Airworthiness Directives; Boeing Model 747-100 and -200 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-100 and -200 series airplanes, that requires repetitive inspections for cracking of the station 800 frame assembly, and repair, if necessary. The actions specified by this AD are intended to find and fix fatigue cracks that could extend and fully sever the frame, which could result in development of skin cracks that could lead to rapid depressurization of the airplane. This action is intended to address the identified unsafe condition.