As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE FLIGHT, LEFT ENGINE OIL PRESSURE STARTED TO FLUCTUATE. A PRECAUTIONARY SHUT DOWN WAS MADE AND THE AIRCRAFT HAD AN UNEVENTFUL LANDING. TROUBLESHOOTING FOUND THE GEARBOX SCAVENGE OIL LINE FITTING IN THE GEARBOX HAD STARTED BACKING OUT. THE THREADS IN THE GEARBOX WERE PARTIALLY RUINED. ENGINE WAS REMOVED AND SENT OUT FOR REPAIR. SUBMITTER RECOMMENDS TORQUE CHECK OF ALL FITTINGS ON GEARBOX EVERY 200 HOURS OF ENGINE OPERATION.