Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires disconnection of the electrical connector to the scavenge pump of the center wing tank. That AD also requires a one-time inspection to identify the part number of the electrical connector; and replacement of the pump with a new or serviceable pump, if necessary. This amendment requires a one-time inspection to identify the part number of the scavenge pump motor-impeller unit; and corrective action, if necessary. This amendment is prompted by a report of damage to the internal wiring of a scavenge pump that had been replaced in accordance with the existing AD. The actions specified in this AD are intended to prevent potential failures within the electrical motor assembly of the scavenge pump, which could result in leakage of fuel from the electrical connector into the main landing gear wheel well, or electrical arcing within the scavenge pump motor; these conditions could result in a fuel fire in the wheel well.