What was found
PILOT REPORTED SUDDEN VIBRATION IN FLIGHT, FOLLOWED BY LOSS OF CHT/EGT ON CYLINDERS #1, #3, #5, AND LOSS OF ENGINE OIL PRESSURE. AFTER LANDING AND REMOVING ENGINE COWLING IT WAS DISCOVERED THAT THE #3 CYLINDER EXHAUST ROCKER ARM SHAFT MOUNT STRUCTURE HAD BROKEN OFF OF THE CYLINDER HEAD AND HAD BEEN PUSHED THROUGH THE ROCKER ARM COVER.