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Spent 8 hours chasing a ghost fault in a Garmin G1000 | Avionics Technicians - Librear

Spent 8 hours chasing a ghost fault in a Garmin G1000

Last month I had a G1000 that kept throwing a random AHRS error on startup. Pulled the unit twice, reseated connectors, even swapped a few line replaceable modules. After 8 hours of testing it turned out a tiny bit of metal shavings had gotten stuck in a backshell pin on the pitot static line. Has anyone else dealt with intermittent faults that just seem to vanish when you look at them?

3 comments

3 Comments

avery_nelson4mo ago

Eight hours and you're calling it a ghost fault? That sounds like a learning opportunity not a wild goose chase. Metal shavings in a backshell pin is exactly the kind of stuff that shows up when you get systematic instead of just swapping parts. I've seen guys waste two days swapping radio modules on a King Air only to find a loose shield ground on a coax connector. Next time try a continuity test on every single wire from the sensor back to the box before you pull any modules. It usually bites you in the ass faster. What did you use to find those shavings, a borescope or just a good light?

iris_stone284mo ago

Ha! Good light and magnification, bore scopes are overkill for something that obvious once you look close enough.

thomasm414mo ago

And now you've got the FAA guys nodding knowingly like "yeah, we see that every Tuesday" while you're just standing there holding a piece of metal shavings thinking about those 8 hours you'll never get back... I once spent a whole afternoon chasing a bad alternator that turned out to be a loose screw in a junction box, so I feel your pain. Your problem is the aviation version of the check engine light that mysteriously turns off when you pull into the shop. Next time maybe try offering the plane some coffee and see if it decides to cooperate...