Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, and 747SR series airplanes. This proposed AD would require a one-time general visual inspection for missing fasteners in certain stringer-to- stringer clip joints at the station (STA) 760 through STA 940 frames, and related investigative and corrective actions if necessary. This proposed AD results from a report of broken and cracked frame shear ties, cracks on the frame doubler and frame web, and missing fasteners in the stringer (S)-10L stringer-to-stringer clip joint at the STA 820 frame. We are proposing this AD to detect and correct missing fasteners in the stringer-to-stringer clip joints, which could result in shear tie and skin cracks and rapid in-flight decompression of the airplane.