NTSB says SWA 737 fuselage hole incident caused by 'fatigue cracking'

The US National Transportation Safety Board issued a report stating the Southwest Airlines 737-300 that developed a hole in its fuselage in July 2009 while flying from Nashville to Baltimore suffered from "fatigue cracking of the fuselage skin near the leading edge of the vertical stabilizer."

Flight 2294 experienced "rapid decompression while in cruise flight at approximately 35,000 ft. when the fuselage crown skin ruptured just forward of the vertical stabilizer," according to NTSB. It said magnified inspections of the fracture area revealed "surfaces indicative of fatigue progress." During the July 13 flight, "the fatigue cracking penetrated the fuselage skin and created an approximate 18-inch by 12-inch flap in the skin that depressurized the airplane," the board stated.

At the time of the incident, "the specific area of rupture and skin cracking…was not subject to any inspection Airworthiness Directives or service bulletins," NTSB pointed out. Prompted by the incident, Boeing issued a September 2009 service bulletin calling for repetitive external inspections of the area in question to detect cracks in the fuselage skin of 737 Classics. FAA followed with an AD issued Jan. 12 mandating the inspections.

SWA said in a statement that it is in "full compliance with all new safety regulations developed by Boeing and the FAA and we thank the NTSB for its thorough investigation." It added it has "taken aggressive measures to incorporate additional maintenance inspections…in response to what was learned from flight 2294. Immediately after the accident, we increased our ongoing maintenance inspections in the impacted area to include recurring detailed visual inspections and non-destructive tests, with a goal to not only meet but exceed known safety standards."