As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THE LEFT ENGINE STARTED TO RUN ROUGH DURING FLIGHT AND THE OIL PRESSURE SLOWLY DROPPED. AFTER LANDING, THE CREW REPORTED OIL DRIPPING OFF THE COWL. MAINTENANCE INSPECTED AND FOUND METAL CONTAMINATION IN ENGINE OIL SYSTEM AND THE NR 5 CYLINDER SHOWING SIGNS OF PRE-IGNITION. THE ENGINE WAS REPLACED.