As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AN APPROACH TO LANDING, PILOT REPORTED A VIBRATION IN THE LEFT ENGINE AND OIL LEAKING FROM THE COWLING. HE PERFORMED A PRECAUTIONARY SHUT DOWN AND MADE AN UNEVENTFUL LANDING. INSPECTION REVEALED A HOLE IN NR 1 CYLINDER UNDER THE INTAKE PUSHROD HOUSING. THE HOLE ALLOWED EXHAUST GASSES TO BURN A HOLE IN THE HOUSING ALLOWING OIL LEAKAGE. SUSPECT PROBLEM MAY HAVE BEEN CAUSED BY A POOR WELD.