Possible cause of AA flight 587 crash...a new thought

Vanity | 11/15/01 | Agent Smith

[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.

[Agent Smith]

Please feel free to comment on, or debunk my theory.

[Axeslinger]

I design parts for general aviation and business aviation aircraft. Many of the parts we manufacture are carbon fiber composites. These parts do not shear cleanly on failure. They splinter and the individual plies of carbon fiber that make up a composite part will delaminate and separate from each other. I have seen dozens and dozens of failed parts and have never seen anything remotely approaching a clean break.

[chemainus]

You have a notion , anyone can have one, not a theory. No data, no testing, no0 comment. NTSB floats enough balloons.

[Agent Smith]

Would a composite vertical stabilizer be attached to the tail with bolts or glue, or a combination of the two?

[OwenKellogg]

There is no spoon.

[Tennessee_Bob]

Dodge this...

[Agent Smith]

There is no vertical stabilizer.

[Axeslinger]

At some point you have got to have physical attachments. These would, without question, be hardware of some sort or another. Typically, the hardware has a bushing of some sort to prevent tearing through the composite material. While, I would grant that there is minute chance of hardware tearing through the composite material, there would be very obvious signs of this long before it actually let go. Thus, the maintenance program at AA would have to be utterly and completely derelict to miss this sort of thing.

[Blueflag]

FWIW an earlier report described the composite attachment points on the empennage (at the crash site on the ground) as looking like pieces of straw -- i.e. the compsite failure you describe.

Also, the bolts were STILL IN the attachment points in the empenage, leaving one to infer that the VS indeed did fail above the empennage.

Now the question becomes why.

Another poster makes the point that wake turbulence affect the wings first. Well, if the vortex has persisted as a tight, high velocity spiral, then the aircraft might encounter the bottom of the vortex (horizontal) first, pushing the VS hard to the side, then fly out the top of the vortex, pushing the VS the other way. This could be a plausible scenario for rattling once, rattling again, and departing controlled flight as the VS separated from the airframe.

With reports out now of delaminated compsite IN THAT ASSEMBLY prior to delivery, I think Airbus has big problems headed their way. 250 people died, perhaps because Airbus built the sub-assembly poorly and it failed above the normal inspection areas.

As always, this is just my opinion, and you are welcome to ignore it.

FRegards.

[Blueflag]

Greetings Zordas-- good to have a rational mind on the thread.

[KirklandJunction]

Just a comment: what was different on this flight from all the other gazillions of A300 flights since 1972?

[Agent Smith]

Sabotage is certainly a possibility, but the list of suspects would be pretty short. These facilities operate 24/7 and the chances of an outsider entering and accomplishing this task unnoticed are remote.

[Blueflag]

Just so you know, the fact that the JAL 747 was ABOVE the A300 lends credence to the wake turbulence theory. The wing tip vortices / wake turbulence SINK (as a general rule) behind the flight path. Also, the 747 was likely climbing out on its deprture route, and would naturally leave a wake lower than its flying altitude. 4 miles at ~250KIAS is only what, (help me on the math, guys) 42 seconds separation? Ouch. It's tight airspace in NY, and being ~40 sec behind a true 'heavy' can shake your day. But it should NOT have ruined the airframe of a commercial jet.

[OwenKellogg]

>>> The indicator will be whether or not there was a prominent heading change BEFORE the rattle. <<<

Or a prominent roll -- the WT could likely disrupt the airflow over a single wing.

What I'd like to know -- what did ATC call out for winds? "Flight 587 cleared for takeoff, winds are .... "

This is an important fact needed to debunk or support the WT theory.

[Blueflag]

Really!! While I have never done it, I presume it is a non-trivial task to even get to the innards of the VS. Somebody would know if maintenance was up on that aircraft poking around inside the VS. I doubt sabotage is the reason the VS failed.

[MarkWar]

>Your theory is either debunked our we need to ground all similar air craft as being too feeble to be trusted with lives. Jal was over 4 miles away and 800 feet above 587.

I just re-read Michael Crichton's book "Airframe" -- which is about an investigation into an airline disaster.

This is an interesting book to read today! I recommend it to everyone following the 587 investigation. Lots of the stuff seems _very_ relevent.

First off, right after the disaster, the pilot and carrier report the cause of the disaster as "turbulance" and all the engineers laugh and curse in disugst because -- supposedly -- EVERYONE in the industry knows that "turbulance is a kind of catchall, a handy excuse to cover up pilot error or shoddy maintenance or just about anything else...

The book also has great commentary on the media's role in a crash investigation. Most importantly, however, the book depicts the whole process of an investigation as a kind of tool where the investigators are trying to arrive at an understanding of what's going on, but EVERYONE else is USING the investigation to further one agenda or another -- the manufacturer, competing manufacturers, the engine maker, the carrier, political issues...

Interesting stuff.

Mark W.

[Axeslinger]

In regards to JAL being "4 miles away and 800 feet above". Wake turbulence is left behind an aircraft...up to 10 miles behind. I have been on approach in a Cessna 172, several miles behind a 757 and been tossed around like a rag doll.

[surfer]

That was the only day I wasn't staring at the sun looking for a host and didn't see any of it!!!