Service difficulty report · Alternator · Cessna 172H

Difficulty date
February 17, 2003
Submitted
March 5, 2003
Operation
General aviation
Aircraft
N3941R
Make and model
Cessna 172H
Aircraft serial
17255441
Engine
Cont O300D
Part
Alternator
Part number
DOFF10300F
Part serial
A166333
Condition
Inoperative
Location
Engine
Stage of operation
NR
How discovered
9
Nature of condition
O
Precautionary procedure
O

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

FAILURE OF THE SHAFT ON AN OVERHAULED ALTERNATOR. THE PILOT REPORTED AN AMMETER DISCHARGED WHILE CONDUCTING A PART 61 INSTRUCTIONAL FLIGHT. A PRECAUTIONARY LANDING WAS MADE AT THE NEAREST AIRPORT. INSPECTION OF THE ELECTRICAL SYSTEM INDICATED A FRACTURE OF THE MAIN SHAFT OF THE GEAR DRIVEN ALTERNATOR, AFT OF THE FRONT SEAL POSSIBLY DUE TO A MANUFACTURING DEFECT. NO OTHER DAMAGE WAS NOTED TO EITHER THE ACCESSORY GEARS OR THE ALTERNATOR ITSELF. PICTURES OF THE FRACTURED SHAFT ARE ENCLOSED. THE UNIT WAS INSTALLED IN DECEMBER 2001 AND ACCUMULATED 328 HOURS.

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