Airworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters

We are publishing a new airworthiness directive (AD) for Bell Helicopter Textron Canada Limited (Bell) Model 429 helicopters. This AD was sent previously to all known U.S. owners and operators of these helicopters as Emergency AD 2018-16-51, dated July 26, 2018, which superseded Emergency AD 2018-15-51, dated July 20, 2018. This AD requires inspecting the tail rotor (T/R) gearbox installation, inspecting the T/R gearbox retaining hardware and support attachment point areas, and replacing each nut. This AD is prompted by two reports of T/R gearbox assemblies loosely attached to the gearbox support. The actions of this AD are intended to address an unsafe condition on these products.