– Dave Alden – April 3, 2011. The National Transportation Safety Board is investigating a rupture of the aircraft skin at the top of the cabin of this Boeing 737 being operated on April 1, 2011 as Southwest Airlines flight 812, during a scheduled flight from Phoenix, AZ (PHX) to Sacramento, CA (SMF). The pilots declared an emergency, diverted and landed safely in Yuma, AZ. Passengers were shaken by the sudden decompression, appearance of oxygen masks from panels above their seats and emergency descent, but there were no serious injuries. According to FAA records, the aircraft is a Boeing 737-300 series manufactured in 1996, N632SW registered to Southwest Airlines Co in Dallas, TX. Early speculation points to metal fatigue caused by cabin pressurization and depressurization each time the aircraft is flown. Following the incident, Southwest grounded a number of its 737s for inspection and canceled hundreds of flights.

NTSB flight data recorder

The Flight Data (FDR) and cockpit voice recorders (CVR) arrived at NTSB headquarters in Washington, DC on Saturday April 2nd.

On April 5, 2011 the FAA issued an emergency airworthiness directive which requires initial inspections using electromagnetic, or eddy-current, technology in specific areas of the aircraft fuselage on certain Boeing 737 aircraft in the -300, -400 and -500 series that have accumulated more than 30,000 flight cycles. It will then require repetitive inspections at regular intervals. Here’s the full text of emergency AD 2011-08-51.

The broader implication of the incident is increased scrutiny of older/high flight cycle airplanes. Last November, the FAA published a rule designed specifically to address widespread fatigue damage in aging aircraft. The rule requires aircraft manufacturers to establish a number of flight cycles or hours a plane can operate and be free from fatigue damage.

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