Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This action requires a revision of the Airplane Flight Manual to alert the flightcrew that both flight management computers (FMC's) must be installed and operational. This AD also requires an inspection to determine the serial number of the FMCs, and follow-on corrective actions, if necessary. This amendment is prompted by a report indicating that, due to incorrect multiplexers that were installed in the flight management computer system (FMC'S) during production, certain data busses failed simultaneously during a ground test. The actions specified in this AD are intended to prevent loss of airspeed and altitude indications on both primary flight displays in the cockpit, and/or loss or degradation of the autopilot functionality due to installation of incorrect multiplexers, and consequent failure of the data busses.