Airworthiness Directive Issued for Sikorsky S-70 Variants

The FAA is adopting an airworthiness directive (AD) that establishes a new life limit based on a prorated formula for some Sikorsky S-70, S-70A and S-70C components that were previously installed on military helicopters. Some of the parts, including the main rotor hub, main rotor shaft, main rotor spindle nut, rotating swashplate and main rotor gearbox, have been interchanged with military helicopter models with life limits different from those of the civilian version. The actions are intended to establish a prorated in-service life limit for each identified part to prevent fatigue failure of a part and subsequent loss of control of the helicopter. This AD is effective February 25.