Airworthiness Directives; Bell Textron Canada Limited Helicopters

The FAA is adopting a new airworthiness directive (AD) for certain Bell Textron Canada Limited (Bell) Model 505 helicopters. The FAA previously sent this AD as an emergency AD to all known U.S. owners and operators of these helicopters. This AD was prompted by a failure of the hinge assembly on the aft movable ballast box assembly, which could allow the ballast weights to escape the ballast box and strike the tail rotor assembly. This AD requires revising the Limitations section of the existing rotorcraft flight manual (RFM) for the helicopter to prohibit the use of ballast weights within the aft movable ballast box assembly. The FAA is issuing this AD to address the unsafe condition on these products.