Airworthiness Directives; The Boeing Company Airplanes

We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. This proposed AD was prompted by a report of incidents involving fatigue cracking in transport category airplanes that are approaching or have exceeded their design service objective and a structural reevaluation by the manufacturer that identified additional structural elements that qualify as structural significant items (SSIs). This proposed AD would require revising the maintenance or inspection program, as applicable, to include inspections that will give no less than the required damage tolerance rating (DTR) for certain SSIs, and repairing any cracked structure. This proposed AD would also require inspections to detect cracks of all SSI structure, and repair if necessary. We are proposing this AD to ensure the continued structural integrity of all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes.