Airworthiness Directives; The Boeing Company Airplanes

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747- 200B, 747-300, 747SR, and 747SP series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that certain fuselage skin lap joints are subject to widespread fatigue damage (WFD). This proposed AD would require repetitive post-modification inspections for cracking of the skin or internal doubler along the edge fastener rows of the modification, and repair if necessary. We are proposing this AD to detect and correct fatigue cracking in certain fuselage skin lap joints, which could result in rapid depressurization of the airplane.