Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 737-100, -200, - 200C, -300, -400, and -500 series airplanes. This proposal would require repetitive inspections to detect cracking of the lower corners of the door frame and cross beam of the forward cargo door, and corrective actions, if necessary. This proposal also would require eventual modification of the outboard radius of the lower corners of the door frame and reinforcement of the cross beam of the forward cargo door, which would constitute terminating action for the repetitive inspections. This proposal is prompted by reports indicating that fatigue cracks have been detected in the lower corners of the door frame and cross beam of the forward cargo door. The actions specified by the proposed AD are intended to prevent fatigue cracking of the lower corners of the door frame and cross beam of the forward cargo door, which could result in rapid depressurization of the airplane.