only aircrew error allowed - whenever there's any doubt

By MATTHEW L. WALD

Published: May 30, 2004

ASHINGTON, 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. from this link

NTSB To FAA:
Require Inspection Of Overstressed Aircraft
By Howard Schwach

The vertical stabilizer (tail fin) attachment point from the Airbus A300-600 that was American Airlines Flight 587 after the crash. Notice how the fin has pulled away from the lug that attached it to the body of the plane.

The National Transportation Safety Board (NTSB) has sent a letter to the Federal Aviation Agency (FAA) urging that aircraft that have gone through what the investigative agency calls "severe turbulence or extreme maneuvers" be inspected much more carefully by airlines.

While it is not stated clearly in the safety recommendation letter sent to the FAA, the implication is clear that the letter was spurred by the investigation into the crash of American Airlines Flight 587, which killed 265 people, including five Belle Harbor residents on the ground.

According to earlier reports by the NTSB, the Airbus A-300-600 had hit wake turbulence from a Japan Airlines aircraft that had preceded its departure from JFK's Runway 31 Left on November 12, 2001.

"During the accident event, the vertical stabilizer and rudder departed the airplane in flight," a footnote to the letter states. "...The cause of the accident is still under investigation. Information to date indicates that the vertical stabilizer was subjected to large aerodynamic structural loading during the accident event."

According to the letter, on May 12, 1997, an Airbus Industrie A 300-600 operated by American Airlines as Flight 903, was involved in an "upset event." The plane's stall warning system activated and the plane rolled to extreme bank angles, both right and left.

After the crash of flight 587, the tail was pulled from the flight 903 aircraft and there was found to be delamination around the lugs that hold the tail to the body. That delamination of composite material used in the tail could cause the lugs to rip away and the tail to fall off the aircraft, according to experts.

Mary Ann Greczyn, a spokesperson for Airbus North America, said that the company "has implemented or is in the process

of implementing all of the NTSB's recommendations."

Greg Martin, a spokesperson for the FAA says that the agency is "studying the recommendations."

The NTSB's recommendation is that the FAA require airlines to perform closer inspections of aircraft that have suffered 'upsets" such as wake turbulence.

Meanwhile, the NTSB's accident investigation group's Structures Group is working with NASA and Airbus on a static lug test to be done in Germany in the near future. According to an NTSB update on the crash issued in August, "The left-side rear main attachment lug from an A310 tail fin box will be tested to demonstrate the behavior of the lug under tensile load conditions to which the fin of flight 587 had been exposed during the accident sequence.

A Vanity Fair magazine article about the flight that came out late last year said that the aircraft that became flight 587 had suffered such an "upset" on a flight years earlier.

Ted Lopatkiewicz, a spokesperson for the NTSB, told The Wave that the final report on the flight 587 crash would probably not be issued until "springtime."

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