Airworthiness Directives; The Boeing Company Model 747-400, 747-400D, and 747-400F Series Airplanes Equipped With General Electric CF6-80C2 or Pratt & Whitney PW4000 Series Engines

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We propose to adopt a new airworthiness directive (AD) for certain Model 747-400, 747-400D, and 747-400F series airplanes. This proposed AD would require modifying certain thrust reverser control system wiring to the flap control unit (FCU). This proposed AD results from a report of automatic retraction of the leading edge flaps due to indications transmitted to the FCU from the thrust reverser control system during takeoff. We are proposing this AD to prevent automatic retraction of the leading edge flaps during takeoff, which could result in reduced climb performance and consequent collision with terrain and obstacles or forced landing of the airplane.