The New York Times
Crash Inquiry Turns Up Flaw in Airliner's Rudder System
By MATTHEW L. WALD
Published: May 30, 2004
WASHINGTON, May 29 - The investigation into the November 2001 crash of American Airlines Flight 587 in Queens has turned up an important flaw in the rudder control system of the type of aircraft flown, although the flaw did not play a role in that accident, federal air safety investigators said Friday.
The announcement comes amid a sustained campaign by American Airlines to blame design deficiencies for the crash, which killed all 260 people aboard and five more on the ground. The flight had just taken off from Kennedy International Airport for the Dominican Republic.
In the crash, the pilot swung the rudder in alternate directions, creating a side-to-side motion in the jet that ripped off the tail. Airbus, the plane's manufacturer, blamed the pilot's actions, but American attributed the crash to poor design of the control system.
On Friday, the National Transportation Safety Board said that type of aircraft, the Airbus A-300-600, could suffer tail damage or crash because the rudder could extend too far when the plane was accelerating rapidly. The board recommended that the Federal Aviation Administration order Airbus to redesign the system, and to see if other models of the plane have the same problem.
After the 2001 crash, investigators looked at earlier incidents involving the rudder of the A-300, and focused on another American flight, in May 1997, near West Palm Beach, Fla. In that case, the plane abruptly lost 3,000 feet in altitude because it was flying too slowly. One crew member was seriously injured.
Like all big jets, the A-300 has a rudder that can be extended far to the left or right to point the plane in the desired direction in a crosswind, when maneuvering on the ground or if an engine fails. But as speed increases, less extension of the rudder is needed to produce the same effect, and the plane becomes vulnerable to accident if the rudder moves too far. So the plane has a "limiter" system that progressively reduces the movement of the rudder as speed increases.
But in the West Palm Beach incident, the plane sped up so fast as it lost altitude that the limiter system could not keep up. The safety board, an advisory panel, said Friday that the system could not keep up with velocity changes faster than 2.4 knots a second, and the plane in Florida was accelerating at 10 knots a second.
The New York flight, Flight 587, was not accelerating rapidly.
On Friday, a spokeswoman for Airbus, Mary Anne Greczyn, said the manufacturer was "in absolute agreement" with the recommendation to redesign the system. "We expected it was coming," she said. "It will add another level of safety for those extraordinarily rare times when there are rapid changes in air speed due to aircraft upset."
Ms. Greczyn said that Airbus had learned a great deal from each incident but that "they absolutely have to be separated when you're talking about this kind of recommendation."
But a statement by the airline seemed to run the two together. American said that it had instituted special training for its A-300 pilots after the 587 crash, to address "the specific shortcomings in the Airbus A300-600 rudder control system that the N.T.S.B. recommendation involves." American said it had cited the rudder limiter system as a problem with the plane in its submission to the safety board on the crash of Flight 587.
Laura J. Brown, a spokeswoman for the Federal Aviation Administration, said that her agency had received the recommendation late on Friday afternoon and would look at it next week.
Crash Inquiry Turns Up Flaw in Airliner's Rudder System
By MATTHEW L. WALD
Published: May 30, 2004
WASHINGTON, May 29 - The investigation into the November 2001 crash of American Airlines Flight 587 in Queens has turned up an important flaw in the rudder control system of the type of aircraft flown, although the flaw did not play a role in that accident, federal air safety investigators said Friday.
The announcement comes amid a sustained campaign by American Airlines to blame design deficiencies for the crash, which killed all 260 people aboard and five more on the ground. The flight had just taken off from Kennedy International Airport for the Dominican Republic.
In the crash, the pilot swung the rudder in alternate directions, creating a side-to-side motion in the jet that ripped off the tail. Airbus, the plane's manufacturer, blamed the pilot's actions, but American attributed the crash to poor design of the control system.
On Friday, the National Transportation Safety Board said that type of aircraft, the Airbus A-300-600, could suffer tail damage or crash because the rudder could extend too far when the plane was accelerating rapidly. The board recommended that the Federal Aviation Administration order Airbus to redesign the system, and to see if other models of the plane have the same problem.
After the 2001 crash, investigators looked at earlier incidents involving the rudder of the A-300, and focused on another American flight, in May 1997, near West Palm Beach, Fla. In that case, the plane abruptly lost 3,000 feet in altitude because it was flying too slowly. One crew member was seriously injured.
Like all big jets, the A-300 has a rudder that can be extended far to the left or right to point the plane in the desired direction in a crosswind, when maneuvering on the ground or if an engine fails. But as speed increases, less extension of the rudder is needed to produce the same effect, and the plane becomes vulnerable to accident if the rudder moves too far. So the plane has a "limiter" system that progressively reduces the movement of the rudder as speed increases.
But in the West Palm Beach incident, the plane sped up so fast as it lost altitude that the limiter system could not keep up. The safety board, an advisory panel, said Friday that the system could not keep up with velocity changes faster than 2.4 knots a second, and the plane in Florida was accelerating at 10 knots a second.
The New York flight, Flight 587, was not accelerating rapidly.
On Friday, a spokeswoman for Airbus, Mary Anne Greczyn, said the manufacturer was "in absolute agreement" with the recommendation to redesign the system. "We expected it was coming," she said. "It will add another level of safety for those extraordinarily rare times when there are rapid changes in air speed due to aircraft upset."
Ms. Greczyn said that Airbus had learned a great deal from each incident but that "they absolutely have to be separated when you're talking about this kind of recommendation."
But a statement by the airline seemed to run the two together. American said that it had instituted special training for its A-300 pilots after the 587 crash, to address "the specific shortcomings in the Airbus A300-600 rudder control system that the N.T.S.B. recommendation involves." American said it had cited the rudder limiter system as a problem with the plane in its submission to the safety board on the crash of Flight 587.
Laura J. Brown, a spokeswoman for the Federal Aviation Administration, said that her agency had received the recommendation late on Friday afternoon and would look at it next week.