Summary
This document proposes superseding an existing airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model MD900 helicopters. That AD currently requires reducing the life limit of certain Notar fan system tension-torsion (TT) straps. That AD 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. This AD would require the same actions as the existing AD, but would also require revising the life limit on the component history card or equivalent record, doing repetitive visual and X-ray inspections, and would remove reporting requirements. This proposal is prompted by two in-flight TT strap failures. The actions specified by the proposed AD are intended to prevent failure of a TT strap, loss of directional control, and subsequent loss of control of the helicopter.