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American Morning

Since Crash of American Airlines Flight 587, We Have Heard a Number of Theories

Aired November 19, 2001 - 08:35   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
PAULA ZAHN, CNN ANCHOR: It has been a week, as you had mentioned in your report just a couple of minutes ago, just about to the hour since the crash of American Airlines flight 587, just minutes after it took off from JFK Airport in New York en route to the Dominican Republic.

Since the crash, we have heard a number of theories -- engine failure, turbulence, structural failure, perhaps even birds getting sucked up into the engine.

Well, with his insight now into the investigation process is Greg Feith, a former investigator with the National Transportation Safety Board.

Good morning. Welcome.

GREG FEITH, FMR. NTSB SR. INVESTIGATOR: Good morning, Paula.

ZAHN: thanks for getting up so early this morning.

If you would, walk through the various theories and which ones make sense to you this morning, and what you think we should throw out. What do you think is the most likely cause?

FEITH: Well, of course it's the tail. But let me just start with the first hours of the investigation a week ago, there were a lot of theories about the engines falling off having caused the accident, and a lot of that was based on the fact that witnesses saw the engines come off. But in any kind of accident investigation, while the witness statements are something that the investigators look at, you can't always hang your hat on the first thing. As it panned out a day later, when they pulled the vertical stabilizer and the rudder from Jamaica Bay, the real picture to come together, in that the vertical stabilizer had separated, and that everything that was coming off the airplane that the witnesses saw was the aftermath or the result of that vertical stabilizer.

ZAHN: So what do you think, Greg, is the most likely reason for the tail and the rudder to have become detached from the plane, actually fall off of the plane?

FEITH: Well, I got my simple prop here today. And what it is that when you look at composite materials, composite materials are very difficult to understand, in that they aren't like the conventional piece of metal that you would see. You can make an I- beam or stout structure out of a piece of metal that weighs quite a bit. The composite materials, of course, are layered material. They save weight, but they have the strength of steel, if not greater than steal, or some other kinds of metal.

The problem with composite materials is that when you bond the material, when you put layer upon layer upon layer with any apoxy-type resin between it, you can have what's called delamination. So in your hundred layers or 200 layers, whatever it takes to make up the structure, you could actually have a problem right in the middle and not be able to see it because it doesn't crack or fatigue on the surface like metal does.

ZAHN: So that is nothing that would show up in routine examination? Is there -- aren't their X-ray machines that could determine that kind of fatigue?

FEITH: X-ray machines and ultrasound, but a visual inspection won't show it, because you could have a painted service, and again, because it doesn't crack like metal does, you won't see the crack on the surface, it's deep embedded inside; you need the ultrasound or the X-ray.

So when you look at this vertical stabilizer, the fact that the vertical stabilizer of the airplane had been involved in a severe turbulence event back in 1994, and the fact that back in 1988, when it was delivered, they had to patch one of the areas near one of the attach points. What investigators need to determine now is did that patch or did that severe turbulence event have anything to do with delaminating or compromising the structure, not on the surface, but deep inside, that conventional-type visual inspection didn't reveal, when maintenance people are doing routine maintenance on the aircraft?

ZAHN: Now this may not be fair, but I want to put you on the spot here. I mean, based on your knowledge, you certainly have investigated a number of crashes. What do you think?

FEITH: I think that there was probably a pre-existing structural problem with that vertical stabilizer. Having only basically a little more knowledge than probably you as far as what I've seen on TV and people I've talked to, the fact there was a patch put on one of the attach points early on, investigators -- if it was me, I would be curious as to what that patch may have done to the rest of the structure, because now you make one part of it very stout because it's more or less a doubler, which basically reinforced that particular area, but you don't know what the patch did to weaken the structure downstream, with all of the other attached points, because when you talk about you know patching things, that means that there's a problem somewhere else, and maybe the patch was perfect for that period of time. But a year later they should have looked to see if there was another problem at one of the other attach points.

So I think there was a pre-existing structural failure.

Wake turbulence will not take off vertical stabilizers. If they did, we would have airplanes, unfortunately, crashing every day. The structures are very stout. And one of the things is that, you know, the wake turbulence and just all of the stars and the moons lined up that particular day, all of the factors came together, to cause that tail to fail. But I think there was a pre-existing failure somewhere in that system.

ZAHN: Well, thank you, Greg.

And everything I've read here this morning, all the updates I've been exposed to would basically seems the investigation is narrowing into this area you address this morning.

Thank you very much for your perspective this morning.

FEITH: You're welcome, Paula.

ZAHN: You can go to bed now. We hate to get you up so early with the time change.

FEITH: That's the price you pay for paradise.

ZAHN: Yes, exactly. Lucky man living out there at altitude.

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