My first post here.
I'm a partner in a 95 Mooney Ovation (M20R). On a 2.5 hour flight back to home airport, day VVMC. Hear a whir and then silence in the headset, and then alt/volt light starts flashing on the annuciator panel. Cycle the alternator switch and circuit breakers several times and get nothing. Shed excess electrical load, just running #2 radio and transponder, led beacon and nav light. I have about 80 miles and 11,000 feet to lose. Decide to continue to home. Both batteries are new, figure I can switch batteries if the gear won't come down. Land with no issues.
Buy replacement alternator, pull the old alternator out. The shaft of the alternator had snapped off and dropped the elastomeric washer, gear and shaft. IT was just sitting there grinding against the crankshaft gear. Only reason I didn't have catastrophic failure is because the gear was to big to properly wedge against the crankshaft gear. Lots of metal shavings. Oil pump is destroyed. Camshaft is ruined. I'm hoping the crankshaft is still ok, but will let the shop decide. Will have to replace the gears though.
Prior to event, oil analysis and oil filter visual inspection showed very small pieces of orange substance. Blackstone labs said it was probably intake manifold couplings getting older. The engine was making slightly more metal, but nothing of immediate concern.
Alternator is a Hartzell ALV-9610. The castle nut on the end of the shaft broke in half. We found it in the oil pan. 420 hours since installed. Didn't even make it to the 500 hour inspection. I don't know what the lesson is, but orange stuff in the oil filter could be the elastomeric washer on your alternator giving up.
