AD FAA-2015-6538

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, and -500 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the aft pressure bulkhead is subject to widespread fatigue damage (WFD). This AD requires repetitive inspections of the aft pressure bulkhead web for any cracking, incorrectly drilled fastener holes, and elongated fastener holes; and related investigative and corrective actions, if necessary. We are issuing this AD to detect and correct fatigue cracking of the aft pressure bulkhead web at the "Y"-chord, which could result in reduced structural integrity of the airplane and rapid decompression of the fuselage.