As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING 100 HOUR INSP, NR 4 CYLINDER DID NOT PASSDIFFERENTIAL COMPRESSION TEST. REMOVED CYLINDER, FOUND INTAKE VALVE SEVERELY BURNED ON FACE AND SEAT AREAS. REPLACED INTAKE VALVE AND SEAT. REINSTALLED CYLINDER AND RETURNED TO SERVICE. INTAKE VALVES USUALLY ARE NOT A PROBLEM ON THESE ENGINES, ESPECIALLY AT SUCH A LOW TT. (K)