Summary
We are revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 767 airplanes. The original NPRM would have required sealing certain fasteners and stiffeners in the fuel tank, and changing certain wire bundle clamp configurations on the fuel tank walls. The original NPRM resulted from fuel system reviews conducted by the manufacturer. This action revises the original NPRM by adding inspections, for certain airplanes, of additional fasteners in the fuel tanks and of the method of attachment of the vortex generators, and corrective action if necessary. We are proposing this supplemental NPRM to prevent possible ignition sources in the auxiliary fuel tank, main fuel tanks, and surge tanks caused by a wiring short or lightning strike, which could result in fuel tank explosions and consequent loss of the airplane.