Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, 269A-1, 269B, 269C, and TH-55A Helicopters

This amendment supersedes an existing airworthiness directive (AD), applicable to Schweizer Aircraft Corporation (Schweizer) Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters, that currently requires inspecting the lugs on certain aft cluster fittings and each aluminum end fitting on certain tailboom struts. Modifying or replacing each strut assembly within a specified time period and serializing certain strut assemblies are also required by the existing AD. This amendment requires the same actions as the existing AD, and also requires a one-time inspection and repair, if necessary, of certain additional cluster fittings, and replacement and modification of certain cluster fittings within 150 hours time-in-service (TIS) or 6 months, whichever occurs first. This amendment is prompted by the need to expand the applicability to include certain Hughes-manufactured cluster fittings and to provide a terminating action for the repetitive dye-penetrant inspections of the cluster fittings. The actions specified by this AD are intended to prevent failure of a tailboom support strut or a cluster fitting, which could cause rotation of a tailboom into the main rotor blades, and subsequent loss of control of the helicopter.