AD FAA-2013-0881

We are adopting a new airworthiness directive (AD) for Agusta Model A109A, A109A II, A109C, A109E, A109K2, A109S, AW109SP, A119, and AW119 MKII helicopters. The emergency AD was sent previously to all known U.S. owners and operators of these helicopters. This AD requires, before further flight, inspecting certain Thomas coupling nuts on the tail rotor drive shaft line for a crack and replacing all the nuts if any nut is cracked. Also this AD requires replacing all affected Thomas coupling nuts within 10 hours time-in-service (TIS) or 30 days, whichever occurs first. This AD was prompted by two incidents of cracking on the nuts that connect the flexible disc coupling (Thomas coupling) with the splined adapter on the tail rotor drive shaft. We are issuing this AD to correct the unsafe condition on these helicopters.