On Sunday, June 3, 2018 at 7:21:37 PM UTC-7, Charles Longley wrote:
What’s an informational 337? Never heard of one until now.

Charlie
A&P/IA

Don't worry, you are not alone, this has caused a reasonable amount of confusion and not just with gliders. Have a read of FAA 8900.362 - Policy for Installation of ADS-B OUT Systems. https://www.faa.gov/regulations_poli...mentID/1029526 (no that policy really has not expired).

An "information only" 337 is what the FAA wants you to complete and send to FAA HQ in Oklahoma for an ADS-B out install. It's so they can track what is being installed. It's not the normal use of an 337 sent to the FSFDO for field approval for a major alteration. This has been discussed here in detail before in the thread linked in previous posts. There are multiple other FAA reference docs giving the same guidance listed in that other thread. The FAA may not formally refer to these as "information only" 377 but thats a term used by others, and by FAA folks when you talk to them.

The misconception that an ADS-B out install is by necessity a major alteration and requires a 337 (to the FSDO) has seemed to cause some glider owners unnecessary pain. Folks get confused and send the 337 to the FSDO and then the FSDO assumes they are seeking field approval for a major alteration, and you end up with folks trying to jump through hoops and find STC etc. and other items for install in a glider that are likely not required in the first place. And the pain starts with: there are no STCs for any transponder install in any glider. None, nada, zilch. And if you read the above policy, you'll see the STC mentioned, but it explains that is also a special case for an ADS-B Out install--the STC there is only required to establish the pairing of a particular transponder and GPS source, not the basis for a design approval for a major modification.

Since this confusion has created issues for some owners my effort to explain it here was is to avoid others suffering. Of course if an A&P IA has good reason to determine if any install actually is a major modification then that's a different discussion. Most installs of avionics in gliders are not considered major modifications, and the FAA has been supportive of that position, and there is no regulation that makes ADS-B Out installs special cases where they are automatically major alterations. The other thing I've suggested people do is let their A&P IA seek any clarifications about these from the FAA instead of trying to contact FSDO staff themselves.

There is no FAA notification required for ADS-B Out installs in experimental aircraft and none required for TABS/TSO-C199 (read that TSO for more info) install in any aircraft since 14 CFR 91.225/91.227 (the only thing that policy above applies to) don't apply to TABS... that's another whole point of potential confusion with owners or A&P contacting the FSDO and asking about "ADS-B Out" installs where they mean TABS and the FSDO will likely assume 2020 Complaint systems not TABS, and staff there may just not know what TABS is at all. And now we have at least one glider owners who has got an ADS-B Out non-compliance letter from the FAA for their TABS systems because the FAA ADS-B Out compliance reporting does not understand TABS. I'm helping respond to that letters (and can provide a draft of the response letter to anybody who wants one) and I hope this is a great opportunity to help educate more FAA folks on TABS and gliders in general.