Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747- 200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes. This proposed AD would require inspecting for skin cracks at the shear tie end fastener locations of the fuselage frames, and repair if necessary. This proposed AD results from a wide-spread fatigue damage assessment of Model 747 airplanes. We are proposing this AD to detect and correct cracks in the fuselage skin that can propagate and grow, resulting in a loss of structural integrity and a sudden decompression of the airplane during flight.