What was found
THE AIRCRAFT LOST DIRECTIONAL CONTROL DURING LANDING TO AN OFFSHORE PLATFORM. THE PILOT WAS ABLE TO EXECUTE A SUCCESSFUL AUTOROTATIONAL LANDING TO THE PLATFORM WITHOUT CAUSING DAMAGE TO THE AIRCRAFT. INVESTIGATION OF THE INCIDENT REVEALED THAT THE BONDED COUPLING ON THE NR 5 TAIL ROTOR DRIVESHAFT FAILED. ENGINEERING EVALUATION OF THE SHAFT REVEALED THAT THE SHAFT HAD APPARENTLY BEEN SUBJECTED TO SAND BLASTING, WHICH, IN TURN, MAY HAVE LED TO THE DISBONDING OF THE COUPLING.