Summary
We propose to adopt 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 proposed 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 proposed AD would require repetitive inspections of the improved ventral aft pressure bulkhead tees and replacement if necessary. We are proposing 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.