AD FAA-2009-1066

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Model 747 airplanes. That AD currently requires repetitive inspections to detect cracking in certain fuselage skin lap joints, and repair if necessary. This new AD expands the inspection area in the existing AD, adds a modification of certain lap joints, and adds certain post-repair inspections of the lap joints. Accomplishing the modification ends the repetitive inspections required by the existing AD for the length of lap joint that is modified. This AD results from a structural review of affected skin lap joints for widespread fatigue damage. We are issuing this AD to prevent fatigue cracking in certain lap joints, which could result in rapid depressurization of the airplane.