As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AIRCRAFT WAS IN CRUISE WHEN PILOT HEARD A LOUD BANG ON THE NR 1 ENGINE. WITH LOSS OF 4 INCH MANIFOLD PRESSURE. THE ENGINE WAS MONITORED. AFTER LANDING A RUNUP AN INSPECTION FOUND A BLOWN OUT SPARK PLUG AND A CRACKED AND BURNT CYLINDER. THE CYLINDER WAS REPLACED.