What was found
AIRCRAFT WAS GROUNDED: OILY SMELLING FUMES ENTERED THE FLIGHT DECK ON DESCENT OCCURRING APPROXIMATELY AT 10,000 FEET LASTING UNTIL ABOUT 6,000 FEET WITH APU OFF. AFTER LANDING AND ENGINE SHUTDOWN AND SWITCHING TO APU BLEED AFTER IT HAD BEEN RUNNING FOR 3 MINUTES THE OILY FUMES AGAIN ENTERED THE FLIGHT DECK. TRIED PROCESS OF ELIMINATION BY SHUTTING DOWN BOTH PACKS AND TURNING ONE ON AT A TIME. THE NUMBER ONE PACK SEEMED TO PRODUCE THE FUMES. THE FUMES WERE ALSO REPORTED IN THE AFT GALLEY BY THE FLIGHT ATTENDANT. **ORIGINAL REPORT WAS AALA202411041501** MAINTENANCE FOUND OIL LEAKS AT THE APU COOLING FAN SEAL, WHICH WAS REPLACED, THE APU FCU (AALA202411206677), WHICH WAS REPLACED, THE APU LUBE MODULE (AALA202411202049), WHICH WAS REPLACED AND THE AIR / OIL SEPERATOR J TUBE (AALA202411208750), WHICH WAS REPLACED. A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM WAS ACCOMPLISHED WITH NO LEAKS OR ODORS NOTED.