Transponder failed in flight

[swatson999]

OK...need some help diagnosing this...

After 166 hours of operation, today the SV-XPDR-261 failed in flight during a cross-country. The 1-2-5 reset failed to restart it. Had the big red "X" at the top of the display.

After landing, shutting down and putting the plane in the hangar, powered up the systems and lo and behold, the XPDR was fine.

What gives?

This was not a power problem, as both the XPDR and the ADS-B are on the same fuse (not CB) and the ADS-B continued to work.

Need some suggestions as to what to look for...

TIA!

Steve

 

[dynonsupport]

Rebooting the screen with 1-2-5 doesn't do anything to the transponder. If this ever happens again, I would pull the breaker for the transponder and try cycling it.

But no, we've never heard of this before, so we don't have any idea what is up.

One or two SkyView screens in the plane?

 

[swatson999]

One SV-1000.

Can't pull the breaker...it's fused and they're not accessible in flight.

 

[swatson999]

OK, happened again, just today, at the end of a 45 minute flight. System had a "Caution" and the message was Transponder Offline.

After shutting down and powering down all systems, a flipped the master switch and when the SV booted up, the transponder was fine.

I have a single SV-1000, XPDR-261 (the high altitude high performance one), ADS-B, ARINC 470, EMS module and the backup battery. Oh, and the autopilot servos for both axes.

Help?

 

[Dynon]

Everything else besides the transponder seems to be working OK? Does the GPS location persist on the map?

 

[swatson999]

Yep...GPS is good, autopilot continues to work fine, ADAHRS never skipped a beat...even the ADS-B continued (being in L.A., there were plenty of other aircraft to "wake up" the system and have it send out TIS or whatever other messages it sends).

 

[swatson999]

Any suggestions yet?

 

[jakej]

Steve

Just a thought (you'd probably checked this anyway) - did you confirm that the pins in 14 & 15 in the Transponder plug are actually fully seated ?

Jake J

 

[Dynon]

As Jake says, the thing we'd encourage you to do is to double check every wire for full continuity and positive engagement in the connector. The transponder modules are really robust. The majority of those we get back here don't have anything wrong with them that we can detect. But if you don't find anything and continue to have this issue, we're happy to take a look at it.

 

[swatson999]

I double-checked the connection at annual and it was solid, so let's do this...

I'm getting the plane ready for the paint shop (scheduled for end of April), so I'll keep an eye on it, and if it happens again, when I take everything out for painting, I'll check the connector again, and if it's okay (pins seated and continuity good), how about I contact you and send it in then?

Meantime, if it happens again, is there a log file of any kind that would help?  I know at one point you guys had me grab some sort of "diagnostic" file (which necessarily freezes the system while it downloads the data).

It's a royal pain to pull the interior and the bulkhead and all that to check the connection again, so if that's okay, I'll keep flying and we'll see what happens.

I'd expect a loose connection to show up much more than twice in 180+ hours, but you never know.  I *do* know that every wire was crimped properly with a good tool (the DMC "little blue" crimper), visually inspected, pull tested, and inserted fully into the connector (and checked for seating in the connector when inserted).  I was meticulous on wiring .

(BTW...if it *was* a loose pin or loss of continuity on a wire, would it not show erratic behavior, rather than the complete off-line status, followed by fully working status on a power cycle? I checked the raw data in flight, and it was just "stuck"...the SV was sending via TX, and receiving nothing...the RX field was not updating its count at all).

 

[jakej]

"...I was meticulous on wiring  Smiley"

Steve, I believe you ;D

Why I mentioned it is that I think a well known supplier of connectors has been shipping out some dsub connectors that require the insert tool to make the pins/sockets click home fully - you don't have to ask how i know  : as I've had an issue which caused some grief until I found the problem.  In my case a continuity check confirmed the wiring was okay but pin seating wasn't.  I order the 500 pins & sockets on a regular basis so have had some experience in this area 

Hope you have a solution soon.

Jake J

 

[Dynon]

Steve - That sounds perfectly reasonable, and we agree that intermittency doesn't entirely jive with the power cycle fix. That export still exists but may not be entirely useful here. If you know your way around the setup menu, one thing that might help is to see what the serial port status for the serial port that the xponder is hooked up to when the transponder goes away. A screenshot of that (buttons 2/7 with a USB memory stick attached) would be ideal.

If you do send it in, if you're getting close on warranty (3 years), make sure to reference this thread to establish that we had a record of you reporting the problem.

 

[swatson999]

Roger all that...if it happens again, I'll grab a screenshot.

Will get back with you in the coming few weeks or so as I monitor it.

 

[swatson999]

Argh...it happened again TWICE this weekend (but I forgot to get a screenshot)...first time after about 1.5 hours of flight, second time the next day after about 20 minutes of flight.

So it seems to be happening more and more.

Both times cycling power fixed the issue (first time in flight, which I *don't* like to do, and second time on the ground after the flight (I don't have a separate switch for the XPDR, so I have to cycle Master power...not a good thing in flight).

I'll call customer service tomorrow. This can't continue (it makes passengers nervous and it's a problem for flying around Class B here in L.A., plus it's just not right).

 

[dynonsupport]

Steve,
We do need to figure out if this is SkyView's problem or the transponders. When you power cycle both together, that makes it really hard to figure out the root cause.

Since you can't turn off the transponder independently, I think the test is to turn off the SkyView. You can do this with button #1 by holding it down for 2 seconds. Then wait a second or two and hold it again. This will fully power cycle everything in SkyView without power cycling the transponder. At least then we'll have some more data.

 

[swatson999]

Ah, I tried that on an earlier flight, and it did NOT reset the transponder. (ETA: ref first post in this thread).

I have looked, as well, at the serial data (whatever pager that was, I don't recall), and saw data being sent to the transponder, but nothing coming back.