Service difficulty report · Bearing

Difficulty date
September 19, 1997
Submitted
March 26, 2000
Operation
General aviation
Engine
Pwa PW118A
Part
Bearing
Part number
31073301
Condition
Spalled
Location
Red Grbox Nr 15
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

(CAN) THE REDUCTION GEARBOX WAS FOUND BY THE OPERATOR TO HAVE METAL CONTAMINATION AND WAS SHIPPED FOR INVESTIGATION AND REPAIR. DISASSEMBLY FOUND THE SOURCE OF THE METAL CONTAMINATION TO BE THE NR15 BEARING WHICH HAD SPALLED BADLY ON THE INNER RACE. SUBSTANTIAL RESIDUAL MAGNETISM WAS FOUND ON A NUMBER OF STEEL COMPONENTS AND IT IS CONCLUDED THAT A LIGHTNING STRIKE WAS PROBABLY THE PRIMARY CAUSE OF THIS FAILURE. SECONDARY DAMAGE FROM THE CONTAMINANTS WAS MINIMAL AND ONLY THE NR18 AND NR19 BEARINGS, WHICH WERE FOUND TO HAVE ELECTRICAL DISCHARGE TYPE DAMAGE, REQUIRED REPLACEMENT.