AD FAA-2016-5598

We are superseding Airworthiness Directive (AD) 2012-22-02 for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. AD 2012-22-02 required measuring the web at station (STA) 320 and, depending on findings, various inspections for cracks and missing fasteners, web and fastener replacement, and related investigative and corrective actions if necessary. This new AD requires, for certain airplanes, replacement of the web, including related investigative and corrective actions if necessary. This AD was prompted by a determination that there were no inspection or repair procedures included in AD 2012-22-02 for airplanes with a certain crown frame web thickness. We are issuing this AD to address the unsafe condition on these products.