Beech H35 Bonanza
Improper Mounting
The alternator suffered a total mechanical failure after only 144.7 hours. The replacement unit failed after only 41.8 hours in service. Observation suggests the alternator case hardware was not properly torqued and/or was not assembled with locking fluid. Each failure found the aircraft in near-IMC conditions.
Part total time: 41.8 hours
Cessna 182T Skylane
Case Separation
Alternator failed to charge during cross-country flight. Inspection shows separation of alternator case halves, resulting in sloppy tolerance on drive shaft main bearing and failure to produce current.
Part total time: 1373.0 hours
Cirrus SR20
Unknown Failure
While airborne, the #2 alternator (p/n 653344) was inoperative. Investigation discovered the alternator’s field was open. During replacement, maintenance noted the cooling fan was covered with a dusting of copper-colored particles, which could be from the brush slip rings.
Part total time: 286.0 hours
Mooney M20J 201
Field Circuit
Alternator’s five-amp field circuit breaker popped. Investigation revealed the voltage regulator had shorted internally and the field circuit breaker was fried. Run-up seemed normal until applying a full complement of electrical loads, when the field circuit breaker tripped and fried another regulator. Discovered alternator had no output. It appears failure of the new alternator caused failure of voltage regulator. Voltage regulator does not seem to be protected by five-amp field circuit breaker.
Part total time: 31.0 hours
Piper PA-28-181 Archer II/III
Seized Alternator
The aircraft was in the traffic pattern when pilots noted the alternator was no longer charging, accompanied by a strong burning odor in the cabin. Inspection found the alternator had seized, causing the alternator belt to overheat and melt.
Part total time: Unknown
Piper PA-34-200 Seneca
Internal Short
Left alternator failed in flight, with smoke coming from the cowling. Inspection revealed the alternator would not rotate when turning the propeller. After removal, further inspection revealed that a fairly large piece (approximately one-inch square) of the rotating assembly had broken off and was still in the alternator, preventing rotation. Damage to the associated wiring was also noted.
Part total time: Unknown
