Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

This amendment adopts a new airworthiness directive (AD) for the MD Helicopters, Inc. (MDHI) Model MD900 helicopters. This action requires reducing the life limit of certain Notar fan system tension- torsion (TT) straps. This action also requires, at a specified time interval, removing each affected TT strap from the helicopter, doing a visual and x-ray inspection, and replacing any unairworthy part before further flight. Reporting the discovery of any unairworthy TT strap is also required. This amendment is prompted by two recent in-flight TT strap failures. The actions specified in this AD are intended to prevent failure of a TT strap resulting in loss of directional control and subsequent loss of control of the helicopter.