Airworthiness Directive · Amendment 39-19281 · Tail rotor drive shaft
Bell Helicopter Textron Canada Limited (Bell) Helicopters
This AD applies to Bell Model 407 helicopters, certificated in any category.
We are adopting a new airworthiness directive (AD) for Bell Model 407 helicopters. This AD requires repetitive inspections of the tail rotor (TR) driveshaft segment assemblies and a torque check of the TR adapter retention nuts. This AD was prompted by a report of an in- flight failure of the TR drive system. The actions of this AD are intended to detect and correct an unsafe condition on these products.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
For helicopters with less than 4,000 hours time-in-service (TIS), within 100 hours TIS, and for helicopters with 4,000 or more hours TIS, within 50 hours TIS:
(1) Inspect each TR driveshaft segment assembly for rotational and axial play between the adapter and the TR driveshaft at the four positions depicted in Figure 1 of Bell Alert Service Bulletin (ASB) 407-16-113, dated February 12, 2016 (ASB 407-16-113). If there is any axial or rotational play, remove the adapter from the TR driveshaft segment assembly and inspect the adapter, washers, and TR driveshaft for damage. Replace the adapter retention nut and apply a torque of 30 to 50 inch-pounds (5.7 to 7.9 Nm). Replace any part with damage or repair the part if the damage is within the maximum repair damage limitations.
(2) Determine the torque of each TR adapter retention nut at each of the four segment assembly positions depicted in Figure 1 of Bell ASB 407-16-113. If the torque is less than 30 inch-pounds (5.7 Nm), remove the adapter from the TR driveshaft segment assembly and inspect the adapter, washers, and TR driveshaft for damage. Replace the adapter retention nut and apply a torque of 30 to 50 inch-pounds (5.7 to 7.9 Nm). Replace any part with damage or repair the part if the damage is within the maximum repair damage limitations.
(3) Repeat the actions specified in paragraph (e)(1) of this AD at intervals not to exceed 330 hours TIS.
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.
