As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A CRACKED CYLINDER HEAD FIN WAS DISCOVERED ON NR 1 CYLINDER FOLLOWING THE ACCEPTANCE RUN AFTER THE ENGINE HAD BEEN OVERHAULED. AN ATTEMPT TO DRESS IT OUT INDICATED THAT THE CRACK EXTENDED ON TO THE BASE OF THE FIN AND POSSIBLY CYLINDER HEAD. CYLINDER WAS REMOVED AND REPLACED UNDER FACTORY WARRANTY.