As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION FOUND CYLINDER HEAD WAS SUBSTANTIALLY CRACKED FROM BOTTOM SPARK PLUG HOLE TO TOP SPARK PLUG HOLE THROUGH THE EXHAUST PORT. SUBMITTER STATED THIS IS THE FIFTH (OUT OF SIX) THAT HAVE HAD TO BE REPLACED SINCE ENGINE OVERHAUL (1,339 HOURS AGO) DUE TO HEAD CRACKS AND CYLINDERS WERE EC1 CERMISTEEL WITH IFR HEAD TREATMENT.