THE SOLUTION? |
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THE SOLUTION? |
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| Art
der
van Wald wrote: To ALL I don't know the source (548@aviator), but I give you his comments concerning SR111. If you have anything to add, please do so. Regards, Art der van Wald << "Let me say that I've tossed this around with a few friends who between them have more flying hours than could be added on a calculator. Now let me say that anything I post here is not meant to nor should it upset anyone. While we all saw missed opportunities by the crew to take advantage of the short time they had, this is not our focus. Our focus is what happened to the aircraft itself. We know from the transcripts and the news media that the crew was in control of the aircraft until that final turn to the south to reach the ocean to dump fuel. At this point, he had not dumped any fuel, the aircraft was extremely heavy and we know he was issued vectors for the turn and actually made the turn. After the completion of the turn, the controller tells them they have but a short distance to go which will keep them within 35 miles of the airport during dumping in case they have to get back to the airport quickly. To this the crew responds: "OK, that's fine for us". So even hand flying an extremely heavy aircraft they were still in positive control and responding to commands. Our combined feeling is that as soon as the crew began to dump, something went terribly wrong. This is where the design of the aircraft comes into play. They were dealing with the smoke, they had the aircraft in control, they responded positively to the controllers keeping them 35 miles from the airport to dump. As far as they were concerned, they knew they had trouble but they thought they still had time to dump fuel. As soon as that dumping process started, they had immediate troubles. There were no further transmissions or mayday calls. It's in the design and in the next post I'll describe the design". "We know that as soon as dumping was begun, something catastrophic happened. Not even a quick mayday was flashed off by the crew. This tells us whatever happened was instant and overcame the aircraft. I have read reports that instruments which measure for earthquake activity picked up the tremendous impact of 111 hitting the water. This also tells us that the angle of attack of the aircraft was almost certain to be very "nose low". An aircraft would only gain such speed with its nose low.Again, this is all so significant to it's design that we feel the investigators are concentrating in the wrong area. Understanding it's design and how it shifts fuel to remain balanced is very significant. Again, they would have never responded with a "that's fine for us" if the heat was too intense, if the cockpit was so filled with smoke making the instruments unreadable, became disoriented or some of the wild speculation I've read elsewhere. One posting in another forum had the crew evacuating the cockpit. Needless to say, this is ridiculous. We believe that the design itself will have much to do with this incident. THE DESIGN As we know, the MD11 was an outgrowth of the DC10. While some systems remained the same, most were re-designed. The most important of these re-designs is the fuel system, it's management and it's bearing on the stability of the aircraft. When Douglas re-designed the aircraft, naturally they wanted speed, efficency and good payload capability. To gain these objectives, certain components on the airframe would need to be larger and stronger. ie: wing and empenage. Here, they hit a roadblock. The larger horizontal surfaces on the tail section was directly responsible for added weight which produced increased drag. This would mean the aircraft would fall short of it's performance goals if some re-designing of the horizontal tail was not done. Well, they made it smaller in size and area and recovered the performance goals they were after. However, there was now one more hitch. The smaller size horizontal tail would not be strong enough to handle the trimming forces needed to keep the aircraft stable in high speed flight. Their answer? They designed the horizontal tail with fuel cells incorporated into the tail itself. Fuel could be transferred into these cells in the tail to keep the aircraft within it's center of gravity and add weight to the aft section of the aircraft to reduce the trimming load on the smaller tail surface to keep the nose pitched "up" in high speed flight. Without this shifting of fuel to the aft section of the airframe, the aircraft after burning off fuel would be out of balance limits". |
Subject: Addition to Message from Aviator re SR111 Cause
Date: Tue, 22 Dec 1998 15:41:59 +0800
From: IASA Safety<safety@iasa.com.au>
To: Ader <ader@compuserve.com>,
", timothyclark" <timothyclark@compuserve.com>, jay miller
<JNiessen@aol.com>,
mgoldfein <mgoldfein@belo-dc.com>, david evans <devans@phillips.com>,
edward Block <EdwBlock@aol.com>, clittle <clittle@cari.net>,
john sampson <sampson@iinet.net.au>, john king <jking1@mediaone.net>,
tim dobbyn <tim.dobbyn@reuters.com>, omega <omega@omegainc.com>,
barry smith <barry@corazon.com>, wireman <wireman@hfx.andara.com>,
lyn romano <rosebush2@hotmail.com>, rwroland <rwroland@aol.com>,
References: 1
| Further
to the analysis above (with which I'd largely agreed earlier on - it's still on my
web-site) there are a few further, more significant factors worth noting.
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BACKGROUND TECH INFO
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| 2. IASA Safety comments: The key to all this is the statement that:
" A total loss of electrical power is manageable - Battery power is available for 15 mins with these items operative:.........." Unfortunately the designers didn't allow for the battery draining effect of a short circuit on those "guaranteed" 15 minutes. In other words, shortly after the first officer reported that he'd lost his flight display the aircraft went out of control - BECAUSE THE BATTERY HAD BEEN FLATTENED BY THE SHORT CIRCUIT that started the elec fire - as soon as the Generators were tripped by the smoke/elec switch selections (IAW checklist). [I think I might be correct in saying that reset of a tripped generator does require for there to be some battery power still available]. Anyway, to continue, all Flight Instruments were then lost as a result and, there being no visual horizon (and cockpit being full of smoke), a terminal, unrecoverable unusual attitude soon followed. Faced with such an upset it would have to be a very quick-thinking crew that remembered that salvation might lay in immediately deploying the ADG (air-driven-generator). However.... I'm not sure but I think that the ADG is an electrical deploy (not a mechanical lanyard) - so that action may then not have been possible (had they even thought of it in the scant few seconds before an unusual attitude developed). Of course that 15 mins of available power was stipulated to be with a limited number of items operating. If a considerably greater number of items were actually operating at the time then a short circuit may not have been required to quickly drain that battery. Remember that the Inflight Entertainment System (IFE) was a very high power drain system and it was very foolishly plumbed into AC Bus Two (with all its critical flight items). I'd suggest that, when the generators were tripped as part of the ongoing checklist procedure, the battery was almost instantly drained by the IFE. GEN reset was not possible without some BATT power and so, without Flight Instrumentation, the unrecoverable unusual attitude was then inevitable. Remember that this situation could not be reproduced during drills in the Swissair MD11 simulator because the IFE was not duplicated on AC BUS TWO in the Swissair MD-11 Simulator. This scenario is much more likely than any " out of CG" condition brought about by fuel dumping (which I personally believe never commenced) or #2 flameout due to loss of the aft (tailplane) tank pump. I'd be interested in hearing a rated MD-11 pilot's views of this theory. For the record I disagree with Sean O'Leary that the MD-11 (and other modern jets') automated systems adequately compensate for the absence of a third man (F.E.). Reliance upon the MD-11's automated handling of abnormal developments may well prove to have been a very fundamental cause for the SR111 accident (as outlined above). It's all much akin to trusting your fate upon a fire-engine that is itself on fire.
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