Avionics installation/replacement without STC/change approval (based on a TC installation)

wigglyamp wrote:

Personally I’ve never seen this done on EASA or FAA aircraft in over 30 years of GA maintenance. I certainly wouldn’t certify an installation on this basis but if others want to then that’s entirely their risk of course. I wonder what would happen when a CAMO asked to see the approved modification data and instructions for continuing airworthiness?

Pre EASA this was common in The Netherlands, and nowadays it still is, basically installing options. For these aircraft the wiring diagrams are included in the maintenance manual, and the AFMS supplement allready there or availble from the manufacturer. If anything is unclear, than further information is asked at the manufacturer.
I don’t see an issues with that, and never had any CAMO problems following such work.

As Peter indicated, a limitation was always, that it must be eligible for that S/N. So if it is optional on that S/N, you can install it, your basically installing an option. If not, you have to do a minor or major change.

Going back to the orginal question from Airborne_Again, I think this would be possible, but due to work that is involved and the amount of wiring that needs to be done, you would be better of with a newer unit.

Jesse wrote:

Pre EASA this was common in The Netherlands, and nowadays it still is, basically installing options. For these aircraft the wiring diagrams are included in the maintenance manual, and the AFMS supplement allready there or availble from the manufacturer. If anything is unclear, than further information is asked at the manufacturer.

Would you do this on an N-reg aircraft and if yes, would you raise a 337 or just a logbook entry (assuming for example that it’s Peter’s example of a dual GNS430?
We install Beech factory options (pitot-heat warning on KingAir for example) but Beech supply installation kits with the approved installation data, not just relying on maintenance manual drawings. The same happened with Bell or Sikorsky. Where there’s no factory option kit, we raise an approved design pack and may reference the factory diagrams so our installation will be closely matched to the factory option.

I don’t think one can just raise a 337. A 337 is for a Major Alteration and it needs to relate to something – one of the processes used to do a Major Alteration. I know some firms just raise a 337. For example I know somebody who had an iridium antenna installed (doubler plate etc) and they just did it and wrote out a 337 but it doesn’t mean anything, and the said 337 is never sent to the FAA so is doubly bogus.

But In this case there is no Major Alteration because the approval work for whatever it is was already done by the airframe mfg under their TC.

I know loads of cases where factory-TC options were installed in the USA, using the TC as the basis.

wigglyamp wrote:

Would you do this on an N-reg aircraft and if yes, would you raise a 337 or just a logbook entry (assuming for example that it’s Peter’s example of a dual GNS430?

For N reg I should check with the engineer holding A&P/IA, I don’t. Under EASA I would, and would request any additional information required from manufacture. E.g. exact antenna location, doubler etc and AFMS supplement as required.

For those who grasp the (mostly unspoken) implications, this has been a most interesting thread!

What exactly is the OP wanting to install and what is the regime (FAA, EASA or ?) of the aircraft ?

wigglyamp wrote:

Would you do this on an N-reg aircraft and if yes, would you raise a 337 or just a logbook entry (assuming for example that it’s Peter’s example of a dual GNS430?

For the record, about 10 years ago, the FAA published an AC that specifically stated that a [VFR only] GPS installations are considered a Minor mod, thus no 337 was needed.

Since the GNS430W has an AML STC (assuming the target acft is ON the list), I really don’t see what the fuss is to raise a 337 and be done with it.

Peter wrote:

I don’t think one can just raise a 337. A 337 is for a Major Alteration and it needs to relate to something – one of the processes used to do a Major Alteration. I know some firms just raise a 337. For example I know somebody who had an iridium antenna installed (doubler plate etc) and they just did it and wrote out a 337 but it doesn’t mean anything, and the said 337 is never sent to the FAA so is doubly bogus.
But In this case there is no Major Alteration because the approval work for whatever it is was already done by the airframe mfg under their TC.

I was tempted to ignore this but I do think it justifies a response.

We’re talking just FAA in this case.
When a 337 is raised, it can serve two purposes. In the case of a Field-approval Major alteration, the 337 allows the FAA to approve the data used to support the design by stamping and signing in Box 3. It also serves as a record that the major alteration has been embodied into the particular serial number aircraft, which is why you have to submit a copy to the FAA Oklahoma office.
In the case of installing an existing approved Major Alteration (perhaps via a DER-approved 8110-3) or Major Change to type design (third-party STC) the 337 serves purely as the record of embodiment.

So if we follow the logic of your statement above, then if we embody an existing approved STC, just the same as an existing approved TC change, then no 337 would be needed. I would dispute this. In dealing with many N-reg to UK/EASA reg imports I’ve never come across this situation.

What this thread was initially about is whether a Type Certificated installation can be implemented in the field by someone other than the original airframe manufacturer, without having to take special steps to generate fancy paperwork.

Someone typed up a post (and then deleted it) saying that a TC is Approved Data (or Acceptable Data – not entirely the same thing) and that is very definitely true. A mod done under a TC (or an STC for that matter) can be used to support e.g. a Field Approval application and I have done that myself with assistance from a California FSDO inspector. But that is relevant only if what you are installing something a bit different. This thread is about installing something which is practically speaking the same thing as was approved under the TC.

It would beggar belief that somebody should need to go through a fresh approval process for such an installation – where the TC’d installation is documented and perhaps even available for inspection in the form of an actual aircraft.

The discussion rapidly descends into one of how stupid the installer is assumed to be by the regulatory authorities. In EASA world the installer is indeed assumed to be fairly stupid, hence the more prescriptive nature of everything (words I got from a Part 21 + 145 company, BTW) than is normal in the FAA world where various generic procedures are commonly referenced and the installer doesn’t e.g. need to be supplied with a drawing for a doubler plate for an antenna.

I have been on the receiving (well, cheque writing) end of this a number of times, having had to argue that (for example) you don’t need a DER 8110 design package (for £2000) to cover the screwing of a TAS605 box into the luggage compartment!