What was found
ON FINAL APPROACH, PILOT REPORTED LEFT ENGINE STARTED TO SPUTTER, AND RUN ROUGH, FOLLOWED BY SEVERE VIBRATION AND ENGINE STOPPAGE. MAINTENANCE FOUND CATASTROPHIC FAILURE OF THE LEFT ENGINE WITH A LARGE HOLE IN THE TOP ENGINE CASE FROM CONNECTING ROD PENETRATION. FAILURE ALSO DAMAGED TOP ENGINE COWLING. LEFT ENGINE WAS REPLACED, COWL REPAIRED AND AIRCRAFT WAS RETURNED TO SERVICE. ENGINE SENT TO MANUFACTURER FOR TEARDOWN TO DETERMINE PROBABLE CAUSE OF ENGINE FAILURE.