Summary
The FAA proposes to adopt a new airworthiness directive (AD) for MD Helicopters Inc. (MDHI), Model 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. This proposed AD was prompted by a report of a spiral crack in the pilot-to-copilot tail rotor torque tube (torque tube). This proposed AD would require a one- time visual and recurring borescope inspections of the torque tube and depending on the results, removing the torque tube from service. The FAA is proposing this AD to address the unsafe condition on these products.