LH423
Topic Author
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Tyres Suspect Of Bringing Down Concorde

Sat Jul 29, 2000 8:51 am

I just heard on CNBC, French officials have made it more than clear that blown tyres during the take-off run ignited the fire that brought down the Air France Concorde. As Concorde takes-off at higher speeds than regualr jets, the tyres get blazing hot, and can sometimes explode violently. On one such event, a blown tyre blew a hole into a wing. The plane, obviously didn't crash. The gases, and chunks of rubber appear to have entered the engine intake, and started the fatal fire.

In related news, two more bodies have been found inside the hotel that Concorde crashed into.

LH423
« On ne voit bien qu'avec le cœur. L'essentiel est invisible pour les yeux » Antoine de Saint-Exupéry
 
debn
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RE: Tyres Suspect Of Bringing Down Concorde

Sat Jul 29, 2000 9:20 am

The news is saying that the blown tires punctured a fuel tank, and the leaking gas caused a huge fire.
I guess, this is a lesson for Air france for not listening to NTSB warnings.
Can someone find out, how many BA concordes had tire blowouts ??
 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Sat Jul 29, 2000 12:53 pm

My theory is still what it was before. I believe that one of the engines, 1 or 2, had an uncontained blade separation. When that happened, shrapnel from this would be like a small bomb explosion. The shrapnel that went down, blew the tires, the shrapnel that went up, punctured the fuel tanks, and the shrapnel the went sideways, damaged the other engine. Remember that, on Concorde, the engines are paired almost as one.

Hmmmm...
An optimist robs himself of the joy of being pleasantly surprised
 
Pbb152
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RE: Tyres Suspect Of Bringing Down Concorde

Sat Jul 29, 2000 2:34 pm

I agree with Hmmmm.... on this one. As I said in an earlier post, I think it is too coincidental that the #2 engine (thrust reverser) was worked on just before the Concorde departed, and that happened to be the engine that initially failed. But, a failure of the tires and possibly a resulting failure in the gear assembly could certainly lead to a severing of the wing and fuel tanks. Regardless of the cause, it was a horrible tragedy, and hopefully we can learn from the experience and make sure it never happens again.

Pete
 
OPNLguy
Posts: 11191
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Observation

Sat Jul 29, 2000 9:53 pm

Funny how the cycle gets repeated every time an aircraft goes down the media is right there with the theory of the moment, which of course changes every time a new piece of evidence is uncovered. In the media's haste to fill-in airtime with "news" (or rather, their own perspective of it, constrained by the limits of their understanding of the many technical issues involved, not to mention that the wreckage hasn't cooled yet), the media also often overlooks the context of the information.

For example, take the thrust reverser revelation. Yep, it was reported as inop by the inbound crew (who "managed" to land without problem). Even though the inop reverser was deferrable by their minimum equipment list (MEL), i.e. you can fly without its use as long as restrictions (if any) are complied with, the outbound captain elected (as is his perrogative) to have the item repaired. What the media missed here was the thrust reverser, essentially, is a bolt-on accessory to the engine, and its presence has nothing to do with engine operation withrespect to the generation of thrust. It's used as a braking aid on landings or the rare aborted takeoff, and it's not used in flight. Yet, despite this, the media automatically assumes that since this item (on the number 2 engine) was worked on before takeoff, and the crew reported the number 2 engine had failed, that that's some kind of proof positive that the items are related.

This accident is quite amazing that there is such great photo evidence of the accident sequence. The most recnt pictures that show the near head-on shot of the takeoff roll and rotation are stunning, and telling. Based upon the info known/released at present, my opinion is that the central failure was one or more main gear tires, which led to the sencondary failures of the #2 and then #1 engines, as well as tire/wheel fragments striking the bottom of the wing and compromising the fuel tank.

Check out this link:

http://techreports.larc.nasa.gov/ntrs/hget.cgi?recon?1835/3=/raid5/index/star/80%2522539542%201835%20N19870012445recon1

It's about a NASA Conver 990 that aborted a takeoff back in the mid-1980s due to a main tire failure. Subsequent tire failures on the same gear truck eventually allowed the wheels themselves to contact the runway and start breaking up. One piece impacted the underside of the wing at nearly 200 mph as I recall, and the report photos clearly show the same type of fuel/fire flow as does the most recent Concorde photo. Such an impact from the tire/wheel below would have been a direct one, since it was perpendicular to the wing surface. It's thus difficult to imagine any supposed piece of Concorde engine exiting the pod and causing that level of damage, but certainly not impossible.

Bottom line is that engine failure(s) appear to be a consequence of the tire failure and fire, and not the other way around. Time will tell.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
OPNLguy
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Forget A Link To The Above Post

Sat Jul 29, 2000 10:27 pm

It's a *long* one...  

http://nasdac.faa.gov/lib/vtopic.exe?action=view&ViewTemplate=fw_docview.hts&DocOffset=3&VdkVgwKey=webaids%2Faidspub001.htm__%5B7229%5D&QueryZIP=%3CAnd%3E%28%3CMany%3E%3CPhrase%3E%28%3CMany%3E%27BAE%27%2C+%3CWildcard%3EBAE-CONCRD-*%29%2C+%3CMany%3E%27IAD%27%2C+%3CMany%3E%3CPhrase%3E%28%3CMany%3E%27Foreign%27%2C+%3CMany%3E%27Air%27%2C+%3CMany%3E%27Carrier%27%29%2C+Make_Model+%3CContains%3E+%60BAE+BAE-CONCRD-*%60%2C+Airport_Id+%3CContains%3E+%60IAD%60%2C+Type_Of_Operation+%3CContains%3E+%60Foreign+Air+Carrier%60%29&ss=2
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Sat Jul 29, 2000 11:52 pm

My belief that an engine failure was the initiating event is not based upon the media reporting the fact that the engine received some kind of service just before take-off. I don't know how a thrust reverser would play into this disaster. My contention is based only on the probability that an exploding engine, in my opinion, can do more damage than an exploding tire. It seems more plausible that an exploding engine would be the culprit. I would also expect that a tire would blow at the later stages of take-off when it gets the hottest. Conversly, I expect an engine failure at the beginning of the take-off roll as it is brought to full power. Eyewitness reports seem to indicate that the debris and flames started early on in the take-off.

But I am steeling myself for the possibility that I could be wrong. As unbelievable as that may seem.

Hmmmm...
An optimist robs himself of the joy of being pleasantly surprised
 
VC-10
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 12:16 am

If a tyre bursts and then the wheel hub shatters then there will be some heavy duty bits of metal flying around that could quite conceivably puncture the wing.

Whilst not discounting an uncontained engine failure I would point out that RR have considerable experince in containg a failure in such an engine configuaration, e.g Vickers Valiant, Handley-Page Victor, Avro Vulcan, D.H. Comet & to a certain extent the VC-10. Additionally the UK airframe design team also had similar experince on the above a/c (I don't know enough about the French side to comment on the French input).
 
OPNLguy
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Additional Links

Sun Jul 30, 2000 1:21 am

http://news.bbc.co.uk/hi/english/world/europe/newsid_856000/856423.stm

This is the memo that NTSB sent French authorities back in 1981 after 4 Concorde tire failures between Jul 1979 and February 1981. Particularly noteworthy is their account of the June 4, 1979 incident where major damage occurred, including a fuel leak. The FAA link to this incident is in the link I forgot add added later in the thread above.

>>>My contention is based only on the probability that an exploding engine, in my opinion, can do more damage than an exploding tire.

It depends. Most engine failures are contained ones. Some are not, but only eject parts in small numbers and/or size. The even more rare ones eject entire fan sections (United 232 and that National DC-10 over ABQ; the Delta MD-88 at PNS) that really do some damage. I have yet to see any media mention of Concorde *engine* parts found on the runway, and since tire fragments were, that leads me to believe the tire was the the source of the initial failure. (Hey, I could be wrong too...)  


>>>It seems more plausible that an exploding engine would be the culprit. I would also expect that a tire would blow at the later stages of take-off when it gets the hottest..

When tires fail due to heat, it's most often immediately after a vigorous application upon landing (or the more rare aborted takeoff) where the brakes have just been exposed to a few million-pounds of energy. True, the inbound flight had experienced inop thrust reversers arriving at Paris, and that crew presumably could have used the brakes more than a routine reverser-assisted landing, thus more energy and heat than usual, but certainly not more than an aborted takeoff. That built-up energy/heat translates to the tires, and depending upon several variables, the fuse plugs in the wheels could melt (and deflate the tires) anywhere from immediately or gradually over :45 or so, maybe longer. I'm supposing the Concorde's ground time was a couple of hours, thus any such problem would have been noticed before they pushed the gate.

>>>Conversly, I expect an engine failure at the beginning of the take-off roll as it is brought to full power.

Again, some do, some don't.


>>>Eyewitness reports seem to indicate that the debris and flames started early on in the take-off.

I think the key question are *how* early, and the *specific* debris. Brake release? Prior to V-1 and V-rotate? Afterwards? Was the debris tire-related or engine-related?

If the engine failed at the start of the takeoff role (your full-power scenario) that point would have been far below V-1, and the takeoff could have been aborted. If a tire (or tires) started to fail on the takeoff roll (which can be somewhat more insidous than an engine failure with its associated warning systems), irrespective of having reached V-1 or not, the tires could have come part and damaged the wing, or maybe even the wheels themselves doing likewise. Maybe the IAD tire fragment was smaller than the Paris tire (or wheel) fragments. Maybe the IAD flight was just luckier that an ignition source didn't set it off.

These are the kinds of answers that take investigators time to figure out, much to the disappointment of the media, who proceed to fill otherwise dead-airtime with usually uninformed speculations. Given the incredble photos of this accident, and the past experiences of Concorde susceptibility to secondary damage from blown tires (and the failure sequence seen in the NASA Convair 990 report, I still think the tire was the initial failure with fire and engine failure(s) as some very unfortunate dual consequences.

Not saying this to start a whizzing match by any means, but just to convey my opinion of what I see, and in the context of my personal operational experience (20+ years) on other types of airline aircraft. The Concorde is unique in many respects, but it also shares great commonalites with conventional aircraft.

Cheers...

ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 1:40 am

The dramatic picture of concorde rotating in flames will linger in our minds for many months to come. Yes I beleive a catastrophic multiple tyre failure caused the pucture in the wing and the consequential fuel leak and fire. The theory of the engines ingesting debris is very plausible, especially since it is #2 that sustained the most damage. Does anyone know where I can find the 1979 report of the NTSB on the issue please ?
 
OPNLguy
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Trip17

Sun Jul 30, 2000 1:54 am

I wasn't able to find anything on the NTSB site, probably since was an incident (versus accident) and it occured before the 1983 records the NTSB site starts with. Over on the FAA incident database, they have this, but it's not much:

http://nasdac.faa.gov/lib/vtopic.exe?action=view&ViewTemplate=fw_docview.hts&DocOffset=3&VdkVgwKey=webaids%2Faidspub001.htm__%5B7229%5D&QueryZIP=%3CAnd%3E%28%3CMany%3E%3CPhrase%3E%28%3CMany%3E%27BAE%27%2C+%3CWildcard%3EBAE-CONCRD-*%29%2C+%3CMany%3E%27IAD%27%2C+%3CMany%3E%3CPhrase%3E%28%3CMany%3E%27Foreign%27%2C+%3CMany%3E%27Air%27%2C+%3CMany%3E%27Carrier%27%29%2C+Make_Model+%3CContains%3E+%60BAE+BAE-CONCRD-*%60%2C+Airport_Id+%3CContains%3E+%60IAD%60%2C+Type_Of_Operation+%3CContains%3E+%60Foreign+Air+Carrier%60%29&ss=2
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
VC-10
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 2:36 am

Has anybody considered what the consequence would have been if the a/c had aborted T.O. below V1 ?

My own opinion would be that it would have turned into another Manchester where the a/c burned in its own lake of fuel.
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 2:41 am

Evidence that it was tyres, and not an engine failure that was responsible for the damage to the wing structure and subsequent fire is contained in the photographs taken as F-BTSC departed on its final flight.


The fire and breach in the wing structure are clearly shown as being in front of the engine, in a catastrophic engine failiure debris is thrown out explosively, but generally it is in the plain of rotation of the failed part where the most damage is done. In the above photo there appears to be little/no damage where you would expect to see it from an engine failiure. The fact that all the damage is forward of the engine is very unusual if it turns out to be an uncontained engine failiure.

Also, because of the way Concorde's engines are joined together, and because of the way they are attatched to the underside of the wing (not on pylons) they are encased in titanium, so that, in theory at least an uncontained engine failiure would actually be contained within the engine structure. There is no reason to doubt this, as many people have pointed out, Concorde is over-engineered and generally any given part will be stronger than it need be to perform effectively.

As for the thrust reverser, as OPNguy pointed out it is a bolt-on accessory, its workings are totally separate from the rest of the engine. It isn't a translating thrust reverser that is now almost universal where the engine cowl slides back and blocker doors come down inside the engine, it is the classic thrust reverser, as found on other turbojets with camshell doors which close behind the engine exhaust to deflect the thrust forwards, similar to the type found on 737-200s etc.

It is hard to see how any failure of a thrust reverser of this type would cause what occured at Paris. I would think the engine failure was a secondary cause of the accident from ingestion of tyre debris, not the initial failiure. From the photo all the flames appear to be coming from the breach in the wing structure. It's quite feasible that the engine failiure was non-catastrophic and caused by the ingestion of debris.

This has been a terrible accident, and a terrible loss.
I hope the cause can be discovered before too long.
JAMES
 
OPNLguy
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Jet Setter

Sun Jul 30, 2000 3:44 am

Excellent post....

You make a good point re: the plane-of-rotation aspect, assuming they breached the engine case. If engine failure *was* the initiating event (we sure can't see the *inboard* side of that pod), I'd then be surprised that departing engine parts could strike the underside of the wing at something far less than a 90 degree angle and breach the structure.

For those unconvinced on the tire theory, consider that...

1/ Tire debris, and not engine debris (so far), has reportedly been found on the runway; and

2/ The photo doesn't show any intact main gear tires on that truck, and

3/ The plane-of-rotation associated with any disintegrating tires/wheel frangments would presumable mean a more direct (less glancing) impact on the underside of the wing, and

4/ The failure mode has been seen before in the 7/14/1979 incident at IAD; and

5/ The appearance of the fire on the bottom of the Concorde's wing is very similar to that of the NASA Convair 990 I mentioned/linked earlier.

In the above Convair accident, large wheel fragments reportedly hit the wing at nearly 200mph, puncturing it, and allowing the fire. I rather doubt the designers of the Convair 990 or Concorde wings designed them to withstand the impact of such a heavy mass at such high velocities.

Also, as an aside, isn't bizzare how the media has fixated on the gear not being retracted? After considering the following two links, why would anyone *want* to at an airport with minimal obstacle?

http://www.aviation-safety.net/database/1986/860331-1.htm

http://www.aviation-safety.net/database/1991/910711-0.htm

.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 7:20 am

OPNLguy,
Thanks for those links. If you want to put a direct hotlink in future, it's easy! Just put square brackets at the beiginning and end of the url, < >. Ie to post a link to http://www.xyz.com do this
(http://www.xyz.com) - but using square not rounded brackets.

You're also correct about the port maingear, the tyres definately don't appear to be intact.

Regards
JAMES
 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 9:18 am


While I agree that the tire scenario is likely, I still don't see proof as it has been quoted in the photo.

The fire and breach in the wing structure are clearly shown as being in front of the engine...

It's impossible to see from where the fire is pouring out of that wing. I certainly can not see it coming out in front of engine anymore than beside, or slightly aft, of the engine. If you look at the left engine nacelle, you will see that its profile is silhouetted against the bright orange flame, which, to me, would indicate that the flame is somewhat behind the engine.

Please explain better what is meant by "plane of rotation". The plane of rotation of the wheels is 360 degrees. A tire that bursts can spin out debris in all 360 degrees perpendicular to its axis. That would mean that debris can strike at any point along the wheel's path's 360 degrees, from the wing at the tip to the ground below. How does this fit one theory vs the other?

If the cowling of the engines is titanium and are designed to contain a blade separation, and I'm not sure that it was designed for that, would this not also mean that the engines would offer the same protection from an outside source of projectiles? Keep in mind that the speed of the tire's rotation is considerably less than the speed of a compressor or fan blade rotation. So, if very fast piece of metal can't get out, why then would a piece of metal, travelling much slower, get in?

Unless, of course, the tire debris was ingested by the engines.

Hmmmm...
An optimist robs himself of the joy of being pleasantly surprised
 
777X
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 9:38 am

There is a precedent to back up the theory that tire fragments punctured the fuel tank - this happened with another concorde, although in that indicident the leaking fuel did not ignite. Don't have the details, but I'll look it up and post it.

Regards
777x
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 12:38 pm

OK then, bit of explaining...

The photo isn't the clearest, and I'll take your point that the fire appears to be coming from a point roughly level with the engine intake. I don't know how familiar you are with Concorde's engines, but the intakes are much longer than the engines, which are situated some way back inside. The forward fanblades are actually located over one third of the way along, with the rest of the engine further back still.

Plane of rotation is difficult to explain easily. Basically if a turbine is rotating, its plane of rotation is the flat area, perpendicular to the axis of rotation, level with the fan blades. Put another way, say you put a laser on a fan blade, pointing along it from centre to tip and rotated the blade one full rotation - the infinitely large circle the laser would draw, theoretically, would enclose the plane of rotation.

In this context if there was an uncontained turbine failure you would expect the damage inflicted on the surrounding structure to be level with the failed turbine's position, with little damage forward/aft of this ie damage would be within the plane of rotation. This is because of the incredible speed of rotation and the huge centripetal forces within an engine, so that in a failure the parts of the engine fly out along the plane of rotation and the relative forward/rearward effect of any other forces on their trajectory is negligible.

I have a chart of the damage cause by the uncontained engine failure on the United DC-10 at Sioux City, the spread of damage for/aft of the position of the failed fan blade is no more than 6 inches either way, but it spreads a long way out in the plane of rotation.

Also, if you look at the engine nacelles, they are intact (although it's mostly cut off in this version of the picture, I've seen the full version) and in the Sioux accident there was damage all the way around the engine, which had there been a catastrophic failure would have been visible too.

So, as a quick summary, the damage to the wing is, in my opinion too far forward to have been caused by an uncontained engine failure.

The wheels of course also have a plane of rotation, but their rotational speed is compared to an engine turbine, tiny, and the forces involved nowhere near as great as you would find in an engine. Also in a tyre failure the debris is very likely to go sideways, as well as backwards, and there will generally be a much larger spread of debris/damage.

The titanium case of the engine was designed to contain a catastrophic engine failure, otherwise due to the close proximity of the engine to the wing and the other engine; any serious failure would strongly risk damage to either/both of these structures as well. Yes, the case would offer the same protection from other projectiles. Maybe I didn't express myself clearly...But the I meant that I thought the debris from the tyres had caused the engine failure by being ingested into the front of the engine. Also, just because the debris caused the engine to fail, it does not automatically mean the failure was catastrophic.

As a quick summary of what I think occurred, based on current evidence;
(1) Tyre blow-out
(2) Flying debris punctures wing underside and fuel tank, subsequent fire erupts
(3) Flying debris enters engines 1 and 2, causing (non-catastrophic) failure. Rubber passing through engine 1 would also explain why it failed twice before finally totally failing. Rubber passing through would cause much less damage than a piece of metal which may well stop it straight away
(4) Out of control, fuel-fed fire finally disables vital systems leading to loss of control

I hope I explained myself to your satisfaction, if not get back to me, and I'll do my best to clarify. I know I'm no expert, but I hope my theory is based on good information. Feel free to shoot big holes in it, I can take it!
 
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Bruce
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My Theory - Comments?

Sun Jul 30, 2000 1:43 pm

Here's my theory:

1. Thrust Reverser doesn't work on the inbound flight; Pilot has to apply brakes longer to slow down. This Builds up excessive heat and pressure that doesn't blow the tire but weakens it.

2. Takeoff. Now, tires are run up to speed again, but the compound rubber is weaker, finally giving way disintegrating sending parts flying into the wing and engine.

3. Pilot cannot retract the gear because when the tire burst, it ruptured the hydraulic lines in the gear.

Can they test the runway surface to see if there is evidence of leaking hydraulic fluid along the tires' path? That would be a giveaway.

What do you think?
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
VC-10
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 3:25 pm

Bruce,

You appear to overlook the fact the other three reversers were working, so one reverser out wouldn't make that much difference.

If the tyre's were as suseptable to heat as your theory implies I would have expected to hear of a more frequent tyre failure rate than has already been published.

 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Sun Jul 30, 2000 10:53 pm


After having looked at the above picture, I must agree that the tires could have disabled the engines, but not vice versa. The engines are quite further aback of the wheel boggies. If an engine threw a blade, the plane of rotation could not reach out to the tires. But if a tire blew, then its debris could be ingested into the engine and, I assume, disable it. The wing tank is vulnerable to both engine debris and tire debris. But by process of elimination, it was evidently tire debris that punctured it.

The only question that remains for me, is when did the Captain know he had an engine failure? By all witness accounts, it seems that the whole process started quite early in the take-off. It's hard to believe that the engine indicators only showed a problem after reaching V1. Prior to V1, the tower informed the captain that his plane was already a blow torch, meaning that the whole failure had already taken place. Why didn't he abort? It's almost as if the statistically impossible happened. Not one, but two engines failed, and they failed after V1 together. But according to the tower and other eyewitnesses, the problem occurred long before V1. So that leaves an unanswererd question. Sort of like the question asked of Reagan during the Iran-Contra hearings:
What did the captain know, and when did he know it?
An optimist robs himself of the joy of being pleasantly surprised
 
OPNLguy
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Hmmm, JetSetter, And 1 Other Point..

Mon Jul 31, 2000 12:23 am

Great use of the side-view photo, and I think it more clearly shows how readily main tire failure(s) could have initiated the whole accident sequence.

Looking at this side view, envision the main gears tires rotating, in this view, counter-clockwise. With Concorde tire fragments found on the runway and most airports very good about eliminating potential FOD hazards, it's quite likely they belonged to 4590. Assuming they did, and that one or more main tires tires came apart as the speed increased from brake release to their V1 and VR points, it's quite easy (i think) to envision the tire fragments rotating around (counter-clockwise, based on this view) and detaching due to basic centrigual forces. If a tornado or hurricane can drive a 2x4 through a tree, one can image the impact velocity of tire or wheel fragments (heavier mass) as they came off. How many lower wing skins are stressed for such an impact?

The previous head-on photo (with the flames) appears to show only one remaining tire on the outboard side of that truck, while the inboard side of the truck appears to show both tires gone. Assumng this to be the case, it could be argued that the underside of the wing could have received more damage from tire (or hot metal wheel) fragments, while the number 2 engine got enough ingested debris to cause internal damage/destuction.

Also looking back at this side-view photo, one could also say that any departing engine parts from a blown #2 engine could have also damaged the underside of the wing (and causing the fuel leak/fire). While that's certainly possible, it does not (IMHO) sufficiently explain the loss of the tires on that truck, since the gear is forward of where the engine's core is located. Engines can fail for other reasons of than tire or other FOD ingestion, but again, with tire fragments found on the runway, I think the trail starts there.

Sorry to be long, but one closing point/observation. Notice how the media has reported that the Captain "couldn't raise the landing gear" with the implication that this was all the result of the problems he was experiencing? If one goes back to that BBC story link I posted earlier re: the NTSB's comments and concerns from 20 years ago, you'll note that they recommended that the gear be kept *down* intentionally, rather than retract the gear and risk a tire blowing inside the gear well. Maybe, just maybe, the reports of "I can't raise the landing gear" were meant in the crew's context of "I can't raise the landing gear due to procedures and the risks noted by NTSB" versus assuming it was due to the mechanical inability to do so.

For a look at the failure mode(s) of a tire(s) blowing inside a gearwell, check out these links.

Immediately after takeoff:
[http://www.aviation-safety.net/database/1991/910711-0.htm]

At altitude:
[http://www.aviation-safety.net/database/1986/860331-1.htm]
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
VC-10
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RE: Tyres Suspect Of Bringing Down Concorde - Hmmm

Mon Jul 31, 2000 12:38 am

Have you read my earlier post in this thread regarding the possible consequences if the flight had been aborted prior to V1 ?
 
OPNLguy
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Sunday Update From Paris

Mon Jul 31, 2000 2:37 am

For whatever it's worth... Be interesting to know precisely where (i.e. how far from brake release at the end) it was...

PARIS (Reuters) - The flames spewing from the wing of an Air France Concorde minutes before it crashed last Tuesday were probably due to a massive fuel leak rather than a problem with one or more of the engines, investigators said Sunday.

The French Accident Investigation Bureau (BEA) said part of the debris from the plane found on the runway of Roissy-Charles de Gaulle airport, where it took off, appeared to come from a fuel tank.


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PIT_flyer007
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 4:15 am



I agree. I regularly correspond with a girl who lives close to the site of the accident and the cause has been thought of as the tires. She said she heard this on the radio+tv+newspapers there.
 
OPNLguy
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Link To Concorde Tech Pix

Mon Jul 31, 2000 4:17 am

[ http://www.concordesst.com/inside/inside.html ]
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OPNLguy
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Link To Concorde Tech Pix

Mon Jul 31, 2000 4:18 am

ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 7:55 am

VC-10,
Can you not grasp what was happening there in Paris? You had an airliner, on fire, with two dying engines, and you are suggesting to the forum that the smart thing to do was to continue a take-off, irrespective of the fact that A) the plane is on fire and will consume everything in about three minutes, and B) you will crash into the ground because you don't have enough engine power to effect a safe take-off to begin with.

If you take a crippled airliner into the air, with failing engines, and on fire on top of that, don't you have to land it again? And landing means that you have to come to a stop, doesn't it? So what good would taking-off have done? It just would have delayed the process of coming to a stop which is what is inevitable if anybody wants to get out of the plane. All that continuing to take-off would have meant is that the plane would have been that much more consumed by fire, robbing those poor people of the precious 90 seconds they needed to evacuate the aircraft. Flight 4590's situation was so grave, as they lifted off the runway, that they didn't even have enough time, or engine power, to fly 5 kms to the nearby airport much less fly the 10 kms needed to circle and come in for a landing again at CDG.

Do you know how long it takes for a plane to take-off, circle around, and come in for a landing? At least four minutes. And at the end of those four minutes, everyone would have been dead. And don't forget that the whole reason why the plane crashed when and where it did was because two of its four engines were dying. It is impossible to take a four engined airliner into the air, off the runway, with only two good engines. Impossible. Trying to do so is suicide. The result is a lazy climb to 200 feet until airspeed drops below maximum stall speed, and then gravity slams that thing right back down to ground again. And whomever is in the path of that doomed plane gets killed too.

So what's the point of taking off? The consequences could not have been worse than what happened. The only hope those people had vanished as soon as he rotated and took her into the air. Rather than come to a stop on the runway, or off the runway, or plow into a farmer's field, the plane dive bombed into the ground at 250 mph with no chance of survival, at all, for anybody. Not to mention five more dead in the hotel. Thank heavens the hotel was mostly empty. The toll could have been double otherwise.

If the captain had aborted before V1, like he should have, maybe some of passengers could have escaped the inferno. Maybe. As it was, everyone's fate was sealed by taking to the air.

This is why it is so important to find out the answer to the question:

What did the captain know, and when did he know it?

Hmmmm...

Sorry if I sound harsh.

An optimist robs himself of the joy of being pleasantly surprised
 
MEA-707
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 8:31 am

Maybe, maybe.... After we know what happened, a late aborted take off would be less catastrophical... But I have confidence in the well trained pilot that he made the "right" decision based on the facts HE KNEW AT THE TIME.
I'm certain the crew only knew they were in deep trouble way after V1. Either he could still abort, overrunning and ruining the plane and possible causing MAYBE 30 casualties - remember the speed is a lot higher than a regular plane,
or he could try to make an emergency landing as quickly as possible. If only one engine had been on fire, they had probably made it to Le Bourget - saving passengers and plane. I think he decided that there was a good chance they could make it, backed by the facts he saw and heared on the moment. I think it's probably unfare to blame him -now everyone knows the consequences - for making the wrong decisions. Except of course when the investigations reveal he knew or could have known the plane couldn't make it on or around V1 speed.
nobody has ever died from hard work, but why take the risk?
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 9:22 am

Alarms sounding, lights flashing, one engine failed, another unreliable, possibly warnings regarding burst tyres, low fuel pressure, undercarriage will not retract, speed about 250kts. All this in two minutes with training that says V1 is a go situation. How many pilots if put into a simulator facing the same situation would have reacted differently.

Sure the tower informed the pilots that there was a fire, but it was only the photos that showed us that it was not an engine fire. The crew did not have the benefit of those photos in the cruciual two minutes, and would have assumed that they had an engine fire which is why they chose to land at Le Bourget. At V1 an engine fire is a containable situation which can be controlled in the air.

 
hmmmm...
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 10:29 am

Alarms sounding, lights flashing, one engine failed, another unreliable, possibly warnings regarding burst tyres, low fuel pressure, undercarriage will not retract, speed about 250kts. All this in two minutes with training that says V1 is a go situation...

That doesn't sound like a "go at V1" scenario to me. That was every reason in the world not to go.

If, at V1, you have a failed engine, you do not proceed to V2. The pilots were also told that their plane was on fire prior to V1. That is reason enough to abort.

You must remember what V1 is about. V1 is the maximum speed that you can attain while still having the option of aborting the take-off which will still leave you with plenty of room to spare at the end of the runway. After V1, you are not guaranteed to have enough runway left to make it to a dead stop before reaching the end of the paved runway. But so what? What is worse, running off the end of the paved runway, or taking a dying, burning plane for ride to see if it will fly?

If at V1, everything is not right, that is your opportunity to abort. Why didn't this captain take that opportunity? That is why we have the V1-V2 system. To remind pilots that they can still safely abort the take-off at that point if things are not okey-dokey.

And still have room left at the end.

And he had the benefit of the tower who informed him of the sorry state of his plane as he was going down the runway.

But even after V1, which comes a couple of seconds before V2, aborting a take-off would be a wise choice if you were already informed by the gentlemen in the tower that the left side of your plane is now a blow torch and your left main landing gear has left most of itself on the runway behind you.

Even if the engines were at full power, and he was able to fly and set up for another landing, and even if the fuel tanks were not punctured and there was no fire, the plane was still doomed based upon what they were told by the tower about the condition of the landing gear. After the left main landing gear boggie was destroyed as the plane sped down the runway, how was he going to land that Concorde? They have landing gear like an flamingo has legs.


Hmmmm...

This is a quality thread.
An optimist robs himself of the joy of being pleasantly surprised
 
dnalor
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RE: Bruce's Theory

Mon Jul 31, 2000 11:22 am

Bruce's theory might well hold some weight

VC10, if the pilot on the incoming flight knew of the faulty reverser, would he/she then not use symetric reverse thrust, ie. use only one reverser on the other side??

Hence if one of the tyres or rim had a fault it would have been somewhat more stressed than usual via braking on that particular landing, then perhaps failing on its next high speed run.

 
hmmmm...
Posts: 1959
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 12:40 pm

Here's a new twist by an educated source: Maybe both theories are incorrect.


CONCORDE CRASH
Location of Fire Seat on AF 4590


Exploded diagrammatic view of Concorde, the fire seat clearly visible on runway rotation photographs highlighted here in yellow.
The equipment located in the highlighted area suggests strongly that the media has its facts back to front. Rather than the engine or undercarriage starting a fire in the wing, all evidence to date suggests a distant fire in the wing initially starved #2 engine of fuel, then #1 engine, finally causing both to fail with catastrophic results.


The area highlighted in the exploded diagram is one of those disliked intensely by all engineers, because it contains two components we would much rather keep entirely separate - electricity and Jet Petrol One (JP1). The first can initiate and and sustain ignition, while the second can provide continuous fuel to feed the fire.


As shown on the diagram, the suspect area contains exactly these components, including the tank vent gallery, engine fuel feed system, tank and jettison fuel feed valves, plus an accumulator. All fuel required to feed both #1 and #2 engines must transit through this zone to keep them alight. If we have a disruption in this zone, fuel flow to #1 or #2 (or both) will be interrupted and eventually cease altogether, causing the engine(s) to run out of fuel and spool down. We already know from the Cockpit Voice Recorder (CVR) that #2 engine spooled down on the runway shortly after the fire started, and we know that #1 engine spooled down shortly thereafter.


How do we know that #2 spooled down after the fire started rather than before? When he started his 26-second takeoff roll and engaged the afterburners, the command pilot had no fire warnings, or he would never have rolled at all. An engine fire is one of the most dreaded emergencies for any aviator, but the CVR shows the captain did not report this (dire) emergency because he did not know about it. The captain radiod that he had an unspecified "#2 engine failure", but it took the control tower to alert him the flames behind the aircraft. If this very experienced captain had engine fire warning lights and buzzers going off in the cockpit, rest assured he would have told the control tower about it, immediately.


One of the most puzzling features of the photographs and videos taken at the time is the sheer size and length of the fiery tail behind the Concorde before it finally crashed. As any Flight Engineer will confirm, the fuel flow needed to sustain this massive blaze, far exceeds that generated by a broken engine fuel line, or even two broken engine fuel lines. Once again, we need to look very carefully at the diagram above.


Running directly aft from the yellow highlighted area are the fuel jettison lines, very big bore pipes normally used to dump fuel to atmosphere if the aircraft needs to make an emergency landing shortly after take off, but is too heavy to do so without risking a collapse of the undercarriage. By way of brief explanation, although the landing gear can sustain the strain of take-off when carrying enough fuel to get to New York, the general idea is that when you finally reach New York a large portion of your fuel will have been used up, thereby reducing landing weight to an safe level.


Critical for Air Accident Investigators is the fact that the suspect zone contains the jettison valves, which are activated electrically. If the fire caused a short circuit and accidentally opened one or more of the jettison lines, huge volumes of fuel (and thus fire) would spew out behind the tail. In fact, exactly like that seen on the photographs and video.
Joe Vialls
Former member Society of Licenced Aeronautical Engineers & Technologists



Contact author

Hmmmm...






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User avatar
Bruce
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Try This One

Mon Jul 31, 2000 3:41 pm

If your left side engines fail and/or go low power, and right is max thrust, won't your plane veer off to the side due to the uneven thrust????

And, if one side tire bogeys are damaged, woudln't that be like having a blowout on your car - you'd go out of control to one side?

How did this speeding blowtorch continue in a straight trajectory?
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
VC-10
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RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 5:54 pm

Hmmmm,

Lets look at the the abandoned T.O. senario.

The Capt's elects to abandon T.O. because he is told that the a/c is trailing 200 ft of flame. He chops the throttles and selects reverse thrust and stands on the brakes. The reveser buckets operate and deflect the gas flow in a 45 degree fwd direction. Now what is going to happen to the flames and fuel mist that is pouring out of the wing ? It's going to go all over the fuselage and wing. Now at least one tyre has burst so the remaing tyres are under extra stress so there is a good chance the remaining tyres will burst and cause more damage, and possibly the brakes may catch fire.

The a/c comes to a halt possibly in two or more pieces after running off the runway and instead of the fire tailing behind the a/c the fire is now directly below the
the wing being fed by fuel pouring directly on it from above, assuming the a/c is still on its landing gear. The fire heating up the remaining fuel tanks.

I am not suggesting the Capt considerered all this before he took off I am merely suggesting the likely results of not taking off.


In your other post you mention the fuel Jett line. The jettison line terminates in the fuselage tail cone so if the Jett vlvs had opened the fire, if any, would have been seen comeing from the tail cone.

Incidentally Concorde uses Jet A-1 for fuel.

VC-10
Former Associate Fellow of the Society of Licenced Aeronautical Engineers & Technologists
 
OPNLguy
Posts: 11191
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Fire Site Link/theory

Mon Jul 31, 2000 9:37 pm

The fellow that posted this new theory (another thread elsewhere on airliners.net) is starting to take some hits on this. One thing in his post caught my eye:

>>>huge volumes of fuel (and thus fire) would spew out behind the tail. In fact, exactly like that seen on the photographs and video.

I'm not an accident investigator, nor a rocket scientist, but does anyone out there concur that the pix indicates fuel/flame "spew[ing] out **behind** the tail"? Sure loonks like it's originating under the wing to me.

I also have to maintain my difference of opinion with the poster of the above stuff, that all the tires are intact. If one compares the size of the shapes on end of the left truck (helpfully backlit by the flames) one is noticeably bigger than the other three, and it still appears to me that 3 of the 4 main tires are gone. Compare this truck with those of the other side, which appear to match the size of the remaining tire on the left truck.

Given that tire and now fuel tank fragments have reportedly been found on the runway at Paris, and that the June 14,1979 takeoff incident at IAD indicate that the failure mode could produce a fuel leak and other damage, plus other industry history (NASA Convair 990 at March AFB, 1985), well, what can I say. At this point, I think we all have to wait for what the investigators find out and report today at their meeting.

We'll see...

ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
hmmmm...
Posts: 1959
Joined: Tue May 18, 1999 8:32 am

RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 9:46 pm

VC-10, everything you mention in your last post is still going to happen if he continues the take-off. He still has to land again, right? Except now, instead of slowing down to a stop and letting a few people jump from the burning plane, the plane continues to fly, burn, fly, burn, fly, and then crash. That way no one has a chance to get out. What is the benefit of taking-off?

BTW, I never mentioned anything about a fuel jettison line in any post, or the type of fuel the Concorde uses. That was Joe Vialls who, it seems, is a peer of yours. He too is a member of the Society of Licenced Aeronautical Engineers & Technologists.

Hmmmm...
An optimist robs himself of the joy of being pleasantly surprised
 
Guest

RE: Tyres Suspect Of Bringing Down Concorde

Mon Jul 31, 2000 10:46 pm

Seems like they should put on the Concorde tires that are made for supersonic military fighters & bombers that can withstand the extreme heat during takeoffs.
 
OPNLguy
Posts: 11191
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New Info

Mon Jul 31, 2000 10:52 pm

From www.abcnews.com

"Investigators also revealed today that all of the runway debris found so far is located beyond the point where the plane reached so-called "V-1" speed, the moment in the takeoff when the pilot is committed to get airborne, and can no longer abort the takeoff. "

Assuming it's as reported, maybe this will help end the debate by others as to whether the crew should have abourted or not...

Also, I had a question from another forum about that NASA Convair 990 I mentioned. That aircraft had a tire/brake/wheel fragment punch the bottom of the wing/fuel tank with an ensuing fire. Even though that aircraft was aborting the takeoff and DE-accelerating, the impact speed against the bottom of the wing was still somewhere near 200mph as I recall. Now, if AF4590 blew tire(s) at its normal V-1 and/or rotations speeds, one can imagine how much higher the impact speeds would have been on the bottom of its wing from any fragments that may have hit it. As the Brithish AirTours 737 accident at Manchester showed, wings are designed for many things, but high velocity impacts from dense metal objects coming from directly underneath are not necessarily one of them...
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VC-10
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RE: Tyres Suspect Of Bringing Down Concorde

Tue Aug 01, 2000 2:19 am

All I am saying is abandoning the T.O. would not have avoided a disaster as some contributors seem to have thought.
 
OPNLguy
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VC-10

Tue Aug 01, 2000 3:18 am

VC-10 wrote:
-------------------------------
All I am saying is abandoning the T.O. would not have avoided a disaster as some contributors seem to have thought.
-------------------------------

Agree completely, in the sense it couldn't be completely avoided. Had they aborted, it's at least conceivable that at least some could/would have survived, but that's another topic entirely.

My comment re: the debate was intended to hopefully quell some of the post-accident quarterbacking as to what the crew should/shouldn't have done, especially based on early reports filtered by media misunderstanding(s). Engine failures are usually pretty pronounced (sensation, cockpit indications, etc.) while some tire failures may not be as obvious. That close to V-1, it's a moot point, and the safest thing to do is get in the airborne and sort it out there.

The only exception I can recall from past history was an Air Florida DC-10 that aborted beyond V-1 back in the 1980s from the longest runway MIA has. One of the wing engines suffered a massive failure, and being very lightly loaded (domestic flight, few pax) they aborted and got it stopped on the remaining runway. After looking at all the schrapnel damage (including damage to L/E slats and associated items) I recall it being concluded that the aircraft would have lost slats on one side ala' AA191 back at ORD (1979) and rolled over, etc.

Ya never know until you're there making the decision...
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VC-10
Posts: 3546
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RE: Tyres Suspect Of Bringing Down Concorde

Tue Aug 01, 2000 6:54 am

I didn't know of the Air Florida post V1 abandonment, but I do recall the Spantax DC10 that abondoned T.O. after V1 at Malaga. In that case it over-ran the runway & caught fire. And the cause of the incident...... a burst nosewheel tyre.

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