As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB A METALLIC ODOR WAS REPORTED IN THE AFT CABIN THAT APPEARED TO MOVE FORWARD THROUGH CABIN. BECAME MORE INTENSE THEN VARIED TO A POINT OF ALMOST TOTAL DISSIPATION THEN INTENSIFIED WORSE. EMERGENCY DECLARED. RETURNED TO DEPARTURE. TROUBLESHOT AND FOUND APU TO BE SOURCE OF CABIN ODOR. AIRCRAFT WAS GROUNDED. MAINTENANCE FOUND OIL CONTAMINATION ON RIGHT A/C PACK SYSTEM. REPLACED APU IAW JOB CARD 33L3154900. ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK.