As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AUS) NO4 CYLINDER EXHAUST VALVE SEAT LEAKING. FOLLOWING VALVE REMOVALSEVERE EROSION WAS THEN FOUND ON THE NECK OF THE VALVE. NO5 CYLINDER EXHAUST VALVE WAS ALSO FOUND TO HAVE A SIMILAR EROSION PROBLEM. ALL OTHER VALVES WERE CHECKED AND FOUND TO BE IN NORMALCONDITION.