Airworthiness Directives; Boeing Model 737-200, -200C, -300, -400, and -500 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 737 series airplanes, that currently requires repetitive inspections to find cracking of the lower skin at the lower row of fasteners in the lap joints of the fuselage, and repair of any cracking found. That amendment also requires modification of the fuselage lap joints at certain locations, which constitutes terminating action for repetitive inspections of the modified areas. This amendment adds repetitive inspections and requires replacement of the current preventive modification with an improved modification. This amendment is prompted by the FAA's determination that, in light of additional crack findings, certain modifications of the fuselage lap joints do not provide an adequate level of safety. The actions specified by this AD are intended to find and fix cracking of the fuselage lap joints, which could result in sudden decompression of the airplane.