Apparently metal fatigue was the cause of the hole that opened up the roof of a Southwest Boeing 373 at 35,000 feet last year. Although skylights can make all the difference in say a dark powder room. Looking up and seeing the sky does not quite have the same calming effect when in an aircraft.
According to the NTSB, the 14-inch crack appeared where two sheets of aluminum skin had been bonded together. The safety board discovered the fault by magnifying the surfaces in front of the jet’s tail fin.
Southwest has since increased visual inspections of that area of the skin on its all-737 fleet.
When the event took place last July the aircraft was en route from Nashville to Baltimore and lost cabin pressure. The pilot made an emergency landing in Charleston, West Virginia with no injuries. In total, that aircraft had logged 50,500 hours and made 42,500 takeoffs and landings before the incident. According to FAA records, eight cracks had been found and repaired in the fuselage during the Southwest aircraft’s mandatory, 14-year check that took place six months prior to the incident.
Afterwards, Boeing directed all carriers with 737s to conduct detailed and repeated inspections of the fuselage near the vertical tail fin. The FAA has since made those inspections mandatory.