As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE THE PILOT NOTICED THAT NR 3 ENGINE WAS BACKFIRING EXCESSIVELY. THE ENGINE WAS SHUT DOWN AND FEATHERED. WHEN MAINTENANCE INSPECTED THE ENGINE, THEY FOUND NR 4 CYLINDER WAS CRACKED BETWEEN BOTH SPARK PLUG HOLES. THE CYLINDER WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.