As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE NR ONE CYLINDER COMPRESSION WAS FOUND BELOW SPECIFICATION. SUBSEQUENT INSPECTION FOUND A CRACK IN THE CYLINDER HEAD. THE CRACK WAS LOCATED OUTBOARD OF THE INTAKE VALVE SEAT. THE CRACK WAS APPROXIMATELY TWO INCHES LONG AND FOLLOWED THE CURVE OF THE VALVE SEAT. THE CYLINDER WAS REPLACED WITH A SERVICEABLE PART.