Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 747SP series airplanes, and certain The Boeing Company Model 747-100B SUD and 747-300 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that the fuselage skin just above certain lap splice locations is subject to widespread fatigue damage (WFD). This proposed AD would require repetitive inspections for cracking of the fuselage skin above certain lap splice locations, and repair if necessary. We are proposing this AD to detect and correct fatigue cracking of the fuselage skin, which could result in reduced structural integrity of the airplane and sudden loss of cabin pressure.