SDR 20001113SH010

Service difficulty report · Pinion Gear · Bell 407

Difficulty date: August 19, 2000
Submitted: November 13, 2000
Operation: General aviation
Aircraft: N417AL
Make and model: Bell 407
Aircraft serial: 53054
Engine: Allsn 250C47B
System (JASC): 7210 · Turbine Engine Reduction Gear
Part: Pinion Gear
Part number: 6893672
Part serial: NN77819
Condition: Making Metal
Location: Gearbox
Part time: 591 hours
Component: Gearbox · Allsn
Component part number: 23063393
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

DISASSEMBLED GEARBOX DUE TO METAL IN OIL. CLEANED AND INSPECTED, FOUND EXCESSIVE GALLING ON PINION GEAR AND TORQUEMETER GEAR TEETH. PINION GEAR HAD EXCESSIVE GALLING ON GEAR TEETH DUE TO IMPROPER MESHING OF T/M AND PINION GEARS. SECONDARY DAMAGE: T/M GEAR PN 23071895, SN NN146407, TT 591.3 HOURS, SPALLING AND GALLING ON GEAR TEETH. (X)

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