As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS AT A CRUISING ALTITUDE OF 6000 FT MSL WHEN PILOT HEARD A LOUD BANG AND FELT SEVERE VIBRATION. PILOT STATED THAT WHEN HE LOOKED OUT AT THE LEFT ENGINE HE SAW SMOKE AND OIL COMING FROM THE COWLING; AT WHICH TIME HE ELECTED TO SHUT THAT ENGINE DOWN. AFTER LANDING, VISUAL INSPECTION OF THE LT ENGINE VERIFIED THAT THE NR ONE CYLINDER BARREL WAS CRACKED. CAUSE OF FAILURE, UNKNOWN.