Airworthiness Directives; Bell Textron Canada Limited

FAA / Federal Register · 2021-19605

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bell Textron Canada Limited Model 206, 206A, 206A-1, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters. This proposed AD was prompted by reports of cracked or missing nuts on the tail rotor drive shaft (TRDS) disc pack (Thomas) couplings. This proposed AD would require removing certain nuts from service, installing newly designed nuts, and applying a specific torque and a torque stripe to each newly installed nut. This proposed AD would then require, after the installation of each newly designed nut, inspecting the torque and, depending on the inspection results, either applying a torque stripe or performing further inspections and removing certain parts from service. Finally, this proposed AD would prohibit installing any affected nut on any TRDS Thomas coupling. The FAA is proposing this AD to address the unsafe condition on these products.