ALTERNATOR FAILURE

[david.2.wilcox]

With 875 hours on 22A-1770, the alternator failed in flight. First indication was a tachometer failure on the GR EIS. Switched over to see the voltage and it only read 12, battery voltage. Then notice the smell of burning insulation. I was at 9500 msl about 15 miles into a flight from Payson to Winslow. Return flight after a 180 turn was uneventful with intermittent tachometer indications.

Investigation showed no under cowling wires distressed. Removed the alternator coil and found one of ten coils with a dull insulation finish with the other nine, nice and shinny. The same pole coil was the first in the series and had one of the two lead wire going to it. The lead wires are not strain relieved, which I believe to be the root cause of the failure. Inevitable movement of the lead wires from the regulator to the coil worked the wrapped coil wires loose causing a short to ground.

Krotje has a new 12 pole coil and rotor on the way to me. The upgrade to 20 amps is welcome and timely as I am in the middle of installing a VAL-2000. There are four internal wrenching button head screws holding the rotor to the flywheel. It was recommended to me to heat the screws and use a new wrench to withdraw them. It's a waste of time. Grind off the heads, remove the rotor, and the screw studs remove with vice grips quite easily.

If the new coil has the same design flaw, I plan to install some type of strain relief at the using one of the coil mount screws.

[WaiexN143NM]

Hi david,
What is the cost of the new 12 pole rotor coil from jab usa?

WaiexN143NM
Michael

[vwglenn]

Looks a heck of a lot better than mine did when I had my issues coming back from OSH last year. My two leads became one. Never had any smell but all my electrics failed about 5-10 miles from my destination. New stator from Sonex was pretty cheap.