your avionic services can read the document, and see that they are incorrect.

If an aircraft has an EASA approved modification incorporated as specified in the mod. document, then it is legal.