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

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737-300, -400, and -500 series airplanes, that requires repetitive inspections to detect cracking of certain areas of the forward pressure bulkhead, and repair, if necessary. This amendment also requires certain preventive modifications, which, when accomplished, terminate the repetitive inspections for the affected areas. This action is necessary to prevent fatigue cracking on critical areas of the forward pressure bulkhead, which could result in rapid decompression of the airplane fuselage. This action is intended to address the identified unsafe condition.