Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SP series airplanes. This proposed AD would require reconfiguring the clamps of certain wire bundles and applying insulating sealant to certain fasteners inside the fuel tanks. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent arcing inside the fuel tanks in the event of a lightning strike or high-powered short circuit, which could result in a fuel tank explosion or fire.