Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2001-25-51, which was sent previously to all known U.S. owners and operators of MD Helicopters, Inc. (MDHI) Model MD900 helicopters by individual letters. This AD requires performing a dual power confirmation test on the Integrated Instrument Display System (IIDS) and inserting a revision to the Rotorcraft Flight Manual (RFM), as applicable. If the IIDS fails the power test, replacing it is required before further flight. Removing the temporary revision when the IIDS is replaced and inserting the applicable revision into the RFM is also required. This AD is prompted by the failure of the IIDS during a helicopter hover operation. The actions specified by this AD are intended to prevent total power failure of the IIDS and the subsequent inability to monitor information and warning indications essential for the operation of the helicopter.