American Airlines canceled more than 1,000 flights Wednesday, stranding about 100,000 people and adding to flights grounded a day earlier, as it inspected wiring on some of its jets that could cause a short or even a fire. Airline executives said the safety of passengers was never in jeopardy. It was American's second bout with mass cancellations in less than two weeks for failing to meet rules set by the Federal Aviation Administration.
Some questions and answers about the groundings:
Q: What prompted the FAA to issue the order on the MD-80 wiring bundles?
A: Reports of shorted wires, evidence of worn-down power cables, and fuel system reviews conducted by the manufacturer, Boeing Co. The airworthiness directive carried an effective date of Sept. 5, 2006, and airlines had 18 months to comply.
Q: What could happen if the wires shorted out?
A: Besides the loss of auxiliary hydraulic power, a fire in the wheel well of the airplane could be sparked by a short from the wires. The actions required by the government also are intended to reduce the possibility of fire or a fuel tank explosion that would destroy the plane, according to the FAA.
Q: Why were airlines given 18 months to comply?
A: Officials assessed the risks that the wires posed, and in the case of those that are near, but not inside a fuel tank, they determined that carriers would have 18 months, said FAA spokesman Les Dorr. Two things are required for an explosion — fire and the proper mix of fuel and air — and the wire bundles inspected in the MD-80s were not in a position where an explosion was likely, he added.
Q: Why didn't the airlines comply by the deadline?
A: Assuming the airlines received and understood the FAA order, "the likely answer is they believed they didn't have to," said Daniel Petree, dean of the College of Business at Embry-Riddle Aeronautical University in Daytona Beach, Fla. In general, businesses don't like to take on extra costs "if there is no payoff for them in doing it."
The carriers likely also assessed the risks to their fleet and weighed that against disrupting service on planes that already yield little revenue per seat.
Brian Stirm, director of aircraft maintenance at Purdue University's aviation technology department, added that 18 months was "more than adequate time to do a visual inspection." Even untrained mechanics and inspectors could identify chafing, which is the "wire bundle rubbing on something else," he added.
Q: What did it cost to comply, and how many aircraft were affected?
A: More than 1,000 airplanes worldwide were affected, including an estimated 732 in the U.S. Based on the required parts and labor time, the FAA estimated the cost to U.S. operators would be up to $1,304 per airplane.
While that figure may seem small, the FAA did not factor in revenue lost to the airlines if the planes are taken out of service, Petree said — something the carriers likely did. Removing an aircraft for 12 hours could mean losing up to five trips, and having to compensate passengers for cancellations and missed connections with hotel rooms and other perks, he said.
Q: Didn't wiring problems lead to the explosion and crash of TWA Flight 800 that killed all 230 people aboard in July 1996?
A: Yes, but the explosion in the fuel tank of that plane, a Boeing 747, most likely came through a different wiring system, according to the National Transportation Safety Board. Air-conditioning units underneath the fuel tanks also are believed to have heated the vapors inside the tank, which made them more vulnerable to explosion.