What was found
PILOT REPORTED LOSS OF POWER AND LOWERED TEMP READINGS FROM CYLINDER 2 IN FLIGHT. SHORTLY AFTER THAT ON APPROACH, HE LOST NR 4 TEMP READINGS AND MORE POWER LOSS. TROUBLESHOOTING REVEALED BROKEN INTAKE AND EXHAUST VALVE INNER SPRINGS ON NR 2 CYLINDER, BROKEN INTAKE VALVE INNER SPRINGS ON NR 4 AND 5 CYLINDER. ACFT HAD SAT FOR A WHILE AND MOISTURE IS CONSIDERED THE MAIN CAUSE AS ALL EXHAUST AND INTAKE VALVE INNER SPRINGS AND SOME OUTER SPRINGS SHOWED RUST. PROPER ENGINE PRESERVATION WOULD HAVE PREVENTED THIS CORROSION FROM DEVELOPING.