What was found
WHEN APU IS OPERATING THERE IS AN OIL SMELL IN CABIN. ON APU DRAIN THERE IS A BLACK OILY STREAK. FOUND OIL STREAK TO BE CAUSED BY OIL DRIPS COMING FROM GANG DRAIN FCU MOUNT PAD LOCATION & EJECTOR OVERBOARD EXHAUST DUCT DRAIN. REMOVED PAU INTAKE PLENUM DRAIN & PERFORMED BOROSCOPE OF COMPRESSOR INLET. FOUND EVIDENCE OF COMPRESSOR CARBON SEAL OIL LEAK. MANUFACTURER RECOMMENDS APU REMOVAL FOR SEAL REPLACEMENT. WORK DONE IAW AMM 49-11. REMOVED AND REPLACED THE APU IAW AMM 44-11-01. COMPLIED WITH CLEANING PROCEDURE FOR OIL IN BLEED AIR SYSTEM AND CONDITIONED AIR PACK NO FURTHER OIL SMELL IN CABIN NOTED OPS AND LEAK CHECKED GOOD PER AMM 49-11-01-400-801.