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Lost a transponder squawk on a 172 during a ramp check at KAPA and I'm still not sure why
Last Tuesday I was doing a quick preflight on a 172 at Centennial and the transponder wouldn't hold its assigned code, it kept dropping back to 1200 on the ramp check. I cycled the avionics master twice, reseated the tray connector, and it still flaked out until I tapped the panel above it. Turned out to be a loose ground stud behind the panel, but I burned 40 minutes chasing the wrong thing first. Any of you run into a transponder that only fails when the cabin is cold?
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kim.nancy28d ago
That loose ground stud behind the panel is such a classic. What I want to know is whether you ever got it to fail on the ground when it was warm, or did it only act up on that cold morning? I've chased a bad tray pin before that only showed up below about 40 degrees, and it was because the metal shrank just enough to lose contact. Did you try wiggling the tray while it was in the fail state, or did you go straight to the avionics master? Also curious if the squawk dropped to 1200 or if it blanked out completely, since those point to two pretty different problems.
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