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Possible cause of AA flight 587 crash...a new thought
Vanity | 11/15/01 | Agent Smith

Posted on 11/16/2001 1:16:03 PM PST by Agent Smith

Up until now, my best guess as to the cause of the 587 crash was defective/substandard bolts used in attaching the vertical stabilizer to the tail and a failure to detect the problem through inspections.

However, I heard on the news last night that the vertical stabilizer was not fabricated from aluminium, but from a carbon fiber composite. This material is very strong and light but can fail catastrophically if a stress fracture/crack develops. Based on the photos of the recovered stabilizer showing that it was cleanly severed from the tail, I now believe that this is the most likely cause of the accident.

The turbulence from the JAL 747 was the straw that broke the camel's back.


TOPICS: Announcements; News/Current Events
KEYWORDS: aaflight587; flight587
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To: dahlilaso
I agree that planes ARE designed to withstand this kind of stress. This one may NOT have been built well enough. Also, there is a term called Vne, or velocity never exceed, for all aircraft in a variety of attitudes and conditions. The wing vortex of a fully loaded 747 MIGHT be able to cause very localized conditions that exceeded Vne for th A300. This would be especially true if the structure were weakened.

What's my point? That violent wake turbulence is plausible in this tragedy, BUT should not have knocked the A300 from the sky, and should NOT have knocked off the vertical stabiliser.

41 posted on 11/16/2001 1:16:34 PM PST by Blueflag
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To: Daffy
the "wing piece" as you call it is the vertical stabilizer. if the wing did come off why is it not in the water?
42 posted on 11/16/2001 1:16:34 PM PST by Pumba
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To: 1L
Wingtip vortices are generated when air spills over the wingtips from hi-pressure area (bottom of wing) to low-pressure (top). If you look at the picture that was posted, you can see the rolls in the clouds below and behind the jet -- those rolls are caused by the tip vortices that that aircraft shed.

Strong vortices can live for quite a while, particularly in clear air. They persist because of the law of conservation of angular momentum; they are annihilated via dissipation, either through contact with the ground or via mixing with calm air, the latter being a much less efficient mechanism.

Vigorous vortices are generated by low speed flight of heavy aircraft -- such as a departing 747. Passing through one is equivalent to encountering shear.

It certainly a phenomenon that's been encountered many times before. Whether it's a causative factor in this case remains to be seen.

43 posted on 11/16/2001 1:16:37 PM PST by MassLengthTime
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To: Daffy
the "wing piece" as you call it is the vertical stabilizer. if the wing did come off why is it not in the water?
44 posted on 11/16/2001 1:16:37 PM PST by Pumba
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To: Fred Mertz
What we have here; is a failure to communicate.

The Govt talking heads are saying things in the language of X42 and a lot of posters are reacting to the weasel words.

We have had eight years of the clintons' language meant to misdirect, spin and lie to us about govt events.

If it sounds like spin and weasel words, I am going to take it as that.

The NTSB probably doesn't know yet and neither do I.

I just wish they could be a little more forth coming in the statements, but I recognize that the media dictates the terms.

45 posted on 11/16/2001 1:16:37 PM PST by razorback-bert
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To: Agent Smith
The wake turbulance answer is nonsense. There are not sufficient forces to affect structural damage. There was at least a 15 knot wind (which would have cleared any turbulance out long before the airplane got there) and the hypothetical generator was at least 1 1/2 minutes ahead--there would not have been any turbulance. If you had been right on the tail of the 747 in no wind conditions, wake turbulance is not a structural threat--it bites pilots who are not paying attention and wind up in uncontrollable flying attitudes. It didn't happen this way.

I think all the focus on the Vertical Stabilizer is also nonsense. All of the airplanes I have ever flown (probably forty or fifty different types--no Airbuses) could be flown without any vertical stabilizer. Some American production airplanes do not even have a vertical stabilizer.

If all that happened was that the vertical stabilizer came off, you could stear the airplane back to a landing with the alierons. There are really two choices here: All this nonesense is an effort to prepare the public and the media for a full court press cover up; or they really don't know what caused this and are trying to figure it out.

46 posted on 11/16/2001 1:16:37 PM PST by David
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To: Gadsden1st
Sorry if wasn't clear. I don't think that wake turbulence was necessarily a huge factor in this crash. It may have been one of several factors, but I don't believe it to be the dominant one. I was merely addressing dahlilaso's comments about the JAL flight.

It is painfully obvious that something went very wrong with that airplane. Of course, it should have not had any problem with the wake turbulence. Parts should not just fall off. The only real question is what happened, structurally, to that aircraft? Everything else is just window dressing. Something physical happened to that airplane. What was it?

47 posted on 11/16/2001 1:16:38 PM PST by Axeslinger
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To: Axeslinger
"Wake turbulence is left behind an aircraft up to 10 miles."

I know nothing about planes, but at many major airports there are takeoffs and landings every 2-3 minutes. If wake turbulence is such a dangerous phenomenon - if it can rip a plane apart as this one did - I would expect this kind of accident to be much more common. If wake turbulence was indeed a factor here, it seems to me that this plane must have had some serious structural defect in order for the turbulence to have such a devastating effect.
48 posted on 11/16/2001 1:16:38 PM PST by Steve_Seattle
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To: MassLengthTime
Ahh. The image I mentioned was in a different thread. Here's a good one illustrating the phenomenon:


49 posted on 11/16/2001 1:16:38 PM PST by MassLengthTime
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To: Steve_Seattle
You are completely correct.
50 posted on 11/16/2001 1:16:39 PM PST by Axeslinger
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To: Pumba
Oops! It sure looks like a wing when viewed from a certain angle. Thanks for the correction.
51 posted on 11/16/2001 1:16:39 PM PST by Daffy
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To: MassLengthTime
HEY! It's that missing yellow cropduster!
52 posted on 11/16/2001 1:16:40 PM PST by steveo
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To: razorback-bert
"weasel words"

I don't think they are using weasel words, I think the public is misinterpreting what they are saying. If they say, at the outset of the investigation, that "there is no evidence of terrorist involvement," they mean that quite literally: at this point in time there is no evidence of terrorism. That is not the same as saying "we can categorically state there was no terrorist involvement," but that is how many people interpret it. The government has not ruled out terrorism, they have just said that right now there is no evidence of it.
53 posted on 11/16/2001 1:16:40 PM PST by Steve_Seattle
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To: Agent Smith
The tail malfunctioned on being BUILT! An article somewhere stated that the tail on the plane was found to have been defective after inspection immediately after manufacture. The manufacturer added some more laminate and declared the tail safe; no more tests were warranted. So it is either that or a "little sab-o-tag-é, ey. Nyuk, nyuk,nyuk."
54 posted on 11/16/2001 1:16:40 PM PST by Henchman
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To: David
David--

First let me respect your credentials as a high-time pilot, truly. Permit me to go through your points.

The wake turbulance answer is nonsense. There are not sufficient forces to affect structural damage. We do not yet know the amount of force or degree of deflection from the flight path or attitude, or even if there was any. I think we all agree that WT should NOT have caused the VS to separate from the aircraft. I think we all agree. It did, however, separate from the airframe, above the attachment points, indicating failure, as opposed to falling off. This SHOULD NOT have happened. WT may have been the 'last straw'.

There was at least a 15 knot wind (which would have cleared any turbulance out long before the airplane got there) and the hypothetical generator was at least 1 1/2 minutes ahead--there would not have been any turbulance.

Some data indicate the A300's departure path generated an intersection as little as 45 seconds behind and below the departure path of the 747. It is plausible SOME WT would have persisted, and we do not have data on winds aloft.

If you had been right on the tail of the 747 in no wind conditions, wake turbulance is not a structural threat--it bites pilots who are not paying attention and wind up in uncontrollable flying attitudes. It didn't happen this way.

Agreed. The VS should not have failed, all things being normal.

I think all the focus on the Vertical Stabilizer is also nonsense. All of the airplanes I have ever flown (probably forty or fifty different types--no Airbuses) could be flown without any vertical stabilizer. Some American production airplanes do not even have a vertical stabilizer. If all that happened was that the vertical stabilizer came off, you could stear the airplane back to a landing with the alierons.

Other discussion threads have introduced a different plausible scenario. Indeed several aircraft have been successfully flown without a VS in place. But ... Suppose the VS detached from the airframe while the first officer has stepped on the left rudder (appropriately, no pilot error implied) to in part correct for WT. The VS detaches, the yaw moment is to port, and the right wing is generating more lift and roll moment than the left. The WT that had been trying to roll the aircaft to the right now pushes on the wings to roll it to the left (other side of vortex) and encounters an aircraft trying its best already to roll to the left. Without a VS in place, (because it failed, not the pilot) the plane departed controlled flight with no means of recovery.

There are really two choices here: All this nonesense is an effort to prepare the public and the media for a full court press cover up; or they really don't know what caused this and are trying to figure it out. Well, this could all be mechanical and tragic, and the industry, as usual, will try to cover for AA and Airbus and blame the pilot and ATC.

55 posted on 11/16/2001 1:16:43 PM PST by Blueflag
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To: David
Some American production airplanes do not even have a vertical stabilizer.

Which ones?

56 posted on 11/16/2001 1:16:48 PM PST by cinFLA
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To: 1L
Go sailing some time and sail up close to and around other sail boats.

The "wind shadow" that extends in and around a working air foil is pretty large. You can feel it and you will be able to see how it impacts the sails.

The more efficient a foil is, the larger the wind shadow. Foils work because the foil shape warps the fluid and the foil moves to fill he low pressure area created. The thing is, the laminar flow over the surface is what is actually creating the warp. The foil just initiates it. The more efficient the foil, the farther out the laminar flow is attached and the bigger the warp (thus the increased efficiency of the foil).

As the foil moves through the fluid, the fluid "slams shut" behind the warp, and it leaves lots of vortecese (or whatever the plural of vortex is).

This is "wake turbulence" (It can also be seen if you look at the water behind the boat as it moves. Air and water are both fluids, just different viscosities. In fact, it is the differential between the viscosities and the differential between the keel and rudder foils in the water and the sails in the air that make a sailboat work.

Anyway, in the water behind the boat there will be lots of swirls and whirlpools left as the boat passes by. "Wake turbulence".

Move through this turbulence and the foils are tugged this way and that.

57 posted on 11/16/2001 1:16:48 PM PST by steve in DC
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To: Henchman
Henchman-- The stabilizer did NOT fail at the repair point, but appears to have failed above it. My inferring finger of blame is starting to point at Airbus anyway, however.
58 posted on 11/16/2001 1:16:48 PM PST by Blueflag
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To: cinFLA
Beech Bonanza is a great example of a fine aircraft without one.
59 posted on 11/16/2001 1:16:48 PM PST by Blueflag
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To: Steve_Seattle
The effect of wake turbulence is related to the relative sizes of the planes involved. A wake which could roll a small plane over may feel like a small bump on a plane of equal size. While not as large as the JAL 747, the A300 is not a small plane, and 2 minutes spacing is usually enough to remove ALL wake effects from the next departing plane.
60 posted on 11/16/2001 1:16:51 PM PST by PaulKersey
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