CNN BREAKING NEWS
Possible Compound Situation Caused Crash
Aired January 8, 2003 - 11:44 ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
MILES O'BRIEN, CNN ANCHOR: Let's bring in John Wiley, our aviation analyst, one more time. I want to focus for just a moment on that left engine, because that is going to be a focus and undoubtedly, the go team, the power plant folks will be focusing on it.
John, we've been talking about the possibility of a loss of power in that left engine. That in and of itself, what -- if it's just a loss of power, first of all, what is a pilot to do? What is the procedure? How are they supposed to go about it?
JOHN WYLIE, AVIATION EXPERT: Well, I've not spent a lot of time flying turbo props, but obviously you are going to want to shut the engine down. You're looking at a very time compressed situation from the time -- if we are theorizing there was an engine failure, we talked a little bit and again, I'm trying to verify my information. I would imagine there's an auto feathering on the engine which senses torque...
O'BRIEN: Let's not get too deep in that, let's talk about feathering for just a minute. Anybody who's hung their hand out the window of a car understands what we're talking about when your hand is edge on to the wind, there's not a lot of resistance. When it is flat out, it wants to pull your hand back toward the trunk.
Let's now explain feathering, now that we understand what we're talking about here, John.
WYLIE: Well, what you're talking about -- a propeller is basically just a swinging wing, and as long as it's swinging around, it's creating lift. If it is not swinging sufficiently fast enough, then it starts creating drag, which slows the airplane down, if it doesn't auto feather.
O'BRIEN: So what you're saying is, if for some reason that wing surface, as we look at the telestrator for a minute, the wing surface is edge on to the wind, you're creating a fair amount of drag right there.
WYLIE: Well, it is a flat plate...
O'BRIEN: The flap.
WYLIE: The flat plate description that you've got on the screen now creates a lot of drag. It's just a flat plate surface.
O'BRIEN: Would that be enough to put the plane in a steep left pitch in this scenario? WYLIE: Well, more than likely, it's the lot of thrust that's going to be yawing the airplane.
O'BRIEN: Already the loss of power on that side predisposes it to the left, right?
WYLIE: You've got a compound situation. If the left engine fails, your system operates correctly, then the prop would feather. The prop would be in -- as you said, the foil would be perpendicular to the air flow, there would be very little drag. So then you're basically contending with just loss of thrust rather than also loss of thrust and increased drag.
O'BRIEN: All right. Let's get back to this concept of feathering. Give me the telestrator one more time, if you would.
If the feather is accomplished, the propeller, and you're looking at the cross-section of it, would be edge on, the wind would pass over it, and it is no different than wind passing over a wing. It wouldn't cause a problem. In this airplane, we believe, we're checking on it right now, probably this size and type of aircraft, probably has some auto feathering capability so the pilot doesn't have to contend with that, right?
WYLIE: I would think so, yes.
O'BRIEN: If that failed, however, then you've got another situation which could cause a lot of what they call, what the investigators call parasitic drag, which is another way of saying forcing it into a steep left bank, and ultimately if it's unrecoverable -- in other words, if the other control surfaces here cannot compensate for it, that could very well put it into a spin, an inverted position that cannot be recovered no matter how hard the pilot tries -- John, any other thoughts?
WYLIE: Well, as we mentioned before in some of the other discussions that we've had, Miles, the focus is going to be on two primary points, and that is that we know that machines break, and we know that people make mistakes, and those are going to be the two areas that the investigators are going to be focusing on.
You're looking at a very time compressed event where things are happening extremely rapidly, and so the margins of error, or the margins for action, reaction are going to be very time critical. So this airplane, I've had a chance to fly it before on a very short -- a very short flight a number of years ago. This is not a very difficult airplane to fly. I've heard some people discussing the various airfoils that are sticking around on it. Those are to improve the characteristics of it. It doesn't have anything to do with the poor flying characteristics of it as much as increasing the stabilization of the airplane, so...
O'BRIEN: And we'll just show our viewers quickly what you're talking about so they know what is going on. They're talking about some little winglets that are on the end of the elevator there, at the end of the wing. That is not to imply -- what do you call those at the tail there, what are those?
WYLIE: Those are winglets.
O'BRIEN: At the very rear section there.
WYLIE: To reduce drag. You've circled on the tail, you have a couple of tips which are primarily there to reduce the yaw, I guess, during turbulence. There are a couple of other surfaces that are there. There's a horizontal surface that's just about the top of your lower right circle, and that is to improve the center of gravity on the airplane so that they could have greater flexibility in loading the airplane. There is a series of fins on the bottom also that stabilize the airplane in turbulence.
So they were not added as -- I hate to say this, I was surfing some other channels and some people were disparaging the handling characteristics of the airplane, and that is incorrect.
O'BRIEN: Well, we appreciate you correcting the general body of conventional wisdom, which sometimes can be neither, and we're also glad that we didn't report anything like that which would put us in the area of inaccurate reporting.
Not only are the witnesses' reports inaccurate, generally speaking, we end up heading down, Leon and Daryn, down an awful lot of dead ends in these scenarios. So I caution our viewers that it takes many months for the NTSB to come up with a determination on these kinds of things. Here we are just minutes and hours afterward trying to come up with some scenarios. So put that grain of salt in there as we continue to discuss what are possible scenarios.
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