Transponder check

I had similar on my first check flight.Â* In 3 or so hours of so of
flying I had a momentary GPS drop out and that caused the failure. I
repeated the flight in an area outside the GPS interference testing area
and got a perfect score.Â* I don't worry about it any more.Â* OBTW, I just
had a perfect 2-year transponder ground check.

On 6/8/2019 8:04 AM, Sandy Coleman wrote:
On Saturday, June 8, 2019 at 7:36:22 AM UTC-6, wrote:
I recently installed Trig-22, TN-72 in my glider and passed ground test. After 3 competition days I pulled free FAA reports- two days are fine and in one day I have red value in NIC column (integrity and accuracy) of 0.41% fail. PAPR user guide does not say much what can be cause of this fail. Is anyone experienced willing to help evaluate failed report? Should I turn off TN-72 on my panel even only 0,42% in one flight was faulty(red) report out of 3 flights of 13 hours? Thank you. pavel
Search for "transponder 2 year check". Look at the May 9 posts. The answer is there as well as an offer to evaluate the report. One thing PAPR cannot measure is power out at the antenna.

Please do not turn off your GPS for the transponder! You may become invisible to aircraft with ADS-B in.

--
Dan, 5J

I suggest the two year transponder checks are a waste of time and money. A PAPR check proves my transponder is working properly. And the FAA can perform that check every flight, rather than allowing me to fly for 2 years with a faulty transponder.

How does the PAPR check verify receiver sensitivity, and suppression of side lobes to the standards set in 43 appendix F?

On Saturday, June 8, 2019 at 7:04:28 AM UTC-7, Sandy Coleman wrote:
On Saturday, June 8, 2019 at 7:36:22 AM UTC-6, wrote:
I recently installed Trig-22, TN-72 in my glider and passed ground test. After 3 competition days I pulled free FAA reports- two days are fine and in one day I have red value in NIC column (integrity and accuracy) of 0.41% fail. PAPR user guide does not say much what can be cause of this fail. Is anyone experienced willing to help evaluate failed report? Should I turn off TN-72 on my panel even only 0,42% in one flight was faulty(red) report out of 3 flights of 13 hours? Thank you.. pavel

Search for "transponder 2 year check". Look at the May 9 posts. The answer is there as well as an offer to evaluate the report. One thing PAPR cannot measure is power out at the antenna.

Please do not turn off your GPS for the transponder! You may become invisible to aircraft with ADS-B in.

Darryl Ramm

May 9



- show quoted text -
What tests exactly? There are two transponder tests, Part 43 appendix E (altitude encoder test) and Part 43 appendix F (Transponder RF test).

The encoder test (required when the static system is opened, etc) could not be achieved by the FAA Public ADS-B Performance Report, it relies on the encoder being correct.

The transponder RF test verifies the transponder replies correctly to a Mode A, C and S interrogations and checks for some corner cases of known possible issues, the FAA Public ADS-B Performance Report does not provide that information, there is no guarantee that an aircraft will experience all those different interrogations during a flight, etc. and the system may not be able to tell what is going on in a "live" non-test environment. Things that might be doable very roughly like infer transmitted power would be relatively inaccurate, better to measure those at the aircraft.

Now, two year checks made a lot more sense when transponders were powered by unreliable traveling wave tubes and had lots of components inside. Modern solid state transponders, with highly integrated digital components are much more reliable. So two years may be overkill, but I'd not hold my breath waiting for that to change.

The FAA Public ADS-B Performance Report are great for letting owners see that an ADS-B Out system is configured and working properly. Including being the *only* way for most glider pilots to know a 2020 Compliant or TABS ADS-B Out system is fully working... e.g. on a Trig transponder you can't just rely on seeing a lat/lon display on your transponder... the transponder can show you a lat/lon but you don't know the actual GPS reception is giving you a high enough NIC quality parameter, or that the SIL setup parameter is set correctly, ... things that can stop ATC or some airborne ADS-B In receivers being able to see your aircraft via ADS-B Out. And just asking ATC "can you see me" at times may not help, if you are within SSR coverage the controller can't tell if they are seeing you via SSR or ADS-B. And your buddy seeing you on a PowerFLARM also does not tell you if ATC or IFR/certified ADS-B In system can see your ADS-B position. ... so look at those performance reports. https://adsbperformance.faa.gov/paprrequest.aspx

Everybody flying with ADS-B Out should pull a report or two after installation to make sure things are OK, and maybe once a year or so after that. Those reports can be used by an A&P as part of a install in a type certified aircraft, or they can utilize ADS-B capable ground test equipment -- more $$$ than Mode-S transponder test gear -- which few folks working with gliders will have access to. For experimental aircraft installs there is no documentation needed of a test, but get one done yourself. And regardless of who installed and claimed to test or not what they did, pull your own report and check.

The FAA is looking at the equivalent of those reports as well. And they are likely to contact you eventually if there are glaring problems (and as I mentioned before they are likely to contact folks with TABS systems (which by definition are not 2020 Compliant)... the FAA has no way of knowing the install is not intended to be 2020 Compliant).

As always anybody with a Public ADS-B Performance Report and has questions about it can email the PDF report to me. I'm getting about one a week. GPS Antenna installation quality (affecting NIC), basic TT21/TT22 setup menu mistakes, flying on the edge of ADS-B ground coverage, or forgetting to get the transponder firmware updated, are the most likely causes of issues being flagged in those reports. I'm updating some of the Trig setup instructions (most folks have hopefully been using the notes that Richard and I wrote on the Craggy website) and will get those updated soon.

I just took my Pegasus in to have the Trig T21 checked. The glider is relatively new to me and this is the first time I've personally taken it for the test. My former partner took it to the same shop two years ago and it passed and without comment from the tester, as far as I know. The guy doing the testing said that the power output was low - getting 35 watts while the glider was in the cradle, 65 watts at some point after we backed it off and some other, higher, reading a bit later after jockeying the test antenna around a bit. I don't know what that figure was. The antenna in the glider is a flat type that is mounted on the belly under the seat pan. The connection looked good but he cleaned it anyway. Its to the right of center line and the testing was done from the left, if that matters. He tried using his own antenna and didn't see any improvement. He did a fair amount of button pushing equipment moving and finally said, "I got it to pass but in the off season send it out to get checked." He also mentioned that the frequencies were a bit off.

I got the impression that he wasn't that familiar with the Trig unit or gliders. So, what kind output should I be seeing 4' from the glider? What could be causing the low output? The battery was almost, if not completely, fully charged. Why would the frequencies drift?

On Sunday, June 9, 2019 at 8:43:42 AM UTC-4, wrote:
I just took my Pegasus in to have the Trig T21 checked. The glider is relatively new to me and this is the first time I've personally taken it for the test. My former partner took it to the same shop two years ago and it passed and without comment from the tester, as far as I know. The guy doing the testing said that the power output was low - getting 35 watts while the glider was in the cradle, 65 watts at some point after we backed it off and some other, higher, reading a bit later after jockeying the test antenna around a bit. I don't know what that figure was. The antenna in the glider is a flat type that is mounted on the belly under the seat pan. The connection looked good but he cleaned it anyway. Its to the right of center line and the testing was done from the left, if that matters. He tried using his own antenna and didn't see any improvement. He did a fair amount of button pushing equipment moving and finally said, "I got it to pass but in the off season send it out to get checked." He also mentioned that the frequencies were a bit off.

I got the impression that he wasn't that familiar with the Trig unit or gliders. So, what kind output should I be seeing 4' from the glider? What could be causing the low output? The battery was almost, if not completely, fully charged. Why would the frequencies drift?

Is your transponder firmware up to date? https://trig-avionics.com/support/tr...duct-software/ "The current version of software installed in your Trig product will be shown on the display at initial power up." Version 2.13 is current.

I wouldn't want the antenna under my seat pan...

Yesterday the company I work for had a problem with many aircraft (hundreds) that had ADSB recently installed. There was an unusual amount of solar activity that knocked out the ADSB and as a consequence the transponder too. I dont know the details but it was only a problem for one aircraft type in the fleet. My point here is that in some equipment/instalation combinations solar activity will effect reliability of these systems.

On Sunday, June 9, 2019 at 6:56:53 AM UTC-7, wrote:
Yesterday the company I work for had a problem with many aircraft (hundreds) that had ADSB recently installed. There was an unusual amount of solar activity that knocked out the ADSB and as a consequence the transponder too.. I dont know the details but it was only a problem for one aircraft type in the fleet. My point here is that in some equipment/instalation combinations solar activity will effect reliability of these systems.

It will be interesting to understand what is going on there, multiple reports on twitter and elsewhere of CRJ and some Boeing aircraft having issues.

It should take a very large solar flare to affect GPS reception. With a few quick searches I don’t see reports of large solar flares or geomagnetic storms. Where is John Leibacher when you need him? :-)

An ADS-B GPS receiver problem should not ever “knock-out� a transponder. It may prevent the transponder transmitting ADS-B position data, but the device should keep working as a transponder. If it is then... wholly ASB and AD Batman.

I am curious if all those aircraft have Rockwell Collins receivers like GLU-925/GLU-2100 series?

On Sunday, June 9, 2019 at 5:43:42 AM UTC-7, wrote:
I got the impression that he wasn't that familiar with the Trig unit or gliders. So, what kind output should I be seeing 4' from the glider? What could be causing the low output? The battery was almost, if not completely, fully charged. Why would the frequencies drift?

Why are you asking r.a.s. these questions?... the test technician was right there testing your transponder. Ask him. Especially ask him exactly what he did to get it to pass.

I also would not be sitting on a transponder antenna. You are also a sack of water that may affect/obstruct some of the signal. I would get the antenna back in the tail boom. Away from metal structures. An external 1/4 wave antenna with ground plane may be better.

The RF output that should be seen is at least what is specified in the transponder RF test in 14 CFR Part 43 Appendix F. But it’s aiming at seeing 70W for a nominal 125W or 125W for a nominal 250W transponder. So what is you transponder a TT21 or TT22? But either way, the initial power measurements you mention are a clear fail.

Trig transponders rely on the use of low-loss cabling and proper antenna installation. The Trig install documentation is well written and very clear about what is needed. With any transponder cabling and antenna are suspect any time the power is too low. I would hope a technician connects direct to the coax or transponder RF output connector and checks that if in doubt.

Why do frequencies drift? Why do they not (well strictly they always are)? It’s all the magic power of crystals. Frequency reference crystals sometimes age badly, might not like the transponder being dropped or vibrated around in a trailer, or the electronics that drive the phase lock loop/frequency multipliers goes wonky... but I would not rely on one test with one technician with one test set. Have it rechecked by somebody else and/or just get it to Midcontibent for them to check out.

On Sunday, June 9, 2019 at 10:16:44 AM UTC-7, Darryl Ramm wrote:
On Sunday, June 9, 2019 at 6:56:53 AM UTC-7, wrote:
Yesterday the company I work for had a problem with many aircraft (hundreds) that had ADSB recently installed. There was an unusual amount of solar activity that knocked out the ADSB and as a consequence the transponder too. I dont know the details but it was only a problem for one aircraft type in the fleet. My point here is that in some equipment/instalation combinations solar activity will effect reliability of these systems.

It will be interesting to understand what is going on there, multiple reports on twitter and elsewhere of CRJ and some Boeing aircraft having issues..

It should take a very large solar flare to affect GPS reception. With a few quick searches I don’t see reports of large solar flares or geomagnetic storms. Where is John Leibacher when you need him? :-)

An ADS-B GPS receiver problem should not ever “knock-out� a transponder. It may prevent the transponder transmitting ADS-B position data, but the device should keep working as a transponder. If it is then... wholly ASB and AD Batman.

I am curious if all those aircraft have Rockwell Collins receivers like GLU-925/GLU-2100 series?

....and the FAA is officially fingering Rockwell Collins. I'll wager good money this is nothing to do with solar activity, and wager less money that somebody gooched some software... the same company that cannot get GPS epoch rollover done properly.

https://www.fly.faa.gov/adv/adv_othe...eDate=06/09/19