Alternator Failure -- Now for something different

[Auburntsts]

So we just got home from to Tampa after a trip to Iowa. As I was putting the plane away I noticed a huge oil leak dripping oil all over my front gear fairing and all down the belly. The trip today was 6 hrs in the air with a fuel stop at the 3 hr point. No oil found during the initial preflight or the fuel stop. There were also no adverse engine indications in the cockpit. So I surmise it happened during the last leg relatively close to home. Anyway, I pulled the cowl and this is what I found -- my backup alt, a PP FS1-14 had backed of its vacuum pad adapter. Never heard of this ever happening before.

[Steve Melton]

overhung mass of the alternator may be finding a natural frequency and then it's only matter of time. lack of Engineering, did not consider vibration. even my daughter can do better than this.

[PilotjohnS]

If that picture is exactly as you found it, i would be interested to know how those threads are in the adapter/case; if the bolt was sticking thru, unlikely it backed out due to vibration. Could have been installed without using a torque wrench and the bolt was too tight. Bolts that are going into aluminum housings always should use a torque wrench; if done without, they are almost always overtorqued.JMHO. YMMV

[Auburntsts]

Yep, that’s how I found it. I have no clue as to how the alternator body gets attached to the adapter as it comes already attached from the factory. I’m going to contact PP and send them the pics.