Airworthiness Directives; Agusta S.p.A. Model A109E Helicopters

This amendment adopts a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109E helicopters. This action requires replacing certain tail rotor blades with airworthy tail rotor blades. This amendment is prompted by a tail rotor blade (blade) failure that caused a high vibration level in the helicopter. Investigation revealed that the failure was due to a change in the manufacturing process for an identified production lot of blades. This condition, if not corrected, could result in a failure of a blade and subsequent loss of control of the helicopter.