WASHINGTON (AP) _ One aspect of this week's crash of an American Airlines jetliner stands out, aviation experts say: No matter what else went wrong, the tail shouldn't have fallen off.
Neither the turbulence from the jumbo jet that took off just before doomed Flight 587, nor pressure put on the rudder by pilots reacting to the wake, should have been strong enough to break off the tail.
The Airbus A300 plunged into a New York neighborhood Monday, minutes after taking off from Kennedy International Airport. All 260 people aboard the plane and five on the ground were killed.
``I think there was a pre-existing structural problem with the tail,'' former National Transportation Safety Board investigator Greg Feith said. ``It was going to fail regardless. It just so happened the conditions were right.''
The Federal Aviation Administration on Friday ordered airlines to immediately inspect the tail assemblies of their Airbus A300-600 and A310 planes. American and two cargo carriers, FedEx and United Parcel Service, have around 135 of the French-made jets in their fleets.
Investigators say Flight 587 was buffeted by two wakes, generated by the wings of the Japan Air Lines Boeing 747 jet that took off from Kennedy shortly before the American Airlines plane lifted off. Because of its size and weight, a 747 generates heavy wakes.
``The wake vortex of a 747 should not bring down an aircraft,'' said Tom Ellis, a spokesman for the Nolan Law Group, a Chicago-based firm that represents victims of airline accidents. ``The A300 is designed to withstand forces of that nature. It should be well within its design tolerance. There's got to be something that interferes with the ability to recover.''
The American plane was more than the FAA-required four miles behind the 747. NTSB spokesman Keith Holloway said the agency was looking at whether to suggest keeping planes farther apart, since wakes dissipate over distance.
Investigators found that the plane's rudders, which help steer the aircraft, moved sharply. Experts said the movement could have resulted from the pilot hitting the rudder pedals hard or from a jerk on the other end of the cable as the tail snapped off. But experts said pilots of large planes don't usually use rudders, except when they lose an engine or for help during landings.
Even if the pilots were rough with the rudder, that should not have caused the tail to fall off, said David Stempler, president of the Air Travelers Association, an advocacy group.
``Planes should be designed to withstand even abuse and still be able to maintain structural integrity,'' Stempler said. ``The pilots may have done something but a plane has to be designed to even withstand harsh treatment by flight crews and not lose major structural elements.''
That has led several aviation experts to suggest that there was some unseen weakness in the tail assembly, which was made of carbon-reinforced plastic, a composite material that is lighter than aluminum.
The problems could have dated from 1994, when the American Airlines plane was severely shaken by air turbulence in an episode that injured 47 people, even though the plane was inspected after the incident.
``That's where the investigation really has to start,'' Feith said. ``It may be the inspection was just a visible inspection. They're not going to be looking inside that fin area, they're going to be looking for obvious damage. Something could have happened that, although it didn't immediately fail the tail at that point, did set up a fail scenario.''