NTSB finds rudder problem in Airbus-300 (AA Flight 587)

Washington Times ^ | June 1, 2004 | staff

[Boot Hill]

WASHINGTON, DC, May. 29 (UPI) -- An investigation into the November 2001 crash of an Airbus A-300-600 in New York has found an unrelated potentially lethal design flaw, the New York Times reports.

The newspaper says the National Transportation Safety Board does not believe that problems with the rudder control system caused the crash of American Airlines Flight 287 [should be: 587]. The plane came down shortly after taking off from Kennedy International Airport en route to the Dominican Republic, killing all 260 people on the plane and five on the ground.

[Caleb Ian]

Foggiest writing I've ever seen. It must not take much to get a journalism degree these days. That piece would have failed when I was in college.

[baltodog]

As far as a composite tail goes, it's perfectly OK if it has been designed correctly.

Remember that the definition of composite is simply "the joining together of". Composites can handle more stress than any metal if they are layered correctly. You need to understand the forces applied and redirected through fibers. It's kind of complicated.

You might be surprised (or terrified) to find out just how much of a plane's control surfaces are laminate glass, carbon fiber.

The only trouble with composites is that they give little or no warning when about to fail. Also, repairs to the exterior surfaces are commonplace, but it is impossible to re-align or repair re-inforcement plies that are mislocated or misengineered.

So, yeah, I can understand why the ENTIRE tail (stabilizer) would have to be replaced.

By the way, isn't there a photo of them pulling the tail out of the water?? If I saw it correctly, that tail separated from a VERY clean break.

I do composites for a living.

[onedoug]

bump

[COEXERJ145]

[Boot Hill]

"The rudder/tail assembly is not at fault."

Although I can see how the thread story led you to that erroneous conclusion, it is, nonetheless, incorrect.

The NTSB announcement dealt only with the flaw in the velocity response of the actuator control limiter system. Nobody has ever suggested that the velocity response flaw was at fault in the AA-587 crash.

But the NTSB announcement does relate to the AA-587 crash, in that it offers another example of an Airbus design flaws that can lead to (an almost did in a separate incident) the separation of the vertical stabilizer from the aircraft.

While he NTSB has not issued a final conclusion as to the cause of the AA-587 accident, nevertheless, documents the NTSB have publicly posted say that the tail fin tore loose after the pilot moved the rudder sharply back and forth several times.

In other words, while the velocity response fault of the limiter system may not have been the cause of the AA-587 crash, the NTSB will likely conclude that is was another aspect of the limiter system that was at fault.

--Boot Hill

[Boot Hill]

"Foggiest writing I've ever seen. It must not take much to get a journalism degree these days."

Agreed. UPI story. I suspect a drinking problem, not an education problem.

--Boot Hill

[RandyRep]

I agree with your statement about metal vs. composites -- Boeing still doesn't have much composite material in primary structures like the vertical tail. However, I think the new 7E7 will have more composites, and probably in some primary structure.

I'm sure that the final NTSB report will cover all of these issues - it should be interesting to see what they say about the material choice.

[Boot Hill]

"Boeing still doesn't have much composite material in primary structures like the vertical tail."

The vertical stabilizer of Boeing's 777 is composite.

--Boot Hill

[e_castillo]

Pretty obvious from day one that Airbus tails are junk and maybe even other parts yet to fall off...

[Boot Hill]

"Pretty obvious from day one that Airbus tails are junk..."

One time I sat down and ran the numbers for the force on the vertical stabilizer versus yaw angle for the A-300. The numbers are astronomically high. It seems to me that the tail is adequately designed and built, it is the rudder, or more specifically, the rudder controls, that seem to be the culprit here.

But I think I understand your basic point. When one trusts science more than baseless fear, it becomes abundantly clear that "shoe bombers" didn't have diddly squat to do with this crash.

--Boot Hill

[RandyRep]

The skins AND the spars? Or only the skins? Big difference, obviously. I don't know if the Airbus spars are composite or not - perhaps none of them are? The spars are primary structure, as are the attach flanges.

You said something about a chunk of titanium in place of the composite in an earlier post. Titanium weighs quite a bit more than aluminum and composite for equivalent loads and temperatures. Titanium is used when you need a high-emperature capability (but not as high as steel) but want to save weight over steel. Aluminum is only 10-15% heavier than carbon-fiber composites for equal loads and temperatures. However, aluminum yields plastically and fails gradually while composites yield quickly and fail quickly - so aluminum as a much better choice for low temperature primary structure.

[e_castillo]

Vertical stabilizer (tail fin) attachment point from AA-587



Doesn't look like much material to me. Nice big bolt hole though! Click on the image to go to the NTSB site or Click here to view the image full size.

[wtc911]

"the NTSB will likely conclude that is was another aspect of the limiter system that was at fault."

Speculation. I live in the area. The local news had a van on the scene in no time. The response was still in very early stage. Belle Harbor is a haven for multi-generations of mostly Irish NYPD and FDNY members. A few who were either off duty or retired were interviewed live at the scene. I remember it well. These very reliable types all spoke of seeing flames past the mid section while the plane was in the air.

For days before the Feds were warning us that something big was about to happen. When it did they rushed to tell us it was a design flaw, but they didn't ground the hundreds of other similar planes.

I am no conspiracy theorist but I'll take the word of a retired FDNY Lt. eyewitness on this one.

[e_castillo]

it is the rudder, or more specifically, the rudder controls, that seem to be the culprit here

I seem to remember that the aircraft flew thru the wake vortex of another heavy right before the tail or vertical stabilizer :) came off. Since then Pilots have been told to not use the rudder to manuever Airbus aircraft out of a wake vortex. If this is the case then they seem to have a problem with the strenght of the material holding the vertical stabilizer in place.

[Boot Hill]

"AlQ claimed this [the dowing of AA-587] on the islamic website on Friday."

Greetings and salutations, "cgk" and "bvw".

I'm Osama bin Laden and Boot Hill was kind enough to let me use his computer for a few minutes so that I could publicly take credit for being that mysterious figure on the Grassy Knoll that day in Dallas in 1963. That's right! It was me all along! Just wanted to set the record straight.

Your in eternal Jihad against the infidels...

Osama

[DuncanWaring]

For example (and I don't know the exact numbers here), at airspeeds below say 180 KIAS, the allowable rudder deflection might be 30 degrees. Above say 180 KIAS, the allowable rudder deflection might be 15 degrees. At higher airspeeds, say 250 KIAS, the allowable rudder deflection might be 10 degrees.

Ah, yes. The infamous "gain schedule". Probably went through a washout filter too to keep it from changing too fast.

I've been told by a former F-4 pilot that it had a sorta-similar problem. One axis of flight control (elevator/pitch?) lost a lot of its effectiveness when going supersonic. As a result, the pilot had to really lean into it to control the aircraft, and if the aircraft happened to drop into the transonic/subsonic region while being "vigorously" controlled, it caused a sudden major g-load.

[Pukin Dog]

The point in question, is the stress point where the tail attaches to the fuselage, which in the 777, you have much, MUCH more plain old steel, than you have in the AirBus. It does not matter how much composite is in the tail itself, only where the pieces come together.

[okie01]

Since the A-300 is a fly-by-wire...

This was an early version of the A-300. It was not "fly by wire".

[bvw]

Things happen that sometimes we don't want to happen, or wish with all our might musterable could have happened another way.

When the process of crash investigation is opened up to FULL citizen participation -- say via random special jury with some standard of non-political certification (say a techincal degree and no felonies) -- why until then we'll have NO closure on events like these.

Until then the propagandists and professional excusers (aka PR firms) shall have the field like mice in the silo. Enjoy the grain while you may!

[Yo-Yo]

I'm Osama bin Laden and Boot Hill was kind enough to let me use his computer for a few minutes so that I could publicly take credit for being that mysterious figure on the Grassy Knoll that day in Dallas in 1963. That's right! It was me all along! Just wanted to set the record straight.

And I suppose that BUSH KNEW?