Airworthiness Directives; Bell Helicopter Textron Canada Limited Model 427 Helicopters

This amendment adopts a new airworthiness directive (AD) for the specified Bell Helicopter Textron Canada (Bell) model helicopters that requires modifying the auxiliary fin assemblies and revising the Limitations section of the Rotorcraft Flight Manual (RFM) to reduce the never-exceed speed (Vne) for a tail rotor pedal stop failure. This amendment is prompted by several incidents of main rotor blades contacting the top of the fin that have resulted in an upper tuning weight (weight) becoming loose. The actions specified by this AD are intended to prevent a main rotor blade from striking an auxiliary fin, loss of a tuning weight, impact with a tail or main rotor blade, and subsequent loss of control of the helicopter.