Planemaker Preparing A Service Bulletin To Address Fatigue Cracking

As the cancellations of Southwest Airlines flights continues to mount up, Boeing is reportedly preparing a service bulletin recommending the inspection of all older-model B737s worldwide, while the FAA is preparing an emergency AD to address the problem.

The moves come as cracks have been discovered in the fuselages of a third Southwest 737. Multiple media sources cite Reuters in indicating that the planmaker said in a statement Monday that the directive will apply to the more heavily-used airplanes in carriers' fleets.

There are more than 900 of the single-aisle aircraft flying with airlines around the world. A Southwest 737 experienced a decompression event Friday when a five-foot tear opened up in the roof of a 737 about 20 minutes after takeoff. The plane landed safely, and the incident was attributed to cracks in the fuselage due to a high number of pressurization cycles on the aircraft.

The FAA levied a fine of over $10 million against Southwest in 2008 for not performing mandated inspections for fuselage cracks in its fleet of 737s. It eventually settled with the agency for a $7.5 million fine along with updated inspection guidelines.

Southwest 737s On The Ramp At Midway. Photo By Robert Randall

The agency now says it will issue an emergency AD Tuesday that will require operators of specific early Boeing 737 models to conduct initial and repetitive electromagnetic inspections for fatigue damage. This action will initially apply to a total of approximately 175 aircraft worldwide, 80 of which are U.S.-registered aircraft. Most of the aircraft in the U.S. are operated by Southwest Airlines.

"Safety is our number one priority," said Transportation Secretary Ray LaHood. "Last Friday's incident was very serious and could result in additional action depending on the outcome of the investigation."

"The FAA has comprehensive programs in place to protect commercial aircraft from structural damage as they age," said FAA Administrator Randy Babbitt. "This action is designed to detect cracking in a specific part of the aircraft that cannot be spotted with visual inspection."

The FAA airworthiness directive will require 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.

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. The rule requires aircraft manufacturers to incorporate the limits into their maintenance programs.

FMI: www.boeing.com. www.faa.gov, www.southwest.com