As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG OIL SMELL IN CABIN. SHUT DOWN APU AND ATTACHED PC AIR, SMELL WENT AWAY. HOOKED UP GROUND AIR AND RAN PACKS, SMELL INCREASED. FOUND OIL IN BLEED DUCT FROM APU. ACP'D ECS DE-CONTAMINATION. COMPLETED INSTALLATION OF APU. DUE TO PACK BURNOUT NEED TO REPLACE RECIRCULATION FILTERS. REPLACED RECIRCULATION FILTERS.