Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model DC-9-10, DC-9-20, and DC-9-30 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the improved (shot-peened) aft fuselage non-ventral pressure bulkhead tee is subject to widespread fatigue damage (WFD). This AD requires repetitive inspections for cracking of the improved (shot-peened) non-ventral aft pressure bulkhead tees, and replacement if necessary. We are issuing this AD to detect and correct fatigue cracking of the improved (shot-peened) non-ventral aft pressure bulkhead tees connecting the bulkhead web to the fuselage, which could result in reduced structural integrity and rapid decompression of the airplane.