Skip to comments.The Mystery of Flight 587
Posted on 11/24/2001 5:35:14 PM PST by Swordmaker
(Brother Jonathan News, November 15, 2001) On Monday, November 12, 2001 American Airlines Airbus A300 Flight 587 crashed and burned, just two minutes and 24 seconds after take off from JFK International Airport in New York City. Within minutes the speculation for the cause ran from aircraft failure to terrorist attack. Immediately, both the FBI and the NTSB began a formal investigation. The NTSB was in charge of investigating the crash and the FBI would take over if evidence of sabotage were found. So far, the investigators have eliminated a number of possible theories, such as birds damaging the engines, simple engine failure, or possible bomb or missile attacks.
On Tuesday, the 13th, during the NTSB press conference, one of the reporters asked, "What about the possibility of a thrust reverser failure?" The reporters were told there was no evidence of that and its not possible for that to occur during flight. What the NTSB and FBI failed to tell the reporters is that it is not possible for there to be a thrust reverser failure in flight, UNLESS the thrust reverser controls were sabotaged by a terrorist. Instead, the investigation seems to focus on the possibility that wake turbulence from a 747 jumbo jet which had taken off just minutes before Flight 587 had caused the damage to the plane and caused the crash.
What is confusing to most knowledgeable aircraft investigators is that this is completely impossible. It is not possible for any type of turbulence to rip off the tail of an airplane, and then have it go out of control in such a way that both engines would also fall off. In August 1985 a Japanese Boeing 747 with the vertical tail assembly completely torn away continued to fly in large circles for over half an hour before it hit a mountain. But only because the pilots were busy trying to figure out what happened to the plane and did not watch where they were going. It did not go into an instant out of control spin with complete loss of the engines.The Air Force's B-2 Flying Wing stealth bomber is a perfect example to prove that a plane with absolutely NO vertical fin or stabilizer is able to fly and does not instantly become unstable and crash. The B-2 uses modern "fly-by-wire" computers to keep the plane flying straight and level. The original flying wing design from the 1950's also flew but using manual flight controls made it rather difficult to steer with no rudder. The Airbus A300 uses a modern "fly-by-wire" computer system and would fly quite easily with complete loss of the vertical fin and rudder. The NTSB's claim that the loss of Flight 587's vertical fin and rudder might be the cause of the loss of the control of the plane which caused it to crash is both misleading and deceptive.
Any theory blaming the failure of the vertical fin and rudder assembly as the cause cannot account for why the engines would fall off the plane. Any theory blaming an engine failure as the cause cannot account for why the tail assembly would snap off cleanly with no appearance of blast damage from an exploding engine. Thus there would need to be three separate simultaneous failures, of the tail assembly and both pylons holding the engines on the plane to account for those three effects observed before the plane crashed. Most air accident investigators would easily conclude that the chances of three simultaneous airframe failures all occurring at the same time is not probable. It must be one or the other but not all three. It would be much easier to conclude that something else actually caused all three failures. Thus the breaking off of the tail and both engines is not the cause of the crash, but is the effect of some other single failure which caused the crash. And what would that be?If the left engine thrust reverser had either partially or completely actuated during flight, it would cause the plane to go into a flat spin to the left. The airplane would spin something like a flat Frisbee with the right engine pushing forward and the left engine pushing backwards. Within a second of the flat spin occurring, the sideways wind blast would rip off the tail assembly since it was never designed to take such a side blast of air.
As soon as the tail assembly broke off there is now very little wind resistance to the flat spin. At this point the engines would cause the aircraft to spin even faster with the g-forces away from the center of the spin becoming so great that both engines would be violently ripped off the wings and thrown outward away from the plane. This accounts for why the engines were found so far away from the crash site and why the tail came off first. Thus a single point failure, the in-flight actuation of the left engine thrust reverser, can account for all three observed phenomena of the clean breaking off of the tail and the failure of both engine pylons holding the engines. But how can that happen when there are so many safety devices to ensure that it never occurs?
That is quite simple. The American Airlines Airbus was parked overnight in preparation for its flight to Santo Domingo the next morning. During the night, a terrorist saboteur disguised as a ground crew mechanic could reach up in the back of the left jet engine and with a pair of diagonal cutter pliers simply cut the hydraulic line going to the thrust reverser actuator and the control safety sensor lines. The next morning about an hour after the jet engines were started, the hydraulic fluid now under pressure would drip from the cut line until none was left in the line and the thrust reverser would simply slowly drift into the full on condition while in flight and a catastrophic crash would occur only seconds later.
Until September 11th, 2001, nobody would have believed that 19 airplane hijackers armed only with box cutters could bring down both towers of the World Trade Center. But now we know better. Is it now so hard to believe that a single terrorist armed with a pair of pliers could bring down an A300 Airbus? This is called "asymmetric warfare," or "thinking outside the box," or simply using low-tech tools in a new way to destroy the high-technology of an advanced culture.Is it possible to show that the in-flight actuation of the left thrust reverser is the actual cause of the Flight 587 Crash? Yes. But you would probably ask, "How do you know such things?" First, I have been a pilot since 1962. I have put planes in almost every possible flight configuration. I am not a flight instructor, but for years I taught ground school classes in airframes, aircraft engines and air navigation. Second, I have degrees in mechanical and electrical engineering and physics, and for many years I was assigned to do failure analysis for many NASA Space Shuttle incidents.
In 1983, two communications satellites were left useless in low-orbit because the firing mechanism to launch them into hi-orbit failed. Several years later Shuttle flights recaptured the failed satellites and I was tasked to determine the cause of the failure. In three days of analysis I found the cause and the controls were redesigned and the failure never occurred again. In 1987, the Air Force was launching a secret satellite from the Shuttle using a Boeing supplied launch system. The actuators for the launch system were made by UTC. Final checks before launch showed that one of the actuators appeared to be faulty and had failed the initial tests at UTC but somehow had been installed into the Shuttle anyway. My task was to prove that the actuator was not faulty but only appeared faulty due to an improper testing device. In four days I found the faulty test device and proved the launch actuator was in fact ready for space flight. I did my usual scientific analysis "dog and pony show" for two Air Force Generals, and the Vice-presidents of both Boeing and UTC. Everybody was happy. The Air Force got their satellite on orbit on schedule. The VPs from Boeing and UTC were happy since they did not need to pay the $5 million penalty the government would assess for unstacking the Shuttle to replace the "defective" launch actuator and for delaying the project. Thus, what I am about to explain comes from many years of flight experience, along with years of experience in aerospace failure analysis.
According to the publicly available information from the NTSB, the Cockpit Voice Recorder (CVR) shows everything was normal in the flight until about 107 seconds after the initial run-up of the engines as Flight 587 began to roll down the runway for takeoff. At this point in time the plane is about 3,000 feet in the air and the sound of an "airframe rattle" is heard in the CVR record. No explanation was given for this noise. But as I propose, what was happening was the left thrust reverser was starting to close and this caused the plane to turn to the left. The pilot would compensate by using his feet to apply right rudder to bring the nose back to straight flight by turning to the right. When applying strong right rudder this usually causes the left wing to tilt upward so most pilots would instinctively also apply opposite or left aileron to keep the plane straight and level. Most pilots would recognize this flight configuration as a side-slip. This would be a rather strange maneuver for a commercial airliner especially during take off. This is often called the "poor mans air-brakes" since this odd configuration results in the opposite compensating controls surfaces to stick out in the wind and really slow down the aircraft.
I have done this maneuver many times in small aircraft to quickly lose airspeed or drop in altitude in preparation for landing. During this condition the burbling air flowing over the extended control surfaces makes a lot of noise and seems to make the plane shake, rattle and roll. This would account for the airframe rattle noise heard on the CVR at 107 seconds into the flight. The pilot probably thought he had overcompensated and was worried about losing too much airspeed and so then returned the controls back to normal and the rattling momentarily stopped. But the plane continued to turn back to the left. Seven seconds later, one of the flight crew comments about "air turbulence" with no further comment, and it would seem the pilot again tried to compensate for the strong drift of the plane to the left caused by the partially closing thrust reverser by again applying strong right rudder and opposite aileron as the same rattling sound is heard again several seconds later at 121 seconds into the flight. Four seconds later, at 125 seconds into the flight, the first officer calls for "full power" presumably to compensate for the side-slip maneuvers which had really slowed the plane down to dangerously slow speed. This was a fatal mistake, but not caused by the pilot.
As soon as the power went to full, the spinning effect caused by the partially or fully actuated thrust reverser would cause the plane to now spin out of control in a flat spin. Two seconds later, at 127 seconds, the CVR shows one of the flight crew makes a comment about being out of control. No more comments are made after that and the recording ends 17 seconds later when the plane hits the ground. But what happened when the captain called for full power?
If the pilot were holding full right rudder and almost full left aileron to compensate just as the left thrust reverser came into the full on position, the application of full power would have greatly increased the turn to the left and would have created a huge side force on the tail and rudder assembly which simply broke off cleanly and fluttered away. Within another second, without the vertical tail assembly to slow the spin, the plane would have begun to spin violently to the left about the center of gravity of the airplane. It now was not an airplane but a giant spinning Frisbee, or maybe a giant horizontal boomerang. Yes, you can take a scale model airplane and holding one wing throw it like a boomerang and make it fly. I know, since I used to do that as a kid. It works. A modern swept-wing jet aircraft with the tail torn off is simply a boomerang with a large stick, the passenger cabin, stuck in the middle.
Since the pilot had been holding opposite or left aileron, as soon as the plane started to spin, the left wing would be going backwards. But with the left aileron in the upward position the left wing becomes a lifting surface which keeps the spinning plane level, since both wings are lifting. The plane is now spinning horizontally with the full power from both engines increasing the spin faster and faster until both engines break off and are flung sideways away from the plane. As soon as the tail assembly broke away and the spin started, the plane became like one of those spinning centrifuges used by the astronauts for testing at high g-forces.
Within a second or so the people at the front and back of the plane were being thrown violently away from the center of the plane with a tremendous force. The seats with passengers in the very back of the plane were probably ripped out of the floor and thrown to the back of the plane. The flight crew at the front of the plane were thrown violently forward with such g-force they were instantly rendered unconscious or killed. This would explain why no more comments from the flight crew are heard after applying full power. The plane was spinning horizontally to the left completely out of control.
With the engines still running at full power, they broke away ripping the fuel tanks in both wings and Fight 587 became a flaming Frisbee. Something which nobody, and especially none of the people who witnessed the accident, had ever seen before. Small pieces of the airframe along with the engines were thrown by centrifugal force away from the flaming plane, giving the appearance of an explosion blasting parts away.
This also accounts for the many strange witness reports. I watched the news channels live and heard many witnesses swear that they saw the left engine come off first. Many other witnesses also were just as sure that the right engine was the first to come off. How to account for these strange opposite reports? Simply, all those witnesses had never seen a plane in a flat spin before. In a flat spin most of the plane's forward motion is stopped and the plane is like a spinning flaming Frisbee floating in the air. The flames hid the shape of the plane and the witnesses could not see the plane spinning, they only saw a ball of fire with pieces of plane blasting out from the center. At that point the concept of right or left engine no longer has any meaning, they are both going in the same circle. Thus depending on where the witness observer was standing when the first engine dropped off, half of the people would see it as going to the right and the other half would see it as going to the left. Thus both groups of observers were correct in reporting what they saw, they only misinterpreted what it meant.There were even professional pilots who reported they saw the plane in a "spinning nose dive." Is it possible that they were also mistaken? Is it possible the plane was not in a nose dive but was actually spinning flat with one wing going backwards, all caused by a thrust reverser actuated in flight? Since the other pilots reported they saw a flaming spinning plane arcing into the ground, and since they too probably had never seen a plane in a flat spin, they simply assumed what they saw was a spinning plane nosing into the ground. Is it possible to prove that it was not a plane nose-diving into the ground but a flat spin caused by a terrorist? Yes.
When the plane began the flat spin right after the tail assembly broke off over Jamaica Bay, the passengers in the front and back of the plane would experience high g-forces which threw them to the front and back of the plane. But those passengers in the center of the plane between the two engines and over the wings would simply spin around with no lateral g-forces. They would just spin around similar to sitting and spinning on a rotating piano stool. For them the plane simply floated downward as they rotated. What would happen to them? According to a statement made by New York mayor Giuliani in a news conference on Wednesday November 14th, the rescue workers recovered 262 bodies including "a man still holding a baby." How is that possible if the plane had nose-dived into the ground?
A nose dive into the ground would have produced such a violent forward force that all objects in the plane would have been thrown forward with most of the seats ripped out of the floor. Certainly no man can be strong enough to hold on to a baby through that force, unless instead the plane was in a flat spin. For the passengers in the center of the plane the force would have been downward as the plane hit the ground and the baby would be simply forced deeper into the man's lap as he sat in the passenger seat. Is that sufficient evidence to prove the plane was in a flat spin at impact with the earth and the crash was caused by a thrust reverser being actuated in flight? Yes. It could not have been a forward nose dive.
Further evidence is shown by the fact that on the many live news videos of the crash scene as the firemen are putting out the flames, a large section of the central portion of the plane is lying on the ground almost intact but in flames. If the flaming spinning Frisbee of Flight 587 had impacted the ground in a flat spin the front and back ends of the plane would have impacted with high rotating speed and thrown pieces of the plane, including the Flight Data Recorder in the rear of the plane many blocks away. But the center of the plane would be left intact. Analysis of the debris field would show material from the front of the plane went in one direction while material from the back of the plane went in the opposite direction. Is there clear evidence for sabotage by a terrorist? Yes. But it seems the FBI does not want to know. Maybe the airlines, especially American Airlines, do not want anybody to know they are so easily vulnerable to terrorist attack. For whatever reason, it seems the NTSB and the FBI do not want to know what happened to Flight 587. The clear evidence for the flat spinning impact is shown by the condition of the passengers and seats in the front and rear of the plane compared to the conditions in the almost intact center portion of the plane. Is the NTSB going to reassemble the plane parts to investigate that? According to NTSB Chairman Marion Blakey in the news conference on Tuesday the 13th, the NTSB was not going to reassemble the plane for analysis. The two engines are being sent under sealed bonded cover to American's Tulsa, Okla. facility for disassembly and analysis. But it would seem the engines were not the cause of the crash, so that is an investigative dead end. The real evidence, the conditions of the cabin and fuselage which would show and prove the plane crashed while in a flat spin, is simply going to be carted away and tossed in the trash. The FBI will never find the terrorist who caused the crash, if they are not looking for one.
----------- Marshall SmithEditor, BroJon Gazette
NEW FLIGHT DATA RECORDER UPDATE NOV. 17, 2001 Note, it does not say it "began rolling rapidly" to the left. It says it "began revolving rapidly" to the left. And that would be known as a flat spin. The rapid revolving was due to the engines at full power. Most pilots would recognize the 30-degree drop at the end as slowing to the stall speed as if the plane were simply stalling or entering into a recoverable vertical spin. A single engine plane would be very difficult to fly into a horizontal or flat spin. But any twin or mulit-engine plane like the A300 can easily enter a non-recoverable flat spin when reaching the stall point if the forward thrust on each side of the plane's centerline is not equal. The worst case being equal and opposite thrust around the plane's center of gravity caused by an inflight actuation of a thrust reverser.
The above article was prepared and written based only on data from the Cockpit Voice Recorder. The NTSB has since then released data from the Flight Data Recorder showing the position of controls and configuration of the aircraft. It is entirely consistent with the above analysis, including the turns to the left, right, left, right with the "rattling" occurring during the two turns to the right. Followed quickly by the loss of the vertical tail assembly, then the rapid break into a flat spin. The FDR data shows: " ... the Airbus began a series of oscillations, yawing from left to right, then back again. Seconds later, the data stream from the Airbus's rudder 'becomes unreliable,' (meaning it had torn off) ... the jet began rolling to its left side ... the flight data recorder shows the Airbus rolled 25 degrees to the left, even though the pilots applied full-right roll control. The recorder also shows the jet dropped into a 30-degree dive, and began revolving rapidly toward the left.
The NTSB continues to insist there is no evidence of a terrorist attack. (The Brojon Gazette throws up its hands in complete disbelief.
Note, it does not say it "began rolling rapidly" to the left. It says it "began revolving rapidly" to the left. And that would be known as a flat spin. The rapid revolving was due to the engines at full power. Most pilots would recognize the 30-degree drop at the end as slowing to the stall speed as if the plane were simply stalling or entering into a recoverable vertical spin. A single engine plane would be very difficult to fly into a horizontal or flat spin. But any twin or mulit-engine plane like the A300 can easily enter a non-recoverable flat spin when reaching the stall point if the forward thrust on each side of the plane's centerline is not equal. The worst case being equal and opposite thrust around the plane's center of gravity caused by an inflight actuation of a thrust reverser.
"Investigators at first believed the plane landed nose-down -- because of the lack of wider destruction that would have resulted had it hit the ground at a shallower angle. That did not explain, however, why they found so many intact or nearly intact bodies so quickly."
Washington Post article, Published Nov, 15, 2001, Page A18
Unless we are looking at a sudden, simultaneous, never before experienced, depolymerization of the carbon fiber composite materials that make up the tail and engine pylons, we must look for another logical modality of failure.
The sudden deployment of the left engine Thrust Reverser fits the picture of what apparently happened... and the evidence seems to comfirm it.
As to whether it was sabotage (sabatuer cuts hydraulic line to thrust reverser just before take-off) or mechanical failure (the hydraulic line to the thrust reverser breaks because of age, wear, constriction, whatever) is another question.
Timing and location suggest sabotage. The investigators need to look closely at the left hand engine and specifically at the hydraulic lines to the thrust reverser.
And I thought this article was like reading a horror story-never have a read a more devastating rendition of the conditions of the cabin during a mechanical failure in flight. Horrendous.
I really believe that all mechanics and other personnel associated with maintenance and repair of aircraft need to be vetted-yesterday.
How easy this author makes it seem for someone to clip a few critical wires within an engine, making cuts that bring down an airliner without fail. I wonder how the delayed flight of this airliner fits into this scenario? It would be so nice to know exactly what caused the delay in lift-off since the critical time for the sabotage suggested by the author means that the engines needed to be running for only a certain time before failure would occur. IF it was a terrorist, he sure as heck did not want the engines to start leaking before the plane was airborne. Timing was everything in this event. And there must be plenty of leads. I sure hope they are looking at ground crews-big time.
This is the most plausible explantion yet for this crash.
The only problem with it is that I thought Al Queda would only do showy attacks that were against targets where there would be no ambiguity over whether it's terrorism or not. We're going to know for sure what happened only when all the data is analyzed; I don't think this is the sort of dramatic attack bin Laden specializes in. By the time we know what happened to Flight 587, it will have long since been overtaken by subsequent events.
I just don't think it fits the big egos of Al Queda.
I have two questions:
1) Wouldn't an indicator ("idiot light") illuminate on the flight deck during the pre-flight checks, indicating a loss of hydraulic pressure in the left thrust-reverser?
2) What evidence do you have to show that a thrust-reverser would gradually slip into the acuated position when pressure is lost in the hydraulic line?
Like the article says, the old "flying wing" of decades ago flew around quite nicely, without a tail configuration and without modern computors...Highly conceivable...
"The board [NTSB] confirmed that Flight 593's thrust reversers were stowed, the flaps were apparently retracted, and the landing gear was up when the plane went down."
In the previous 24 hours the plane underwent a low class maintenance inspection, I believe. Would the lines have been cut then? Would hydraulic fluid have been leaking from the plane when it was parked in front of the terminal? Why didn't the pilot see the leak in his walk around?
Maybe the terrorist got lucky...Could be that is was only known that the plane would drop out of the sky somewhere between the beginning and the end of the flight, depending on how quickly or slowly the oil leaked out...I'd like to see a schematic of the hydraulic system...
The checks, mandated for U.S. and French carriers under directives issued in those two countries Friday, were deemed necessary once investigators determined that the American aircraft's tail separated along an attachment point. About 20% of the world's 410-odd affected aircraft have been checked, and no carrier has reported anything unusual, sources tell AviationNow.com."
Problem here is after the NTSB investigated the crash site, who investigated the NTSB????
As I have also pointed out, there are a number of cases where these large airliners have been returned to landing after losing their vertical stabilizer--the fact the stab was gone would not be expected to have caused the airplane to fall out of the sky either.
"This is way beyond my expertise. But the statement about the B-2 fly-by-wire requiring no vertical tail doesn't prove a thing. There's nothing resembling that kind of special computer controls in an Airbus." Cicero, you are wrong. To the contrary, the Airbus is a pure fly by computer airplane. And in fact, that should not make any difference either--unless the pilots made serious errors which do not appear in the record, if they could have hand flown the airplane, loss of the vertical stab would not have kept them from returning to make a safe landing. The pilots were dependant on a computer driven control system to fly the airplane--although most of the new commercial airliners are fly by wire airplanes (electrical inputs to a computer run the control surfaces), the Airbus is the most dependant on the electrical computer system.
"I, too, thought that was a bit off the wall... the B1 and B2 will NOT fly without computer assistance because of their inherent instability." (From Swordmaker)
Sure but so what--there are other airplanes out there that also do not have vertical stabilizers and which have no computer or electrical servo driven flying systems either--the Bonanza V34 is one example. Loss of the vertical stab did not have anything to do with this event either.
The author here advances an analysis that would account for the accident--uncommanded deployment of the thrust reverser. He accounts for the event by sabotage. Well and good--that is a possibility. "How easy this author makes it seem for someone to clip a few critical wires within an engine, making cuts that bring down an airliner without fail. I wonder how the delayed flight of this airliner fits into this scenario?" (By Republic) No. His suggestion is a little more complicated than that--his sabotaur was not cutting wires, he was cutting hydraulic tubeing which is a little more difficult and requires a fair amount of knowledge because there are a number of metal tubes up there and if you cut the wrong one, the fan simply does not spin. But his thesis is possible although I think remote. Your point about the late departure is however relevant--by the time they were off the ground, they would have run out of the sabotaur's time line which makes the authors suggestion a little less likely.
For one thing, no reason an uncommanded thrust reverser event requires sabotage--it happens more often than the flying public wants to know for a whole host of reasons other than sabotage. One of the Boeing airplanes had a reputation for regular uncommanded deployments because of some glitch in the way the systems were wired.
The pilot is trained to recognize the problem and the usual remedy ought to have been to cut power to the engine. Even if the pilots screwed up and failed to recognize the problem, they still had to make a number of other mistakes to get this result--it is possible but in my view remote. Further, if it happened that way, the NTSB would have jumped on it because they could have said it happened by accident. So I tend to doubt the evidence will support this series of events.
My own view is that there is much more likely series of events that explains the crash and those events start with an incendary device in the checked baggage compartment. That explanation also deals with another piece of evidence which is the reliable eyewitness testimony to fire at the root of the wings on both sides of the airplane.
Do you know and, if yes, will you list the URL for the website displayed behind TV newscastes which displays all the flights in the air at that time. It was widely used on 9-11 as the planes were being grounded. Perhaps you saw it and know it.
Should another reader have the URL, please post it as a ping to me.
It seems to display flight's locations, superimposed on a regional map of the country, with light blue arrows showing the direction and the flight number, with possibly more information.
I have looked but could not find it. The fellow on MSNBC never responded to my email request, either.
Many thanks, in advance.
The thrust reverser is driven by an air motor powered with pneudraulic (air) pressure drawn from a bleed air duct off the compressor. Connection between the air motor and the reverser cowls is accomplished with the use of flexshafts (flexible drive shafts).
The next morning about an hour after the jet engines were started, the hydraulic fluid now under pressure would drip from the cut line until none was left in the line and the thrust reverser would simply slowly drift into the full on condition while in flight and a catastrophic crash would occur only seconds later.
Hydraulic fluid under pressure wouldn't drip from a cut or severed line. It would fly out of there, rather like a severed artery. Any falling onto the hot section would cause a massive amount of smoke to come from the engine, enough that the ground start crew would stop the startup procedure. If it leaked out overnight, then it would have leaked through the cowling as well, and left a puddle on the ground.
With regards to the thrust reverser cowl "simply slowly" drifting into the full on condition. It would have to be driven into position by the flexshafts. At full power, depending on the model, the CF6 puts out between 40,000 and 72,000 pounds of thrust. Reverser cowls are driven into place and held there...because that much thrust will just blow them open.
Now we move into the realm of science fiction, or even fantasy. Suppose that there is a teleportation device, carried back to us by time travelers, to inject these mysterious occurrences into our everyday lives, at a time in history where there was great turmoil about bacteriological agents, and terrorist attacks using airliners. A small piece of a structural part on the tail surface of the airliner was teleported away, so it looked like a stress failure, and a small quantity of anthrax spores were teleported into the woman's nasal passages.
But of course there shall be developed much more rational explanations, for each of these seemingly unrelated events. Just keep in mind, that not all the frontiers have yet been explored, or even defined very well so far.
1.Thrust reversers are normally stowed in a mechanically locked position, so that in case of a hydraulic system failure they remain closed.
2.Hydraulic pumps are mechanically driven by the engine during and after engine start. A "cut" hydraulic line would spew tremendous amounts of fluid while under pressure at 3000 psi and trigger a cockpit warning light. Hydraulics power all major aircraft systems including brakes and nose-wheel steering. I doubt Flight 587 would even have been able to taxi to the runway for takeoff had this "cut line" scenario occurred.
4. The vertical fin and rudder, at the most critical stage of flight, failed due [Probably] to the acculmination of a series of small errors, break downs and failures which may or may not eventually include such contributing factors as bad design, material failure, fatigued components, previous maintenance damage -- etceteras;
When the Vertical fin failed at that potentially most unstable stage of flight -- and especially when bearing in mind that it did not leave cleanly and most certainly caused the aircraft to yaw violently -- all "yaw-damping" control was lost.
Once the aircraft began yawing under take-off and then increased to the "maximum power" setting the pilot [It was the F/O's leg, he handled the controls] called for, the potential that an assemetric thrust condition existed and/or was caused increased.
Once that happened it was only milliseconds before the gyroscopic effect of violent yawing on turbine rotors spinning in excess of 10,000 RPM caused the engines to be ripped from mounts not designed to handle such incredible forces applied to them at 90 degrees around the engines plane of rotation.
The forces were such it was as iff a giant hand had grabbed hold of the engines on a childs model an simply twisted them off.
Cutting hydraulic lines before the engine is started guarantees a hydraulic fluid gusher that would be easily discerned before takeoff - it would take just a few seconds to gush ALL aircraft hydraulic fluid onto the runway - it works at 3000 psi.
All thrust reversers are manufactured and fitted with a system of locks and feedback mechanisms. Lock failures show up on the cockpit instruments, and having a red light on will prevent the flight from occurring. The feedback mechanism detects a thrust reverser starting to deploy, and then sends the hydraulic fluid to stow the reverser before it can deploy. If they can't fix the T/R system on the ground, then they put a pin in the reverser structure to prevent commanded or uncommanded deployment.
After the Air Lauda crash in Thailand, caused by a T/R inadvertently deploying, all aircraft makers had to declare their aircraft either reliable or controllable. The big twins like the A300 are not controllable with a T/R deployed, so they had to go the reliability route and install a better safety system with 3 redundant locks. There was a deadline to do it, which has passed, I think. Therefore, it's highly likely that this aircraft had the redundant system installed.
The author is correct that an in-flight T/R deployment would cause the aircraft to fly approximately the way it did. It was the first comment in my office after the crash - it may be a T/R deployment. But the statements from the NTSB make it clear that the T/R's were not the cause.
I've previously offered two probable causes to this crash - a rudder partially breaking loose from the vertical tail, causing high static and dynamic loads before it departs the aircraft; or a latent structural defect in the vertical tail skins that was excited by either the wake turbulence or anomalous rudder operations.
As I've stated before, I am an aerospace engineer at a company that makes engine nacelles, including thrust reversers.
The fan duct lines in the CF6-80C2 create pressure forces such that the thrust reverser should remain stowed (and not drift back) during high power flight.
If the reverser was the cause, we would have heard about it already. An earlier poster noted that the NTSB stated the T/R's had not deployed. [but then some folks don't believe the NTSB or other alphabet agencies!].
Anyone else know for sure?
The A-320 is. But this was an A-300, which is not "pure fly by computer".
From witnesses on the ground indicate the aircraft was experiencing a compressor surge in one of the engines. The popping sound and flames are the trademarks. A compressor surge used to be common with older engine but rare by today's standards with the digital engine controls. The compressor surges, putting out the flame within the engine, the engine loads up with unburnt fuel and when the engine goes into automatic restart, it produces a loud bang and lots of flames. Most engines are made to withstand these backfires but last year; an Alaska 757 had a serious compressor surge that blew off the front cowl of the engine, damaging the engine and wing which forced an emergency landing. They can be quite violent. Witnesses stated that the engine made popping sound and flame could be seen between the wing and body. They also state that parts of the wing left the aircraft and hit the tail. The one report indicates that the flaps were fully retracted as indicated by the black box but have all the panels been accounted for on the ground? I am curious as to what else was they had dredged from the bay.
The flat spin does account for the break up of the aircraft and lost of vertical surfaces but the cause still seems to be engine failure with possible damage to flight surfaces. The full thrust of one engine without rudder control would put it into flat spin. The popping sounds heard would indicate that one engine was not working properly. Fuel delivery seemed to be intermittent or low. The rumblings may be key.
My theory is a main tire exploded after stowing (first rumble), causing damage to fuel feed line and pumps within the wheel well. This downed a 727 in Mexico in the 70s which caused the segregation and protection of hydraulics and fuel lines running within the wheel wells. This lesson has been lost on modern aircraft designers which routinely run hydraulics and fuel lines through the wheel wells without any shrapnel protection. The second rumble was the engine starting to miss from lack of fuel and going into a series of compressor surges that loosen something that hit the tail causing lost of rudder control (three violent full swings were recorded).
The crash and fire usually make analysis of wheel failure impossible to determine but I would start looking there.
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