What was found
AIRCRAFT WAS GROUNDED: PUNGENT SMELL IN CABIN AND COCKPIT WHEN PACKS ARE POWERED WITH APU BLEED. MAINTENANCE ACCOMPLISHED TASK CARDS 26L0021001 AND 26L00021002, FOUND OIL COKING ON APU LOWER COMPRESSOR SCREEN. RAN ENGINES 10 MINUTES EACH WITH LEFT AND RIGHT PACKS, NO ODOR SMELLED IN CABIN AND FLIGHT DECK. PLACED APU ON MEL FOR FURTHER TROUBLESHOOTING. ACCOMPLISHED GENERAL VISUAL INSPECTION OF APU, FOUND EVIDENCE OF OIL AROUND PLENUM & FAN. DETERMINED LEAK WAS CAUSED BY THE APU OIL SYSTEM BEING OVER SERVICED. CLEANED APU EXTERNAL & RAN FOR 2 HOURS. NO EXTERNAL LEAKS NOTED. DRAINED OIL TO FULL MARK. MAINTENANCE ALSO PERFORMED DECONTAMINATION OF THE APU PER TASK CARD 26L00021004 WITH NO LEAKS OR ODORS NOTED.