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I finally caught why my ground checks kept failing on the same panel
So I've been working on a King Air 350 out of a hangar in Boise for the last two weeks, chasing a weird intermittent fault on the weather radar display. Kept getting a ground check failure every third or fourth time. Replaced the waveguide, swapped the antenna drive, even pulled the display unit and bench tested it. Everything passed. Then last Friday I noticed the copilot's side window seal was letting a tiny drip of water in right above the radar controller. Must have been moisture causing a short on the connector pins. Nobody else thought to look up there because the radar antenna is in the nose. Now I always run a moisture check on any panel near a window seal before swapping parts. Anyone else found corrosion in weird places from something dumb like a leaky seal?
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skylerg171mo ago
A buddy of mine at the regional airline in Salt Lake had a similar thing happen on a CRJ-200. The weather radar was flaking out and throwing a ground fault error code that nobody could pin down. He spent two days swapping out the radar receiver and all the coax cables behind the nose cone, even changed the power supply. Turned out the forward galley drain line had a pinhole leak right above the overhead panel where the radar controller wiring runs. Just a slow drip that had corroded three pins in the connector green and fuzzy. He only found it because he got a weird static sound on the cabin intercom when it rained. Now every time we get a radar glitch in the hangar, he checks all the water drain paths first before touching any avionics.
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marymorgan1mo ago
Hear you on that, that CRJ story sounds exactly like something I'd run into. You start chasing the obvious stuff like the antenna or the waveguide and the real problem is something stupid like a leaky coffee pot or a drain line dripping on the wrong spot. I've gotten to where I just assume every time I dry out a connector or pull a board that's got corrosion on it, there's a water trail somewhere above it. Now I keep a flashlight and a little mirror on a stick in my bag just to look up behind panels on a rainy day before I do anything else. It's saved me a ton of time and a few parts swaps that would have been a waste.
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