What was found
AFTER APPROXIMATELY 5 MINUTES IN CRUISE FLIGHT, THE PILOT REPORT A LOSS OF ENGINE POWER AND A SEVERE ROUGHNESS AND AN AIRPORT LANDING WAS MADE WITHOUT INCIDENT. INVESTIGATION REVEALED NR 4 CYLINDER INTAKE VALVE PUSH ROD AND SHROUD WERE BURNED AND LEAKING OIL. THE EXHAUST VALVE RETAIN STUD FOR THE FULCRUM AND ROCKER ARM HAD BACKED OUT APPROXIMATELY 5 THREADS; THUS, CREATING EXCESSIVE VALVE CLEARANCE. THE OTHER 3 CYLINDERS WERE INSPECTED AND THIS CONDITION OF THE ROCKER ASSY RETAIN STUD ALSO EXSISTED ON NR 2 CYLINDER.