Service difficulty report · Pinion Gear · Bell 407

Difficulty date
May 12, 2002
Submitted
June 21, 2002
Operation
Air carrier
Aircraft
N577AL
Make and model
Bell 407
Aircraft serial
53247
Engine
Allsn 250C47B
Part
Pinion Gear
Part number
23071895
Part serial
NN147472
Condition
Worn
Location
Engine
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

ENGINE WAS REMOVED DUE TO CHIP LIGHT. GEARBOX WAS DISASSEMBLED TO FIND SOURCE OF METAL. FOUND EXCESSIVE GALLING ON PINION GEAR, SPALLING AND GALLING ON T/M GEAR. BOTH GEARS HAVE VERY UNUSUAL WEAR PATTERN. ASSURE PROPER MESHING AND MACHINING OF GEAR TEETH AT FACTORY.

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