AD 2021-24-15 Amendment 39-21836

The FAA is adopting a new airworthiness directive (AD) for Bell Textron Canada Limited Model 206L-1, 206L-3, and 206L-4 helicopters with certain Air Comm Corporation air conditioning systems installed. This AD was prompted by reports of damage to the drive ring spline teeth and the mating spline teeth. This AD requires visually inspecting the drive ring spline teeth and the mating area spline teeth on the oil cooler blower shaft for signs of deformation and fretting and depending on the results of the inspection, removing certain parts from service. This AD also requires reinstalling certain parts, applying torque, and aligning certain bolt holes. The FAA is issuing this AD to address the unsafe condition on these products.