As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 5004- ATB - AIR TURN BACK TO SEA DUE TO ODOR IN THE CABIN WHILE CLIMBING THROUGH 10K FEET. DECLARED EMERGENCY AND CREW USED MASKS. CORRECTIVE ACTION: SNIFFER SHOWING LEFT ENGINE AS SOURCE OF ODOR. BORESCOPED LEFT ENGINE AND FOUND OIL WETTING IN LPC AND HPC. REPLACED LEFT ENGINE AND RECIRCULATION FILTER.(6767894)