Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires an internal visual inspection to detect cracks of the skin and internal doublers above main entry door 1 at body station 460, and various follow-on actions. This amendment is prompted by reports indicating that multiple fatigue cracks were found in both internal skin doublers. The actions specified by this AD are intended to detect and correct such fatigue cracking, which could result in reduced structural integrity of the fuselage and consequent rapid depressurization of the cabin.