As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED, F/A REPORTED ODOR IN REAR OF AIRCRAFT DURING CLIMB. AIRCRAFT RETURNED TO PHL, LANDED SAFELY WITHOUT FURTHER INCIDENT. MAINTENANCE ISOLATED THE SOURCE OF THE ODOR TO THE APU AFTER FINDING EVIDENCE OF AN OIL LEAK. MAINTENANCE REPLACED THE APU OIL COOLING FAN IAW AMM 49-52-51.