As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THE AIRCRAFT WAS ORBITING THE FIRE WHEN THE FLIGHT CREW HEARD A BACKFIRE FROM THE NR 4 ENGINE. THE ENGINE WAS SHUT DOWN AND THE PROPELLER WAS FEATHERED. THE AIRCRAFT RETURNED TO BASE. MAINTENANCE CREWS FOUND THE NR 2 CYLINDER WAS CRACKED AT THE EXHAUST EAR. THE CYLINDER WAS REPLACED WITH A SERVICEABLE ASSEMBLY. THE ENGINE WAS GROUND RUN AND LEAK CHECKED SERVICEABLE. THE AIRCRAFT WAS RETURNED TO SERVICE.