Service difficulty report · Seal

Difficulty date
June 2, 2008
Submitted
November 3, 2008
Operation
General aviation
Engine
Pwa PT6A60
Part
Seal
Condition
Leaking
Location
Nr 1 Bearing
Stage of operation
IN
How discovered
9
Nature of condition
K
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

(CAN) DURING ENG COMPRESSOR RECOVERY WASH, ENGINE OIL LOSS FROM NR 1 BEARING SEAL. MULTIPLE ENGINE SPOOLS ARE REQUIRED TO COMPLETE AN ENG COMPRESSOR RECOVERY WASH IAW ENG MFG. MAINT FOUND IN CARRYING OUT MULTIPLE ENGINE SPOOLS, INTERNAL ENG SCAVANGE PUMPS LOCATED IN THE AGB WERE NOT EFFICIENT ENOUGH THROUGH THE SPOOLING PROCESS AT LOW ENG SPEEDS TO SUCSESSFULLY SCAVANGE ENOUGH ENGINE OIL OUT OF THE AGB TO AVOID AN OVER FILL CONDITION OF THE AGB. SCAVANGE PUMPS ARE DESIGNED TO TAKE THE USED ENGINE OIL FROM THE AGB AND RGB AND PUMP THE OIL BACK INTO THE MAIN ENGINE OIL RESERVOIR. MAINT FOUND DURING ENGINE SPOOLING ALONE, THE PUMPS COULD NOT KEEP THE OIL AT A SAFE LEVEL IN THE AGB IN ORDER TO AVOID THE OIL TO SEEP OUT OF THE NR1 BEARING SEAL AND OBSERVED DRIPPING FROM THE ENGINE INTAKE. MAINTENANCE FOUND THAT ANY MORE THAN THREE ENGINE DRY SPOOLS WOULD RESULT IN AGB OIL LEAKING FROM THE NR 1 AIR/OIL BEARING SEAL.