Airworthiness Directives; Boeing Model 747-100, -100B, 100B SUD, -200B, -200C, -200F, and -300 Series Airplanes; and Model 747SP and 747SR Series Airplanes

The FAA is superseding two existing airworthiness directives (ADs) that apply to certain Boeing Model 747-100, -100B, 100B SUD, - 200B, -200C, -200F, and -300 series airplanes; and Model 747SP and 747SR series airplanes. One of those ADs currently requires inspections for cracked body frames, skin, and other internal structure in fuselage section 41; and repair of any cracked frame, skin, or other internal structure. For certain airplanes, the other AD currently requires inspections for cracked skin or loose or missing fasteners of the body skin between body stations 420 and 460 and between stringers S-8 and S- 12; an inspection for cracked body frames if necessary; and repair of any cracked frame or skin and replacement of any loose or missing fastener. This new AD adds inspections and removes a one-time deferral of an inspection. This AD is prompted by reports of large cracks common to fuselage frames in the upper deck area, and severed or nearly severed adjacent frames. We are issuing this AD to detect and correct fatigue cracks in the body frames, skin and other internal structure in fuselage section 41, which could lead to rapid decompression and loss of the structural integrity of the airplane.