Airworthiness Directives; Boeing Model 737 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 737 series airplanes, that currently requires repetitive inspections for cracking of the aft frame and frame support structure of the forward service doorway, and repair, if necessary. This amendment reduces the compliance time for performing the initial inspection, and reduces the repetitive inspection intervals. This amendment also adds repetitive inspections for cracking of the aft frame web of the forward service doorway, and follow-on corrective actions, if necessary. This amendment also provides for an optional terminating action for the repetitive inspection requirements of this AD. This amendment is prompted by reports indicating that the repetitive inspections required by the existing AD may not detect cracking of the aft frame and frame support structure of the forward service doorway in a timely manner. The actions specified in this AD are intended to prevent fatigue cracking of the aft frame and frame support structure of the forward service doorway, which could result in loss of the door, and consequent rapid decompression of the fuselage.