Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Bell Helicopter Textron Canada (BHTC) Model 407 helicopters, that currently requires installing a tail rotor pitch-limiting left-pedal stop (pedal stop), installing an airspeed limitation placard, marking a never-exceed velocity (Vne) placard on all airspeed indicators, and revising the Limitations section of the Rotorcraft Flight Manual (RFM). This action would require installing a redesigned tail rotor system and modifying the vertical fin and horizontal stabilizer to allow restoring the Vne to 140 knots indicated airspeed (IAS). This proposal is prompted by design changes to the tail rotor system and modification of the pedal stop for airspeed actuation to eliminate a tail rotor strike to the tailboom. The actions specified by the proposed AD are intended to prevent the tail rotor blades from striking the tailboom, separation of the aft section of the tailboom with the tail rotor gearbox and vertical fin, and subsequent loss of control of the helicopter.