As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED A BANG WITH AN IMMEDIATE DROP OF 300 RPM. ENGINE CONTINUED TO RUN, DIVERTED. THERE WAS AN EXTENSIVE AMOUNT OF OIL ON THE AIRCRAFT. WHEN THE COWLING WAS REMOVED A VISUAL INSPECTION SHOWED THE NR 3 CYLINDER BARREL WAS BROKEN ALL THE WAY AROUND AT THE TOP OF THE CYLINDER AND ONLY HELD ON BY THE EXHAUST AND INTAKE CONNECTIONS.