As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 308 - CABIN ODOR - FLIGHT ATTENDANT REPORTED OIL SMELL IN CABIN AFTER BOTH ENGINES WERE STARTED. DURING CRUISE, BOTH AFT LAV SMOKE DETECTORS SOUNDED BUT NO SIGN OF SMOKE OR FIRE NOTED. TURNED OFF RECIRCULATION FANS - NO SMOKE NOTED IN CABIN. MAINTENANCE REMOVED AND REPLACED THE AUXILIARY POWER UNIT. TEARDOWN REPORT INDICATES COOLING FAN WAS FOUND LEAKING DUE TO A FAULTY SEAL.