Eight AA pilots join Airbus warnings
Plane flew 4 years after 1997 tail fin incident
WASHINGTON (CNN) -- In the ongoing investigation into the November crash of American Airlines Flight 587 in Queens, New York, pilots are sounding warnings that the damage to the tail section of another A300 tested for comparison may have been worse than reported.
The damage in question was found earlier this month on an A300 whose tail fin was exposed in 1997 to extremely high side-to-side forces it was not designed to handle.
A source directly involved in the Flight 587 investigation told CNN that the "delamination," or weakening of the composite material in that second plane was so severe that the tail was "just a shade short of tearing off."
CNN has obtained exclusive photos in which pencil sketches show the hidden damage found by ultrasound testing.
A Federal Aviation Administration (FAA) memo shown to CNN concludes that the stress was concentrated at the same points as those at which National Transportation Safety Board (NTSB) investigators found stress evidence on Flight 587's tail fin.
Airbus insists there was no danger in the more than four years the plane flew after the 1997 Flight 903 incident. In that event, the aircraft abruptly veered up and down and side to side as the pilots tried for about 34 seconds to recover from an inadvertent stall over West Palm Beach, Florida.
In regard to that event, an Airbus statement says, "The fail-safe design is made so that if there is a failure -- one of those points comes up weak -- the plane can continue to fly."
American pilots join FedEx, UPS
Still, eight American Airlines pilots have joined FedEx and UPS pilots in asking that all tail fins of A300s be examined by ultrasound immediately. In addition to American Airlines, FedEx and UPS operate Airbus A300-600s.
And the union representing all of American's pilots -- the Allied Pilots Association -- wants more comprehensive testing of A300s than currently is under way. The union issued a statement calling for "more regular, intense inspections of the entire plane to make certain that these aircraft are airworthy and safe to fly."
So far, the FAA has ordered ultrasonic testing of A300s that have experienced unusual side-to-side forces on the tail section. It has identified five planes in that category, two of which have checked out fine and three of which have not been tested.
A former NTSB official said it is unlikely the government will require such tests for all A300s, since the examination requires the removal of the entire tail fin.
"What you get yourself into is a position of unintended consequences. You may well -- in taking that off and putting it back on to do your exam -- do more damage than you're likely to find," said Bob Frances, former NTSB vice chairman.
CNN has learned that crash investigators are increasingly focusing on what, if anything, is in the design and operation of the Airbus A300 that may allow it to become stressed beyond its design limits in somewhat routine flight scenarios.
The NTSB last month advised pilots to be careful to note that various rudder movements under certain conditions could cause structural failure.
Selective ultrasound exams ordered
The FAA ordered ultrasound inspections of certain Airbus A300-600 tail sections to start as early as March 12. At that time, American Airlines -- less than 4 percent of whose fleet is made up of 34 A300-600s -- said it supported the FAA's decision.
That order followed an announcement from the NTSB that previously undetected damage was found during ultrasonic testing of the tail section, or vertical stabilizer, of the American Airlines Flight 903 Airbus that experienced such high lateral loads when the pilot used the rudder to steady the plane in 1997 over Florida.
Flight 903 landed safely with one injury.
The NTSB said damage was found in one of the six attachment points, or lugs, which attach the vertical stabilizer to the fuselage.
Federal aviation safety officials called the finding "very significant," saying it calls into question the adequacy of visual inspections to detect potential flaws in composite materials.
Another official involved in the investigation said the inspection of the American Airlines tail section and discovery of damage may have averted an accident.
But Airbus Industrie spokeswoman Mary Anne Greczyn said the damage was within the certifiable limits of allowable damage and the plane could have flown safely indefinitely.
American Airlines also said the aircraft's tail section was structurally sound.
"The remaining lugs were able to carry the flight loads they were designed to carry even if one lug was completely missing," the written statement said.
"Delamination" refers to a separation of layers in a composite material, such as that used to manufacture the tail section of the Airbus A300-600.
Airbus A300s were the first generation of commercial aircraft to contain this kind of non-metal, fiberglass material. Composite materials are also used on military jets such as F-14s and F-16s.
Both the FAA and Airbus Industrie had maintained that visual inspections were adequate to detect any failures of the composite material in the A300-600 tail sections.
In January, Airbus officials told the news media they believed ultrasound inspections were not needed to assure the safety of A300-600 tails.
"If the damage is not visible, then it is not of concern," said John Lauber, Airbus Industrie vice president of safety and technical affairs. "It will not grow to the point that it will not meet certification requirements."
Earlier this month, the company said the earlier comments referred to planes that had not exceeded the loads they were certified to handle. The plane involved in the 1997 incident had exceeded those loads, said Airbus spokeswoman Greczyn.
"This is the only one, the only incident that we know of, in which the certifiable loads of the aircraft were exceeded," she said.
Airbus and the FAA are evaluating the service history data for the 91 Airbuses in service in the United States to identify those planes that have experienced similar events as candidates for further ultrasound inspection.
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Allied Pilots Association
Federal Aviation Administration
National Transportation Safety Board
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