As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLIGHT, PILOT NOTICED REDUCTION IN MANIFOLD PRESSURE. PILOT DESCENDED WHEN COMPLETE FAILURE AND SEPARATION OF THE NR 4 CYLINDER ON THE LEFT ENGINE OCCURRED. CYLINDER HEAD SEPARATED FROM BARREL. ENGINE WAS SECURED AND SHUT DOWN. PROP WAS FEATHERED. THE AIR CRAFT LANDED SAFELY.