Airworthiness Directives; the Boeing Company Airplanes

We are superseding Airworthiness Directive (AD) 2012-13-08 for certain the Boeing Company Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-400F, 747SR, and 747SP series airplanes, without a stretched upper deck or stretched upper deck modification. AD 2012-13- 08 required inspections of tension ties and surrounding structure for cracking, and related investigative and corrective actions if necessary; modification of tension tie structure or tension tie and frame structure at specified stations; and post-modification inspections of some modified and unmodified areas, and repair if necessary. This new AD adds inspections in unmodified center section tension ties, and repair if necessary; post-modification inspections of modified and unmodified areas, and repair if necessary; a new modification of tension tie and frame structures; and inspections of tension ties and surrounding structure, and related investigative and corrective actions if necessary. This new AD reduces an inspection interval. This AD was prompted by widespread fatigue damage analysis that resulted in a determination that more inspections are necessary. We are issuing this AD to prevent tension ties from becoming severed or disconnected from the frames, which could lead to reduced structural integrity and sudden decompression of the airplane in flight.