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Alternator Drop Out

John Tierney

Well Known Member
Sponsor
Electrical problems are so much fun...

On the last few flights my 60 amp Plane Power Alternator has dropped offline, then a while later in flight come back on. I did an oil change last week and checked all the FWF connections and everything seemed tight and secure.

While flying yesterday it quit again, about 5 minutes from home base. Now here is the weird part...when I engaged the flap switch (standard Van's setup) in the downwind for landing the alternator came back on and stayed on. I have attached the Savvy Analysis image showing volts/amps and flap position/fuel pressure (yes I forgot to shut off the fuel pump until mid-flight, thus the higher amps for a while). Ignore the first 10-min., that was unrelated Skyview ground time.

My setup is a PP 60 amp alternator, pullable field CB, split master switch and Dynon Skyview. I have an idiot light from the PP alternator and stand alone voltmeter/clock, so I know it isn't just a bad Skyview indication. Only about 100-hours on the engine/alternator.

Since I didn't see a problem FWF, my next step if more behind the panel checks for security. Any other suggestions would be welcome.
 

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The flaps are mostly coincidental to the alt issues, even though their draw kicked the alt back on once.

search and look for the very common PP alt issues on this site. Two that come to mind are the connectors that go bad or had bad crimps from the factory and the stator ring failing at 100-200 hours. A failing VR typically doesn't go off then on again, without also showing problems holding a voltage.

Larry
 
Check the integrity of the field wire at the 3 pin connector on the back of the Alternator.
 
Thanks guys. I will check the plug next time I'm at the hangar, though I did pot the connector with RTV based on Dan H's experience.
May need to get that Sumitomo connector with isolators.
 
In the FWIW category, I just ran across a failed split master/alt switch. Alt field was intermittent; pressing on the operator would bring the field back online…
 
In the FWIW category, I just ran across a failed split master/alt switch. Alt field was intermittent; pressing on the operator would bring the field back online…

This was my first thought...
Try bypassing the alternator half of that switch, temporarily as a diagnostic step.
 
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