Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing transport category airplanes. This proposed AD would require repetitive tests of the overwing fuel fill ports for certain wing tanks; an electrical bonding resistance test between the bulkhead fittings of the engine fuel feed tube and the front spar inside the fuel tank of the wings; other specified actions; and applicable corrective actions if necessary. This proposed AD is prompted by our determination that this AD is necessary to reduce the potential for ignition sources inside fuel tanks. We are proposing this AD to prevent arcing or sparking at the interface between the bulkhead fittings of the engine fuel feed tube and the front spar inside the fuel tank of the wings and between the overwing fuel fill ports and the airplane structure during a lightning strike. Such arcing or sparking could provide a possible ignition source for the fuel vapor inside the fuel tank and cause consequent fuel tank explosions.