What was found
PILOT REPORTED A NOTICEABLE VIBRATION SHORTLY AFTER TAKEOFF AND DURING CLIMB AND INTO CRUISE. AFTER LANDING AT FINAL DESTINATION, MAINTENANCE PERFORMED A CYLINDER COMPRESSION CHECK. ALL CYLINDERS ON BOTH ENGINES SHOWED NO EVIDENCE OF LEAKAGE. AFTER FURTHER GROUND RUN-UPS, IT WAS DETERMINED TO BE THE RIGHT ENGINE. AFTER ALL CYLINDER VALVE COVERS WERE REMOVED, A TOTAL OF 9 OUTER VALVE SPRINGS WERE FOUND BROKEN. ALL VALVE SPRINGS WERE REPLACED, AND THE DEFECTIVE SPRINGS SENT TO TCM FOR FURTHER INVESTIGATION.