Airworthiness Directives; Boeing Model 747-100, -200B, -200F, -200C, -100B, -300, -100B SUD, -400, -400D, -400F, and 747SR Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires repetitive inspections to find cracking of the frame web, strap, inner chords, and inner chord angle of the forward edge frame of the number 5 main entry door cutout, and repair, if necessary. These actions are necessary to find and fix such cracking, which could result in severing of the frame, inability of the edge frame to react door stop loads, and consequent rapid depressurization of the airplane. This action is intended to address the identified unsafe condition.