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Took me 6 hours to find a simple ground fault today
Working on a 737 in Atlanta. Got a flickering NAV light on the right wing. Guess I was too quick to blame the ballast. Chased wiring for 5 hours before I realized it was just a bad ground pin in the connector. One crimp fixed it. Anyone else spend way too long on something that simple?
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felix_lane992mo ago
On the 737, the ground pins in the connector are usually crimped with a specific tool that puts a little dimple in the pin. If you don't use that tool, it might test fine but slip under vibration. I've seen guys just squeeze them with regular pliers and think it's good. That dimple is what locks the pin into the connector housing and keeps the ground solid. Without it, you get exactly what you described - a flickering light that passes a multimeter test. It's a pain but that's why Boeing calls for the special crimper.
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charlie_ellis2mo ago
And that's the thing with grounds specifically, they can test fine with a multimeter but still fail under load. Had a similar issue on a Gulfstream where the ground looked perfect on paper but would just randomly drop out when the vibes got going.
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hall.nina2mo ago
My buddy Mark had this exact thing happen on a Learjet once. He spent two whole days chasing a flickering nav light that would only cut out during takeoff rolls. Ohm test passed every time on the bench but soon as the engines spooled up it would go dark. Finally found a ground lug that was barely hanging on by a few strands of wire inside the insulation. Looked perfect from the outside but the crimp had basically turned to dust.
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