The Federal Aviation Administration will issue an emergency directive tomorrow that will require operators of specific Boeing 737 models to "conduct initial and repetitive electromagnetic inspections for fatigue damage" on those planes.
"This action will initially apply to a total of approximately 175 aircraft worldwide, 80 of which are U.S.-registered aircraft," said the FAA. Most of the aircraft in the U.S. covered in the directive are operated by Southwest Airlines, the agency said.
It is not immediately clear if this directive will affect the Boeing 737-300s that Southwest has said it has already inspected for possible cracks, and returned to service, since the weekend.
Southwest said today that as of 3:30 p.m. Central Time it had inspected most of the 79 Boeing 737-300s it grounded Saturday. Inspection has been completed on 67 aircraft, 64 of which were returned to service.
"The remaining three aircraft did have findings of subsurface cracks and will be out of service until Boeing recommends an appropriate repair," Southwest said. As usual, Southwest makes it a point to include the aircraft's manufacturer, Boeing, in its updates on the problems.
Southwest also said today that it believes the inspections over the weekend and on Monday put it already in compliance with the emergency directive that the FAA will issue tomorrow. "With our knowledge of what the FAA has planned, we believe the 79 aircraft already identified for inspection will accomplish this directive for Southwest Airlines," the airline said in a statement this afternoon.
Southwest said it expects to be able to operate its full schedule tomorrow.
During the inspections of the grounded jets, Southwest said it found "small subsurface cracks" in three planes, which are being repaired. Southwest is continuing to inspect the remaining grounded 737-300s.
If Southwest is wrong about being in compliance already with the new FAA emergency directive, it might need to re-inspect some of those planes, and maybe ground some others, and cancellations and delays that have been affecting the airline since Saturday could continue.
The planes covered by the new FAA directive are 737s with high flight cycles (the number of takeoffs and landings), in the 300, 400 and 500 series. Southwest's flies 25 of the 500-series 737s, none of which had been affected by the airline's decision to insect the 79 Boeing 737s. Most Southwest's 737s are later-model 700 series.
Southwest flies a total of 548 Boeing 737s of all models.
Transportation Secretary Ray LaHood said of the Southwest incident, in which a five-foot hole ripped open on a 737-300 over Arizona late Friday afternoon: "Last Friday’s incident was very serious and could result in additional action depending on the outcome of the investigation."
FAA Administrator Randy Babbitt said, “The FAA has comprehensive programs in place to protect commercial aircraft from structural damage as they age. 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 require repetitive inspections at regular intervals.
My pal Joe Brancatelli at Joesentme.com speculated that mostly 737-300s would be affected by the FAA order, because Southwest typically uses that model on shorter-haul routes, where planes take off and land more often, and thus log higher use cycles.
Why issue an "emergency" directive that doesn't take effect till tomorrow? Unclear to me at this point. A cynic might suspect that the FAA could be hoping to retroactively cover itself on the Southwest incident with the new directive.
Last November, the FAA published a rule designed to address widespread fatigue damage in aging aircraft. The rule requires aircraft manufacturers to establish a number of flight cycles or flight hours a plane can operate and be free from fatigue damage. The rule requires aircraft manufacturers to incorporate the limits into their maintenance programs.