The Mystery of Flight 587

Brother Jonathan Gazette -- Scroll Down all the way ^ | 11/15/2001 | Marshall Smith

[RandyRep]

Concerning the "fly-by-wire" control system - I doubt that the Airbus A300 control system is as sophisticated as the active stability and control system used on the B-2 and other tailless aircraft. I think, but don't know 100% positively, that the control system is electronic - they use sensors to sense the rudder pressure, then wires give signals to the control surfaces (like, rudder - deflect 8 degrees) rather than the old system of pulleys and cables connected directly to the rudder pedals or the stick. On the tailless aircraft, the computer system senses the aircraft stability and modifies the control inputs to the control surfaces to stabilize the aircraft.

Anyone else know for sure?

[okie01]

"Cicero, you are wrong. To the contrary, the Airbus is a pure fly by computer airplane."

The A-320 is. But this was an A-300, which is not "pure fly by computer".

[Traction]

I do not buy the thrust reverser theory as the redundancy of the thrust reverser systems means that multiple sabotage would have to take place. Two solenoid control valves, mechanical locks and the power drive actuators would have to be tampered with along with enunciators in the cockpit showing the thrust reverser had come out of lock. As previously stated, almost all domestic airlines had to retrofit their thrust reversers with multiple fail-safes which include mechanical locks. Per the article and comments, the thrust reversers were found stowed.

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.

[First Conservative]

Not a technical comment, but I wrote US News after reading their article on the crash in their Nov 26 issue strongly criticizing them ("shoddy reporting") for making no mention or explanation of the eyewitness reports of fire and explosion/disintegration, nor any mention of the MTA bridge surveillance tapes turned over to the FBI (why not the NTSB) which reportedly showed 587 taking off. Do the tapes show the aircraft flying apart less than three minutes into the flight? Inquiring minds want to know.

[Native American Female Vet]

BUMP

[RonDog]

bump

[patriciaruth]

Bump.

[tuesday afternoon]

Complicated, what?

[Swordmaker]

Thanks for you comments. I posted this here for just this kind of feedback.

[republius]

From here.

Within the high mud walls of this compound,members of Mr bin Laden's clan lived ...

There is a catalogue of electronic switches published by the Japan Aviation Electronics Industry and an empty box that once contained a kit for building a toy lorry.

An aviation switch catalog. Hmmm.

[peabers]

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.

A friend of mine was on a Fokker F-50 that sprung a major leak on the left main landing gear. The fluid was literally gushing out as the plane was taxiing out to the runway. The flight crew had no indication in the cockpit.

I used to work on F-4J AWG-10 radar, and saw a radome full of hydraulic fluid that leaked from the antenna.

[JimVT]

My experience was with air traffic control rather than design and mechanics.

I donno......

But why in the world would there be a cover-up?

If it is proved to be a terrorist act it will just further inflame Americans and make it easier for the Administration to pursue its goal of killing OBN et al.

[eno_]

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).

Truly excellent analysis! But wouldn't a tire exploding be picked up on the CVR? Or, for that matter, if a tire can explode and not be picked up on a cockpit audio recording, could a bomb explode in the luggage and not be picked up? In either case, I think you are correct that it was a loss of controls due to some kind of failure, explosion, incendiary, etc. This is consistent with eyewitness reports of a "flash" and debris coming from the wing-root.

I also think the loss of the vert stab and engines were both due to air load, not a g-load on the engines. That would have sent the engines in opposite directions. They were found near each other. I also doubt there was sufficient energy in the system to create such a g-load. The engines, after all, have to stay on at maximum thrust. But get the cowling sideways, and the mass of the airplane becomes the hammer and the air becomes the anvil.

[eno_]

I cannot explain this inconsistency: The FBI is known to be investigating the otherwise unremarkable disappearance of a Harvard biologist, and they are swabbing down every inch of a 94 year old woman's house, the hair salon she went to, etc. while there is no criminal invetisgation in an airplane crash that happened almost within sight of the WTC ruins when Bush was standing right there, there was a specific threat of more plane disasters, and a probable saboteur had been caught in a shipping container on his way to Canada with fake airline maintenence IDs. Nope, can't be terrorism!

"Coverup" is too strong a word. It implies some kind of criminal intent. I think the downplaying of terrorism in this case is just part of general propoganda and ass-covering. Who would want to admit they could still reach out and touch us that way? Why risk an unpredictable public reaction? So those of us who fly a lot are left to our own to figure out what probably happened.

[ivanhoe116]

I am a private pilot with 3500 hours. I have also discussed this event with my brother who is a retired Delta captain.

This is the most plausible explantion yet for this crash.

You mean to say that the puddle of hydraulic fluid on the ground beneath you aircraft wouldn’t give you pause? Wouldn’t other pilots lining up for take-off be “eyeballing” your equipment?

[BADJOE]

A puddle yes. But a tiny hole drilled in a hydraulic line would hardly make a puddle. Even under pressure the stream would be small but steady. And there are plenty of places the fluid could pool within the engine narcell and not be visable from the outside.

[alloysteel]

Going back to this problem with the yaw that would have occurred in a climbing turn, by failure of the vertical fin on the rudder. The first response of the airframe based on physics would be to move out at a straight vector from the point where the tail fin became detached, as there was no further force application to continue the turn. Then, in a effort by the pilot to compensate, greater power was applied to the engine on the outside radius of the (formerly) curvilinear path, which is now proceeding out at a tangent. This caused the now rudderless airframe to spin like a boomerang, all the while with increasing engine speed on the outside engine. But now the plane of rotation is turned sharply, on both engines, which are, remember, essentially huge gyroscopes, and in attempting to maintain the motion vectors, twist OFF their pylon mounts and fall away from the plane.

This brings us back to the original question - why did the vertical tail fin mounts, and consequently the rudder mechanism, fail?

[Chad]

I have flown the Fk-100 and any sort of hydraulic leak like you described would trigger a hydraulic "LO QTY" (low quantity) warning light with repetitive aural chimes. The quantity is sensed inside the reservoir, so the lines would have to bleed off before the reservoir level dropped, but that wouldn't take long at 3000 psi. I'll bet the Fk-50 is similar, and can't explain your friend's experience.

[Chad]

Your point is well-taken!