flashmeister
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AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 7:15 am

Does anyone else think it strange that the rudder and tail fin of 587 was recovered from Jamaica Bay?

I would think that an engine separation and/or the hydraulic havok that it would wreak should leave the tail fin intact, and that it would therefore be found near the rest of the main debris field.

It could be that the engine went up and over the wing, but would it have then flew back at an angle to strike the fin and literally knock it off?

From the video I saw on MSNBC, the fin looked intact. The rudder tab was gone, but otherwise it was in good shape. No big dents or holes. The AA decal was even in good shape.

Does anyone else find this odd?
 
jaysit
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 7:52 am

I do.
I was just wondering why the tail fin separated before impact.
Also, apparently it was reported that one of the wings fell off before the fuselage hit the ground. I find that rather odd too.
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heavymetal
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 7:56 am

A catosrophic engine explosion and resulting fire could theoretically weaken the spar....I'm a little interested in how it happened so fast.

As to the tail, it was designed aerodynamically to have air flowing from forward to back. If the fuselage was falling sideways, the air pressure could easily snap it off.
 
prebennorholm
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 8:43 am

If one wing came off before impact, then it could have snapped the fin.

The fin is quite lightweight and would stop and fall rather vertically, while the rather heavy wing would take an entirely different trajectory.

But that's pure speculation. I wonder that there are not a lot of people who actually saw these things happen.
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Crosswind
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:01 am


[Link via PPRuNE]

Yes, the fin has been recovered from Jamaica Bay, however, from the photo you can see it is intact, but missing the rudder. It could have been thrown clear on impact, or more likely separated due to excessive aerodynamic loads in the dive to the ground.

Whatever, the fin being undamaged would suggests it was not a factor in the cause of the accident, wouldn't it?

Regards
CROSSWIND
 
artsyman
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:06 am

I just fail to see how this could be a mechanical issue and not a terrorist issue. If the plane exploded in mid-air which is what it would take for the tail to be found as far away from the fuselage as it was, what made it explode ? uncontained engine failure wouldnt cause this, therefore I cant help but think it isnt a machanical failure

Jer
 
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Crosswind
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:16 am

Hi Artsyman!

I'm sure you're familiar with the JAL 747 that suffered a rear pressure-bulkead failiure - the plane crashed into a mountain, the tail was found relatively undamaged many miles away in Tokyo Bay. Or what about the TWA 747 that exploded in mid-flight, everyone said "Another Lockerbie" because of the ferocity of the explosion and breakup. In the end the cause of the accident was an explosion in the centre fuel tank.

You can't draw inferences about the cause of an accident because of superficial evidence. As I said above, aerodynamic loads in an extreme dive, beyond the design limits of the aircraft could cause it to fail.

In the 1960s a Braniff BAC1-11 lost it's tail over Iowa due to an undraft from a thunderstorm, and a BOAC 707 lost it's tail due to a montain wave over Japan. Tails are quite vulnerable structures under extreme aerodynamic loads - they aren't built to withstand the same forces as wings.

Regards
CROSSWIND
 
chiawei
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:18 am

Depends. This accident now looks very similar to the Lauda Air crash in 1991.

Could it just be the same reason that some how the left engine went into full-reverse during take off. In this car, the stress will cause the engine and left wing to break away. Moreover, the sudden assymetrical thrust would also result in high stress on the fuselage causing the tail to separate. Minute by minute, I really believe that this is now similar.

Does anyone know whether or not the Lauda 767 that broke apart over thailand was powered by CF6?

 
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Crosswind
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:36 am

The Lauda B767 had PW4000 engines, the fault was unique to that engine series - it could not have affected the GE CF6, or the older PWJT9D on the 767.

Secondly, the extreme asymentric thrust caused the inflight breakup due to the high speed involved - the Lauda B767 was at high altitude at cruise speed when the breakup occured. The American A300 was at low atltude/low speed, the effects of asymetric thrust caused by reverser deployment would be insufficient to cause the sequence of events that befel the Lauda aircraft.

Regards
CROSSWIND
 
chiawei
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:49 am

May be I am an idiot asking this. But at higher altitude the indicated airspeed would not be much different than those of lower altitude. In other words the rate of air flow passing through the plane is quiet similar regardless of the height even though ground speed is very different. For example, at 41,000 ft, the indicated air speed of 250 knots is about 550 miles per hour. But at 500 ft it's about 260 miles per hour. But the speed of airflow is actually same. Hence I would assume that the force exerted by the airflow would be very similar.

So I believe that it is still quiet possible to have the same Lauda Air incident effect.
 
seagull
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 9:56 am

While the q may be the same, the damping effect is not, so the altitude has a significant affect on the outcome.
 
Beefmoney
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 10:08 am

Dispite what you have said, after thinking about it, the reverser malfunction seems the most resonable. I mean, 200-250 kts, one reverser opens, causes A300 to yaw wildly, aerodynamic forces cause vertical stabilizer, engine, maybe other parts, to break off. Eyewitness say that it hit the ground at a very steep angle and not a shallow angle, which would indicate a stall/spin caused by what ive mention above.
 
hkgspotter1
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 10:17 am

That tail section is in amazing shape. It looks like it just fell off the pier into the water.
 
spacecadet
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 10:26 am

AFAIK all modern passenger a/c are designed (possibly even required) to operate with reversers deployed in-flight. It's not even entirely unusual for it to happen - the media made it out to be after the Lauda Air crash, but I mean, they use reversers occasionally as air brakes in some aircraft. I suppose in a twin-engine plane a surprise deployment would be a bit more troublesome than on a four-engine aircraft, but investigators determined that even the Lauda Air crash was avoidable if the pilot had taken immediate corrective action. They did not blame the crash on pilot error, however, because there was no training program in place for this kind of failure at the time. Nowadays, pilots are trained for an in-flight failure of the reverser locking mechanism. It is not, by definition, a catastrophic failure, especially not at 270 knots. It would not cause an engine to separate from a wing, much less two of them (both engines were found in separate areas away from the main wreckage).

I dunno what caused this crash, but a reverser problem seems unlikely to me.
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Beefmoney
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 11:39 am

Full thrust on one engine, reverse thrust on the other, veeeeery hard if not impossible to regain control after such an event only 3000-5000 ft off the ground
 
chrisair
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 12:52 pm

I hate to speculate on this, but I can't understand how that tail didn't break up upon hitting the water. I know that honeycomb and aircraft material is incredibly strong, but hitting water is just the same as hitting concrete. Am I missing a piece of the puzzle here or what?

 
transswede
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 1:11 pm

Chrisair, due to aerodynamics, the tail would tend to hit the water edge-on, thus it could easily survive imoace unscathed.

Its like diving into the water from a great height, versus a bellyflop.
 
Pilot1113
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 1:17 pm

It would explain the nose dive into Rockaway. Remember that the tail is a lifting device, like the wings. Without it controlled flight would be virtually impossible.

- Neil Harrison
 
chiawei
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 1:23 pm

It's true that the modern aircraft were designed if thrust reverser was deployed while in flight.

But keep in mind, A300-600R is an early 80's design. Similar to 767-300 that went down in Thailand. The pilots were not able to respoind within 4-7 second window they had. What makes you think that an AA crew busy with departure tasks has time to react? The Lauda 767's reverse thrust deployed while in cruise. Totally different situation.

Also, at take off, the A300 is probably under full power. The 767 in cruise is probably operating at 75 to 80% N1. Hence totally different situation.

The more i look it, the more is looks like this is what exactly happened.
 
POSITIVE RATE
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 1:27 pm

Does anyone think this crash resembles the crash of AA 191 in Chicago in 1979? In this case it may have been a catastrophic engine failure/fire but if the engine did physically seperate from the wing itself like in AA 191 then the hydraulic line would be severed causing the fluid to bleed out and in turn perhaps retraction of the slats on one wing causing that wing to stall and the a/c to go in vertically.
 
We're Nuts
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RE: AA 587 Tail Fin In Jamaica Bay?

Tue Nov 13, 2001 2:53 pm

When USAir 427 went down, the FIRST thing they looked at was the engines. And when one was found in full-reverse, the case was almost closed. But it was later decided that the reverser got that way on impact. So it isn't totally unlikely.

BUT, I say leave the investigating to the professionals. No one here knows enough to understand what happened.
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