As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) "O" RING ON THE OIL PRESSURE TRANSFER TUBE AT THE "C" FLANGE WAS FOUND WORN FLAT IN ONE AREA, CAUSING OIL TO LEAK OUT ON TO THE EXHAUST CAN. THIS CAUSED A FLUCTUATION IN OIL PRESSURE AND TORQUE PROMOTED THE PILOT TO DO A PRECAUTIONARY SHUTDOWN AND RETURN TO BASE.