PPRuNe Forums - New Clues deepen AA587 Crash Mystery

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I have not so far seen any discussion of flutter in this accident, a mode that seems to absorb a fair bit of attention in the design and test of airframes.
The following email was forwarded to me which seems to resonate, so to speak, with the sequence of events.

Quote:

Howdy,

Re: the New York 11-12-2001 Airbus crash.

I found this photo of the vertical stabilizer's failed composite
Attachment blades or webs. The bolts that attached the composite vertical stabilizer to the fuselage, remain properly attached. Clearly, the failure is a delamination of the composite vertical tail above the points of attachment to the fuselage.

There are reasons (despite the weight savings) why Douglas Aircraft and Boeing have never used composites this way - and you're looking at one. As the delamination of the composite progressed, the entire 37-ft. tall vertical tail would have fluttered briefly & violently. That would explain why both engines were literally shaken off the airplane. (This is particularly remarkable, because unlike Douglas and Boeing, Airbus has bragged of purposely designing their engine mounting pylons to keep the engines in place no matter what!) One wing tip was found several blocks away from the main wreckage.

BTW, you'll be hearing a lot about an encounter with wake turbulence. That is a red herring. Wake turbulence can make it difficult - maybe even impossible to control the airplane - but no amount of wake turbulence can remove the vertical tail at such low flight speeds unless there is a pre-existing structural fault.

What is flutter? This morning, I got an email from a friend who is the Director of Structural Engineering of a major American aircraft maker. He described a chilling picture: "Flutter modes often have an explosively quick onset, rising from nothing to catastrophic in the blink of an eye.
Furthermore, the shaking can happen so fast that, despite the large (huge) deflections involved, an observer on the ground might not see it. It's just a blur. The people in the back of the airplane would have been shaken senseless and worse as the seats tore lose and everything was homogenized back there; but it was all over a few seconds later."

The design weakness can and will be fixed on other Airbuses. If not, there are plenty of nice Boeing jetliners mothballed in the Mojave Desert, that can trade places with the Airbuses. In the meantime, I'm not riding Airbus.

The email might sound a little US v European product but IMHO does raise an interesting point which should not be lost in that argument.
BTW I am Australian so I don't have any commercial or national agenda beyond riding safely in whoevers product.

Blacksheep
Hi long time no seeum.
Don't think the Harrier/AV8 has any problems, it's had the best from both worlds methinks.

Which is the way it should be with passenger airframes.

Quote:

SLB
bad taste plain & simple. are you implying that airbus would conciously put pax at risk to save remanufacturing a part? idiot.

The implication was your interpretation, not mine. I would not suggest that anyone made a conscious decision to risk pax lives. I am suggesting their is a paucity of reliable knowledge related to repairing manufacturing defects in load bearing composite structures. If the decision to repair rather than replace was unrelated to costs, then it most certainly should have been replaced?

Quote:

I'm not saying Airbus did this either, but there are precedents where large corporations - US automobile manufacturers have been caught out here - have made safety based decisions based purely upon cost.

You don't need to look any further than this Forum to find that supposition put forward as it relates to Airbus and its sub contracting process. HOW SAFE IS THE AIRPLANE YOU DRIVE?

These composite materials DO deteriorate with age. Whyy would an engineering firm liek Airbus Consortium not realise this? They must have.

I had no idea these things were made of this material. The particular aircraft was 13 years old.

This bears watching, and thanks for the info GG - I never saw this in anything published. I forewarded it to severl chemichal engineers of my aquaintance for their opinions.

Thankfully this thread has sorted itself out into a reasonably mature discussion on the issues of concern and the few who try to deflect it with conspiracy theories or "sounds good questions" of little substance have been ignored.

Unfortunately, due to the constraints we have with the server this thread has reached its limit of 100 replies and must be closed. Please feel free to continue the debate in a new thread and you can of course reference this thread.

I would like to suggest that technical discussion take place in the Tech log forum.