What was found
THE PILOT REPORTED ENGINE SURGING AND MANIFOLD PRESSURE DROP IN FLIGHT, AND THEN SHUT DOWN ENGINE IN-FLIGHT ACCORDING TO THE QRH. DURING THE INITIAL INSPECTION, FOUND SHINY PARTICLES IN THE OIL FILTER, AND SPARK PLUG DAMAGED, AND PARTICLES IN THE PROPELLER GOVERNOR. MAINTENANCE CONFIRMED PREIGNITION OCCURRED ON THE NUMBER LEFT ENGINE #6 CYLINDER. ENGINE CHANGE IN PROGRESS.