The National Transportation Safety Board has revealed that the five-foot long chunk of aluminum that blew out of Southwest Airlines Flight 812 last Friday triggered an explosive decompression that literally sucked the air out of the airplane.
In this kind of explosive decompression, someone could get sucked out of the airplane, said Dallas aviation attorney John Kettles. A flight attendant walking down the aisle... anyone who does not have their seat belt fastened.
Even normal use stresses an airliner. With every takeoff and landing, the skin expands and contracts.
That produces cracks, which are considered normal. The problem for aircraft manufacturers like Boeing is finding the cracks before they become killers.
A fuselage disintegration nearly doomed Aloha Airlines Flight 248 in 1988. A flight attendant was sucked out of the cabin to her death and 65 others were hurt. In that case, the cause of the failure was not cracking, but corrosion.
Nonetheless, the explosive decompression opened the industry's eyes to a lurking problem.
It's no good for Boeing or Southwest to say this is the first time this has happened, attorney Kettles said. They should have done the research to make sure this doesn't happen.
Inspecting a plane for cracks invisible to the eye is no easy task. It's done with a device called a dual frequency eddy current, which uses electromagnetism to peer into an aircraft's metal skin.
The skin at issue in Friday's accident was called a lap joint, a kind of seam that runs fore-to-aft on either side of the top of an airplane's hull.
Southwest had actually modified the lap joints on 92 of its 171 Boeing 737-300 jets before Friday's explosion.
But 79 of the carrier's planes had not been modified. Nearly all of those planes have now been reinspected, and three of them were found to have cracks.
Southwest is awaiting guidance from the manufacturer, Boeing, on how to repair them.
The issue of aircraft inspection and crack repair, already simmering between Southwest Airlines and the FAA, may burst again after Friday's incident. The FAA fined Southwest $7.5 million over 737 inspections in 2008, but in the process, the FAA's integrity was questioned. Top managers resigned.
Now the maintenance issue has popped open again.
E-mail bharris@wfaa.com
