Airworthiness Directives; Boeing Model 757 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes. This action requires a one-time inspection to detect discrepancies of the main battery shunt, and replacement with a serviceable part, if necessary. This action also requires inspection of certain wires, washers, and brass jam nuts to detect any discrepancy, and replacement with a serviceable part, if necessary. Additionally, this action requires inspection, and adjustment if necessary, of the torque and resistance of the installation of the main battery ground stud. This amendment is prompted by a report of interruption of electrical power during flight due to improper installation of the main battery shunt and ground stud connection of the main battery. The actions specified in this AD are intended to prevent such electrical power interruptions, which could result in loss of battery power to the source of standby power for the airplane.