As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 3 CYLINDER ON LT ENGINE HAD A COMPLETE HEAD SEPARATION CAUSED BY THE FAILURE OF THE AREA AROUND THE INTAKE VALVE. THIS AREA IS THE COMMON FAILURE FOR MFG REV NR 3 CYLINDERS DUE TO A MFG DEFECT/DESIGN IN THE HEAD CASTING. THE AREA THICKNESS WAS MFG TOO THIN IN THIS AREA AROUND THE INTAKE VALVE WHEN MFG SWITCHED SUPPLIER.