What was found
(CAN) IN FLIGHT PILOT COULD FEEL VIBRATION IN THE AIRFRAME, DECIDED TO LAND. ENGINEER INSPECTED AIRFRAME INCLUDING REMOVAL OF DRIVESHAFT COVERS AND COWLS AS REQUIRED AND A DETAILED INSPECTION OF THE TAIL ROTOR AND DRIVE SYS ACCOMPLISHED. A TEST FLIGHT WAS ACCOMPLISHED BUT THE VIBRATION WAS STILL PRESENT. ON FUTHER INSPECTION FOUND A TAIL ROTOR BLADE BOLT SHEARED. THE TAIL ROTOR BLADES AND HUB WERE REMOVED AND INSPECTED. ALL 4 BLADE BOLTS WERE REPLACED. ENTIRE DRIVE SYSTEM INSPECTED AND A TAIL ROTOR DYNAMIC BALANCE WAS COMPLETED SATISFACTORY.