The FAA adopted an airworthiness directive for Eurocopter Deutschland MBB-Kawasaki BK117C2 helicopters requiring inspection of the long tail-rotor drive shaft assembly for blind rivets. If any blind rivets are located, the shaft assembly must be replaced. The AD was prompted by the discovery that some helicopters have blind rivets installed in place of solid rivets, which could lead to failure of the tail rotor drive shaft and subsequent loss of control of the helicopter.