As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANT REPORTS MUSTY SMELL IN CABIN ON ARRIVAL DESCENT. MAINTENANCE FOUND THE APU AIR /OIL SEPERATOR LEAKING OIL AND REPLACED THE SEAL PER AMM 49-26-54. A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM WAS ACCOMPLISHED PER TASK CARD 26L00021014. A SATASFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO LEAKS OR ODORS NOTED.