Service difficulty report · Bearing · Dhav DHC8301

Difficulty date
November 26, 1998
Submitted
March 26, 2000
Operation
General aviation
Make and model
Dhav DHC8301
Engine
Pwa PW123
Part
Bearing
Part number
31073301
Condition
Spalled
Location
Gearbox
Part time
8,940 hours
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 ENGINE WAS REMOVED AFTER METAL FLAKES WERE FOUND ON THE REDUCTION GEARBOX CHIP DETECTOR AND THE RGB SCAVENGE FILTER. DISASSEMBLY OF THE RGB FOUND THE SOURCE OF THE METAL CONTAMINATION WAS THE MASSIVE SPALLING OF THE NR 15 BEARING WITH MATERIAL LOSS FROM ALL ROLLERS AND FROM THE OUTER RACE. THE CAUSE OF THE SPALLING COULD NOT BE CONCLUSIVELY DETERMINED, BUT IT IS CONSIDERED TO BE MOST LIKELY THE RESULT OF LOW LEVEL ELECTRICAL DISCHARGE PITTING OF THE BEARING. LIGHTNING STRIKE CAUSING HIGH LEVEL DISCHARGE DAMAGE TO THE BEARING IS ALSO CONSIDERED A POSSIBILITY. PART TC: 18,264.