Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require inspections to detect cracking of the frame web, doubler, and inner chord of the forward edge frame of main entry door number 1, and various follow-on actions. This proposal is prompted by reports of cracking in the frame web, doubler, inner chord, and strap of the forward edge frame of main entry door number 1. The actions specified by the proposed AD are intended to prevent cracks in the frame web and doubler of the forward edge frame of main entry door number 1, which could result in inability of the edge frame to react door stop loads, and consequent rapid depressurization of the airplane.