What was found
DURING ENROUTE CRUISE FLIGHT NR 4 CYLINDER INTAKE VALVE STEM FAILED ALLOWING VALVE TO ENTER CYLINDER, DAMAGE PISTON AND SPARK PLUGS AND SUBSEQUENTLY SENT PIECES OF VALVE INTO NR 1 CYLINDER SMASHING SPARK PLUGS, PISTON AND RENDERING A VERY ROUGH ENGINE RUNNING ON 2 CYLINDERS. SUCCESSFUL EMERGENCY LANDING WAS PERFORMED TO AN AIRPORT WITH NO DAMAGE. PRIOR THE OCCURRENCE ON MAY 11, 2026, THIS ENGINE HAD A PREVIOUS #3 CYLINDER INTAKE VALVE FAILURE IN FLIGHT. TSO 15.1 HOURS. INTAKE VALVE WAS NEW AT OVERHAUL. THERE WAS NO DAMAGE TO THE AIRFRAME.