Airworthiness Directives; Agusta S.p.A. (Agusta) Model A119 and AW119 MKII Helicopters

This document publishes in the Federal Register an amendment adopting Emergency Airworthiness Directive (AD) 2010-12-51, which was sent previously to all known U.S. owners and operators of the specified Agusta model helicopters by individual letters. This AD requires, before further flight, removing the forward boot from the hub-locking nut (nut) and inserting a gauge between the tail rotor control rod (rod) and nut until the gauge stops. This AD then requires, depending on the depth measurement from the face of the nut, either reidentifying the tail rotor gearbox (TGB) with a new part number (P/N) or replacing the TGB and the associated parts with airworthy parts. This AD is prompted by a report of a missing rod bushing (bushing) from a 90- degree TGB installed on a Model AW119 MKII helicopter. The Agusta Model A119 helicopters also have the affected TGB installed; therefore, they are also included in the applicability of this AD. The actions specified by this AD are intended to detect a missing bushing in the TGB and to prevent abnormal vibration, damage to the tail rotor system, loss of the yaw control function, and subsequent loss of control of the helicopter.