As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROTATION OF ENGINE, MECHANIC HEARD HISSING FROM THE NR 1 CYLINDER. FURTHER INSPECTION REVEALED A CRACK ON THE INTAKE SIDE OF THE CYLINDER HEAD BELOW THE INTAKE PORT APPROXIMATELY 2 INCHES LONG. REMOVED THE CYLINDER AND FOUND A CRACK APPROXIMATELY HALF WAY AROUND THE INTAKE SEAT, ABOUT .250 INCH FROM EDGE OF THE SEAT. INSTALLED A NEW CYLINDER ASSEMBLY.