As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ACFT RETURNED TO DEPARTURE AIRPORT WITH ROUGH RUNNING AND PARTIAL POWER LOSS ON LT ENGINE. MX FOUND "0" COMPRESSION IN NR 3 CYLINDER DURING DPT CHECK. AFTER NR 3 CYLINDER REMOVAL FOUND EXHAUST VALVE DESTROYED AND VALVE HEAD MISSING. SMALL PORTION OF VALVE IMBEDED INTO CYLINDER COMPRESSION CHAMBER HEAD AND SEVERE GOUGING ON THE PISTON COMBUSTION SURFACE. FURTHER INVESTIGATION ALSO REVEALED TURBOCHARGER TURBINE BLADE DAMAGE. NR 3 CYL ASSY AND TURBOCHARGER REPLACED AND ENGINE OPS CHECKED SERVICEABLE.