WASHINGTON (Reuters) - United Airlines said Thursday it had detected evidence of a flaw in the vertical stabilizer on one of its Airbus planes, raising more questions about the composite makeup of the tail fin on an aircraft that crashed in New York last month, killing 265 people.
Safety investigators, probing why the tail fin of an American Airlines Airbus A300 fell off seconds before that plane crashed after takeoff in New York in November, have talked with United and the manufacturer about the discovery made by mechanics on the United jetliner, an A320.
The latest development was first reported by USA Today.
Airbus said the tail fin composition of both model planes is similar even though the A300 is a wide-body aircraft, while the A320 is a smaller single-aisle jet.
Airbus and United said evidence of a flaw was revealed during recent ultrasonic tests in an area where the tail connects to the fuselage. The defect was described as a possible tiny ply separation within layered carbon fiber.
David Venz, a spokesman for Airbus, said the problem was in the rear section of the tail structure in an area that did not support the weight of the stabilizer.
The aircraft, which was made in 1994, was being returned to service by United, which said it would conduct ultrasonic tests on the tail sections of two other A320s.
The flaw was found on the opposite side of the tail section of the A320 where repairs were made at the factory on a different problem before being delivered to the airline.
``We just decided to take a look at it and we did,'' said United spokesman Joe Hopkins. He added that there were no problems detected in the area that had been previously repaired.
After the November crash of American Flight 587 that killed 265 people, the Federal Aviation Administration ordered carriers to visually inspect tail sections of A300s.
No problems were discovered during those checks, an FAA spokesman said.
Some safety experts have criticized the agency for not mandating ultrasonic inspections on the relatively small U.S. fleet of A300s, saying visual checks could not do a thorough job. The FAA has not ruled out additional tests down the road. The agency said it would closely watch the latest development.
``Certainly we'll want to know additional information to see if there is any safety issue to address,'' FAA spokesman Les Dorr said about the United discovery and its subsequent tests on two other aircraft.
While National Transportation Safety Board investigators will not likely determine what caused the crash of Flight 587 for a year or so, a critical part of the probe has focused on the tail fin and why it fell off.
NASA engineers are analyzing the tail's composites for any defects.
Advanced composites are increasingly used in commercial aircraft construction for their weight advantages and durability. These materials are usually constructed in layers, like pages in a book.
Composites are extremely resistant to fatigue, but when they fail it is usually catastrophic, experts said.
Investigators also are looking at the plane's rudder movements, and are examining at least four flight control mishaps over the past several years involving the A300 series aircraft. One involved the ill-fated American plane in 1994.
United is a unit of UAL Corp. while American is a unit of AMR Corp., and Airbus, based in Toulouse, France, is owned by European Aeronautic, Defense & Space Co and BAE Systems Plc.
Interesting. Probably not linked to the A300 crash. Still, makes you wonder...
Your bone's got a little machine