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, DC-9-30, DC-9-40, and DC-9- 50 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the bulkhead dome tees, which connect the bulkhead web to the fuselage, are subject to widespread fatigue damage (WFD). This AD requires repetitive inspections of the improved ventral aft pressure bulkhead tees, and replacement if necessary. We are issuing this AD to detect and correct fatigue cracking of the bulkhead dome tees, which could result in reduced structural integrity and rapid decompression of the airplane.