Concorde crash: Continental Airlines cleared by France court
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Howdy Chris, CliveL
Quote:
A displacement in the horizontal plane is, on the other hand, abnormal. It requires predominance of horizontal loads over vertical loads, which is not the case during the takeoff phase.
My guess is there was vibration as the vertical loads lessened, and not by much, until the bogie wobbled to its limit. In the crush of alarms, and confusion, the FE may have associated this extreme vibration with an immediate need to cage the engine that may be causing it. I merely suggest that pulling an engine at rotation is not done, so the conditions were likely extreme, and needed some action. I believe FE believed he was doing the right thing...
The spacer was NOT inconsequential. It may have played a direct part in crashing the aircraft so quickly after take off. The cause of the disaster was fire. Dozens of opportunities for this result were on record. Blown out fuel tanks, disintegrating tyres, loss of wing skin and hydraulics. BTSC (all Concordes) were susceptible.
That the authority allowed the operator to get off claiming it was FOD is contemptible. The aircraft was vulnerable to spontaneous tyre rupture for goodness sake. A fluke piece of metal?
There will be FOD. Easier in the long run to hold operator to account in the long run, Than bend over backwards to protect the responsibles from owning up.
Does BEA address the shimmy? I do. I do not blame shimmy, nor Titane. I blame EASA for letting things slide. The stage is ever full of scapegoats, but lacks responsibility and integrity, all too often.
Quote:
A displacement in the horizontal plane is, on the other hand, abnormal. It requires predominance of horizontal loads over vertical loads, which is not the case during the takeoff phase.
My guess is there was vibration as the vertical loads lessened, and not by much, until the bogie wobbled to its limit. In the crush of alarms, and confusion, the FE may have associated this extreme vibration with an immediate need to cage the engine that may be causing it. I merely suggest that pulling an engine at rotation is not done, so the conditions were likely extreme, and needed some action. I believe FE believed he was doing the right thing...
The spacer was NOT inconsequential. It may have played a direct part in crashing the aircraft so quickly after take off. The cause of the disaster was fire. Dozens of opportunities for this result were on record. Blown out fuel tanks, disintegrating tyres, loss of wing skin and hydraulics. BTSC (all Concordes) were susceptible.
That the authority allowed the operator to get off claiming it was FOD is contemptible. The aircraft was vulnerable to spontaneous tyre rupture for goodness sake. A fluke piece of metal?
There will be FOD. Easier in the long run to hold operator to account in the long run, Than bend over backwards to protect the responsibles from owning up.
Does BEA address the shimmy? I do. I do not blame shimmy, nor Titane. I blame EASA for letting things slide. The stage is ever full of scapegoats, but lacks responsibility and integrity, all too often.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
We know that - he couldn't be certain...
Again, we know that with the benefit of hindsight and rigorous analysis, but the FE was confronted with alarms and indications consistent with fire (the fire alarm and gong sounded at 14:43:22.8) and likely damage. The surges were presumably triggered by the presence of hot gases in the vicinity of the intakes - but the FE didn't have the luxury of definitive evidence that we do. The startle effect would have been sufficient to cause a lapse in procedure on his part, but given the circumstances that would be entirely understandable.
@Lyman - the aircraft's tyre issues were not "spontaneous" in nature - at least some were precipitated by other problems (in one case the brakes locked on the takeoff roll). Not all incidents (in particular the first at Dulles EDIT - incorrect, see below) were investigated for the cause of the tyre failure.
Note that I'm not saying your theory is impossible, simply that given the fact we know the FE was confronted by critical warning indications it is more likely he was responding to those.
But engine 2 had no real internal damage - in fact the BEA report says specifically that the internal state was not such as would cause surge. Equally there is no mention of any engine failures that might give rise to a genuine fire warning from flames inside the nacelle.
@Lyman - the aircraft's tyre issues were not "spontaneous" in nature - at least some were precipitated by other problems (in one case the brakes locked on the takeoff roll). Not all incidents (in particular the first at Dulles EDIT - incorrect, see below) were investigated for the cause of the tyre failure.
Note that I'm not saying your theory is impossible, simply that given the fact we know the FE was confronted by critical warning indications it is more likely he was responding to those.
Last edited by DozyWannabe; 17th Dec 2012 at 17:48.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
@Lyman (below) - that's an assumption. The evidence we have of tyre failures causing subsequent damage to Concorde suggest that in the cases where root cause was investigated, there were mechanical factors leading to failure of the tyre. The other incidents were never investigated to that level - there has never been a documented case of a Concorde tyre incident where there was no plausible explanation for the tyre failure (and thus no evidence to suggest tyres failed "spontaneously").
Last edited by DozyWannabe; 17th Dec 2012 at 17:07.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Dozy
Please read every word, I said the a/c was VULNERABLE to spontaneous rupture.
As to the rest, I like your take on the FE's predicament.
Point being, I think it took something we may not be seeing for him to counter best practice.
Please read every word, I said the a/c was VULNERABLE to spontaneous rupture.
As to the rest, I like your take on the FE's predicament.
Point being, I think it took something we may not be seeing for him to counter best practice.
Last edited by Lyman; 17th Dec 2012 at 17:06.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
Correction:
I have been reliably informed that the cause of the Dulles tyre failure was investigated and determined to be an underinflation of the neighbouring tyre to that which failed - the (arguably inadequate with hindsight) fix was a mechanical device which detected mismatched tyre inflation.
This does not alter the extent of my research indicating that there was no attempt to determine the preceding cause of a tyre failure on Concorde which could not be explained.
Addendum:
As stated earlier, the required time periods for the damaged fuel tank to drain, the potential additional altitude had #2 not been shut down and, crucially, the time taken for the fire to irreparably destroy the controls were thoroughly calculated. There was no way for the aircraft to have reached Le Bourget before control was lost.
The report documents thoroughly the shortcomings of all parties involved and simply lists them, with no implicit or explicit guidance as to relative importance - the initial decision to prosecute CO was judicial - neither regulatory nor investigative.
Yes (as Clive twice stated, check section 18.2.3.3).
Pay close attention to Clive correcting me a short while ago:
Any shimmy or instability would therefore have affected all four tyres to some extent, but it was only the tyre that contacted the metal strip which failed.
I have been reliably informed that the cause of the Dulles tyre failure was investigated and determined to be an underinflation of the neighbouring tyre to that which failed - the (arguably inadequate with hindsight) fix was a mechanical device which detected mismatched tyre inflation.
This does not alter the extent of my research indicating that there was no attempt to determine the preceding cause of a tyre failure on Concorde which could not be explained.
Addendum:
That the authority allowed the operator to get off claiming it was FOD is contemptible.
Does BEA address the shimmy?
Pay close attention to Clive correcting me a short while ago:
Any shimmy or instability would therefore have affected all four tyres to some extent, but it was only the tyre that contacted the metal strip which failed.
Last edited by DozyWannabe; 17th Dec 2012 at 18:14.
Join Date: Nov 2010
Location: FR
Posts: 477
Likes: 0
Received 0 Likes
on
0 Posts
As stated by DW, all other things being the same, yes I think it would have, based on all material available.
Let us begin with brake release. First off, a skidding tyre has less authority to affect direction. If skidding from the start, the left bogie is having less effect on direction than the right. That means the a/c will tend right, and may explain the Captain's initial left ruddering. (with four healthy engines))
And I strongly disagree with "That means the a/c will tend right": Indeed, if skidding from the start, the left side of the aircraft would have been more draggy than the right side. Not the opposite.
My guess is there was vibration as the vertical loads lessened, and not by much, until the bogie wobbled to its limit. In the crush of alarms, and confusion, the FE may have associated this extreme vibration with an immediate need to cage the engine that may be causing it. I merely suggest that pulling an engine at rotation is not done, so the conditions were likely extreme, and needed some action. I believe FE believed he was doing the right thing...
- recorded on the FDR;
- likely commented by the crew (on the CVR)?
AFAIK, no report of important vibrations on the CVR. Didn't check FDR traces, but I suggest it is to be done before pushing further your hypothesis, Lyman.
And I'm sure the FE believed he was doing the right thing, but that's not the point.
You don't know that. We are discussing this right now, and so far no hard indication has been found of its consequentiality, but BEA report strongly suggests it had none (and explains why, and describes the tests done to arrive to that conclusion).
Identified causes of such tyre ruptures were adressed, if my memory serves, in the Washington'79 report, or since then.
Join Date: Mar 2007
Location: Cardiff UK
Age: 69
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
Hi Lyman
You have spent a great amount of time discussing the missing spacer and the possible consequences of it's absence. It may be helpful if you could collect all your thoughts together in one post. I think in doing so, it can be taken for granted that you think the missing spacer is of importance, so for clarity sake it may be wise not to repeat your detailed analysis of that absence, but instead concentrate on it's relevance to the final outcome.
You have spent a great amount of time discussing the missing spacer and the possible consequences of it's absence. It may be helpful if you could collect all your thoughts together in one post. I think in doing so, it can be taken for granted that you think the missing spacer is of importance, so for clarity sake it may be wise not to repeat your detailed analysis of that absence, but instead concentrate on it's relevance to the final outcome.
Last edited by Nick Thomas; 17th Dec 2012 at 19:02.
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,777
Likes: 0
Received 0 Likes
on
0 Posts
The jargon of BEA
Concorde trial 2 March 2010
Concorde trial 2 March 2010
Me RAPPAPORT
Ce qui est développé est que le risque incendie était imprévisible donc en sa qualité de patron du BEA, M. ARSLANIAN a une connaissance approfondie, c’est pourquoi je veux lui demander si avant 2000 ce risque avait été envisagé.
M. ARSLANIAN
Il est difficile de répondre à la question sans la reformuler. Au cours de l’enquête nous avons remarqué un incendie très spécifique. Auparavant, notamment en 1979, il y a eu une apparition de flamme qui s’éteint tout de suite. Je ne peux répondre qu’en tant qu’enquêteur. Mon opinion est faite même si je ne crois pas en avoir fait part dans ma présentation. J’ai dit qu’il fallait un certain nombre de condition pour obtenir la flamme, que l’on trouvait dans cette énorme fuite très spécifique à l’accident.
Me RAPPAPORT
Il n’a pas été répondu à ma question. Est-ce qu’avant 2000 un incendie quelconque avait été envisagé ?
M. ARSLANIAN
Je réponds de la façon dont je parle. Le BEA travaille sur des évènements. IL n’y a jamais eu d’incendie sur le Concorde avant 2000. La certification ne peut pas se faire sans prendre en compte ce genre de risque. Mais ce n’est pas à moi de répondre sur ce point. Nous ne faisons pas de spéculations. Tous ce que je remarque c’est qu’à l’étude des évènements, nous n’avons pas relevé de risque incendie.
Me RAPPAPORT
M. ARSLANIAN n’a pas répondu
LA PRESIDENTE
Il y a répondu
Me RAPPAPORT
A sa façon.
Ce qui est développé est que le risque incendie était imprévisible donc en sa qualité de patron du BEA, M. ARSLANIAN a une connaissance approfondie, c’est pourquoi je veux lui demander si avant 2000 ce risque avait été envisagé.
M. ARSLANIAN
Il est difficile de répondre à la question sans la reformuler. Au cours de l’enquête nous avons remarqué un incendie très spécifique. Auparavant, notamment en 1979, il y a eu une apparition de flamme qui s’éteint tout de suite. Je ne peux répondre qu’en tant qu’enquêteur. Mon opinion est faite même si je ne crois pas en avoir fait part dans ma présentation. J’ai dit qu’il fallait un certain nombre de condition pour obtenir la flamme, que l’on trouvait dans cette énorme fuite très spécifique à l’accident.
Me RAPPAPORT
Il n’a pas été répondu à ma question. Est-ce qu’avant 2000 un incendie quelconque avait été envisagé ?
M. ARSLANIAN
Je réponds de la façon dont je parle. Le BEA travaille sur des évènements. IL n’y a jamais eu d’incendie sur le Concorde avant 2000. La certification ne peut pas se faire sans prendre en compte ce genre de risque. Mais ce n’est pas à moi de répondre sur ce point. Nous ne faisons pas de spéculations. Tous ce que je remarque c’est qu’à l’étude des évènements, nous n’avons pas relevé de risque incendie.
Me RAPPAPORT
M. ARSLANIAN n’a pas répondu
LA PRESIDENTE
Il y a répondu
Me RAPPAPORT
A sa façon.
I RAPPAPORT (lawyer)
What is developed is that the risk of fire was so unpredictable in his capacity as head of the BEA, Mr. ARSLANIAN has extensive knowledge, which is why I want to ask if this risk before 2000 was considered.
Mr. ARSLANIAN (BEA director)
It is difficult to answer the question without reformulation. During the investigation we noticed a very specific fire. Before, including in 1979, there was an appearance of flame is extinguished immediately. I can not answer that as an investigator. My mind is made even if I do not think I have expressed in my presentation. I said he had a number of conditions for the flame, which was in this huge leak very specific accident.
I RAPPAPORT
It was not answered my question. Does anyone before 2000 fire had been considered?
Mr. ARSLANIAN
I answer the way I speak. BEA working on events. THERE has never been a fire on the Concorde before 2000. Certification can not be made without taking into account this kind of risk. But it is not for me to answer on this point. We do not speculate. All that I see is that the study of events, we found no fire risk.
I RAPPAPORT
Mr. ARSLANIAN did not respond
THE PRESIDENT (of the court)
He responded
I RAPPAPORT
In his own way.
What is developed is that the risk of fire was so unpredictable in his capacity as head of the BEA, Mr. ARSLANIAN has extensive knowledge, which is why I want to ask if this risk before 2000 was considered.
Mr. ARSLANIAN (BEA director)
It is difficult to answer the question without reformulation. During the investigation we noticed a very specific fire. Before, including in 1979, there was an appearance of flame is extinguished immediately. I can not answer that as an investigator. My mind is made even if I do not think I have expressed in my presentation. I said he had a number of conditions for the flame, which was in this huge leak very specific accident.
I RAPPAPORT
It was not answered my question. Does anyone before 2000 fire had been considered?
Mr. ARSLANIAN
I answer the way I speak. BEA working on events. THERE has never been a fire on the Concorde before 2000. Certification can not be made without taking into account this kind of risk. But it is not for me to answer on this point. We do not speculate. All that I see is that the study of events, we found no fire risk.
I RAPPAPORT
Mr. ARSLANIAN did not respond
THE PRESIDENT (of the court)
He responded
I RAPPAPORT
In his own way.
Join Date: Jul 2002
Location: UK
Posts: 3,093
Likes: 0
Received 0 Likes
on
0 Posts
@jcj:
That excerpt has little utility as it is shorn of any context. Were precautions taken in the design of Concorde relating to fire in general? Of course they were - and I'm sure Clive would be able to quote chapter-and-verse on the subject.
The problem is and will always be that fire on an aircraft has a nasty habit of defeating even the best attempts of engineers to minimise its impact - it only takes a minor maintenance or loading error here or an unexpected area of damage there to make the situation considerably worse than envisaged, and Concorde is most certainly not alone in having fallen victim to this unfortunate circumstance.
Additionally, M. Arslanian was well within his rights to answer the way he did, as none of the previous incidents of tyre/fuel tank damage occurred in a manner to which the BEA would have been primary investigators. The lawyer's somewhat facetious response should have resulted in an objection.
That excerpt has little utility as it is shorn of any context. Were precautions taken in the design of Concorde relating to fire in general? Of course they were - and I'm sure Clive would be able to quote chapter-and-verse on the subject.
The problem is and will always be that fire on an aircraft has a nasty habit of defeating even the best attempts of engineers to minimise its impact - it only takes a minor maintenance or loading error here or an unexpected area of damage there to make the situation considerably worse than envisaged, and Concorde is most certainly not alone in having fallen victim to this unfortunate circumstance.
Additionally, M. Arslanian was well within his rights to answer the way he did, as none of the previous incidents of tyre/fuel tank damage occurred in a manner to which the BEA would have been primary investigators. The lawyer's somewhat facetious response should have resulted in an objection.
Last edited by DozyWannabe; 17th Dec 2012 at 19:57.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Nick, CliveL, Chris Scott.
There is evidence the Bogie was rotating in its horizontal plane. That is clear from the images in BEA.
BEA describes such horizontal articulation as an abnormal.
If in evidence (it is), and also an abnormal, we can assume there is a possibility it played a part in the tragic crash.
Unlike the strip, the condition for wobble was present at take off, iow, part of the compromised airframe, not a foreign piece of debris. The legal implications of presence of inherent vunerability as opposed to accidental accumulation of debris are clear.
"Had no effect..." "Played no part in the crash...". "The lack of the spacer was not relevant..."
All demonstrably untrue statements.
Can the misalignment of the left main landing gear be explained in ways that do not involve the missing spacer? Certainly, but those postulates do not eliminate questions that seriously compromise any legal action Air France may entertain against Continental (United/Continental)......
thoughts?
CliveL.... The side loads provided by the misaligned bogie are apparent in the photography. What affect?
There are clues in the record of ruddering by the Captain. Nx would be conclusive, but Captain's inputs as explained in the text of the BEA seem tentative, given the extent of the excursion, and irregular, though the heading seemed consistently left in direction and rate.
There is a possiblity the bogie played a part in the Captain's perception of yaw? The a/c was not answering the right ruddering, yet three times he returned the pedals to neutral? Once he returned to 10 right, from 20?
There is evidence the Bogie was rotating in its horizontal plane. That is clear from the images in BEA.
BEA describes such horizontal articulation as an abnormal.
If in evidence (it is), and also an abnormal, we can assume there is a possibility it played a part in the tragic crash.
Unlike the strip, the condition for wobble was present at take off, iow, part of the compromised airframe, not a foreign piece of debris. The legal implications of presence of inherent vunerability as opposed to accidental accumulation of debris are clear.
"Had no effect..." "Played no part in the crash...". "The lack of the spacer was not relevant..."
All demonstrably untrue statements.
Can the misalignment of the left main landing gear be explained in ways that do not involve the missing spacer? Certainly, but those postulates do not eliminate questions that seriously compromise any legal action Air France may entertain against Continental (United/Continental)......
thoughts?
CliveL.... The side loads provided by the misaligned bogie are apparent in the photography. What affect?
There are clues in the record of ruddering by the Captain. Nx would be conclusive, but Captain's inputs as explained in the text of the BEA seem tentative, given the extent of the excursion, and irregular, though the heading seemed consistently left in direction and rate.
There is a possiblity the bogie played a part in the Captain's perception of yaw? The a/c was not answering the right ruddering, yet three times he returned the pedals to neutral? Once he returned to 10 right, from 20?
Last edited by Lyman; 18th Dec 2012 at 20:46.
Join Date: Dec 2010
Location: Europe
Age: 88
Posts: 290
Likes: 0
Received 0 Likes
on
0 Posts
Lyman
You can find Nx in either in Section 1.16.13.2 of the BEA report or, more exactly, in Fig 1 of Annexe 4p of that report.
Now you are just putting back to me the question I asked you in an earlier posting...
But if you are going to claim that the absence of the spacer had a significant effect on the outcome then you really should provide some more quantitative arguments than anything written so far. Everything I have seen and such calculations as one can make are consistent with the effect of the spacer being rather small - well actually I would say very small.
You can find Nx in either in Section 1.16.13.2 of the BEA report or, more exactly, in Fig 1 of Annexe 4p of that report.
The side loads provided by the misaligned bogie are apparent in the photography. What affect?
Shimmy, as I understand it, is a cyclical rotation of the wheels about the main leg. Again at the time we are talking about, the aircraft sideslip was 3 deg. Allowing for +/- 3 deg oscillation because of the missing spacer that would mean the wheels oscillating between zero and 6 deg would it not? Why would the time they were at less than 3 deg not offset the time they were at more? Or in other words, why should shimmy change the average force?
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Thanks CliveL, your response is appreciated.
Your question is a good one, and I would like to offer that the quantitative component should have been done by BEA in the first place, after all, it is their photography.
I have offered possible approaches to glean some understanding of the affect of tyre rupture, and my suggestions have been ignored. Likewise, an attempt to quantify would be based on data supplied from BEA, data I believe is lacking in sufficiency.
It is BEA who proffered the photography, and begged the work, then did not perform it. Neglectful.
It was BEA that exonerated any complicity of the shoddy Mx by AF. Presumptuous.
It was BEA who did not provide the chemical analysis of the rubber that may have proven the Titanium had been present in the tyre's carcass. In neglecting even the attempt to prove conclusively the strip was involved, they demean the discipline itself. Lazy.
It was BEA that neglected elimination of material other than Titanium as the cause of tyre rupture, Cowcatcher/mount?
Was the area of the truck's mount inspected/analysed by BEA for abnormal wear? The landing gear had travelled several miles carrying two hundred tons, was the spacer's saddle worn?
Was the #2 tyre studiously tested for weakness, as it was two thirds through its useful life, and may have acquired weaknesses unrelated to FOD? Were the other three tyres on the left bogie scrupulously inspected for evidence of misalignment of carriage?
Has anyone found an opinion on why the Captain's rudders were not planted full right? And held?
The report can be described in many terms. Exhaustive is not one such term.
Quote:
Shimmy, as I understand it, is a cyclical rotation of the wheels about the main leg. Again at the time we are talking about, the aircraft sideslip was 3 deg. Allowing for +/- 3 deg oscillation because of the missing spacer that would mean the wheels oscillating between zero and 6 deg would it not? Why would the time they were at less than 3 deg not offset the time they were at more? Or in other words, why should shimmy change the average force?
Shimmy is analogous to a human heart in arrhythmia. A pulse of two hundred, and no blood flows, the pump is stalled. Shimmy means skid, and skid means poor traction, and irregular bite at that.
"Shimmy" makes unlikely any predictable effect of any part (cycle) of the oscillation. Therefore, because the bogie is aligned ("established") part time, one cannot then predict that the corollary alignment is of equal (balanced) force.
Note the shape of the shimmied tyre, number 1. The excursion left is broad, the return to "zero" is sharp, and shortlived. Therefore, the side load is left, and LEFT.....no balancing side load right. This demonstrates that at least in the area of the photographic evidence, the net load is constantly left. This means a bogie that is tracking well left of the longitudinal axis of the airframe.
"Shimmy" in itself does not suggest the kind of conclusion you make, some "balanced" or normed load. There is no reason to assume the shimmy was established in consistent fashion at any time, except for the three arcs of tread deposit we see. It could have been extremely irregular.
An admission. I have not found the reference to shimmy in the Report. Therefore I do not know BEA's conclusions. I'm extrapolating on evidence I see, and read elsewhere and in the BEA work.
My assumption is that BEA rejected the possibility that a missing part contributed to the crash. If they did not, and lay some responsibility on AF, that would be a welcome coincidence?
Your question is a good one, and I would like to offer that the quantitative component should have been done by BEA in the first place, after all, it is their photography.
I have offered possible approaches to glean some understanding of the affect of tyre rupture, and my suggestions have been ignored. Likewise, an attempt to quantify would be based on data supplied from BEA, data I believe is lacking in sufficiency.
It is BEA who proffered the photography, and begged the work, then did not perform it. Neglectful.
It was BEA that exonerated any complicity of the shoddy Mx by AF. Presumptuous.
It was BEA who did not provide the chemical analysis of the rubber that may have proven the Titanium had been present in the tyre's carcass. In neglecting even the attempt to prove conclusively the strip was involved, they demean the discipline itself. Lazy.
It was BEA that neglected elimination of material other than Titanium as the cause of tyre rupture, Cowcatcher/mount?
Was the area of the truck's mount inspected/analysed by BEA for abnormal wear? The landing gear had travelled several miles carrying two hundred tons, was the spacer's saddle worn?
Was the #2 tyre studiously tested for weakness, as it was two thirds through its useful life, and may have acquired weaknesses unrelated to FOD? Were the other three tyres on the left bogie scrupulously inspected for evidence of misalignment of carriage?
Has anyone found an opinion on why the Captain's rudders were not planted full right? And held?
The report can be described in many terms. Exhaustive is not one such term.
Quote:
Shimmy, as I understand it, is a cyclical rotation of the wheels about the main leg. Again at the time we are talking about, the aircraft sideslip was 3 deg. Allowing for +/- 3 deg oscillation because of the missing spacer that would mean the wheels oscillating between zero and 6 deg would it not? Why would the time they were at less than 3 deg not offset the time they were at more? Or in other words, why should shimmy change the average force?
Shimmy is analogous to a human heart in arrhythmia. A pulse of two hundred, and no blood flows, the pump is stalled. Shimmy means skid, and skid means poor traction, and irregular bite at that.
"Shimmy" makes unlikely any predictable effect of any part (cycle) of the oscillation. Therefore, because the bogie is aligned ("established") part time, one cannot then predict that the corollary alignment is of equal (balanced) force.
Note the shape of the shimmied tyre, number 1. The excursion left is broad, the return to "zero" is sharp, and shortlived. Therefore, the side load is left, and LEFT.....no balancing side load right. This demonstrates that at least in the area of the photographic evidence, the net load is constantly left. This means a bogie that is tracking well left of the longitudinal axis of the airframe.
"Shimmy" in itself does not suggest the kind of conclusion you make, some "balanced" or normed load. There is no reason to assume the shimmy was established in consistent fashion at any time, except for the three arcs of tread deposit we see. It could have been extremely irregular.
An admission. I have not found the reference to shimmy in the Report. Therefore I do not know BEA's conclusions. I'm extrapolating on evidence I see, and read elsewhere and in the BEA work.
My assumption is that BEA rejected the possibility that a missing part contributed to the crash. If they did not, and lay some responsibility on AF, that would be a welcome coincidence?
Last edited by Lyman; 18th Dec 2012 at 22:45.
Join Date: Nov 2010
Location: FR
Posts: 477
Likes: 0
Received 0 Likes
on
0 Posts
Hi Lyman,
I'm sorry, but my reaction to that is: Certainly not!
For those to be demonstrably untrue, we need far more than "just" one pic.
Do we have more? In fact yes, see below.
Yes, we could assume that, but only if the "wobble" was present for a "long" time. Was it? What elements do we have? Let's see:
- 1 picture showing what looks like the wobble, that you attributed to the missing spacer (likely, I agree); this pic also show the broken runway light; hence we know that the pic show the runway at ~2,800 meters.
- other pictures not showing the "likely wobble", or not clearly at all, taken from earlier parts of the runway;
- a rather complete description from the BEA, quoted below:
OK, so, probable wobble @ 2,800m, but no wobble on the pic showing the soot on the runway. The soot on the runway, where was it? Easy:
On the pic showing the (dense) soot on the runway, no indication of wobble at all. Only tracks from the (already destroyed/destroying) #2 tyre.
=> No wobble @ somewhere between 1,860 m and 2,300 m.
=> Shown on the picture, and confirmed in the BEA's text (§ 1.12.1.8, quoted above)
At that time (and even considering 'only' the lower value of 1,860 m despite said §), the aircraft is already on fire, meaning the strip/tyre/fuel leak/ignition events already took place.
To be sure, let's search where other relevant items were noted relative to the beginning of the runway:
1,642 m -> the first parts found are from the water deflector, from slab 139 and onwards;
1,740 m -> the titanium strip, at slab 152;
1,740 m -> a big part of tyre (transversally cut) at same slab 152;
1,820 m -> the unburnt kerozen mark at slab 163;
1,860 m -> the first traces of soot (hence: fire);
1,950 m -> the other 'fitting' part of the transversally cut tyre at slab 180.
1,957 m -> signs of an explosion and a piece of concrete separated from the runway (my comment: that shows that the leak/fire was not due to this 'explosion' whatever it really was - EDIT it was not the tyre explosion, as noted in appendix 6 of the final report (which provides a pic): "The explosion could be explained by the forward propagation of the combustion zone").
=> this clearly shows that the fire ignited one kilometer before the only picture we may consider as conclusive of a wobble (@ 2,800 m)...
=> ... and 460 m before the first "irregular tyre tracks" were noted by the BEA (@ 2,340 m).
This is why, I think, the BEA concluded (rightly) that the lack of the spacer - even if one can discern indications it made the bogie wobble around 2,340 to 2,800m from the runway beginning - was not relevant to and played no part in the final outcome, which was sadly certain as soon as the fire broke.
QED.
Regards,
AZR.
For those to be demonstrably untrue, we need far more than "just" one pic.
Do we have more? In fact yes, see below.
- 1 picture showing what looks like the wobble, that you attributed to the missing spacer (likely, I agree); this pic also show the broken runway light; hence we know that the pic show the runway at ~2,800 meters.
- other pictures not showing the "likely wobble", or not clearly at all, taken from earlier parts of the runway;
- a rather complete description from the BEA, quoted below:
1.12.1.8 Tyre tracks
From Slab 161 level to Slab 232 level, that is between 1,807 and 2,340 m, the mark of a deflated tyre with an incomplete tread was observed.
This mark was parallel to the runway axis (at about 3.8 m) then diverged at about 2,200 metres.
When this mark disappeared at about 2,340 m, its displacement from the centreline was about 8 m. This corresponded to the right front tyre of the aircraft’s left landing gear.
Further on, some irregular tyre tracks from the left landing gear were noted up to the broken edge light (2,800 metres).
After that point, the tracks become intermittent then disappear at about 2,830 metres from the runway threshold.
From Slab 161 level to Slab 232 level, that is between 1,807 and 2,340 m, the mark of a deflated tyre with an incomplete tread was observed.
This mark was parallel to the runway axis (at about 3.8 m) then diverged at about 2,200 metres.
When this mark disappeared at about 2,340 m, its displacement from the centreline was about 8 m. This corresponded to the right front tyre of the aircraft’s left landing gear.
Further on, some irregular tyre tracks from the left landing gear were noted up to the broken edge light (2,800 metres).
After that point, the tracks become intermittent then disappear at about 2,830 metres from the runway threshold.
OK, so, probable wobble @ 2,800m, but no wobble on the pic showing the soot on the runway. The soot on the runway, where was it? Easy:
A mark 15 m x 15 m identified as probably being kerosene was noted around line 163, 1,820 metres from the threshold. Then, traces of soot, produced by incomplete combustion of kerosene, were apparent on the runway 1,860 m onward from the origin (Slab 168). These were large and dense up to 2,300 m and then became less dense and rich in carbon up to taxiway S4, at 2,770 metres. The traces, which were on average 7 m wide, were initially centred on the damaged wheel ground mark and progressed towards the left.
=> No wobble @ somewhere between 1,860 m and 2,300 m.
=> Shown on the picture, and confirmed in the BEA's text (§ 1.12.1.8, quoted above)
At that time (and even considering 'only' the lower value of 1,860 m despite said §), the aircraft is already on fire, meaning the strip/tyre/fuel leak/ignition events already took place.
To be sure, let's search where other relevant items were noted relative to the beginning of the runway:
1,642 m -> the first parts found are from the water deflector, from slab 139 and onwards;
1,740 m -> the titanium strip, at slab 152;
1,740 m -> a big part of tyre (transversally cut) at same slab 152;
1,820 m -> the unburnt kerozen mark at slab 163;
1,860 m -> the first traces of soot (hence: fire);
1,950 m -> the other 'fitting' part of the transversally cut tyre at slab 180.
1,957 m -> signs of an explosion and a piece of concrete separated from the runway (my comment: that shows that the leak/fire was not due to this 'explosion' whatever it really was - EDIT it was not the tyre explosion, as noted in appendix 6 of the final report (which provides a pic): "The explosion could be explained by the forward propagation of the combustion zone").
=> this clearly shows that the fire ignited one kilometer before the only picture we may consider as conclusive of a wobble (@ 2,800 m)...
=> ... and 460 m before the first "irregular tyre tracks" were noted by the BEA (@ 2,340 m).
This is why, I think, the BEA concluded (rightly) that the lack of the spacer - even if one can discern indications it made the bogie wobble around 2,340 to 2,800m from the runway beginning - was not relevant to and played no part in the final outcome, which was sadly certain as soon as the fire broke.
QED.
Regards,
AZR.
Last edited by AlphaZuluRomeo; 18th Dec 2012 at 23:27.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Hi AZR
Quote:
Originally Posted by Lyman
"Had no effect..." "Played no part in the crash...". "The lack of the spacer was not relevant..."
All demonstrably untrue statements.
You say then..."certainly not..."
My perverse mind sees it differently, here's why....
There is evidence the tyres were rotating in the horizontal, you agree.
That is positve proof of misalignment, a condition certified by BEA themselves as abnormal.
For the statements in the quote to be true, you offer a lack of evidence that the condition existed elsewhere. The source of your evidence of absence is blurry photography of a carbon stained runway.
Positive evidence (BEA close up photgraphy) is provided that the condition exists. A lack of evidence that it occurred elsewhere is the basis of a professional conclusion, by BEA that it had no effect on the outcome.
To a doubting reader, it seems that proof without evidence exists when the conclusion is foregone?
The "Explosion"? Have we proven without doubt it was not caused by the tyre blowout?
That would be impossible, right? Because it occurred after the fire started, and defeats the tyre as cause of fire?
hmmm......
Quote:
Originally Posted by Lyman
"Had no effect..." "Played no part in the crash...". "The lack of the spacer was not relevant..."
All demonstrably untrue statements.
You say then..."certainly not..."
My perverse mind sees it differently, here's why....
There is evidence the tyres were rotating in the horizontal, you agree.
That is positve proof of misalignment, a condition certified by BEA themselves as abnormal.
For the statements in the quote to be true, you offer a lack of evidence that the condition existed elsewhere. The source of your evidence of absence is blurry photography of a carbon stained runway.
Positive evidence (BEA close up photgraphy) is provided that the condition exists. A lack of evidence that it occurred elsewhere is the basis of a professional conclusion, by BEA that it had no effect on the outcome.
To a doubting reader, it seems that proof without evidence exists when the conclusion is foregone?
The "Explosion"? Have we proven without doubt it was not caused by the tyre blowout?
That would be impossible, right? Because it occurred after the fire started, and defeats the tyre as cause of fire?
hmmm......
Last edited by Lyman; 18th Dec 2012 at 23:47.
Join Date: Nov 2010
Location: FR
Posts: 477
Likes: 0
Received 0 Likes
on
0 Posts
No. Possible/probable indication yes, but not evidence. I'm no more an accident investigator than Nick Thomas is, so I too am unable to draw conclusions or say "evidence" with certainty from those photographs.
No. I you want to call my PoV about those photographs as "evidences", then what I see in pictures showing the runway before 2,800m is an evidence of lack (of wobble), not a lack of evidence.
And that's really different
The source of "my" "evidence" is no more blurry than yours, my dear chap.
And I didn't base my arguments on the pics (or pic) alone.
Yes indeed.
And because parts of tyre were found before the "Explosion" place, as shown in my previous post.
And because, as shown in my edit of the previous post, there is a more sensible explanation provided (even if somehow hidden in the appendix 6, which explains I didn't remembered it.
And that's really different
And I didn't base my arguments on the pics (or pic) alone.
And because parts of tyre were found before the "Explosion" place, as shown in my previous post.
And because, as shown in my edit of the previous post, there is a more sensible explanation provided (even if somehow hidden in the appendix 6, which explains I didn't remembered it.
Last edited by AlphaZuluRomeo; 18th Dec 2012 at 23:38.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
I think Twas CliveL who stipulated shimmy was shown. I think it is....
Parts of tyre can depart without causing blowout, yes? A tyre explosion is consistent with concrete delamination, such as was found.
How is it deflector parts were found before tyre parts? There was damage to bogie unrelated to tyre rupture by strip?
You have photography of the runway taken from a few meters, that shows "no wobble"? The runway pictures that show carbon deposition are aerial, long distance, no?
I acknowledge you are satisfied with the results of BEA. I think the report compelling, but it is too loose, and presumes things that are not shown, nor discussed, imho....
Parts of tyre can depart without causing blowout, yes? A tyre explosion is consistent with concrete delamination, such as was found.
How is it deflector parts were found before tyre parts? There was damage to bogie unrelated to tyre rupture by strip?
You have photography of the runway taken from a few meters, that shows "no wobble"? The runway pictures that show carbon deposition are aerial, long distance, no?
I acknowledge you are satisfied with the results of BEA. I think the report compelling, but it is too loose, and presumes things that are not shown, nor discussed, imho....
Join Date: Mar 2007
Location: Cardiff UK
Age: 69
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
Hi once again Lyman
I have to congratulate you for the way you keep this thread alive. Everything is quiet and then up you pop and we are all of again on the same merry go round! You tenacity is to be admired.
As I said in an earlier post and I quote "I am not an expert in this field and I therefore have to trust those who are considered to be so."
That being the case I have serious doubts about your theories as do some others posting here. In weighing evidence(if it can be called that) one has to take into account the source of that evidence. Those of us who rely on the contents of the report, do so because we know that considerable thought and effort has been put in by the experts who compiled the report. Unfortunately on a forum like this: it's not possible to know the background and experience of people like you, who post alternative theories. Until we can find a way of overcoming that stumbling block we will continue to go round and round in circles.
I have to congratulate you for the way you keep this thread alive. Everything is quiet and then up you pop and we are all of again on the same merry go round! You tenacity is to be admired.
As I said in an earlier post and I quote "I am not an expert in this field and I therefore have to trust those who are considered to be so."
That being the case I have serious doubts about your theories as do some others posting here. In weighing evidence(if it can be called that) one has to take into account the source of that evidence. Those of us who rely on the contents of the report, do so because we know that considerable thought and effort has been put in by the experts who compiled the report. Unfortunately on a forum like this: it's not possible to know the background and experience of people like you, who post alternative theories. Until we can find a way of overcoming that stumbling block we will continue to go round and round in circles.
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes
on
0 Posts
Howdy Nick
That being the case I have serious doubts about your theories as do some others posting here. In weighing evidence (if it can be called that) one has to take into account the source of that evidence.
The wobble of the truck in horizontal is shown in the photograph, you see it differently?
BEA describes this horizontal rotation as "an abnormal"
Is that over-reliance on my opinion?
That being the case I have serious doubts about your theories as do some others posting here. In weighing evidence (if it can be called that) one has to take into account the source of that evidence.
The wobble of the truck in horizontal is shown in the photograph, you see it differently?
BEA describes this horizontal rotation as "an abnormal"
Is that over-reliance on my opinion?