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

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2001-25-52, which was sent previously to all known U.S. owners and operators of Schweizer Aircraft Corporation (Schweizer) Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters by individual letters. This AD supersedes an existing AD that requires inspecting and modifying or replacing, if necessary, the aluminum end fittings of each tailboom support strut (strut). That AD also requires inspecting the tailboom center attach fittings and center frame aft cluster fittings for damage, and if damaged parts are found, replacing the damaged parts. This AD requires inspecting and replacing, if necessary, each strut clevis lug (lug) on each tailboom center frame aft cluster fitting (cluster fitting), certain strut assemblies, certain tailboom attachments, and certain frame aft cluster fittings. Modifying or replacing each strut assembly within a certain time period and serializing certain strut assemblies are also required. This AD is prompted by an accident in the United Kingdom involving the in-flight structural failure of a Schweizer Model 269C helicopter. The actions specified by this AD are intended to prevent failure of a lug on a cluster fitting, rotation of a tailboom into the main rotor blades, and subsequent loss of control of the helicopter.