Alternator Problem
reported by
Rusty Wells
Friday, 5 Sep 03 I left RHV before the tower was open in my Cherokee 150, making the normal calls on ctaf 119.80, receiving no returns, as there was no traffic. Switching to 118.10, I heard some radio traffic, but had no reason to call. At 5000ft over the Altamont, I noticed a faint rattling sound which disappeared on leveling at 5500 over Tracy. Picking up my friend Larry, (A&P/I.A.) at his Lake Commache dirt strip w/out shutting down, we headed back. On the way we talked about some strange electrical problems I'd had and started turning things on and off while monitoring the ammeter. No deflections! Well, it's not the first time I've lost the @#$! electrical system, but the first time it was a nice day and not in the dark or a storm!

We were able to receive radio for a while, but found we couldn't transmit and be heard on arriving near RHV, so scrambled for the handheld and got cleared to 3lR only to have the tower let a C150 onto 31R while we were on short final, (or maybe that guy didn't understand what "cleared for immediate takeoff" means.) The tower apologized, cleared us for 31L and I came around, approaching high and hot, landing long, to be at the last exit, hurrying to the gas pit, as Larry was to drive our beloved '67 Sunbeam home for his beautiful daughter, and get back to work.

At the gas pit, we looked in the cowl and found the alternator lying on the bottom! Looking around the front, the thing had chewed its way into the nose bowl! On a longer flight it might have chewed its way to the prop!!!! VERY SCARY TO LOOK AT!!

At teardown, Deke and I noted the trouble came entirely from the alternator itself. The alternator had literally EXPLODED! The rear needle bearings had failed allowing the rotor to roll around inside and clean out all the tender innards, burst the case bolts and jackhammer the mounts until all the brackets were broken and two bolts were ripped out of the crankcase!

At present, I'm designing and machining special tooling to drill, tap, and install a helicoil in the buggered bracket hole hidden behind the prop flange, have located and ordered replacement brackets, and repaired the fibreglas nose bowl. Larry introduced me to David Aviation at Calaveras County who holds an STC to split the nose bowl on a Cherokee. Best believe the newly accessible alternator will be more carefully inspected in all future annuals.

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