Airworthiness Directive · Amendment 39-21717 · Tail rotor drive system
Bell Textron Canada Limited (Type Certificate Previously Held by Bell Helicopter Textron Canada Limited) Helicopters
This AD applies to Bell Textron Canada Limited (type certificate previously held by Bell Helicopter Textron Canada Limited) Model 429 helicopters, certificated in any category, serial numbers 57001 and subsequent.
The FAA is adopting a new airworthiness directive (AD) for certain Bell Textron Canada Limited (Bell) Model 429 helicopters. This AD was prompted by reports of tail rotor gearbox assemblies found loose on the gearbox support. This AD requires repetitive torque checks of the tail rotor gearbox attachment hardware, and corrective action if necessary. The FAA is issuing this AD to address the unsafe condition on these products.
Within 12 months after the effective date of this AD; or at the next scheduled 200-hours time-in-service (TIS) or 12-month inspection, whichever occurs first, do a torque check of the tail rotor gearbox attachment hardware, in accordance with the Accomplishment Instructions, paragraph 2., of Bell Alert Service Bulletin 429-18-41, dated July 24, 2018. Repeat the torque check thereafter at intervals not to exceed 200 hours TIS or 12 months, whichever occurs first.
If, during any torque check required by paragraph (g) of this AD, any tail rotor gearbox attachment moves during any torque check, repeat the torque check specified in paragraph (g) of this AD at intervals no less than 10 hours TIS and not to exceed 25 hours TIS until the torque stabilizes on all the nuts. Stabilization has occurred when, at the next torque check, the value has remained within the specified acceptable limits (160 to 200 inch-pounds (in-lbs) or 19 to 22 newton meters (Nms), inclusive), preventing movement of the gearbox housing. After the torque stabilizes on all the nuts, the repetitive torque checks specified in paragraph (g) of this AD are still required.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
