Took 4 nights to realize the bus bars were telling me something

We had this intermittent fault on a CRJ at the hangar in Tulsa. Would show up in the logbook maybe twice a week, always the same WOW relay snapshot, never during our ground checks. I pulled every relay on the panel, swapped two with spares, reseated all the connectors, nothing. On the fourth night I got curious and took a voltage reading right at the bus bar feed instead of the load side. 0.4 volts of drop that my meter kept missing because I was testing downstream. The bus bar itself had a hairline crack at the mounting stud, probably from years of vibration and somebody torquing the nut too tight once. Scared to think how many guys before me condemned good relays because of that same sort of build up. Anyone else had a case where the bus bar or power distribution block was the hidden problem? Really makes me want to meter every connection point even when the test points look fine.

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abby_palmer1mo ago

One cracked bus bar and suddenly every relay on the plane is guilty until proven innocent? Ngl, that sounds like a stretch. You found one bad connection after four nights of digging, that doesn't mean the whole power distribution system is lying to you. Test points exist for a reason and if they're giving consistent readings, most guys aren't going to rip the panel apart hunting for a ghost. Plus, you said the voltage drop was only 0.4 volts, that's not exactly screaming at you from across the hangar. Maybe the real lesson is just to trust your meter when it says the relays are fine, not to assume every component is secretly cracked. I'd rather swap a few cheap relays than chase a hairline fracture that shows up once in a blue moon.

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