By BOB COX
STAR-TELEGRAM STAFF WRITER
Five years after an American Airlines jet crashed in New York City and killed all 260 passengers and crew members, questions linger about whether the type of plane involved has flaws that could imperil other flights.
An investigation concluded that the crash of Flight 587, on Nov. 12, 2001, in a Belle Harbor neighborhood, was largely due to pilot error. The co-pilot made overly aggressive attempts to steer the Airbus A300 as it bounced from side to side in turbulence created by another jet that had taken off ahead of it.
The pilot's actions put so much stress on the aircraft's vertical stabilizer, or tail fin, that it was torn off, fatally crippling the wide-body jet, the National Transportation Safety Board said in its final report. For a pilot to break the airplane's structure in flight was unprecedented, the NTSB said.
But to this day, American, a group of its pilots who flew the jets and other observers contend that the safety board and its investigators rushed to blame the pilot and gave short shrift to evidence that pointed to potential flaws with the Airbus rudder controls or even a structural defect.
"I think there are a large number of troubling, unanswered questions" regarding the A300, said Michael Slack, an Austin attorney and former aerospace engineer. Slack represents the families of Flight 587 victims in liability lawsuits and has examined documents and questioned witnesses from American and Airbus.
Recently, new incidents involving damage to A300 tails and rudders have called into question the safety and reliability of the Airbus plane. They've also reinforced concerns about the growing use of carbon-fiber composite materials in manufacturing commercial airplanes.On March 6, 2005, the rudder of an A310 operated by Canadian airline Air Transat broke off from the tail on a flight from Cuba to Quebec. Inspection after landing revealed two attachment slugs, where the composite vertical tail is bolted to the fuselage, was damaged by stresses incurred when the rudder tore off.
Last November, mechanics inspecting the rudder of a FedEx A300 found a large area -- about 3 square feet -- of unsuspected and previously undetected damage to the composite structure that could have resulted in failure.
The aircraft models in question are the 267-seat Airbus A300-600 and its smaller, 220-seat cousin, the A310. Both were developed in the early 1980s from the original A300 series. The newer versions of the aircraft, about 400 worldwide, were built with lighter composite rudders and tails -- rather than metal -- and a different rudder-control system.
The rudder is used on the ground to turn the airplane. In flight, turns are accomplished primarily with ailerons, and a plane can be flown after losing a rudder. Loss of the vertical tail, however, leaves the pilots unable to control the direction of the airplane.
On March 2 of this year, after the two incidents, Airbus advised airlines flying the A300-600s and A310s to inspect the composite tails and rudders for damage and make necessary repairs within 2,500 flight cycles, a period that could stretch to a year or more. European Aviation Safety Agency officials ordered airlines under its jurisdiction to perform the inspections.
U.S. and Canadian officials were more alarmed. On March 24, the NTSB urged that the Federal Aviation Administration order urgent inspections and that necessary repairs occur within six months. The FAA issued the order a week later.
The NTSB said inspections of the Air Transat plane showed damage from "high stresses ... dangerously close in magnitude to those that caused the in-flight separation of the vertical stabilizer during the ... accident involving American Airlines Flight 587."
An ad hoc group of American pilots who closely monitored the Flight 587 investigation asked the NTSB to reopen the investigation because of the new incidents.
The pilots group argued that the NTSB should further investigate whether the Flight 587 aircraft had structural flaws in the rudder or tail. The group also said procedures used to test for damage to the composite tail structures were inadequate. The NTSB refused to reopen the investigation, saying there were distinct differences in the circumstances that led to the Flight 587 crash and the other incidents.
Clay McConnell, an Airbus spokesman, said there was no evidence from Flight 587 or the other incidents that suggested systemic problems with the airplane. Government safety officials have said repeatedly that there is "no airworthiness issue" with the A300.
Alison Duquette, an FAA spokeswoman, said the agency has carefully monitored results of the A300 inspections since the order was issued.
"We have found no further safety issues," Duquette said.
The Flight 587 investigation was a highly pressurized, political one, even for major airline crashes. NTSB officials said at the time that they were being heavily lobbied by Airbus and American to try to influence the board's conclusions.
"I've never been involved in an airline crash where the airline and the airframe manufacturer were so at odds," said Slack, the Austin attorney.
When the tail of the plane, minus the rudder, was found intact far from the rest of the wreckage, investigators had a clue as to what had happened but not why.
Investigators seized on evidence culled from the flight data recorder that showed that the rudder had been swung hard one way then the other as the pilot attempted to steer through the turbulent air. With several hard rudder moves in a space of just six to seven seconds, the plane went back and forth to the point that the tail structure was under twice the force it was ever expected to encounter.
Airbus and ultimately the NTSB blamed First Officer Sten Molin, saying his use of the rudder was "unnecessary and excessive." One American pilot who previously flew with Molin testified that he witnessed him using the rudder aggressively on a flight and counseled him that it was unwise.
American was also partly at fault, the NTSB ruled, because it trained pilots to use the rudder aggressively to recover from control upsets caused by turbulence and other unusual events. But the NTSB did rule that the Airbus rudder system, which was highly sensitive and could cause greater control inputs than the pilot expected, was likely a factor in the unprecedented accident.
Ronald Hess, an aerospace engineering professor at the University of California, Davis, analyzed the engineering data from the crash for the NTSB. Although the flight data showed the pilot overreacted and used the rudder too heavily, Hess said the sensitivity of the rudder controls "was a contributing factor."
Airbus took exception to some of the NTSB findings, McConnell said. But "it was a very well-conducted investigation, and the conclusions, we think, are the right ones."
Flight 587, McConnell said, was "one of two or three most thoroughly investigated accidents in history. The NTSB approached this in absolutely the right way in terms of turning over every rock, even some they knew would not lead anywhere."
But John David, an American A300 pilot who worked on the investigation for the pilots union, says the final report disappointed him.
"NTSB took the easy way out, a dead pilot, and exaggerated their evidence," said David, who says he flew extensively with Molin. "I'll be the first to say the pilot was involved ... but they didn't tell the whole story."
American, in its final submission to the NTSB, argued that Airbus had not informed airlines that the rudder system, which it had changed from earlier versions of the A300, was much more sensitive than other Airbus or Boeing aircraft. It also argued that Airbus knew that a pilot could damage the aircraft by using the rudder aggressively but had not notified airlines.
"We believe everything we pointed out in our submission is still valid today," said John Hotard, an American spokesman.
American still operates 34 A300-600s like the one that crashed, primarily on Latin American routes. As a result of the Flight 587 investigation, Hotard said, American believes that it can fly A300s safely "because we know how it acts, which is knowledge we did not have before the crash because Airbus didn't tell us."
NTSB Chairman Mark Rosenker said Wednesday that not all of the safety issues arising from the crash have been addressed by the FAA, EASA and Airbus.
There has been "little progress up to now on recommendations to the FAA" to implement regulations and certification testing procedures to make sure rudder systems on existing planes don't create unsafe handling conditions, Rosenker said. And he said the EASA had not followed up on recommendations that it require Airbus to make improvements to rudder systems.
McConnell, the Airbus spokesman, said the company continues "to work with FAA and EASA to look at what changes might be made to the sensitivity of the rudder pedals in that airplane."
Several American pilots who flew the A300 before and after the Flight 587 crash requalified themselves to fly Boeing jets and no longer pilot the Airbus plane.
"I got off of it because after doing all the research I just didn't feel comfortable," said Robert Tamburini, an American captain based in New York who now flies Boeing 777s. "It's not that I feel it's unsafe, it's just less safe."
May 12, 1997 -- American Airlines Flight 903 experienced an in-flight upset over Florida. The plane rolled sharply left and right, and the rudder was moved back and forth to its limits. Five years later, the NTSB reviewed flight data and found that the vertical stabilizer had been stressed beyond design limits. The aircraft was grounded for repairs.
March 6, 2005 -- Air Transat 961, an A310, was in flight from Veradero, Cuba, to Quebec City, Canada. The flight crew heard a loud bang. The plane returned to Canada and landed. Inspection revealed that the rudder had torn away in flight.
March 24 -- NTSB urged immediate inspections of composite rudders on about 400 Airbus A300-600/310 series planes after Federal Express discovered undetected rudder damage on an A300.
SOURCES: U.S. National Transportation Safety Board and Transportation Safety Board of Canada
Flight 587 crash inquiry findings
Vertical stabilizer separated from the aircraft because of severe forces created by the co-pilot's "unnecessary and excessive" rudder pedal inputs.
Rudder-system design of A300-600 series and A310 aircraft. Highly sensitive rudder-system responses make the system susceptible to hazardous control inputs by pilots at higher speeds.
American Airlines maneuvering training program.
The Federal Aviation Administration should revise aircraft certification standards to ensure safe aircraft handling in the yaw axis (side-to-side), including rudder sensitivity.
The FAA should then review designs of existing airplanes to determine whether they meet the new rudder standards.
The FAA and European safety agency should review "options for modifying the Airbus A300-600 and the Airbus A310" rudder systems.
SOURCE: National Transportation Safety Board aircraft accident report
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