Airworthiness Directives; Boeing Model 757 Airplanes

We are adopting a new airworthiness directive (AD) for certain Boeing Model 757 airplanes. This AD requires sealing the fasteners on the front and rear spars inside the left and right main fuel tanks and on the rear spar and lower panel of the center fuel tank. This AD also requires inspections of the wire bundle support installations to verify if certain clamps are installed and if Teflon sleeving covers the wire bundles inside the left and right equipment cooling system bays, on the left and right rear spars, and on the left and right front spars; and corrective actions if necessary. This AD results from a fuel system review conducted by the manufacturer. We are issuing this AD to detect and correct improper wire bundle support installation and sleeving and to prevent improperly sealed fasteners in the main and center fuel tanks from becoming an ignition source, in the event of a fault current, which could result in a fuel tank explosion and consequent loss of the airplane.