Some AA Pilots Want A300 Grounded

[AA SLF]

I may have missed it somewhere in R&N, but think this is news to this forum. Please see:. . <a href="http://biz.yahoo.com/rf/020124/n24369253_1.html" target="_blank">http://biz.yahoo.com/rf/020124/n24369253_1.html</a> . .Please note - this action NOT sanctioned by APA.

This is very big news in the USA and very bothersome to AA pax/slf on East Coast of USA. For me, I have never seen an AA A300 so far, so doesn't worry me. crosses fingers silently. .dAAvid -. .edited to fix the Union ID -dAAvid

[ 25 January 2002: Message edited by: AA SLF ]</p>

[Rabbit]

Based on this thaught process then B747 and B737 and a number of other aircraft should also be grounded for there very well known and well publicised problems.

Let the authorities make these decisions

Have a nice day <img src="smile.gif" border="0">

[ironbutt57]

That's right rabbit...well known problems....but the reason for this is unknown...that's why it's scary...until they find out why the vertical fin separated

[zerozero]

I wouldn't ground the 747 just because one was shot down over Long Island.

The 737, on the other hand.... .now that's a malfunction of a completely different flavor.

As for the A300: I still have an open mind but I'm not too keen on plastic airplanes.

(Edited because I had a little more to say.)

[ 25 January 2002: Message edited by: zerozero ]</p>

[A and C]

This type of story is good for selling papers and keeping some talking heads on the TV but is will do untold dammage to the aviation industry as mis-understood half facts are reported as cast iron truth for the benifit of the media.

I am sure that if a good technical reason for grounding the A300 had come to light then the NTSB would have recomended it and the FAA taken action.

The whole thing puts me in mind of the press assasination of the Electra in the 60s.

[dallas dude]

Is it fair for some of the A300 fleet's pilots to be somewhat cautious when a tailfin on one of their airplanes just "falls off", so far without explanation?

If you were driving a car and the steering wheel came off in your hand without OBVIOUS cause and the car veered uncontrollably into the nearest crash barrier would you want to jump back into the car and blast up the motorway/freeway without some hesitation?

Were ALL the former Comet pilots just lining up to go fly again, prior to the latent cause of their inflight breakups being discovered?

If you KNOW the reason the A300 crashed please let the pilots know, they're all ears! However, please bear in mind that so far the best brains in the industry (including those in Tolouse) are still puzzled.

As many pilots as AA has lost in the last 6 months, don't knock someone for resisting the urge to join that hallowed list.

[recceguy]

Please wait a little bit until proficient people (FAA, Airbus in Toulouse...) draw their conclusion (which will take a little bit of time)

After all, never an Airbus came and landed as a convertible (or maybe should it be considered as an achievement of sturdiness ?!?)

And the best brains in the industry are definitely not the airline pilots

[Bubbette]

It seems like in the big picture the 737 rudder problem was more widespread. And you never heard calls for them to be grounded from the pilots.

[greatorex]

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!!

[whatshouldiuse]

Rabbit;

. .You're absolutely correct the 737s should have been grounded by the FAA. You know why they weren't? Because commercial flying within the U.S. would have ground to a halt. Period, end of discussion.

A fair decision? Probably not. Economically sound...sure !!

Nuf said

[Wino]

WhatshouldIuse

No that is not true.. .The reason the 737 was not grounded was that an immediate fix was implemented, one that is satisfactory to all parties involved.

That immediate fix required operators to fly the aircraft at all times above "crossover speed" which is the speed at which the ailerons are more powerfull than the rudder. As long as that is done then a rudder hard over is an inconvienience not a tradgedy as witnessed by several aircraft that have been brought back to earth since with rudder problems. Crossoverspeed is an easily definable aerodynamic principal just like lift and drag. If needed I can explain it for you. But the long and the short of it is that 5-10 knots were added to the minimum speeds for all configurations.

There is no speed in the world that will make an A300 flyable without a vertical stab, and all parties involved have admitted there is no way to inspect the stab, hence the call for many pilots to ground the aircraft.

Cheers. .Wino (A300-605R f/o)

[reportfurther]

I flew some time ago on one of the AA A300-600s, as a passenger doing a positioning flight from Miami up to New York, one of the best flights I have ever had.

However I must confess I would be a little nervous repeating that same flight now, cannot really blame those that fly them every day for being concerned, at least until someone finds the cause.

[411A]

For those with looooong memories....the rudder "problems" with the B737 can be directly traced to the original B707 design...and its rudder problems.. .AirBus...with the "plastic" fin...a whole new ballgame.. .Ground the A300-600?...may be the way to go until the "problems" are sorted out. But...will not happen for economic reasons, sad to say.

[ExSimGuy]

411A,

Would I be naive to question your prediction above by pointing out that the Airbus is not built by a US manufacturer <img src="confused.gif" border="0">

[caulfield]

The post-mortems on the 737 Colorado and Pittsburgh accidents are still inconclusive.However,the design of the 737 rudder is flawed and could be the reason behind these accidents.. .I wouldnt use the term ´proficient´when referring either to Airbus or the FAA.One will say white is black to protect its reputation,and the other has to be continually dragged kicking and screaming to mandate AD´s(most notoriously in the DC-10 Windsor incident which would have precluded the THY Paris DC-10 crash).. .The answer is to empower the NTSB who only have one axe to grind,that of improved safety.

[Ignition Override]

Recceguy: Just some comments about our "friends" at the FAA. I never knew that the FAA's Certification Branch cared about the highest levels of flight safety, or were proficient in having common sense regarding flight safety. Many of their upper bureaucrats appear to only want legal documentation to be correct, and in order. Certain concerns with Valuejet (now Airtran) were allegedly "misplaced" for a while. How about certain "alleged" prejudices within the FAA's Western Region during the Continental strike in the early 80's? Threre is plenty of evidence that the FAA was under strong pressure to promote Ronald Reagan's promotion of deregulation, no matter what the consequences upon passenger safety. The FAA was a political tool: all accidents can rightly or wrongly be attributed to the pilots or mechanics-but a corporation's safety culture (i.e. "pilot-pushing": "if you refuse that airplane, Captain, you might need another job for your wife's medical bills") is not always insignificant. I have a newspaper article quoting former maintenance personnel during the Eastern strike, and the management attitude there regarding compliance with FAA-approved manuals and procedures...

Let's all think back to the ATR-42 incidents in Europe, and how the FAA ignored problems with the ATR's roll control in icing conditions, until American passengers died (crewmembers don't count). Has anyone here heard of the earlier Metroliner's rocket in the tail? All of this is only a tiny tip of the iceberg (no pun intended), regarding the FAA's "alleged" (magic word) callous disregard of many known aircraft problems. Never mind their constant refusal over decades to enact a regulation which would designate a planned rest period for crewmembers with multiple 24-hour days and nights (when should I sleep?) of reserve/standby flight duty. The dead passengers in the Little Rock MD-80 accident removed another FAA excuse not to act. The dead or seriously injured pilots in the Kallita DC-8 which cartwheeled at Guantanamo Bay, Cuba, years ago resulted in what new FAA regulations? This was the first accident in which the NTSB (had the 'marbles' to say) claimed that crew fatigue was the primary factor. But no passengers died, therefore there was no public awareness.

I'm not so sure that, in the name of commercial exports, the French 'FAA' is more detached from the industry than are our "friends" over here.

[ 27 January 2002: Message edited by: Ignition Override ]

[ 27 January 2002: Message edited by: Ignition Override ]</p>

[Rabbit]

I have followed this thread with interest. I have some 7000 hours on boeings and a further 8000 hours on various airbus aircraft and I firmly believe that both manufacturers produce very good aircraft.

As was pointed out earlier the 737 was not grounded until the cause of various accidents was determined for purely commercial reasons. To ground the A300-600 would also mean grounding the A310. The resultant commercial impact would be devistating to many companies especially considering the current climate in the industry. The same argument can be applied to the 747 as the real cause of the TWA accident has not been found/released.

The investigators I am sure will look into this situation very thouroughly and hopefully find the reason.

Have a nice day <img src="smile.gif" border="0">

[Albatross]

Anyone watching CNN about a month ago would have seen a lady running a support group trying to get the 737 grounded. She lost relatives on one of the aircraft that fell apart in the states. Her story is that the NTSB has put out an advisory to the FAA that a major redesign needs to take place in the rudder, the FAA agrees but Boeing (with it's pull in Congress) and commercial pressure dictate that it will never happen. There are alot of them flying so I suppose you could have a couple of dozen fall out of the sky due uncommanded yaw before Boeing really needs to listen to the NTSB or FAA. Crashes aside, it makes a very good product. <img src="tongue.gif" border="0">

[jshg]

As I understand it,Airbus has checked the tails of the A300/A310 fleet worldwide and found nothing.. .The FDRs,CVR,wreckage etc all fell to earth in a civilised country where they have been recovered & are being analysed. If there were a 'straightforward' mechanical explanation I would have thought there would have been an AD by now. The continuing silence puts me in mind of the aftermath of the B737 tragedy at Kegworth,UK,a few years ago, and the drawn-out and rather unsatisfactory conlusion in that case.. .I fly the A300-600 myself,and whilst I'm as anxious as everybody to know the reason,I'm happy to wait for the official conclusion.

[I. M. Esperto]

The Latest from AvFlash:. .FLIGHT 587 MAKES SOME A300 PILOTS BALK: Some 60 American Airlines (AA). .pilots know they're not comfortable flying a jet that may shed its. .vertical fin and engines for reasons that can't yet readily be. .explained, and would like to see the jet grounded. An email campaign. .that intended to have A300 pilots at AA boycott the aircraft has so far. .enlisted the "signatures" of roughly 15 percent of the 413 pilots who. .could ultimately contribute their names to the list. Of particular. .concern to the pilots is the inspection technique used to determine the. .tail's structural integrity -- they find existing methods lacking and. .feel that the loss of 265 lives supports that opinion. The AA A300. .that was Flight 587 took less than three minutes to go from takeoff. .roll to ejecting its vertical fin and both engines and impacting the. .densely populated suburb of Belle Harbor, Queens, N.Y.

NOTE: The NTSB is following up on possibly related events aboard. . A300 jets; see AVweb's NewsWire at &lt;http://avweb.com/n/?05a&gt;.

[Bubbette]

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>

[Raas767]

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.

[Belgique]

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 =&gt; 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.

[liebowa]

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>

[oncemorealoft]

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.

[Beausoleil]

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

[Tan]

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...

[stuartbaker]

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??

[Rwy in Sight]

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

[Wino]

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

[RRAAMJET]

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">

[ARFFmmu]

Doesn't the 777 have a lot of plastic parts too?

[PaperTiger]

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>

[Willie Everlearn]

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">

[Cisco Kid]

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?

[SaturnV]

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.

[Captain104]

"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>

[daidalos]

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?

[Captain104]

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>

[Raas767]

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.

[whatshouldiuse]

Wino;

. .Regarding why the 737's weren't grounded after the Colorado Springs and Pittsburgh disasters, you state an immediate fix was implemented, namely to fly 5 to 10 miles faster during crossover.

You are confusing cause and remedy. Boeing never could find a cause, but they could find a work-around. Two totally different things. If it happens again (and let's pray it doesn't), will Boeing increase it to 15-20mph faster?

You analogy is like to going to a mechanic with your car. Your tell him, every time you reach 40mph it shakes, but when you get above 45mph it's fine. The mechanic tells you not to go 40mph and everything will be fine... or NOT !!

Whatshouldiuse

[ORAC]

SaturnV, you mean this link?:

<a href="http://pull.xmr3.com/p/25356-E59F/30254611/rudder.html" target="_blank">http://pull.xmr3.com/p/25356-E59F/30254611/rudder.html</a>. . <img src="smile.gif" border="0">

[Raas767]

Fish.. .I don't think the problem is in the flight control system itself but in the manner that the FDR measures the degree and rate of movement for the individual control surfaces. As far as I know the-600 has a standard hydraulic system similar to the 767/757.

[dallas dude]

raas 767,

The A300 has a multi channel DFDR. However, the signals sent to the DFDR are not the actual "raw data" (real time) signals but are a repeat of the "averaged" signal as indicated on the pilot displays PFD's, ND's etc.

Hypothetically, if the rudder was slamming from stop to stop (NOT saying it was) the indication would be damped and shown to be far less severe on both the turn coordinator and the DFDR rudder channel(s) than it may ACTUALLY have been. Repeat, hypothetically.

I believe the FAA requested Airbus remove the DFDR averaging several years ago but Airbus never "got round to it", at least on this airplane.

Cheers,

[Al Weaver]

&gt;I believe the FAA requested Airbus remove the DFDR averaging several years ago but Airbus never "got round to it", at least on this airplane.&lt;

Why is this an Airbus responsibility. They don't own or maintain the airplane. Why wasn't this an AAL responsibility?

I suppose all this will be revealed at the NTSB public hearing someday.

[Wino]

The aircraft are still supported by Airbus. That is who does the engineering, issues revisions to the software (The yawdampener is revision 7 fyi) and generally makes changes as requested by the customer or atleast creates the procedure that is then used by the customer to carry out the change.

As to the 737 fix being a work around, yep it is, but tell me, what sort of work around would you have for a structural failure where the tail falls off? As an A300 pilot for AA tell me, I would love to know! Find me a work around and I will shout down anyone who says to ground the aircraft.

While I haven't advocated grounding the aircraft myself, I certainly see my fellow pilot;s point of view.

Even on the Colorado springs or the Pittsburg 737 I can say to myself, I would have reduced angle of attack firewalled the engines and flown it out instead of snap rolling it. Whether I really would have or not is not the issue, atleast there was a chance to fly those aircraft out. When the tail came off of 587 2 good friends of mine were dead, even though their hearts kept beating for another minute or so till they hit the ground, no chance at all. That is hard to accept.

Tails should not fall off of aircraft, can anyone really argue with that? Oddly enough it is airbus's own statements that flooring the rudder in response to an upset would snap the fin off makes me now think that it is a yaw damper problem, not a composit problem. There have been numerous cases of yawdamper failures on the A300 where the airplane swings violently from side to side. Airbus's own statements say that the fin could snap if opposit rudder is applied into a slip, which is what happens in the failure mode of the airbus yawdamper.

So now I am thinking its a computer problem and not a structures problem...

Cheers. .Wino

[PaperTiger]

IIRC, the initial post-crash reports mentioned the yaw-damper software had to be 'fixed' (rebooted, reloaded or what ?). Everybody seems to have been very quiet about that since.

Coincidentally, Airwise is reporting the findings of the Kenya A310 crash (but not the full text).. .A faulty stall warning ? I can't tell from the sparse details if it went off when it shouldn't or didn't when it should have. . .<a href="http://news.airwise.com/stories/2002/02/1012570108.html" target="_blank">http://news.airwise.com/stories/2002/02/1012570108.html</a>

[ 02 February 2002: Message edited by: PaperTiger ]</p>

[whatshouldiuse]

Wino;

. .My deepest sympathies regarding the untimely deaths of your fellow pilots. And yes, the tail did fall off the plane. The question becomes whether this was the 1st failure or as a result of another failure. I don't know. Hopefully, the NTSB final report will shed some light on this. Having said that, and living in New York, this was the last thing the city needed after September 11th....it was the last thing anybody needed !!!

. .Rumor has it however, a New Jersey transit camera caught most of the unfolding events on film. Hopefully this will at least come close to pin-pointing the sequence of events.

. .Whatshouldiuse

[Hand Solo]

PaperTiger - my hazy memory of the Kenyan crash was that one of the angle of attack vanes was bent by a ground handling vehicle, which caused a false stall warning once airborne. Unfortunately in responding to the stall warning at night the crew flew the aircraft into the sea.

[boss man]

Quote

Tails should not fall off of aircraft, can anyone really argue with that?

Says it all really if the guy’s up front don’t feel 100% about the AC then they shouldn’t fly them.

[GeofJ]

All of this talk regarding Airbus "plastic tails" - if you care to check the details modern Boeing planes have composite tail sections as well - it is the modern weight saving method of construction.

[SaturnV]

ORAC, yes that is the link to the Aviation Week engineering analysis, complete with diagrams and all.

Thank you.

[PaperTiger]

HS. .That makes the 'pi**t er**r' finding even more outrageous. WTF were they supposed to do - keep the nose up believing they'd fall out of the sky, or push it down ? Fate is the hunter indeed.

[arcniz]

An alternative to grounding:

At the moment, some things are clear regarding A300 tails and some are not:

Clear: . .a. A lot of A300 flight hours have been logged with tails remaining attached. . .b. AA587 . .c. some plausible reports cite anomalies in rudder ops on other A300's.

Not clear: . .a. cause and mechanism of AA587 failure. .b. potential for similar failure elsewhere in the fleet

If money, careers, and company futures were not at stake, it might be a no-brainer to ground the fleet. Under real-world rules, that is hard to do without a clear and specific reason. Nobody really has the authority to make that decision - absent more facts.

A certain list of people in govt. and industry have a very great responsibility of care and diligence right now - to ascertain the facts. If another accident were to occur, and if it were shown that responsible parties in the chain of accountability had not made the absolute maximum effort to find the cause ASAP, then the folks on that short list might well have civil and possibly criminal responsibility for their failure to act.

Short of grounding aircraft, what can be done to move the failure diagnosis forward faster?

Obtaining better information about the actual performance of flying aircraft could do this. One constraint now is the limitations of the onboard integrated flight data capture systems - which evidently are not generalized enough to provide fully meaningful data in this instance.

I suggest that the airlines, agencies, and/or airframe manufacturer immediately commence a 'Supplemental Data Aquisition' program, whereby a significant number of aircraft are quickly fitted with add-on flight-recording equipment that is optimized to monitor and record all movement at the wiggly end of selected A3xx aircraft in the course of their scheduled operations. This can be done, at least in the first cut, without any modification to aircraft systems - using a self-contained electronics package stowed in the back in the same form factor as a beverage cart or food pod.

The data from deployment of these units would vastly increase our knowledge about:

a) actual tail movements & stresses in normal real-world operations

b) performance variations among individual aircraft, and operators

c) the possibility of occasional 'anomalous events' (hiccups) in the operation of the aircraft controls & systems. . .

Increased flight data collection is something practical, constructive, and quickly do-able in the direction of resolving the A300 tail quandry.

From my own experience - over decades of creating and finding really obscure problems in very complex systems - there are always some telltale precursor signs of systems instability or component flaws that can be detected from measurement and analysis of the operating signature - easy, once you know what to look for.

The cost of this measurement initiative would be very small in relation to the economics of day-to day airline ops, and it would not materially impact ongoing operations. Time to implement a first-cut deployment of the first half-dozen flying packages accumulating real data could be about 30 days from 'go', with more units and improving analytical strategies following in short order after that.

The only way the uncertainty surrounding AA587 can be put to rest is by obtaining better data.. .I will gladly assist, if needed, and welcome any opportunity to help make this happen.

[Captain104]

In my opinion interesting posts yesterday, right back on track. <img src="smile.gif" border="0"> . .ORAC and SaturnV. .Thank you very much for this vital information from Aviation Week. Hopefully a lot of people take their time to read it thoroughly. For me quite new and surprising: yes, it's possible to shake your tail off, at least a yaw damper bug might do it or one in the rudder limiter?. .Can't remember any piece of information in my hands like this before during or after flying A 312/313 or 306(300-600).. .Wino. .Loosing 2 close friends like this is hard to accept, my feelings are with you. . .Mind, me asking where this information is coming from, that there is a known history of yaw damper failures with A 300-600 exeeding normal? Tech.Dep. of my company (one of Europs big 5 and operating Airbus's in Hundreds) tell me, nothing alike, just routine problems as on other AC.. .I am shure, if that's not true or airlines and manufacturer are trying to cover up something we will know some day. . .Hope very much someone with more influence than me little old pilot reads SYSTEMGUY's post. Sounds reasonable, cool and professional. Nice appraoch to the problem and not to expensive. Might this creep into the minds of NTSB or Airbus poeple?

Abidjan crash, like most of other crashes A-310 or A-300-600 under the headline "how to mishandle a modern airplane by not understanding the AFS" has nothing to do with our thread. Left AOA vane damaged, poor guys up front had now idea what was going on. A look for basic settings, i.e. attitude, powersetting, climbrate and speed should have helped. But...at night, tired, I felt sorry for them.

[Belgique]

This snippet below, (from the recent NTSB 7th update) would seem to revisit my theory (http://www.pprune.org/forums/showthread.php?s=&threadid=2617&perpage=15&highlight=AA587&pagenumber=2) of a pressure-wave reverberation induced within the Central Air Data Computer by aberrant pitot-static measured pressure inputs. Whether by water in the system or otherwise-induced pressure fluctuations, in my opinion it remains a mechanism by which a chaotic flutter mode could be introduced into the rudder circuit via the rudder limiter or yaw damper.

This SIA incident (below) could just as likely have been caused by water in the static system. The tricky woo aspect of water in the static system is that normal post-incident trouble-shooting can eliminate it, without its presence (and therefore significance) ever being noted (or suspected). It is then perhaps wishful thinking to cinch up some pneumatic connections a little tighter and then put it all down to having been an air-leak.

I see this incident as a significant development in the sleuthing of AA587's initiating events.

Other Airbus Event

The Safety Board is interested in another upset event last year involving an Airbus aircraft. On November 25, 2001, a Singapore Airlines A340-300 departed Singapore for a scheduled flight to Dhaka, with 96 persons aboard. Shortly after takeoff, the pilots noticed a problem with airspeed indicators. Among other things, there were overspeed warnings and large rudder movements without pilot input. The aircraft returned to Singapore and made a safe landing; there were no injuries.

Inspection subsequently found problems with the pitot and static connections to the air data computers, which may have been introduced during recent maintenance. The Civil Aviation Authority of Singapore is investigating the incident. Due to computed loads that might have been experienced by the vertical stabilizer, it and the attached rudder were removed from the aircraft shortly after the incident and were recently examined in Germany. Although no damage was found in either the stabilizer or the rudder, the Board is interested in the rudder system's role in this event.



http://www.pprune.org/forums/showthread.php?s=&threadid=2617&perpage=15&highlight=AA587&pagenumber=2

[vikingwill]

How a material behaves is typically modeled in mathematical simulations as it is almost impossible to run real time studies under real in-use conditions for a number of reasons:

* can't predict all the variables
* can't run them to exclude all failure modes

Real in-use experience from real flying hours over the years with planes fabricated from lightweight metals such as aluminium, magnesium alloys allows manufacturers to predict part life. However, adding significant structural components made from composites means that ALL we have is mathematical models of stability and performance projected for the lifetime of the part (aircraft). Real time experience is now being gathered. The fact that an A300 rudder or other composite component failed may be the first piece of real time experience that we have a problem.

I suspect that Airbus Industries have masses of data to support the airworthiness of the composites. However, I'll wager that the majority of this is "technical justification" based on so called validated modeling techniques, supplemented by real time flying hours.

This may not be deja vue with the Comet, but its right to be concerned and at minimum inspection frequencies should be reduced.

Vikingwill

[RatherBeFlying]

NTSB update #7 also contains: The Safety Board has asked NASA to produce a model of the wake vortices that flight 587 encountered to further study their possible role in the sequence of events.

Belgique is suspicious of pitot-static system faults and the SIA event certainly adds support for this possibility.

My stronger suspicion still leans on possibly misleading signals from the sideslip sensor as the a/c transected various flow regions of the vortex. I suspect significant periods where the sideslip sensor was in different flow regions within the vortices than the fin and look forward to what the model will show.

[Ignition Override]

How many airlines now operating the 737 or A-300 require pilots to fly through simulated uncommanded rudder "hardovers", even if above crossover speed?

Not all US major airlines require unusual attitude training, although United began this training years ago due to the very controversial B-737 accident at Colorado Springs. This would do much more to improve safety in any plane than doing a [parallel..] PRM approach (yes: early last December), knowing already that the primary airport does not even do PRMs anymore.

But gosh Mr. VP Cost Accounting 501, think of the cost to operate those sims just an extra 10 minutes! That would blow our 4-hour sim session blocks and those precious budgets...those management bonuses are such sacred cows.

[TheShadow]

see their paper via this thread:

AA587 Revisited (http://www.iasa-intl.com/folders/AA587revisited/AA587 Revisited.htm)

[411A]

What a surprise....and to think, some of the AA guys actually have an interest, instead of smiling at their bankbooks..:*

[Ignition Override]

Hey Pprune Crew: for those who believe that the FAA will ground any fleet which suffers a crash due to a flight control malfunction, are you all not aware that the FAA knew about serious control problems with some European airline ATR 42s weeks or months before the terrible disaster in Roselawn, Indiana? The FAA required no new inspections of ATRs with US airlines, and probably never rechecked its icing certification criteria until those people smashed into the frozen Indiana cornfield. Because of the dead people, our dedicated protectors at the FAA then commisioned an Air Force KC-135 tanker to spray water with an ATR flying behind the extended boom, analyzed the surprising results in front of the ailerons, and found that their criteria for icing conditions needed some changes.

Wasn't the American A-300, which crashed near JFK, previously involved in a hard landing incident? If this happened, did it not exert some sort of severe stress on the vertical stabilisor?

Does the FAA ever receive detailed reports on any military aircraft control problems, domestic or overseas (even foreign military?), which involve types with civilian equivalents, i.e. Beechjet trainers, C-130, KC-135, Gulfstreams or 707s at Andrews, Tinker AFB, Lears and 737s at Ramstein AFB (or Stuttgart) etc? Or do the squadrons and wings keep all system anomaly reports (compartmentalized) between them and the manufacturers? Is "plausible denial of info" always a watertight story?

Pprune bosses-nice improvement on the character icons.

[Frangible]

FAA icing certification standards have still not changed. It is no 2 on the NTSB'S hit parade of "most wanted" safety changes. The FAA only has a legal view of safety. They never say such and such is safe, or pretty safe, or damn dangerous, just that it is, or is not "in compliance".

The Chinese alerted FAA in 1996 to the high inflammability of Mylar insulation after some nasty fires, and got a snotty letter back saying, basically, "what you say may be true, but it is still in compliance". They only started to put the changes in after Swissair 111. The idea that something could be in compliance and a threat to air safety, like the ATR 42-72 in freezing rain, is not a permissible concept at FAA HQ.