Airworthiness Directives; Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 Helicopters Manufactured by Bell Helicopter Textron Inc. for the Armed Forces of the United States

This document publishes in the Federal Register an amendment adopting superseding Airworthiness Directive (AD) 2000-22-51, which was sent previously by individual letters to all known U.S. owners and operators of Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH- 1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 helicopters manufactured by Bell Helicopter Textron Inc. (BHTI) for the Armed Forces of the United States. This AD requires establishing a retirement life for certain main rotor masts, creating a component history card or equivalent record, and identifying certain masts as unairworthy. This AD also requires removing the hub spring, if installed, and determining whether a main rotor mast (mast) has ever been installed on a helicopter while operated with a hub spring. Conducting certain inspections based on the retirement index number (RIN) and on whether the helicopter was ever operated with a hub spring is also required. Replacing any mast that has inadequate radius or a burr in the damper clamp splined area is also required. Finally, this AD requires sending information concerning the mast to the FAA. This amendment is prompted by the discovery of a crack in a mast with a lower RIN value than the established life limit. This action is necessary to preclude the occurrence of a fatigue crack in the damper clamp splined area of a mast. This condition, if not corrected, could result in failure of a mast or main rotor trunnion (trunnion), separation of the main rotor system, and subsequent loss of control of the helicopter.