The Federal Aviation Administration has confirmed it will issue an emergency directive requiring operators of specific early Boeing 737 models to conduct initial and repetitive electromagnetic inspections for fatigue damage.

The decision follows a mid-air rupture of the fuselage skin on Southwest Airlines flight 812 on Friday.

“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 action will initially apply to a total of approximately 175 aircraft worldwide, 80 of which are US-registered aircraft.

Most of the aircraft in the US are operated by Southwest Airlines.

“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.

Source: BTN

Boeing will recommend that airlines throughout the world check older 737 aircraft for the kind of fatigue cracks that prompted Southwest Airlines to cancel hundreds of flights.

The manufacturer said in a statement on Monday it is preparing a service bulletin for targeted fuselage inspections of 737-300s. More than 900 are in service around the world, but the directive will only apply to more heavily used aircraft.

Southwest voluntarily launched checks of more than 100 of those models after one landed in Arizona on Friday with a hole in its fuselage.

The airline cancelled 600 flights over the weekend and 70 on Monday. More than half of the planes grounded for inspections have returned to service. Subsurface fuselage cracks were found on three, with inspections expected to finish on Tuesday.

Flight 812 was heading from Phoenix to Sacramento when a 5-foot (1.52 meter) tear opened in the fuselage 20 minutes after takeoff on Friday.

A similar incident occurred two years ago and Southwest paid a USD$7.5 million Federal Aviation Administration fine for operating 737s without required fuselage structural inspections in the 2006-07 timeframe.

Robert Herbst, an independent airline analyst, said Southwest has more take-offs and landings per aircraft than other carriers, putting wear and tear on its planes.

"The industry itself has to replace some of these old ageing aircraft," Herbst said.

Still, he said Southwest is one of the world's safest airlines, noting it has never had a fatal crash.

Southwest said over the weekend its fleet regularly undergoes "rigorous checks and inspections" as directed by the FAA and Boeing. These checks and inspections are partly dictated by number of takeoffs and landings.

Source: Reuters