As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED LEFT ENGINE VIBRATION DURING FLIGHT. MAINTENANCE INSPECTED AND FOUND THE LEFT ENGINE NR 3 CYLINDER WITH A COLLAPSED EXHAUST LIFTER, BROKEN VALVE GUIDE AND THE PISTON PIN BUSHING DAMAGED AND CRACKED. THE CYLINDER AND CONNECTING ROD HAS BEEN CHANGED AND OPERATIONALLY CHECKED WITH NO FURTHER DEFECTS NOTED.