Some AA Pilots Want A300 Grounded
Swounger
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An ex-AA flight attendant says that AA knew for years about the problem:. .AIRBUS WOES WERE OPEN SECRET, SAYS ATTENDANT . . . .By JOHN LEHMANN . .--------------------------------------------------------------------------------
January 29, 2002 -- American Airlines has known for more than 10 years that its Airbus A300s have a tail problem that causes violent reactions to turbulence, says a former flight attendant, who was severely injured on a plane similar to the one that crashed in Belle Harbor. . .Cosette Burke, who worked for American for nine years, sued for $2.5 million after her back was broken when an Airbus A300-600 hit turbulence during a flight from San Juan in July 1991.
Burke, now 46, told The Post that while she was being thrown seven times into the ceiling at the rear of the plane, crew in the cockpit were drinking coffee "without spilling a drop."
. .<a href="http://www.nypost.com/news/nationalnews/40090.htm" target="_blank">http://www.nypost.com/news/nationalnews/40090.htm</a>
January 29, 2002 -- American Airlines has known for more than 10 years that its Airbus A300s have a tail problem that causes violent reactions to turbulence, says a former flight attendant, who was severely injured on a plane similar to the one that crashed in Belle Harbor. . .Cosette Burke, who worked for American for nine years, sued for $2.5 million after her back was broken when an Airbus A300-600 hit turbulence during a flight from San Juan in July 1991.
Burke, now 46, told The Post that while she was being thrown seven times into the ceiling at the rear of the plane, crew in the cockpit were drinking coffee "without spilling a drop."
. .<a href="http://www.nypost.com/news/nationalnews/40090.htm" target="_blank">http://www.nypost.com/news/nationalnews/40090.htm</a>
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From what my friends tell me that fly the A300 it is the stiff wing that causes most of the injuries during turbulence not the tail. In any case, AA's problems with the A300 go back to the first revenue flight of the jet when they almost had to splash one because of a fuel leak. The problems with the aircraft are quite numerous from what I have been told with the rudder problem being the most serious. I have heard people refer to it as the "Repairbus" more than once.. .If I was flying the thing I would want it grounded as well.
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There are many red herring trails springing up around the AA587 accident. But I personally doubt that it has anything to do with pilot inputs, "bogus parts" or a pre-existing fin delamination. The best hope is that enhancement of the toll-booth video will give some more clues. In my opinion the failure mode of the vertical fin was typically "flutter-mode" as induced by the rudder's excitation (and not by the pilots' application of rudder nor the suddenly successive wake turbulence encounters themselves). The clue here is that normally a rudder sits dormantly and passively in trail and only now and again has to soak up a minor load caused by asymmetric thrust or contend with a crosswind on landing. That's the job for which it's designed and the surface upon which this control surface (the rudder) acts is the vertical fin. The vertical fin's primary function is to generate a stabilising (damping) influence about the vertical axis. It normally does this with only very minor corrective displacements of the rudder (as assisted by the sensing and guidance of the yaw dampers). The A300 has a rudder limiter that places variable stops on the actuator input, depending upon airspeed. Two computers electrically drive the stops. Full 30-deg. travel is allowed up to 165 kt., then it is cut back to 3.5 deg. at 395 kt.
So this vital rudder limiter is keyed to proportionately reduce maximum achievable deflection as the IAS increases. However if this limiter fails (or is fooled by any gremlin in the flight control system software) it (the rudder) will still be capable of a full 30 degree "throw" at higher IAS. Keep in mind that this throw won't necessarily be bi-directional. Imagine the confusion for the FCS if deflection is to one loony-tune (of say, max available throw), yet the FCS centring action is dancing to a more normal tune (in keeping with the airspeed at the time). Consider also injecting the yaw damper's tempering influence upon any excessive rudder responses and you can see that this orchestra of the yaw axis has wind, string (its wiring), the brass (of the actuator hardware), the percussion (of the wake) and a moog synthesizer (the computer control of the FCS). There is much scope for disharmony. Unfortunately there is also a known flaw in the DFDR that inhibited it from making a quality recording of that approaching crescendo. There was also no way of telling whether the pilots' rudder pedal movements were being made by the pilots or were just "feedback". The mystery of that strain is concealed within "the system".
If you take this a step further and look into the feedback mechanism (that provides artificial "feel" for the pilots in a powered flight control system), you can envisage a circumstance where the external stimuli (of a wake encounter) might place the FCS into a destructive flutter mode. This flutter mode would be dissimilar to that of (say) an aileron. With aileron flutter, high speed and wing flexure (at the periodicity of the wing's natural harmonic resonance) causes the two wings to flap up and down further and faster - until you have a sudden failure due to exceeding the maximum tolerable bending moments at the wing-roots. I have seen a super-sailplane wreck where the wing spar's FRP root stub clean-fractured behind the pilot's head, shortly thereafter followed by the wing-clap overhead. However that is a well-known aerodynamic phenomenon. My suggestion is that there is a computer-derived equivalent phenomenon that can trigger aerodynamic failure (albeit probably only if a pre-existing condition or out-of-adjustment discrepancy exists). The "step further" on AA587's failure mode is this. As with the abortionate computer simulation testing of the USMC's Osprey, you can never be assured that either the hardware nor the software that drives it, or the interface, is unflawed. They found that out the hard way by extrapolating data via "number-crunching" the Osprey and skimping on wind-tunnel testing and live flight-test in favour of high priority noise-conditioning (in preparation for FAA accreditation of the civil variant). My contention is that, as the nine known yawing incidents on A300's (to date) adequately demonstrate, there is a latent defect in that aircraft's FCS which is capable of producing a high-frequency destructively divergent phugoid around the vertical axis. Further, because of the history of the nine incidents, this rogue phenomenon is a genuine cause for concern and no-one should doubt the sincerity of the AA pilots advocating an interim grounding of the A300. Before you condemn this as "alarmist", you might consider that there is no way of "proving" flight-control software. It is designed to a rigid specification .... but proofing? It is simply a "suck it and see" exercise. There are precedents. After many years of operating the A320, after many incidents and accidents, Airbus had to concede a dangerous software flaw and impose flight limitations for landing approach - whilst it came up with a "patch" fix. The MD-11 went through a similar glitch-fixing cycle - so it can happen. The reinforcing power of accidentally induced asymmetric feedback in a control surface can be likened to the super-heterodyne squeal or "feedback" that can occur in a radio or intercom circuit. If you're unfamiliar with that phenomenon, simply place a live microphone close adjacent to an earphone in the same circuit - but wind the gain (volume) down first - or the loud self-reinforcing squeal can cause damage.
The input response reaction of an A300 flight control system (FCS) depends very much on what its computer interprets the situation to be (i.e. its programming). If it misinterpreted an aircraft acceleration because it is not programmed to recognise a rapidly reversing yaw caused by an external stimuli such as two quick pilot-unopposed wake turbulence encounters, then it might well enter into a twilight zone mode where its reaction won't necessarily be an equal, opposite, or even appropriate reaction. In fact it may get out of synch, fail to dampen that acceleration and start a reinforcement excitation into a quasi-flutter mode. This can either rapidly lead to a destructive overload of the vertical fin (as with AA587) or be below that self-promotion threshold, dissipate and just leave some bewildered crew wondering: "What in Hell was that?". "Did I cause that?". The A300 has a yaw damper that can move the rudder at up to 39 deg. per sec. rate. Maximum throw is limited to ±10 deg. at speeds below 165 kt., reducing to 2 deg. at maximum operating speed. The two-channel yaw damper actuator is separate from the autopilot yaw actuator, and yaw damper inputs are not felt at the pedals.
Because the fin is made of (and attached by) composite material, and is quite rigid, its ability to accommodate rapidly varying out-of-alignment loads is much less than a conventional metal fin. Failure is not progressive in composites, it is sudden and propagates much faster due to the structure quickly losing its inherent integral strength and rapidly delaminating and disbonding. For an example, just rapidly flex a piece of hard plastic to its elastic limit and you will soon see a distress line, much much sooner than you would see one in an equally thick sheet of duraluminum. In the same situation a metal fin might be able to sit it out and later exhibit only minor cracking and distortion or deformation. By comparison the composite fin structure only has to fail at one attachment point and it is well on the way to overload, overstress and progressive failure of the remaining attachment points' composite lugs. Equally, if a rudder hinge or actuator arm was to first fail at one point, there would be a twisting torque imparted to the fin - and that would be superimposed upon the left/right flutter loadings. If you have problems envisaging the destructive power of aerodynamic flutter, try holding firmly (by two corners on one side) a sheet of paper out the car window at zero angle of attack, whilst being driven at high speed. Regardez what happens to the trailing edge. It will beat itself to death and tear into strips along that trailing edge.
Other Possibilities and Plausibilities
1. A software bug in the frequency-time-domain of yaw-axis control response?
2. rudder-trim switch fouling its panel and able to drive rudder to full throw (3 AD's = a number of goes to get it right => a possible choice of two wrong switches)[see .AD/AB3/107 Rudder Trim Control Switch 9/97 "interference between the 408VU panel and the rudder trim control knob, which could prevent the self-recentering of the switch to the neutral position when released, thus causing a rudder movement up to the maximum deflection, and which could lead to critical flight situations." (to quote one of the three applicable AD's).. .There is actually another almost identical AD covering the aileron trim switch (which sits alongside on that same 408VU panel). Anyone want to theorize whether someone managed to "Murphy" an aileron-trim switch into the rudder-trim switch position? Above the panel they look identical. Below the panel the wiring has been modified for the lengthier rudder-trim switch #3.
To quote AC 25.672-1 (in respect of ACS (Active control systems incorporating load alleviation systems (LAS), stability augmentation systems (SAS), and flutter suppression systems (FSS).)
8. SYSTEM RELIABILITY.
a. Since the airplane design criteria for load levels and/or flutter margins are dependent on the reliability of. .the ACS, the probability of loss of system function must be evaluated in a realistic or conservative manner before certification. System and component failure rates for use in probability calculations may be based on. .tests and, when available, on service experience with similar installations. Both the normal operative and the MEL dispatch configuration must be assessed for both loss of function and improper functioning (hardovers,. .etc.).
b. If the systems prove less reliable in service than assessed for certification, adjustments in maintenance schedules, load levels, and/or operating limitations may be required. This will necessitate monitoring of the. .systems for a sufficient period of time to substantiate an adequate level of reliability. Details of the reliability verification program should be based on system criticality and the degree of conservatism inherent in the system design and analysis. Periodic checks for system reliability may be required throughout the service. .life of the ACS.
Those interested in Quality Assurance of Software used in Aircraft or Related Products should look at AC 21-33 (by that well-known factual understatement, Deputy Faa Administrator (but now Boeing Rep), Tom McSweeny). .and AC 25-15 (Approval of Flight Management Systems in Transport Category Airplanes)
. .Conclusion
There's no doubt that it is possible to set up a rudder/fin interaction (courtesy of an FCS flawed input) that could lead to fin flutter, rudder separation/failure and fin departure. Stepping ahead a little here, I think that the real challenge is in detecting that flight control system failure mode, not in working out more esoteric inspection methods for composites.. . . . What is the likelihood of ever proving this (or any other) theory about AA587? The NTSB actually despatched two teams after AA587. One taskforce was to become the NASA deep look into composite testing and checking, but the other was despatched to Toulouse on a relatively low-key mission. They were to look into the A300 flight-control design and certification characteristics and experiment with the A300's engineering simulator. Whilst there is never any guarantee that they will reach a conclusion, any lack of one [or one that clears composites whilst not pinning down the AA587 cause] would only deepen the anxiety about the initiator for AA587. . . . .Me? I'm betting that it was the tail that wagged the dog.
So this vital rudder limiter is keyed to proportionately reduce maximum achievable deflection as the IAS increases. However if this limiter fails (or is fooled by any gremlin in the flight control system software) it (the rudder) will still be capable of a full 30 degree "throw" at higher IAS. Keep in mind that this throw won't necessarily be bi-directional. Imagine the confusion for the FCS if deflection is to one loony-tune (of say, max available throw), yet the FCS centring action is dancing to a more normal tune (in keeping with the airspeed at the time). Consider also injecting the yaw damper's tempering influence upon any excessive rudder responses and you can see that this orchestra of the yaw axis has wind, string (its wiring), the brass (of the actuator hardware), the percussion (of the wake) and a moog synthesizer (the computer control of the FCS). There is much scope for disharmony. Unfortunately there is also a known flaw in the DFDR that inhibited it from making a quality recording of that approaching crescendo. There was also no way of telling whether the pilots' rudder pedal movements were being made by the pilots or were just "feedback". The mystery of that strain is concealed within "the system".
If you take this a step further and look into the feedback mechanism (that provides artificial "feel" for the pilots in a powered flight control system), you can envisage a circumstance where the external stimuli (of a wake encounter) might place the FCS into a destructive flutter mode. This flutter mode would be dissimilar to that of (say) an aileron. With aileron flutter, high speed and wing flexure (at the periodicity of the wing's natural harmonic resonance) causes the two wings to flap up and down further and faster - until you have a sudden failure due to exceeding the maximum tolerable bending moments at the wing-roots. I have seen a super-sailplane wreck where the wing spar's FRP root stub clean-fractured behind the pilot's head, shortly thereafter followed by the wing-clap overhead. However that is a well-known aerodynamic phenomenon. My suggestion is that there is a computer-derived equivalent phenomenon that can trigger aerodynamic failure (albeit probably only if a pre-existing condition or out-of-adjustment discrepancy exists). The "step further" on AA587's failure mode is this. As with the abortionate computer simulation testing of the USMC's Osprey, you can never be assured that either the hardware nor the software that drives it, or the interface, is unflawed. They found that out the hard way by extrapolating data via "number-crunching" the Osprey and skimping on wind-tunnel testing and live flight-test in favour of high priority noise-conditioning (in preparation for FAA accreditation of the civil variant). My contention is that, as the nine known yawing incidents on A300's (to date) adequately demonstrate, there is a latent defect in that aircraft's FCS which is capable of producing a high-frequency destructively divergent phugoid around the vertical axis. Further, because of the history of the nine incidents, this rogue phenomenon is a genuine cause for concern and no-one should doubt the sincerity of the AA pilots advocating an interim grounding of the A300. Before you condemn this as "alarmist", you might consider that there is no way of "proving" flight-control software. It is designed to a rigid specification .... but proofing? It is simply a "suck it and see" exercise. There are precedents. After many years of operating the A320, after many incidents and accidents, Airbus had to concede a dangerous software flaw and impose flight limitations for landing approach - whilst it came up with a "patch" fix. The MD-11 went through a similar glitch-fixing cycle - so it can happen. The reinforcing power of accidentally induced asymmetric feedback in a control surface can be likened to the super-heterodyne squeal or "feedback" that can occur in a radio or intercom circuit. If you're unfamiliar with that phenomenon, simply place a live microphone close adjacent to an earphone in the same circuit - but wind the gain (volume) down first - or the loud self-reinforcing squeal can cause damage.
The input response reaction of an A300 flight control system (FCS) depends very much on what its computer interprets the situation to be (i.e. its programming). If it misinterpreted an aircraft acceleration because it is not programmed to recognise a rapidly reversing yaw caused by an external stimuli such as two quick pilot-unopposed wake turbulence encounters, then it might well enter into a twilight zone mode where its reaction won't necessarily be an equal, opposite, or even appropriate reaction. In fact it may get out of synch, fail to dampen that acceleration and start a reinforcement excitation into a quasi-flutter mode. This can either rapidly lead to a destructive overload of the vertical fin (as with AA587) or be below that self-promotion threshold, dissipate and just leave some bewildered crew wondering: "What in Hell was that?". "Did I cause that?". The A300 has a yaw damper that can move the rudder at up to 39 deg. per sec. rate. Maximum throw is limited to ±10 deg. at speeds below 165 kt., reducing to 2 deg. at maximum operating speed. The two-channel yaw damper actuator is separate from the autopilot yaw actuator, and yaw damper inputs are not felt at the pedals.
Because the fin is made of (and attached by) composite material, and is quite rigid, its ability to accommodate rapidly varying out-of-alignment loads is much less than a conventional metal fin. Failure is not progressive in composites, it is sudden and propagates much faster due to the structure quickly losing its inherent integral strength and rapidly delaminating and disbonding. For an example, just rapidly flex a piece of hard plastic to its elastic limit and you will soon see a distress line, much much sooner than you would see one in an equally thick sheet of duraluminum. In the same situation a metal fin might be able to sit it out and later exhibit only minor cracking and distortion or deformation. By comparison the composite fin structure only has to fail at one attachment point and it is well on the way to overload, overstress and progressive failure of the remaining attachment points' composite lugs. Equally, if a rudder hinge or actuator arm was to first fail at one point, there would be a twisting torque imparted to the fin - and that would be superimposed upon the left/right flutter loadings. If you have problems envisaging the destructive power of aerodynamic flutter, try holding firmly (by two corners on one side) a sheet of paper out the car window at zero angle of attack, whilst being driven at high speed. Regardez what happens to the trailing edge. It will beat itself to death and tear into strips along that trailing edge.
Other Possibilities and Plausibilities
1. A software bug in the frequency-time-domain of yaw-axis control response?
2. rudder-trim switch fouling its panel and able to drive rudder to full throw (3 AD's = a number of goes to get it right => a possible choice of two wrong switches)[see .AD/AB3/107 Rudder Trim Control Switch 9/97 "interference between the 408VU panel and the rudder trim control knob, which could prevent the self-recentering of the switch to the neutral position when released, thus causing a rudder movement up to the maximum deflection, and which could lead to critical flight situations." (to quote one of the three applicable AD's).. .There is actually another almost identical AD covering the aileron trim switch (which sits alongside on that same 408VU panel). Anyone want to theorize whether someone managed to "Murphy" an aileron-trim switch into the rudder-trim switch position? Above the panel they look identical. Below the panel the wiring has been modified for the lengthier rudder-trim switch #3.
To quote AC 25.672-1 (in respect of ACS (Active control systems incorporating load alleviation systems (LAS), stability augmentation systems (SAS), and flutter suppression systems (FSS).)
8. SYSTEM RELIABILITY.
a. Since the airplane design criteria for load levels and/or flutter margins are dependent on the reliability of. .the ACS, the probability of loss of system function must be evaluated in a realistic or conservative manner before certification. System and component failure rates for use in probability calculations may be based on. .tests and, when available, on service experience with similar installations. Both the normal operative and the MEL dispatch configuration must be assessed for both loss of function and improper functioning (hardovers,. .etc.).
b. If the systems prove less reliable in service than assessed for certification, adjustments in maintenance schedules, load levels, and/or operating limitations may be required. This will necessitate monitoring of the. .systems for a sufficient period of time to substantiate an adequate level of reliability. Details of the reliability verification program should be based on system criticality and the degree of conservatism inherent in the system design and analysis. Periodic checks for system reliability may be required throughout the service. .life of the ACS.
Those interested in Quality Assurance of Software used in Aircraft or Related Products should look at AC 21-33 (by that well-known factual understatement, Deputy Faa Administrator (but now Boeing Rep), Tom McSweeny). .and AC 25-15 (Approval of Flight Management Systems in Transport Category Airplanes)
. .Conclusion
There's no doubt that it is possible to set up a rudder/fin interaction (courtesy of an FCS flawed input) that could lead to fin flutter, rudder separation/failure and fin departure. Stepping ahead a little here, I think that the real challenge is in detecting that flight control system failure mode, not in working out more esoteric inspection methods for composites.. . . . What is the likelihood of ever proving this (or any other) theory about AA587? The NTSB actually despatched two teams after AA587. One taskforce was to become the NASA deep look into composite testing and checking, but the other was despatched to Toulouse on a relatively low-key mission. They were to look into the A300 flight-control design and certification characteristics and experiment with the A300's engineering simulator. Whilst there is never any guarantee that they will reach a conclusion, any lack of one [or one that clears composites whilst not pinning down the AA587 cause] would only deepen the anxiety about the initiator for AA587. . . . .Me? I'm betting that it was the tail that wagged the dog.
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From <a href="http://money.cnn.com/2002/01/30/travel/american_airbus/index.htm" target="_blank">CNN/Money</a>:
"American Airlines is taking its Airbus A300 off its trans-Atlantic routes, and several senior Airbus pilots have decided to switch to flying other jumbo jets.
The scheduling change comes in the wake of the Airbus crash that took 265 lives in New York Nov. 12 when the tail snapped off that plane less than two minutes after takeoff.
The last Airbus to London was scheduled to depart Boston at 9 a.m. ET Wednesday. The last flight back to the United States arrives in Newark, N.J., Thursday afternoon.
With fewer pilots needed, 10 of American's most experienced A300 pilots have exercised their seniority to switch to other planes. Some did so for personal convenience; others expressed safety concerns.
One captain switching to a different plane wrote to American's president a few weeks ago to suggest the tail be removed from an Airbus and taken apart to check for any hidden problems in light of the New York crash.
An American Airlines official said the Airbus is being replaced on trans-Atlantic routes because larger planes are now available, and that the switch was planned before the November accident. But pilot sources said they were told business travelers were hesitant to fly the Airbus and were booking on other airlines."
[ 30 January 2002: Message edited by: liebowa ]</p>
"American Airlines is taking its Airbus A300 off its trans-Atlantic routes, and several senior Airbus pilots have decided to switch to flying other jumbo jets.
The scheduling change comes in the wake of the Airbus crash that took 265 lives in New York Nov. 12 when the tail snapped off that plane less than two minutes after takeoff.
The last Airbus to London was scheduled to depart Boston at 9 a.m. ET Wednesday. The last flight back to the United States arrives in Newark, N.J., Thursday afternoon.
With fewer pilots needed, 10 of American's most experienced A300 pilots have exercised their seniority to switch to other planes. Some did so for personal convenience; others expressed safety concerns.
One captain switching to a different plane wrote to American's president a few weeks ago to suggest the tail be removed from an Airbus and taken apart to check for any hidden problems in light of the New York crash.
An American Airlines official said the Airbus is being replaced on trans-Atlantic routes because larger planes are now available, and that the switch was planned before the November accident. But pilot sources said they were told business travelers were hesitant to fly the Airbus and were booking on other airlines."
[ 30 January 2002: Message edited by: liebowa ]</p>
CNN taking the lazy route and doesn't bother checking the facts.
The A300-600 was always marginal as a transatlantic airliner. AA announced last year that they were planning to withdraw the a/c from the atlantic in favour of an all 767/777 operation which makes more economic, operational and customer service sense. They decided in December to move this date forward when more 767s became available following the post-11 Sept cutbacks.
There are a number of people (politicians, pilots with union ambitions), stirring it up for their own ends over the Airbus issue. There's also pilots, cabin crew and passengers with understandable concerns about the A300 not being seved by the media feeding frenzy. Of course it's too much to hope there be some straight factual reporting that might put things into perspective.
The A300-600 was always marginal as a transatlantic airliner. AA announced last year that they were planning to withdraw the a/c from the atlantic in favour of an all 767/777 operation which makes more economic, operational and customer service sense. They decided in December to move this date forward when more 767s became available following the post-11 Sept cutbacks.
There are a number of people (politicians, pilots with union ambitions), stirring it up for their own ends over the Airbus issue. There's also pilots, cabin crew and passengers with understandable concerns about the A300 not being seved by the media feeding frenzy. Of course it's too much to hope there be some straight factual reporting that might put things into perspective.
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Michael B Wrote:
it took just one Concorde crash to ground the entire fleet until fixed, this sounds like a. .much more general and serious problem than the likelihood of hitting large metal parts on the runway.
That, is a VERY good point!!
--------------------
Not really. One such accident in 8 million flights vs. one accident in 80,000 flights. That accident rate is in the noise compared to other causes, hence no grounding.. .n
it took just one Concorde crash to ground the entire fleet until fixed, this sounds like a. .much more general and serious problem than the likelihood of hitting large metal parts on the runway.
That, is a VERY good point!!
--------------------
Not really. One such accident in 8 million flights vs. one accident in 80,000 flights. That accident rate is in the noise compared to other causes, hence no grounding.. .n
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Belgique . .
What an excellent technical post, it has to be one of the best technical posts that I have ever read...I even understood it..
oncemorealoft
Hey, you're right lets not fall into the trap of the media feeding frenzy...
What an excellent technical post, it has to be one of the best technical posts that I have ever read...I even understood it..
oncemorealoft
Hey, you're right lets not fall into the trap of the media feeding frenzy...
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Michael B
A little more info on the A320 elevator problem would be interesting. I don't have access to AIRWAYS.
If the FAA is mandating something then that suggests they have another mod available which fixes the problem. Any clues what it is??
A little more info on the A320 elevator problem would be interesting. I don't have access to AIRWAYS.
If the FAA is mandating something then that suggests they have another mod available which fixes the problem. Any clues what it is??
Up until the AA accident Airbus A300 need to be shot down to crash (you remember 87 Iran Air accident.
Since when do we ground a safe aircraft on first suspision of a malfunction. Well if it is not a Boeing.
. .Tasso
Since when do we ground a safe aircraft on first suspision of a malfunction. Well if it is not a Boeing.
. .Tasso
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Actually there have been many A300 crashes . There was one in Japan with the autopilot, another one in Romania with autothrottle problem and most distressing of all, just last year a Kenya Airlines one that crashed 3 minutes after takeoff where the tail also fell off.
The A300=600 safety record has not been particularly good, and I sorry that IRAN air is the only one that you can remember but I can go on and on.
Cheers. .Wino
The A300=600 safety record has not been particularly good, and I sorry that IRAN air is the only one that you can remember but I can go on and on.
Cheers. .Wino
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Some excellent posts here, particularly Belgique's.
A couple of thoughts:
5 years ago, Cathay were about to take unilateral action to ground their A-330's because of a problem with the gearbox oil scavenge system. Airbus would not take grounding action, so CX forced their hand ( correctly, in my opinion ).
I recently flew with a senior Capt with many years on the A-300 before transferring to the 767. He noted that it might be a good idea to look into the effects of thermal cycles on a composite structure, commenting that the APU ducting amongst others is up near the attachment points. Iow: the fin gets heated a great deal on the ground and then subjected to rapid cooling in flight, many times over it's life. Anyone know of any studies in this area?
In any case, there should be no flight control movement possible below maneuvering speed that causes the disintegration of the aircraft in less than 10 secs. Big difference: the 737's didn't break up.... <img src="confused.gif" border="0">
A couple of thoughts:
5 years ago, Cathay were about to take unilateral action to ground their A-330's because of a problem with the gearbox oil scavenge system. Airbus would not take grounding action, so CX forced their hand ( correctly, in my opinion ).
I recently flew with a senior Capt with many years on the A-300 before transferring to the 767. He noted that it might be a good idea to look into the effects of thermal cycles on a composite structure, commenting that the APU ducting amongst others is up near the attachment points. Iow: the fin gets heated a great deal on the ground and then subjected to rapid cooling in flight, many times over it's life. Anyone know of any studies in this area?
In any case, there should be no flight control movement possible below maneuvering speed that causes the disintegration of the aircraft in less than 10 secs. Big difference: the 737's didn't break up.... <img src="confused.gif" border="0">
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Actually there have been many A300 crashes . There was one in Japan with the autopilot,
With the crew fighting the A/P actually <a href="http://aviation-safety.net/database/1994/940426-0.htm" target="_blank">http://aviation-safety.net/database/1994/940426-0.htm</a> .
another one in Romania with autothrottle problem
An A310, but close enough I suppose.
and most distressing of all, just last year a Kenya Airlines one that crashed 3 minutes after takeoff
Also A310.
where the tail also fell off.
Well yes it did, after the impact. Hardly think that counts though.
[ 31 January 2002: Message edited by: PaperTiger ]</p>
With the crew fighting the A/P actually <a href="http://aviation-safety.net/database/1994/940426-0.htm" target="_blank">http://aviation-safety.net/database/1994/940426-0.htm</a> .
another one in Romania with autothrottle problem
An A310, but close enough I suppose.
and most distressing of all, just last year a Kenya Airlines one that crashed 3 minutes after takeoff
Also A310.
where the tail also fell off.
Well yes it did, after the impact. Hardly think that counts though.
[ 31 January 2002: Message edited by: PaperTiger ]</p>
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Gentlemen,. . Gentlemen,. . Gentlemen!
There is nothing wrong with the A300-600.. .It is one of the best aircraft flying today.. .It has been mishandled on numerous occasions by crews who were either disorientated, didn't understand the technology, or did not keep up with their OEBs.. .Simple as that.
"My dog's better than your dog." Doesn't apply in this most unfortunate accident and calling for its 'grounding' is both inappropriate and irresponsible.
...and that's the name of THAT tune.
Willie,. .A300-600 pilot of average ability, an embarrasing number of fairly good landings and rather short list of 'thumpers'. So there.. . <img src="wink.gif" border="0">
There is nothing wrong with the A300-600.. .It is one of the best aircraft flying today.. .It has been mishandled on numerous occasions by crews who were either disorientated, didn't understand the technology, or did not keep up with their OEBs.. .Simple as that.
"My dog's better than your dog." Doesn't apply in this most unfortunate accident and calling for its 'grounding' is both inappropriate and irresponsible.
...and that's the name of THAT tune.
Willie,. .A300-600 pilot of average ability, an embarrasing number of fairly good landings and rather short list of 'thumpers'. So there.. . <img src="wink.gif" border="0">
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I have enjoyed this thread, Belgique´s post was. . technically interesting to say the least,the thermal aspect also fascinating.At the risk of appearing crude, the vertical stabilser detached from an aircraft shortly after take off, we all agree on this..frankly I´d like to know why? or at least hope for a plausible "non political"answer from the manufacturer and operator.Pilots faced with this are not over reacting in my opinion,just possibly their actions might be the only way to encourage a thorough investigation.. sad but true.
I have flown all Airbus types ,except A340, and whilst I think they are wonderful Aircraft the oscillations at the rear end are well known, ask any cabin crew member,or pax who has the misfortune to sit "in the back" Belgique what do you think? yaw damper related(software) or fuselage/wing design causing this empennage rotation, could it cause stress fatigue on a vertical stabilser´s fixation points over time?
I really don´t know, but concern is valid I think.. .Also the B737´s yaw damper/rudder problems haven´t really disappeared or have they?
I have flown all Airbus types ,except A340, and whilst I think they are wonderful Aircraft the oscillations at the rear end are well known, ask any cabin crew member,or pax who has the misfortune to sit "in the back" Belgique what do you think? yaw damper related(software) or fuselage/wing design causing this empennage rotation, could it cause stress fatigue on a vertical stabilser´s fixation points over time?
I really don´t know, but concern is valid I think.. .Also the B737´s yaw damper/rudder problems haven´t really disappeared or have they?
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The January 21 edition of Aviation Week had a detailed engineering analysis of potential failure modes of the A300 fin. Unfortunately, I failed to save the link, and it does not currently appear among the publicly-available archived articles on the Aviation Week website. Perhaps the link to the article will be posted in a week or two. As I recall, the article covered in detail, similar to Belgique's excellent analysis, of how a rudder going through the stops could rapidly lead to fin failure.
The fact the tails of A300's have been re-inspected is not entirely reassuring. NASA's examination of the AA587 vertical stab discovered delamination of the composite. It could not be initially determined whether the delamination was a pre-existant condition or was caused by the stab separating from the aircraft. The delamination was apparently found through destructive testing, as the NTSB and NASA are looking for A300 fins with significant flight hours that have been discarded (and I suppose, if none are to be found, look for a fin on a stored aircraft) so that destructive inspection and testing of the stab composite can be performed.
Th search for more fins for further destructive testing SUGGESTS that the delamination was not discovered using various non-destructive inspection and test regimes.
The fact the tails of A300's have been re-inspected is not entirely reassuring. NASA's examination of the AA587 vertical stab discovered delamination of the composite. It could not be initially determined whether the delamination was a pre-existant condition or was caused by the stab separating from the aircraft. The delamination was apparently found through destructive testing, as the NTSB and NASA are looking for A300 fins with significant flight hours that have been discarded (and I suppose, if none are to be found, look for a fin on a stored aircraft) so that destructive inspection and testing of the stab composite can be performed.
Th search for more fins for further destructive testing SUGGESTS that the delamination was not discovered using various non-destructive inspection and test regimes.
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"My dog's better than your dog." . .WILLI EVERLEARN, you hit the nail! All those weeks I'm following different threads in different Forums dealing with AA 587, it's noticable, that blood starts boiling, emotions are rising and than it ends up in the old Boing/Airbus dispute mixed with political darts fired back and forth.. .Amazing, those 3 to 4 gentlemen, who are stirring the soup constantly without to much knowledge about facts continue their play despite reading those brilliant posts like Belgique's, which should cool down emotions a little. . .Or take Volume's reply dealing with FIR requirements for structural integrity or AB rudder and fin attachement in the Tech Log, indicating profound knowledge in those areas.
I flew 2,3 and 4 engine powered Boings, beautiful airplanes. Still love them. I also logged some hours and years on Airbus 310-200, 310-300 and 300-600. (Mixed operation). Nice reliable birds, I still adore them. Granted, you had to know what you were doing with the Autoflight system or ATS. Not made for ignorants, reqires good training, right Willi?. .Understand those AA pilots demanding to ground A300-600 very well, but why not trust those knowlegdeable NTSB experts and wait until they come up with their findings as proposed by so many? <img src="smile.gif" border="0">
[ 04 February 2002: Message edited by: Captain104 ]</p>
I flew 2,3 and 4 engine powered Boings, beautiful airplanes. Still love them. I also logged some hours and years on Airbus 310-200, 310-300 and 300-600. (Mixed operation). Nice reliable birds, I still adore them. Granted, you had to know what you were doing with the Autoflight system or ATS. Not made for ignorants, reqires good training, right Willi?. .Understand those AA pilots demanding to ground A300-600 very well, but why not trust those knowlegdeable NTSB experts and wait until they come up with their findings as proposed by so many? <img src="smile.gif" border="0">
[ 04 February 2002: Message edited by: Captain104 ]</p>
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Captain104. .I couldn’t agree more!. .I’ve flown Boeings and Airbuses with the same pleasure and confidence. Presently I fly A340. My previous aircraft was A300-600. We never had any problems or indication of a possible problem, especially in the fin area. It is common knowledge that cabin crew and pax are ranking the aircraft types according to their comfort in turbulence (one of the ratings at least). I expect that the 60+ pilots in AA would have their reasons to ask for such a severe action, but have you heard of any such cases in Europe?. .I wonder why?
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Andreas,. .to answer your question and speculate would take us exactly in that corner I try to avoid. Perhaps it's not only politics behind their demand to ground A 300-600, perhaps some are really scared and have to answer question by their wifes and kids? So, I try to understand.. .Otherwise I agree with your judgement concerning A 306. In my company we call it the "gentle giant", if I translate it right. You know what I mean ?! Have a nice time on your A 340 and enjoy it. . .By the way: I should like to sit behind you flying over some of your breathtaking islands.
Fish,. .understand, you like BMW more than Saab and cornflakes?
. .Good taste! Otherwise could'nt agree more. . .Being a newcomer to pprune, I can't avoid to note this sometimes heated discussion about Airbus/Boing. You express it cristal clear and a little bit "sharper" than me: lets try to be mature. <img src="smile.gif" border="0">
[ 04 February 2002: Message edited by: Captain104 ]</p>
Fish,. .understand, you like BMW more than Saab and cornflakes?
. .Good taste! Otherwise could'nt agree more. . .Being a newcomer to pprune, I can't avoid to note this sometimes heated discussion about Airbus/Boing. You express it cristal clear and a little bit "sharper" than me: lets try to be mature. <img src="smile.gif" border="0">[ 04 February 2002: Message edited by: Captain104 ]</p>
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According to an article in the January 21st. edition of Aviation Week NTSB officials are having trouble obtaining "true" readings from the FDR because of someting called averaging. During very rapid or extreme control movements the FDR does not actually measure the true speed of the flight control movement but instead measures the average movement. This becomes problematic in the search for answers in the "tail wagging the dog" scenario and will require lengthy examination.