Airworthiness Directives; Boeing Model 747 Airplanes

We are adopting a new airworthiness directive (AD) for all Boeing Model 747 airplanes. This AD requires a one-time inspection of certain fuselage skins at section 41 to find any external doublers that cover the inspection areas and to identify the external doublers that end on a stringer and those that do not, and related investigative and corrective actions if necessary. This AD results from reports of cracks found at fastener locations in the fuselage skins at section 41. We are issuing this AD to detect and correct fuselage skin cracks at fastener locations along the skin-to-stringer attachments, which could join together and become large and consequently result in rapid decompression of the cabin.