Summary
We propose to adopt a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109A, A109A II, A109C, A109E, A109K2, A109S and AW109SP helicopters. This proposed AD would require visually inspecting the tail rotor drive shaft assembly (drive shaft) for a crack. This proposed AD is prompted by the discovery of three cracks on the drive shaft of a Model A109S helicopter. The proposed actions 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.