ADSB out in tow planes

I don’t know if I agree with you. If an ADSB out can be installed in any type certified aircraft without a 337 why do the manufacturers bother with a STC? I’ve installed a Stratus transponder in a Pawnee using the policy you quoted. I didn’t consider it an informational 337 when I did it. The FAA gets information on which airplanes have ADSB when they’re flown in the national airspace system.

Experimental aircraft are a whole different subject.

On Monday, June 4, 2018 at 7:38:18 AM UTC-7, Charles Longley wrote:
I don’t know if I agree with you. If an ADSB out can be installed in any type certified aircraft without a 337 why do the manufacturers bother with a STC? I’ve installed a Stratus transponder in a Pawnee using the policy you quoted. I didn’t consider it an informational 337 when I did it. The FAA gets information on which airplanes have ADSB when they’re flown in the national airspace system.

Experimental aircraft are a whole different subject.

This has been flogged to death on r.a.s. in the recent past, and the person who was then confused about it went to his FSDO, which confirmed what I was saying. But I'll spare your the pain of wading though that tangled ball.

I did try to addressed exactly the reason an STC is usually needed in the post before. The STC is needed (as the easiest way) to establish a valid pairing between a ADS-B Out tranmitter (e.g. transponder) and a GPS source. You are expected (by that FAA policy) to follow that STC for the configuration related to that device pairing (or if a single box, presumably the setup in that box related to the GPS source). This stuff is in pretty clear English (especially section (6)) of the FAA policy doc I gave you the link to.

You are not required to treat the install as a major alteration and to use that STC for an approval basis just because this is an ADS-B install (if you think you are please explain exactly what establishes that). If you otherwise determine the install is a major alteration then an STC specific to the install in that aircraft is going to provide the basis for a field approval, and you would file a 337 with the FSDO. If it's not a major alteration then you just need an STC that establishes the pairing of those devices, and it does not need to be specific to that aircraft.

Manufactures here clearly need STCs for the pairing basis. Manufacturers also need some STCs for installs as a major alteration approval basis because well those installs are really major alterations, manufactures also like to have STCs to cover stuff where they may not really raise to the level of major alterations but some A&Ps (and FSDO staff) might be nervous about doing stuff without an STC. Many of the existing install STCs were also developed in the past where the installs process was more complex.

The FAA cannot get information they want from the equipment installed in aircraft from direct monitoring of the ADS-B Out signal. There is no data transmitted over ADS-B Out that describes the transmitter or GPS source manufacturer or model (I wish there was), and no way to collect from that the magic info of which A&P signed off on the install. Which given how many ADS-B Out install fail from basic setup/software configurations I suspect they want to know and track down those responsible--to help avoid more, the FAA seems to be being very supportive/helpful with installs but there are so many problems with installs for them to track down. Since an ADS-B Out install is not necessarily a major alteration a 337s would not necessarily be filed with the FSDO so the FAA is seeking a way here to collect all this information and using a 337 form in an unusual way to do that. They would never have bothered with creating that extra process if all installs were major modifications with 337s going to the FSDOs.

I hope you did followed the process the FAA expects for the ADS-B Out equipment you installed in the Pawnee. If you also decided that install required a major alteration approval for other reasons then that that was your decision. I hope you submitted the "notification only" 337 to Oklahoma, if not you may want to go ahead and do that. Not doing that might eventually get the club a "please explain" letter.

Did you not read my post? I said I sent a 337 in per the FAA’s guidance. I disagree with you that it was a “notification� 337. But everyone is entitled to their opinion.

On Monday, June 4, 2018 at 7:07:57 PM UTC-7, Charles Longley wrote:
Did you not read my post? I said I sent a 337 in per the FAA’s guidance. I disagree with you that it was a “notification� 337. But everyone is entitled to their opinion.

I read your post, very carefully, and its not clear what you have done. Did you send a 337 to Oklahoma or the FSDO? Did you treat the installation was a major modification, and if so would you mind explaining why? Did you get the FSDO to approve Block 3 before sending it to Oklahoma? Did Oklahoma send you back the 337 with Block 3 approved? I appreciate your help here explaining exactly what you did, I suspect we may be talking at crossed purposes.

I again want to reiterate that ADS-B Out installations in gliders (I know you did a towplane) should normally be minor modifications, and therefore do not need major modification approval, but do require a "notification only" 337 filed with FAA HQ.

I followed FAA guidance and installed a Stratus transponder with its associated GPS antenna in accordance with the STC. The STC only has a few models in it not including the Pawnee. I filled out the 337 per FAA guidance and sent it off to OK City. It wasn’t a field approval but was a Major Alteration so no need to send it to the local FSDO. Again per FAA guidance. I don’t expect to get the 337 back. I expect it to just be filed with the aircrafts records as usual.

To reiterate there is no such thing as a “notification� 337..

I haven’t been asked to or researched putting an ADS-B out transponder into a glider so I can’t really speak to that. When I install the PowerFLARM brick into my glider in the fall I’ll get the ADSB out option and do the appropriate research/ paperwork.