Airworthiness Directives; GKN Westland Helicopters Limited WG-30 Series 100 and 100-60 Helicopters

This amendment adopts a new airworthiness directive (AD) that is applicable to GKN Westland Helicopters Limited (Westland) WG-30 series 100 and 100-60 helicopters. This action requires an initial visual inspection and replacement, if necessary, of all main rotor head tie-bars. Thereafter, this AD requires, at intervals not to exceed 220 hours time-in-service (TIS), replacing each main rotor head tie-bar (tie-bar) with an airworthy tie-bar. This amendment is prompted by an accident on a similar model military helicopter in which a tie-bar failed; it is suspected that the military helicopter involved in the accident exceeded the power-off transient rotor speed limitation. This condition, if not corrected, could result in failure of a tie-bar, loss of a main rotor blade, and subsequent loss of control of the helicopter.