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TIL the hard way about wiring a standby alternator wrong
Had a Cessna 172 come in last Tuesday with an intermittant charging issue. Spent 4 hours chasing the wrong circuit because I assumed the field wire was hot with the master on. Anyone else trip over this sneaky pitot-static ground setup?
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wendy2052mo ago
Did you end up checking the pitot-static ground before or after you realized you'd been chasing ghosts? I once spent an entire afternoon troubleshooting a standby alternator only to find out I'd wired the field backwards and it was just sitting there looking pretty. My mentor still brings it up at every shop BBQ.
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sandrap402mo ago
That 200 hour inspection when I was still pretty green, maybe it's just me but I always thought the pitot-static ground was fine because the system looked clean. I mean, I spent two days swapping pitot masts and chasing pressure leaks before someone asked if I actually checked the ground path. Turned out it was a tiny bit of corrosion under the screw that made the whole thing act flaky. Now I always hit that ground first no matter what.
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stone.simon1mo ago
Oh man, that corrosion under a screw has bitten me more times than I care to admit. It's always the little things that get you, isn't it? I remember a similar situation with a fuel quantity sending unit that kept showing erratic readings. Spent a full day chasing wires and swapping parts only to find a tiny bit of paint under the ground screw that was making a poor connection. These days I tell every new guy to start with the simple stuff first, because it's almost never the big complicated part that's the problem. It's just frustrating how much time you can waste when you assume the clean-looking connection is actually good.
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