SDR 97ZZZX4464

Service difficulty report · Bearing

Difficulty date
September 30, 1997
Submitted
March 26, 2000
Operation
General aviation
Filed by
JYDR439F
Erickson Incorporated
Engine
Pwa JFTD12A5A
Part
Bearing
Part number
PWA419403
Condition
Failed
Location
Engine Comp
Part time
1,692 hours
Component
Skf
Stage of operation
IN
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

BEARING REMOVED FROM ENG DURING OVERHAUL WITH TT OF 1691.6 HRS. DURING OVERHAUL, BEARING WAS INSPECTED AND 2 UNUSUAL CONDITIONS FOUND: BALLS EXHIBITED SEVERE SCRATCHES AND RETAINER SHOWED SMEARED SILVER PLATING IN THE BALL RETENTION AREA. AFTER ANALYSIS, REPORT SHOWED RESIDUAL SILICA CARBIDE EMBEDDED IN THE BRONZE RETAINER CAUSING THE BALL SCRATCHES. SILICA CARBIDE WAS LIKELY FROM A MEDIA BLAST DURING MFG PROCESS. THE SILVER PLATING DISCREPANCY WAS ATTRIBUTED TO A LACK OF CLEARANCE BETWEEN THE RETAINER AND BALL DURING THE STAKING PROCESS. A TYPICAL CLEARANCE OF 0.002 INCH IS NORMAL. FOUND CLEARANCE TO BE NEAR 0.0000 INCH. AS THE SILVER PLATING WAS WORN, THE EMBEDDED SILICA CARBIDE SCRATCHED THE BALLS.