http://www.boston.com/dailynews/005/nation/Report_Investigation_into_Flig:.shtml

Report: Investigation into Flight 587 crash focusing on pilots

By Associated Press, 1/5/2002 19:59

NEW YORK (AP) Aviation investigators probing the November crash of American Airlines Flight 587 are reportedly focusing on the actions of the pilots.

Investigators have found no pre-existing flaw in the jet's tail section, which broke off, and are looking into whether the pilots may have put too much stress on it, The New York Times reported Saturday.

American Airlines spokesman John Hotard declined to comment on the report when contacted by The Associated Press.

National Transportation and Safety Board spokesman Paul Schlamm said Saturday that investigators were still doing tests on the wreckage, and it could be another year before they establish a cause.

Flight 587 crashed in Queens on Nov. 12 moments after takeoff from John F. Kennedy International Airport on its way to the Dominican Republic. All 260 people on board were killed along with five people on the ground.

The NTSB has said the tail fin, rudder and two engines fell off the plane before it crashed.

The Times said investigators are exploring whether the pilots trying to control the plane after it hit turbulence may have put so much stress on the tail with their maneuverings that it tore off.

-- Anonymous, January 06, 2002

Answers

I'm not surprised that they are looking for a way to blame the pilots, since that always lurks in the background of every accident. However, it's just not possible for the pilots to do anything that would cause the tail to tear off. The speed at that time was very low as they were still in their initial climb out. The tail section is designed to take severe turbulence without breaking off. The aircraft also has internal safeguards to prevent the pilots from using enough control force to cause a structural failure.

Regardless, no matter what the pilots did, it couldn't cause more than a structural bending of the tail section, never a complete failure. Not possible. Unless, unless, there was already a stress fracture in the tail that was ready to go into complete failure with any unusual control movements. But that would either be a manufacturing defect or an ongoing creeping degradation of the metal structure. Hardly something any individual flight crew could anticipate.

-- Anonymous, January 06, 2002

Gordon, I don't recall you sharing your theories about what really happened on this one...

-- Anonymous, January 06, 2002

Yeah, Gordon, what do you think happened? Some kind of, well, not metal fatigue because the tail was made of a composite, but something like that?

-- Anonymous, January 07, 2002

More particularly, Gordon, do you think that sabotage has been ruled out?

-- Anonymous, January 07, 2002

Remember that article that mentioned this plane was in a freak accident while finishing touches were being done in manufacturing? The wind at the plant caused the plane to go back on the tail. they said they checked it out and it was okay...

Could have been something they missed, which weakened the tail assembly, and then over NY it finally gave away under the stress from the turbulence of the other aircraft in the area.

-- Anonymous, January 07, 2002

Barefoot, yes that is where I would start looking for the initial stress problem. If it fell on its tail it could easily have caused a stress problem in the tail section. Such stress problems can take 100's of hours of flying before they finally go into catastrophic failure. The only way to determine such stress problems is to disassemble the tail and put each component through x-ray and/or magnetic resonance testing. No way they were going to do that with a virtually finished, new aircraft, right off the assembly line. They probable gave it the best visual inspection they could, but that's all.

The fact remains that the tail section is considered one of the strongest structural areas of the aircraft, and has to be. It not only must survive any rudder commands, but elevator and stabilizer commands as well. And it is the primary control section for keeping the plane in straight and level flight regardless of turbulence. As I say, it's designed to survive *severe* turbulence, which means it must be able to get through extreme bucking and shaking that would throw unbelted passengers into the ceiling, yet still not fail. Bend a little, maybe, but never tear off the airframe.I doubt that terrorism was involved, unless they can show that something exploded in the far rear belly compartment. So far I have seen nothing to indicate that though.

While the skin surfaces are often now composite materials, such as carbon fiber, the actual framework underneath the skin is still either aluminum, titanium, or some other lightweight metal. The thing that must fail for the tail to come off is the actual framework at the heart of it all. You have probably seen films of WWII bombers coming back with whole sections of the tail shot off and skin missing, but still no structural failure.

-- Anonymous, January 07, 2002

But Gordon, aside from the tail, do you not suspect sabotage for the other concurrent failures the plane was experiencing? For instance, whether the witness accounts of the order in which the tail and engines fell off could be explained by just a bad tail and/or turbulence?

-- Anonymous, January 07, 2002

Brooks, the only way I can conceive of the tail falling off is either a structural failure or intentional sabotage, meaning an explosion in the aft baggage area or something done by a mechanic to a vital part of the tail framework. Same with the engines. Either the engines were sabotaged to fall off, or they fell off due to failure of the engine mounts. The engines could tear off the mounts by themselves if the aircraft went into severe enough yawing movements after the tail broke.

If there is sabotage here, it would have to be very sophisticated to escape being detected by numerous other maintainance people. However, if the tail failed first, causing exteme yawing movements of the wings, the engines could be broken loose. Those engines are acting like massive gyroscopes, turning extremely fast, and can't take too much violent *yawing* motion without overstressing the mounts. The engine is typically held onto the mount with only 3 bolts and is free to swing about a little bit in order to relieve stesses. But it can't be swung about too violently without causing possible mount failure.

-- Anonymous, January 07, 2002