As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING FLIGHT, THE OIL PRESSURE STARTED TO FLUCTUATE. THE PILOT ELECTED TO SHUT THE ENGINE DOWN BEFORE MAKING AN UNEVENTFUL SINGLE ENGINE LANDING AT THE DEPARTURE AIRPORT. POST FLIGHT INSPECTION FOUND AN IMPROPERLY SECURED OIL FILLER CAP. MFG HAS RECOMMENDED INCORPORATION OF THE BALL VALVE MODIFICATION IAW SB 1506.