Service difficulty report · Sun Gear

Difficulty date
March 9, 2005
Submitted
April 1, 2005
Operation
General aviation
Engine
Pwa PT6A28
Part
Sun Gear
Condition
Spalled
Location
Engine
Part time
14,967 hours, 18,043 cycles
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

(CAN) THE SOURCE OF THE METAL CONTAMINATION WAS THE SUN GEAR FROM THE 1ST STAGE REDUCTION GEAR. THE SUN GEAR HAD LOST A CONSIDERABLE AMOUNT OF MATERIAL FROM THE GEAR TEETH FACES. DAMAGE IS THOUGHT TO HAVE STARTED AS A GEARTOOTH SPALLING WHICH PROGRESSED, GRADUALLY LOOSING SMALL PARTICLES FROM THE TEETH SURFACES AND CONTAMINATING THE OIL SYSTEM. PRESENCE OF SCORING IN THE RGB SCAVENGE PUMP AND MAIN PRESSURE PUMP HOUSINGS WAS DIRECT RESULT OF PUMPING CONTAMINATED OIL. THERE WAS NO SIGN THAT CONTAMINATED OIL BYPASSED THE OIL FILTER AND IT IS NOT FELT THAT THERE WAS ANY CONTAMINATION OF THE PRESSURE SIDE OF THE ENGINE LUBRICATING SYSTEM. THE CAUSE OF SUN GEAR SPALLING IS NOT APPARENT.