AD FAA-2013-0790

We are superseding Airworthiness Directive (AD) 89-12-10, for certain The Boeing Company Model 747 airplanes. AD 89-12-10 required replacement of certain underwing fuel tank access doors with stronger, fire-resistant doors. This new AD requires inspecting certain fuel tank access doors for installation of impact-resistant doors, and stencils and index markers; corrective actions if necessary; revising the maintenance program to incorporate certain new airworthiness limitations; and adding airplanes to the applicability. This AD was prompted by a report of a standard access door installed instead of an impact-resistant access door and stencils missing from some impact- resistant access doors and adjacent wing skin. We are issuing this AD to prevent foreign object penetration of the fuel tank, which could cause a fuel leak near an ignition source (e.g., hot brakes or engine exhaust nozzle), consequently leading to a fuel-fed fire.