As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING BORE SCOPE INSPECTION OF CYLINDER ASSEMBLIES THE NUMBER 3 CYLINDER EXHAUST VALVE WAS FOUND TO BEY HEAVILY PITTED ON VALVE BELL. THE ENGINE HAS ACCUMULATED 398.4 HOURS SINCE MAJOR OVERHAUL. NEW CYLINDER ASSEMBLIES INCLUDING VALVES WERE INSTALLED AT OVERHAUL AT ENGINE TOTAL TIME 2041.0. THIS IS THE JUST LATEST EVENT IN A GROWING TREND OF INTAKE AND EXHAUST VALVE DEFECTS AND FAILURES IN OUR FLEET OF LYCOMING POWERED AIRCRAFT.