Service difficulty report · Gear · Cessna R172K

Difficulty date
July 14, 2011
Submitted
July 14, 2011
Operation
General aviation
Aircraft
N8186V
Make and model
Cessna R172K
Aircraft serial
R1722319
Aircraft time
1,150 hours
Engine
Cont IO550N
Engine time
1,150 hours
Propeller
Hartzl PHCJ3YF1
Part
Gear
Part number
632018
Condition
Worn
Location
Crank Shaft
Part time
1,150 hours
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

WHILE PERFORMING AN ANNUAL INSP OF THE ENGINE, NOTICED ALTERNATOR HSG LOOSE. 500HR ALTERNATOR INSP WAS DUE. SO UPON REMOVAL OF ALTERNATOR FOR INSP IT WAS DISCOVERED THAT ALL OF THE TEETH ON THE CRANKSHAFT GEAR FACE WERE EITHER MISSING OF SEVERLY WORN. THERE WAS NO INDICATION OF ALTERNATOR FAILURE PRIOR TO THIS DISCOVERY. ON THE INCOMING RUN-UP ENGINE OIL PRESSURE WAS ON THE LOWER SIDE OF THE GREEN BAND. HOWEVER THE MAGNETIC OIL DRAIN PLUG WAS COVERED WITH FILINGS. CUTTING OPEN THE OIL FILTER FOUND THE PAPER ELEMENT WAS COVERED IN SILVER WITH NO DEBRIS. IF THERE WASN'T A 500 HR INSP DUE ON THE ALTERNATOR THIS PROBLEM WOULDN'T HAVE BEEN FOUND.

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