AD FAA-2015-3781

We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109A, A109A II, A109C, A109E, A109K2, A109S, and AW109SP helicopters. This AD requires visually inspecting the tail rotor drive shaft assembly (drive shaft) for a crack. This AD was prompted by the discovery of three cracks on the drive shaft of a Model A109S helicopter. The actions of this AD are intended to detect a crack on the drive shaft to prevent failure of the driveshaft, failure of the tail rotor, and subsequent loss of helicopter control.