Summary
We propose to adopt a new airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS350 and AS355 helicopters, to require inspecting for a crack in the control lever attachment yokes, and if needed, replacing the tail rotor gearbox (TGB). This proposed AD is prompted by improper casting of TGB casing assemblies, which may lead to cracking. A crack in the control lever attachment yokes could cause a loss of tail rotor pitch control, and consequently, loss of control of the helicopter.