That old 727 in Tulsa still haunts my pin tests

Back in 2004 I was doing a pre-purchase check on a 727 that had sat in a Tulsa hangar for nearly a decade. The wiring looked perfect from the outside, but every continuity test gave me readings that flipped around depending on the humidity that day. Turns out the previous shop had used this weird gray sealant on the cannon plugs that absorbed moisture and turned into a semi-conductor. I ended up chasing phantom shorts for two full weeks before I stripped every connector and re-terminated them. Anyone else run into corrosion or goop that hides until you apply heat or vibration?

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1 Comment

james_davis1616d ago

I read a piece in an old Avionics Maintenance journal a few years back about a similar issue with silicone-based sealants in the Gulfstream fleet. The article said these compounds can pull moisture right into the pins and change their resistance values, which matches what you saw. Heat and vibration just make it worse because the conductive path shifts around.

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