My buddy had a mechanical after he flew me back to KADS yesterday evening that's leaving our heads scratching.
Short story - Electrical works fine with the engine off, the moment you turn it on it *all* fails except the courtesy light under the wing.
He had a pretty substantial amount of panel work completed recently, so there's a lot of "new" in this plane that could be at play.
Battery
Alternator
Voltage regulator
Dual G5
JPI EMD 930
GMX200
420 and 530
Garmin AP
The only anomaly that we noticed in our flights this past weekend is that volts go up and down approximately +/- 0.25V when the beacon is on.
As he went to depart yesterday, just before takeoff, every screen went out. That includes everything on the avionics bus and on the master switch (EDM930). He taxied it back and we checked that there wasn't corrosion on the battery terminals. We did find a broken plastic housing on the avionics switch so we had that replaced last night. It was a let down after five or ten minutes of working fine with the engine off, to only have it fail immediately once the starter was disengaged.
- Electrical fails w/o the alternator on
- It's becoming more frequent, it was failing after a few minutes, to now immediately.
- We tried to isolate by turning everything off on the avionics bus, turning them on one by one and sometimes that works and sometimes it doesn't.
- Connections on the master switch behind the panel look firm.
- There is no electrical burning smell
I thought the JPI wasn't recording, but, then realized just now that it was but Savvy by default doesn't show you short flights. I did notice this oddity:
Yesterday's long flight (showing the +/- 0.25V):
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Electrical failure just before T/O... high amps after starting then falling towards normal. Could be nothing but everything is suspect now.
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Any ideas on where we should look next?