FAA ADSB Report Questions

[jmurtagh13]

I have all Dynon SV equipment + GTN650, I received my ADSB report back from the FAA with some exceptions.

Under missing Elements the Geo Alt is showing a 3.2% failure rate.  I've run 3 previous reports over the last year and they've all shown this failure.

And then under Other checks:
Flight ID 100% fail, No"N" 100% fail and Partial 100% fail, these I've not gotten in previous reports.

I've attached the report.  Any help in solving these issues would be much appreciated

Thank you

John

 

[rogersmart]

Can someone please explain how to get a ADS-B Aircraft Operation Compliance Report from the FAA

 

[jmurtagh13]

Send an email with N-number to;
9-AWA-AFS-300-ADSB-AvionicsCheck@faa.gov and request a detailed report.

Include the following info:

Tail Number: N1354J
Transponder: Dynon SV-XPNDR-261 (Class 1 Mode S)
GPS: Garmin GTN650

Flight Date / Times;

June 19th 10:00am EDT – 12:00pm EDT KCRG to KLZU

 

[Dynon]

So most of the red things at the bottom of the report are because your tail in SkyView does not have the "N" in it in SkyView's TAIL NUMBER setting. So change that and I think everything but GEO ALT should go away.

As for GEO ALT: GEO ALT is GPS ALT, and GPS ALT is the first thing to go when you have bad GPS reception for some reason. So first, you might check on your GPS signal via the GTN itself. I think we've seen a report like this before, and in that case it was a GPS antenna install issue on the GPS device (it was a 430 in that case). I believe the previous customer had put the antenna too close to the COM antenna.

Beyond that, are you on the latest GTN and transponder software? Also, are you running SkyView 4.2.1? From your report, it looks like you probably are.

 

[jmurtagh13]

Dynon,

Thank you for the quick reply. I'll update the tail number in the SV.
The GPS antenna is on top in front of the wind screen, all the other antennas including both coms are on the bottom of the fuse. I am running 14.2.1 and I did update the transponder software. On my next flight I'll check the GPS signal strength.

Thank you

John

 

[dpbarnes]

I fought a similar problem for months.  I had errors in the report and transponder complained every so often about loosing gps and my lpv approaches would downgrade to lnav.  The signal level on the 650 was good. I tried changing antennas, coax, the 650 itself with no change.  I moved the antenna and made it worse.  That was good because it made it easier to trouble shoot. I figured it must be interference. After flying with various devices shut off I finally figured out that the door seal pump which ran automatically every so often as the pressure in the seal dropped was causing the gps to loose signal.  When I moved the antenna I moved it closer to the pump which made it worse.  Looking back at it, it all seems so logical but the time I spent trying to find the problem was enormous.  I guess I can be happy it was my time and I wasn't paying an avionics tech to look for this needle in a haystack. I have a vp-200 so I just programmed the pump to run in taxi mode but not in any modes of flight.  I also replaced the pump motor with a brushless motor.  I have not tested whether the brushless motor will interfere with the signal yet.  Maybe this week.

 

[jmurtagh13]

Dan,

Thank you for the very helpful reply. There are items I turn on during the flight i.e fuel pump for short periods of time that maybe causing this issue, so this give me a good starting point for tracking this down.

Another question, I was told that the GTN650 requires a minimum of 8 feet of coax cable for the GPS antenna which I did and I have coiled up behind the panel, is that truly required?