DC10 hollow fuse pins :confused:

What about the cracks in the bulkhead?

I agree with PBL 99% of people misunderstand the term "fuse pins"

Once a boeing designed "fuse pin" got inadvertently installed on a DC9 powered by the same model engine "bad move"

Back on subject...
 

PBL

These are excellent pieces of writing:

http://www.abnormaldistribution.org/...-ten-years-on/

http://www.abnormaldistribution.org/...ars-on-part-2/

I think we can all agree that lacking an inquest system as it does, that in France it is necessary to hold a criminal trial to apportion the costs of compensation is deplorable.

Your first piece effectively reaffirms the BEA report and the findings and verdict based upon it. I think the "cross-examination" in your second piece rather comprehensively plants a stake through the heart of the "Concorde wasn't airworthy because it was susceptible to severe damage from a relatively common occurrence" argument. That only leaves the CAL allegation of a pre-existing fire. In several posts I have asked, given that the engines show no physical signs of fire damage, what the nature of the alleged fire might have been and what might have caused it.

There have been two answers: here, FAStoat said that there might have been an afterburner fire. Apart from whether such a fire could have been caused by an improperly fitted fuel pump (I don't know - I'm not an engineer), this raises the questions of whether such a fire would have left any physical evidence behind, and whether the existence of such a fire would have been causally necessary, given that it seems ordinary afterburner might well have been able to ignite the fuel spill unaided.

Bearfoil reckons here that sparks from the misaligned bogie could have been an ignition source. It seems to me that that would require spilling fuel to be able to travel almost vertically down from the hole in the fuel tank to the bogie several metres below, against a 200Kph airspeed. Is such a thing likely?

Does anyone else fancy having a pop at the pre-existing fire theory, before we allow Concorde to rest in peace?

This has been a very interesting and informative thread. I've learned quite a bit here. Thank you all, for that.

iron duck

JetBlue had a nosewheel event at LAX where the wheel was ninety degrees to the Heading on landing, It left a trail of sparks that extended 20-30 feet back, and to a height of perhaps at least two metres.

I already did earlier....
Without any physical proof at all of such a fire, we only have a few highly contradictory "witness reports".
And postulating a pre-existing fire, starting a few seconds before all the conditions were reunited for a real fire, is really pushing things a bit too far from the bounds of probability and reality.
So?
We can all quote even worse incidents/accidents of the same style, but where is this relevant here?
We're talking about the MLG here, and a tyre burst.
Unless you are suggesting sparks from the MLG wheel after the tyre burst ignited the fire... not totally impossible, I suppose, but not even mentioned in the report as a possible cause.
Probably because some sparks well aft of the MLG would not have had enough energy to ignite the fuel leak to the extent of the flame propagating back to the wheel well (my opinion entirely).

CJ.

ChristiaanJ

I should have made myself clearer and said "does anyone else fancy having a pop at postulating a pre-existing fire theory?"

I'm with you and PBL on this one, and I'm only an interested SLF. Nonetheless, after PBL so beautifully skewered the "airworthiness" argument, the only possible remaining challenge to the the BEA report and the Court's conclusions might come from a pre-existing fire theory, as advanced by CAL.

Genghis Khan (alledgedly) said: "It's not enough just to win. The other side have to know that they have lost." Perhaps I'm being mischievous, but that's why I'm asking for any further theories. Let's see if they fly.

iron duck

The Wheel Spacer was left off the MLG. I assume the job of the Spacer is to insure Space between wheels. Also space between Tyres, and tyre and bits. If allowed to rub, Rubber casings can ignite into an impressive display within moments. The Tyres may have been afire before the burst, liberating already burning torch bits to then ignite the Fuel, post-burst. Burt Rutan's Space Rocket Fuel? Rubber. Not kidding. Are we sure it was not the Spacer that started the Fire/Burst, or Burst/Fire?

merely a 'post-existing' theory :ok:

da bear

The missing spacer is interesting, however...
 

The tires would have had to have been of different diameters (inflation, tread wear) in order for them to be spinning at substantially different rates.

Hi,

http://enperspective.pagesperso-orange.fr/figure43.gif

http://enperspective.pagesperso-orange.fr/figure42.gif

Source:
Crash du Concorde: la loi de Murphy

Only if one limits the possibility to Tyres rubbing each other. Per the diagram from jcjeant, if the bearings were free to drift toward the center, a wobble is possible, and tyres would not track correctly on this truck. It has been a long while since I viewed the takeoff video, but I remember "seeing" the Fire start at the Wheels, not aft the Wheels.

If she had lost stability in this MLG, all manner of stress would impinge on the tyres, and the metal. A Tyre Fire is reasonable, Titanium road hazard is also possible, but slower to eventuate, and less of a trigger. Occam says Tyre Fire.

bear

I have personal experience of an aircraft moving at around 150 m/sec suffering a fuel leak and which then ignited and the subsequent fire very, very definitely propagated forward despite the airspeeds involved . The flame remained stubbornly well and truely attached to the airframe even with IAS's in excess of 350 kts and it subsequently transpired there was significant fire damage to the a**e end of the airframe ....so the oft expressed "fact" that you can outrun a flame front at subsonic speeds seems to me to be hopelessly optimistic.

IMVHO once you have a fuel leak, an ignition source and turbulent flow/flame front all bets as to propagation are off.

Yes, Occam to me says - fuel leak, reheat ignites the plume, which then burns forward into the structure. You don't need another ignition source, such as a tyre fire, forward of the leak, to get things going.

I thought that the tire failure had damaged the Weight-on-Wheels switches/sensors AND their associated wiring on the Left MG leg, and the sparking there had been a source of the spilled / leaking fuel ignition.

Was also mentioned as the reason the crew was unable to raise the gear (the system defaulting to GROUND status when failed).

wiggy,

Did the flame propagate forward in the boundary layer in your fire? A fire started by the reheat flame would not benefit from any boundary layer effects in its attempt to 'catch up'.

Iron Duck,

concerning reports of fire on the right side of the aircraft, I think we can see in the front TO photo that there is nothing. Furthermore, the BEA says there are no traces. They also report the RHS engines as functioning normally, which they would not do if there were untoward combustion in the vicinity. So whether or not there was visible burning on the RHS of the aircraft, it did not affect the performance of the flight in the way in which the conflagration on the left has been shown to have done so.

So the fire question must concern mainly the conflagration on the left. The 32 cm square chunk that was exploded out of the fuel tank, and the resulting hole, is, I hope, not in question. Fuel would have been coming out of that hole in large quantity, and can be seen doing so by tracing the fire in the photographs. It is clearly seen in the photos to have ignited, and that the fire is huge. It is this fire, intuitively, and also from the investigation's statements about how the power produced by the left-side engines was affected, that we should be most concerned about. It is this fire which altered the engine parameters to reduce the thrust, and very likely would have burned through the wing maybe even before the aircraft had reached Le Bourget.

Whether or not people have observed flame fronts travelling forward on other aircraft, the BAC engineers were completely unable to reproduce a forward-travelling flame front from afterburner ignition on this aircraft in their post-crash experiments. Nobody intimately involved with this aircraft sees how the flame front could have so travelled. So ChristiaanJ's supposition remains very much alive in the minds of many. A related question is whether such damage to wiring would have been pre-existing, or whether it would have been engendered by debris from the tire burst. I would guess this question will remain forever unanswerable.

Concerning sparks from tires due to misalignment - bearfoil, do give us a break! Look at the size of the spacer in the diagrams; look at the gap between the wheels; draw the obvious conclusion.

Also, does anyone see the burning in the photos anywhere near the left main gear bogie? No? Neither do I. So how exactly is anything to do with that bogie supposed to have ignited the fire?

PBL

The links to PBL's pieces at abnormaldistriubution point to nowhere - anybody got working links?

Core Cowl Wear Strip
 

CF6-50 Core Cowl wear strips were notoriously bad for fretting and falling out. The problem was then, that the preload on the over-centre latches was reduced and the consequence of that was in extreme cases that the cowls undid themselves and as I saw on one sorry B747 , they came off - sheared at the pylon hinges. A mod came out, inserting a stainless steel screw/pin which effectively locked the two cowls together.
Now, the strips still got renewed and they were always meant to be made of Stainless Steel. The report shows that the Titanium strip that alegedly caused the crash, to have been attached with Cherry-Loc rivets. Had they been monel with stainless mandrels, I doubt accident would have happened. Stainless wear-strip, ally Cherries, strip on runway, tire bursts, Concorde in Hotel except for one thing....... Titanium burns with a fierce bright flame. Source of ignition??

I think they've been quoted in someone's post above and that has mangled them. I think these are working links:

http://www.abnormaldistribution.org/...-ten-years-on/
http://www.abnormaldistribution.org/...ars-on-part-2/

If not, trying to put in text form so it doesn't get messed up, you want:then either of:Thanks to PBL for posting these, well written and well worth reading.

PBL

Please note that you've quoted rotation speeds in your articles in kph when the numbers used are actually in mph (or more likely in knots). Probably a good idea to correct them.....

ok, found the cross-examination

was the whole 32 cm x 32 cm or was it 32 cm²

"....sparks from tires...." Words not said, and a studied response meant to mislead/demean. Sparks from H member? possibly, as well as shed bits of tyre independent, precedent, and unconnected to Titanium Strip? Of course it's possible. To be fully committed to tyre burst via Ti, at the complete exclusion of defects known to have started at Brakes release? A leap, a leap. The a/c was known to have been tracking indifferently. Yet all focus is on the Ti, conveniently lying in wait in a place that would have been benign, had she been tracking true. A theory, and worthy of attention equal to the "Slasher" theory. The Fire was a follow on, regardless of Fuel dump causation. The Titanium had not started the Fire, technically, it could have had nothing to do with it, absent a slewing airframe? All causes are contributory, except the ones that are not.

BRE,
If you look at the report, it's about 30x30cm (not exactly square).
32cm² would have been less than 6x6cm.
The flow rate of the leak was about 60 kg/sec (estimated in three or four different ways).

CJ