As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER LANDING, THE CREW CONTACTED MAINTENANCE AND ADVISED THAT THEY HAD DONNED THEIR OXYGEN MASKS DUE TO AN OIL ODOR. REPORTED PASSENGERS WERE GETTING SICK DUE TO THE ODOR. MAINTENANCE FOUND HYDRUALIC FLUID IN INTAKE DUCT AND PLENUM OF APU. ALSO FOUND LT GEAR B-NUT ON ACTUATOR LOOSE; SECURED AND SAFTIED B-NUT. REPLACED CATALITIC CONVERTOR, APU OIL COOLER AND FUNCTIONAL CHECK WAS NORMAL.