Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR Series Airplanes

الملخص

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR series airplanes, that requires one-time inspections for cracking in certain upper deck floor beams and follow-on actions. The actions specified by this AD are intended to find and fix cracking in certain upper deck floor beams. Such cracking could extend and sever floor beams adjacent to the body frame and result in rapid depressurization of the airplane. This action is intended to address the identified unsafe condition.