As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) TWO HOURS FLIGHT TIME AFTER INSPECTION THE PORCELAIN PORTION OF THE SPARK PLUG, ON #6 CYLINDER BLEW COMPLETELY OUT. INTERNAL INSPECTION OF THE CYLINDER SHOWED NO DAMAGE. THE SPARK PLUG WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.