As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PILOT REPORTED A LOSS OF MANIFOLD PRESSURE IN FLIGHT ALONG WITH A REDUCTION IN POWER AND CRUISE SPEED. THE AIRCRAFT SAT UNTIL THE 28TH OF MARCH AWAITING MAINTENANCE. UPON INVESTIGATION, THE CYLINDER HEAD WAS FOUND TO HAVE SEPARATED FROM THE CYLINDER BODY AROUND THE ENTIRE CIRCUMFERENCE. THE CYLINDER IS IN QUARANTINE. TOTAL TIME IS NOT KNOWN, NO LOGS ARE AVAILABLE AT THIS TIME.