As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING AN ENGINE NR 2 SCHEDULE OIL CHANGE WHILE REMOVING OIL AT THE ACCESSORY GB DRAIN PLUG PORT HOLE, A METALLIC COLLAR HALF (P/N 3008779) FELL OUT. SUSPECTED THAT THIS COLLAR HALF HAD FALLEN OFF THE SCAVENGE OIL PUMP DRIVESHAFT. ENGINE REMOVED FROM AIRCRAFT AND SENT TO MFG FOR INVESTIGATION. (TC NR 20071228003)