Airworthiness Directives; The Boeing Company Model 747-400 and -400D Series Airplanes

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires a general visual inspection to determine the routing of the wire bundles in the number two and number three engine pylons near the leading edge, and related investigative and corrective actions if necessary. For certain airplanes, this AD also requires certain concurrent actions. This AD was prompted by a report of a fuel leak from the main fuel feed tube at the number two engine pylon. We are issuing this AD to detect and correct chafing of the main fuel feed tube and the alternating current motor-driven hydraulic pump wire bundle, which could lead to arcing from the exposed wire to the fuel feed tube, and could result in a fire or explosion.