As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT .33 OF THE EXHAUST VALVE IN THE NR 4 CYLINDER BROKE CAUSING EXTENSIVE DAMAGE TO THE PISTON AND THE CYLINDER HEAD. DURING THE HIDDEN DAMAGE INSPECTION THE BROKEN VALVE WAS FOUND IN THE INTAKE PORT OF THE CYLINDER ON THE SAME CYLINDER. NO DAMAGE WAS FOUND IN THE REMAINING CYLINDERS OF THE TURBO CHARGER ON THE ENGINE. NO DEFECTS NOTED IN THE OIL FILTER.