Airworthiness Directives; MD Helicopters Inc. (MDHI) Model MD600N Helicopters

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2007-05-51, which was sent previously to all known U.S. owners and operators of MDHI Model MD600N helicopters by individual letters. This AD requires, before further flight, a visual and eddy current inspection of each lateral mixer output link assembly (mixer link) and replacing any cracked mixer link. This AD also requires performing an eddy current inspection on each mixer link before installing it on any helicopter. This amendment is prompted by the discovery of 3 cracked mixer links. The actions specified by this AD are intended to detect a crack in the mixer link, which could result in failure of the mixer link and subsequent loss of control of the helicopter.