As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TEAR DOWN FOR OVERHAUL A PIECE OF METAL WAS FOUND IN OIL SUMP. FURTHER INSPECTION FOUND THAT THE HEAD OF LIFTER BODY FOR NR 1 CYLINDER EXHAUST VALVE WAS HALF GONE. (PIECE IN OIL SUMP) FROM WEAR ON REMAINING PART, APPEARS THAT IT HAD BEEN THAT WAY FOR SEVERAL HOURS. PART HAD AT LEAST 2600 HOURS SINCE OVERHAUL.