Concorde Paris crash, questions, facts, opinions
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Originally Posted by G-SXTY
From the BEA report - numerous pieces of aircraft were found between the end of the runway and the crash site, including; access panels, fuel tank fragments, tail cone structural parts and anti-collision light, ducting, hydraulic lines and shut-off valves, and parts of the left wing and fuselage structure. Many of these parts were damaged by fire.
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ex cargo clown
Despite the denial of obviously a well intentioned ChristianJ you have the whole episode in a nutshell. The final nail in the coffin was the Flight Engineer shutting down an engine without instruction from the Captain. My teaching by very experienced trainers over many years was never stop an engine on fire, if it's producing thrust, below 1000 feet agl.
Is there a result from the judicial review due anytime ?
Is there a result from the judicial review due anytime ?
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Despite the denial of obviously a well intentioned ChristianJ you have the whole episode in a nutshell. The final nail in the coffin was the Flight Engineer shutting down an engine without instruction from the Captain. My teaching by very experienced trainers over many years was never stop an engine on fire, if it's producing thrust, below 1000 feet agl.
This was not a case of an engine fire as such (and you learned your lesson well... you always think twice before shutting down an engine).
The aircraft itself was already on fire, scattering bits and pieces all over the landscape before it crashed.
If the engine had not been shut down, the aircraft might have flown another half-mile....
Even if it could have reached Le Bourget, it could not have "landed", with a fire already raging in one of the wheelwells.
Robert, like 'Cargo Clown', you make the major mistake of confusing the causes, that started the chain of events, with the various factors that determined the exact sequence until the crash.
To be crude... those factors only determined where the final fireball occurred, not why.
Is there a result from the judicial review due anytime ?
CJ
The aircraft itself was already on fire, scattering bits and pieces all over the landscape before it crashed.
If the engine had not been shut down, the aircraft might have flown another half-mile....
If the engine had not been shut down, the aircraft might have flown another half-mile....
CJ
Well since we are a having a sharing of open minded opinions I will venture an opinionated reply.
Stuff found on a runway after a plane takes off is typically mechanically liberated over a very short time. I thought it unlikely that a fuel rich fire dependant on swirling airflow would generate enough heat to release debris while still on the runway. Albeit ccorching of local areas of the wing including some flap damage. So I continue with my own opinion that the thrust performance degradation of the flight during climb out was the archilies heel.
Neither the initiating first layer of swiss cheese nor the final layer of cheese where the aircraft falls out the sky is of interest to me either. Instead my thoughts are to the multiple layers of cheese that were thought to be unlikely to line up in the middle.
Unfortunately the courts have a myopic way of assessing blame to satisfy the greater public and that is fed by the favorite plantif lawyers term of " if not for the *** " (pick one layer of cheese) and assign the blame. While my modus operandi looks for the barrier layers that were intended as "in-spite-of"
Quote:
Originally Posted by lomapaseo
...I'm not sure that I agree with you that the fire would have been catastrophic to the ability to land.
The flames were certainly spectacular but it appears to me that the fire was entirely outside the structural interior and streaming in the slipstream.
Your answer is already here :
Quote:
Originally Posted by G-SXTY
From the BEA report - numerous pieces of aircraft were found between the end of the runway and the crash site, including; access panels, fuel tank fragments, tail cone structural parts and anti-collision light, ducting, hydraulic lines and shut-off valves, and parts of the left wing and fuselage structure. Many of these parts were damaged by fire.
The aircraft was already coming apart, well before it could even have reached Le Bourget.
CJ
Originally Posted by lomapaseo
...I'm not sure that I agree with you that the fire would have been catastrophic to the ability to land.
The flames were certainly spectacular but it appears to me that the fire was entirely outside the structural interior and streaming in the slipstream.
Your answer is already here :
Quote:
Originally Posted by G-SXTY
From the BEA report - numerous pieces of aircraft were found between the end of the runway and the crash site, including; access panels, fuel tank fragments, tail cone structural parts and anti-collision light, ducting, hydraulic lines and shut-off valves, and parts of the left wing and fuselage structure. Many of these parts were damaged by fire.
The aircraft was already coming apart, well before it could even have reached Le Bourget.
CJ
Stuff found on a runway after a plane takes off is typically mechanically liberated over a very short time. I thought it unlikely that a fuel rich fire dependant on swirling airflow would generate enough heat to release debris while still on the runway. Albeit ccorching of local areas of the wing including some flap damage. So I continue with my own opinion that the thrust performance degradation of the flight during climb out was the archilies heel.
Neither the initiating first layer of swiss cheese nor the final layer of cheese where the aircraft falls out the sky is of interest to me either. Instead my thoughts are to the multiple layers of cheese that were thought to be unlikely to line up in the middle.
Unfortunately the courts have a myopic way of assessing blame to satisfy the greater public and that is fed by the favorite plantif lawyers term of " if not for the *** " (pick one layer of cheese) and assign the blame. While my modus operandi looks for the barrier layers that were intended as "in-spite-of"
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I think the final two findings in the report are interesting:
- Many pieces of the aircraft found along the track indicate that severe damage to the aircraft’s structure was caused in flight by the fire.
- Even with the engines operating normally, the significant damage caused to the aircraft’s structure would have led to the loss of the aircraft.
They would have had better access to and more time to consider the available evidence in person than we get from just reading the previous chapters of the report. I am not an accident investigator though. 
I also think it is interesting that the VMCA with two engines out and the plane intact is 157 kt, and the aircraft was flying faster when engine 1 had its final surge; still the aircraft described what looks similar to a VMCA roll over. It should have been controllable with two engines out if it was otherwise intact, although rate of descent would have been high. Even before that investigators could start seeing discrepancies between the control deflections commanded and the aircraft behavior, indicating the flight controls were being progressively destroyed. The elevons on the left wing would have been in or near the flame.
I also think it is interesting that the VMCA with two engines out and the plane intact is 157 kt, and the aircraft was flying faster when engine 1 had its final surge; still the aircraft described what looks similar to a VMCA roll over. It should have been controllable with two engines out if it was otherwise intact, although rate of descent would have been high. Even before that investigators could start seeing discrepancies between the control deflections commanded and the aircraft behavior, indicating the flight controls were being progressively destroyed. The elevons on the left wing would have been in or near the flame.
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This kind of stuff should not be left unanswered:
It was about one ton overweight. A lot on a C172, 0.5 % on a Concorde. It had no influence on anything. Not good, but not a factor.
Are you talking about the missing spacer? Or the intermittent fault in one out of three flight control channels, which was an acceptable defect in the MEL? Again, not good, but no factors.
Huh? Where did you get that idea from? 
All available data says it was inside limits.
Wind was light and variable at the time. The tower reported 8 kt tailwind may or may not have been present on the runway during the takeoff (it would have been present at the wind sensor, which is not the same thing), but analysing the aircrafts actual performance during the takeoff indicates it was not present.
The captain ordered fire drill at the same time when the flight engineer announced "shut down engine 2". So the captain did order the shut down.
Hardly. Engine 2 never recovered from the surges, and was producing no more than 15% of thrust when it was shut down. Shutting down engine two put the other three engines in contingency, increasing the thrust on these engines. They probably got more thrust when they shut down engine 2, not less.
Could engine 2 have recovered and started producing thrust had it not shut down? Maybe; I doubt it, but maybe. But with a fire alarm from engine 2 it would have been shut down in short order anyway. Keep in mind that engine 1 was less affected than engine 2, it was not shut down, and it still surged a short time into the flight. Engine 2 would not have ran for long even if it wasn't shut down.
an aircraft that was overweight
, had maintenance issues,
out of trim limits,
All available data says it was inside limits.
taking off downwind,
with a non-captain commanded shut down of an engine
developing thrust
Could engine 2 have recovered and started producing thrust had it not shut down? Maybe; I doubt it, but maybe. But with a fire alarm from engine 2 it would have been shut down in short order anyway. Keep in mind that engine 1 was less affected than engine 2, it was not shut down, and it still surged a short time into the flight. Engine 2 would not have ran for long even if it wasn't shut down.
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However; could this have played out any differently? Possible (right...) alternative outcomes:
Miracle outcome #1: The crew rejects at some 190 kts and roll onto the grass doing at least 100 kts. Miraculously they aircraft does not collide with any obstacle and stops more or less intact on the grass. A few people make it out despite the fire. For the rest of aviation history this event is held up as yet another example of a needless crash caused by the captain's flawed decision to reject above V1, since "everybody knows" that the aircraft could have flown away and landed safely had the takeoff not been rejected.
Miracle outcome #2: The crew makes a snap decision to land on Le Bourget, somehow manage to line up with the runway and land somewhere close to the threshold, brakes are able to slow it down despite being massively above max landing weight, and the aircraft stops without hitting any obstacles (the last point is incredible given the surroundings at Le Bourget). A few people make it out despite the fire.
Miracle outcome #3: By some kind of magic both the flight controls, systems, structure and engine 1 survive the onslaught of the fire for another 45 seconds or so; I have no idea how that could be possible but let us assume it is. By that time the fuel in the breached tank would be depleted. The fire did not damage any other tanks (big assumption here), so the fire actually stops at this time. The crew manage to nurse the damaged aircraft, left elevons all but burned off and unknown other systems malfunctions, to a safe landing. Everyone lives happily ever after.
Would any of those three miracles have been possible? To my mind #2 and #3 are pure fairy tales, and the chance of someone surviving miracle #1 seems remote. Possible, maybe; likely, not a chance.
Yet those who argue that this accident had anything whatsoever to do with the crew's actions are placing their bets on the crew managing to achieve one of the three miracles above. I am not buying it.
Miracle outcome #1: The crew rejects at some 190 kts and roll onto the grass doing at least 100 kts. Miraculously they aircraft does not collide with any obstacle and stops more or less intact on the grass. A few people make it out despite the fire. For the rest of aviation history this event is held up as yet another example of a needless crash caused by the captain's flawed decision to reject above V1, since "everybody knows" that the aircraft could have flown away and landed safely had the takeoff not been rejected.
Miracle outcome #2: The crew makes a snap decision to land on Le Bourget, somehow manage to line up with the runway and land somewhere close to the threshold, brakes are able to slow it down despite being massively above max landing weight, and the aircraft stops without hitting any obstacles (the last point is incredible given the surroundings at Le Bourget). A few people make it out despite the fire.
Miracle outcome #3: By some kind of magic both the flight controls, systems, structure and engine 1 survive the onslaught of the fire for another 45 seconds or so; I have no idea how that could be possible but let us assume it is. By that time the fuel in the breached tank would be depleted. The fire did not damage any other tanks (big assumption here), so the fire actually stops at this time. The crew manage to nurse the damaged aircraft, left elevons all but burned off and unknown other systems malfunctions, to a safe landing. Everyone lives happily ever after.
Would any of those three miracles have been possible? To my mind #2 and #3 are pure fairy tales, and the chance of someone surviving miracle #1 seems remote. Possible, maybe; likely, not a chance.
Yet those who argue that this accident had anything whatsoever to do with the crew's actions are placing their bets on the crew managing to achieve one of the three miracles above. I am not buying it.
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Hokay - so as a secret aviation nut I followed events at the time very closely, but it was 10 years ago, so I'm working purely from memory here...
EXWOK - if the scenario could not be reproduced with setup as prescribed by the flight manual, did they not attempt to reproduce in accordance with the theory that the fuel tanks were slightly over-filled due to not burning as much on the taxi as they were expecting?
lomapaseo - The hydraulic shockwave theory and the fact that no fuel tank had ever been penetrated by a tyre fragment are compatible, because no penetration is required if it was the fluid dynamics of the fuel that punched the hole in the tank, not the tyre. Another interesting (if somewhat grim) theory on fluid dynamics provides an addendum to the Aloha Airlines 737 accident.
robertbartsch - Have a look at the other thread regarding BA's modifications to the main gear in the wake of problems caused by tyre bursts - the later kevlar modification obviated the need for it and it was subsequently removed. AF did not perform the same modification, but they were using different tyres with completely different characteristics. In fact, the new tyre technology developed in the wake of the accident probably obviated the need for the Kevlar lining according to one engineer, but at that stage the work was already underway. You've also got to remember that despite the unprecedented level of R&D that went into Concorde, she is very much a design of the 1960s. System-level failure engineering to the extent of the multiple events that caused the accident didn't come around until the mid-late 1970s, in the wake of the very public DC-10 incidents that occurred around that time.
I'm a little confused by the invective surrounding the FE's engine shutdown decision, especially as so many posts on here bemoan the disappearance of the FE from the flight deck, in part because they were qualified engineers and capable of independent thought and action. Bjornhall and ChristiaanJ are right - all evidence suggests that the structural failures caused by the fire would have doomed the aircraft whether number 2 was turning and burning or not.
I can understand the attitude of those in the documentary (I remember Captain John Hutchinson from a prior appearance on a BBC Concorde special in the late '80s - particularly memorable for his ****-eating grin whenever he was handling the controls) saying that it should never have happened and that Concorde should not have been taken out of service - she was and will always be an aviation gem and a source of pride to anyone involved with her. But I believe that even if Airbus could have been persuaded to continue producing parts, even if AF could have been persuaded to keep her flying, and yes - even if BA had bitten the bullet and gone it alone (though the unseemly haste with which they disposed of the airframes suggests that the end of Concorde operations was more of a relief to BA Corporate than they are prepared to admit) - I very much doubt Concorde operations would have survived the multiple global economic slowdowns of the last decade - and as such, going out with her head held high when she was still in her prime was a far better way to go than meekly submitting to dwindling demand over several years.
EXWOK - if the scenario could not be reproduced with setup as prescribed by the flight manual, did they not attempt to reproduce in accordance with the theory that the fuel tanks were slightly over-filled due to not burning as much on the taxi as they were expecting?
lomapaseo - The hydraulic shockwave theory and the fact that no fuel tank had ever been penetrated by a tyre fragment are compatible, because no penetration is required if it was the fluid dynamics of the fuel that punched the hole in the tank, not the tyre. Another interesting (if somewhat grim) theory on fluid dynamics provides an addendum to the Aloha Airlines 737 accident.
robertbartsch - Have a look at the other thread regarding BA's modifications to the main gear in the wake of problems caused by tyre bursts - the later kevlar modification obviated the need for it and it was subsequently removed. AF did not perform the same modification, but they were using different tyres with completely different characteristics. In fact, the new tyre technology developed in the wake of the accident probably obviated the need for the Kevlar lining according to one engineer, but at that stage the work was already underway. You've also got to remember that despite the unprecedented level of R&D that went into Concorde, she is very much a design of the 1960s. System-level failure engineering to the extent of the multiple events that caused the accident didn't come around until the mid-late 1970s, in the wake of the very public DC-10 incidents that occurred around that time.
I'm a little confused by the invective surrounding the FE's engine shutdown decision, especially as so many posts on here bemoan the disappearance of the FE from the flight deck, in part because they were qualified engineers and capable of independent thought and action. Bjornhall and ChristiaanJ are right - all evidence suggests that the structural failures caused by the fire would have doomed the aircraft whether number 2 was turning and burning or not.
I can understand the attitude of those in the documentary (I remember Captain John Hutchinson from a prior appearance on a BBC Concorde special in the late '80s - particularly memorable for his ****-eating grin whenever he was handling the controls) saying that it should never have happened and that Concorde should not have been taken out of service - she was and will always be an aviation gem and a source of pride to anyone involved with her. But I believe that even if Airbus could have been persuaded to continue producing parts, even if AF could have been persuaded to keep her flying, and yes - even if BA had bitten the bullet and gone it alone (though the unseemly haste with which they disposed of the airframes suggests that the end of Concorde operations was more of a relief to BA Corporate than they are prepared to admit) - I very much doubt Concorde operations would have survived the multiple global economic slowdowns of the last decade - and as such, going out with her head held high when she was still in her prime was a far better way to go than meekly submitting to dwindling demand over several years.
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I've only just started to re-read the original BEA report, to clear up some of the tank 5 issues in my own mind.
Tank 5 is nominal 9090 litres. I haven't found the estimated value for the fuel leak yet, so I don't know yet how long it would have taken for tank 5 to empty through the leak. Does somebody already have the figure?
However, there has been a lot of talk about "overfilling".
Now, first of all, this is (was...) a normal practice for range or weight limited flights. Let me explain.
During refuelling, there would be an automatic cut-off for each tank, when the tank was about 95% full (fuel quantity sensor).
Afterwards, it was possible to add about 1500 litres, by a carefully measured "topping up" of each tank, to compensate for the 1 to 2 tons that would be used during taxying.
This "overfilling" and the resulting lack of airspace has been blamed for the 'oil-canning' (hydraulic shockwave) of tank 5, it seems.
Well, we now have a minor problem....
The BEA report states that only about 300 litres (about 500 lbs) was 'overfilled', and only into tanks 1, 2, 3 and 4, NOT into tank 5.
CJ
Tank 5 is nominal 9090 litres. I haven't found the estimated value for the fuel leak yet, so I don't know yet how long it would have taken for tank 5 to empty through the leak. Does somebody already have the figure?
However, there has been a lot of talk about "overfilling".
Now, first of all, this is (was...) a normal practice for range or weight limited flights. Let me explain.
During refuelling, there would be an automatic cut-off for each tank, when the tank was about 95% full (fuel quantity sensor).
Afterwards, it was possible to add about 1500 litres, by a carefully measured "topping up" of each tank, to compensate for the 1 to 2 tons that would be used during taxying.
This "overfilling" and the resulting lack of airspace has been blamed for the 'oil-canning' (hydraulic shockwave) of tank 5, it seems.
Well, we now have a minor problem....
The BEA report states that only about 300 litres (about 500 lbs) was 'overfilled', and only into tanks 1, 2, 3 and 4, NOT into tank 5.
CJ
Interesting thread
Did someone say earlier it was on just two engines ? For the tank, presumably the geometry of the tank determined which part failed (it's not like spalling off the back side of RHA through a tensile reflected wave).
Last edited by Mr Optimistic; 11th Sep 2010 at 22:20.
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I still think you remark is revolting....
CJ
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Hi,
A bit away from a main topic ...
I do not see anything shocking in about Optmistic post
It is a fact that passengers should not be in a comfortable environment.
Talking about death should not be a taboo .. since no pun .. death is an integral part of the life of human beings.
Perhaps in some societies sweetened .. People were packed in a certain way and can not even bear to be about death and its realities.
It is therefore not surprising that more and more death leaves indifferent .. or is something to hide ..
Let us die in indifference.
A bit away from a main topic ...
I do not see anything shocking in about Optmistic post
It is a fact that passengers should not be in a comfortable environment.
Talking about death should not be a taboo .. since no pun .. death is an integral part of the life of human beings.
Perhaps in some societies sweetened .. People were packed in a certain way and can not even bear to be about death and its realities.
It is therefore not surprising that more and more death leaves indifferent .. or is something to hide ..
Let us die in indifference.
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Originally Posted by ChristiaanJ
This "overfilling" and the resulting lack of airspace has been blamed for the 'oil-canning' (hydraulic shockwave) of tank 5, it seems.
One of the things I forgot in my last post was the reference to eyewitnesses who stated that they thought they saw flames before F-BTSC hit the part of the runway where the debris lay. While it would be churlish to disregard it completely, experience shows that of all the types of evidence available, eyewitness evidence tends to be the least accurate - and in fact one of the recurring factors is that human beings seem to be bad at remembering at what point in the sequence fire was involved - in many accidents where the craft was intact until it hit the ground, contemporary eyewitnesses have said that the craft caught fire in the air.
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that human beings seem to be bad at remembering at what point in the sequence fire was involved
One of the controllers on duty that day said to me that from the start and during accelleration the noise was not the normal noise a Concorde makes during take off.
But again perhaps that was due to the above post accident phenomenae.
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G SXTY
It is highly questionable whether they could ever have made it to Le Bourget – regardless of the number of functioning engines or the position of the landing gear.
The Concorde only achieved 200' altitude [lower than the height of the air traffic control tower], and the copilot had warned Capt Christian Marty at least three times of decreasing airspeed....but Le Bourget runway was in view only 7 miles straight ahead.
My take is that the airplane should have been landed on a farmer's field straight ahead. It would have been a controlled crash, rather than an in flight stall and uncontrolled crash.
There was no logic in attempting to stay airborne without sufficient airspeed.
My take is that the airplane should have been landed on a farmer's field straight ahead. It would have been a controlled crash, rather than an in flight stall and uncontrolled crash.
That being said it is pretty clear that the pilots where not aware of the nature and scope of the fire. Remember that it took weeks to actually understand that it was not an engine fire !
Not specific to this accident but I still wonder why some micro cameras are not strategically placed on all modern airframes - they might save quite a few life IMHO
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A few more remarks about tank 5 (the one that was at the origin of the huge fuel leak).
First of all, for the moment, the theory that the tank was "full to the brim", with very little air space left, which led to the impact of a large piece of tyre provoking a shockwave in the fuel, knocking out part of the tank structure, is still the most likely one.
It's also one of the essential parts of the sequence of events that led to the crash, (unlike all the other details being dragged in, like the wind or the exact take-off weight).
It has been proved difficult, if not impossible, to reproduce the exact conditions during tests.... not that amazing really... but the huge piece of tyre and the panel punched out of the tank were there on the runway for all to see, even if the mechanism wasn't fully understood.
Second, as mentioned earlier, only tanks 1 to 4 had some fuel added during ground refuelling ; however (as somebody just reminded me), the flight engineer could use 'override' switches on the fuel control panel to top off tanks like tanks 5 and 8 to 'fine-tune' the tank contents and the CG during taxy, and probably did, so there is nothing very mysterious about tank 5 being "full to the brim" during take-off.
Third.... I think, in the context, "over-filling" is an unfortunate expression that has caused unnecessary confusion.
It evokes images of "over-doing it" or "over-eating".... something that maybe should not have been done.
In reality, maybe a term like "manual topping-up" would have been better.
The procedure is perfectly normal, without any danger in normal operation, and was used regularly.
It's exactly like your car at the petrol station... the petrol pump will cut out automatically when the tank is about 95% full. You can squeeze in a few more litres if you want to.
For your car it's just a matter of getting the pump to show a round figure in pounds (or euros), for Concorde it was a matter of adding the few hundred litres that would be burned during taxy.
So, on Concorde, there was nothing wrong with "topping up" tank 5 "to the brim", whether done during refuelling or by the F/E during taxying.
What nobody could have foreseen was that it would become one of the primary items on that ghastly day in July 2000....
CJ
First of all, for the moment, the theory that the tank was "full to the brim", with very little air space left, which led to the impact of a large piece of tyre provoking a shockwave in the fuel, knocking out part of the tank structure, is still the most likely one.
It's also one of the essential parts of the sequence of events that led to the crash, (unlike all the other details being dragged in, like the wind or the exact take-off weight).
It has been proved difficult, if not impossible, to reproduce the exact conditions during tests.... not that amazing really... but the huge piece of tyre and the panel punched out of the tank were there on the runway for all to see, even if the mechanism wasn't fully understood.
Second, as mentioned earlier, only tanks 1 to 4 had some fuel added during ground refuelling ; however (as somebody just reminded me), the flight engineer could use 'override' switches on the fuel control panel to top off tanks like tanks 5 and 8 to 'fine-tune' the tank contents and the CG during taxy, and probably did, so there is nothing very mysterious about tank 5 being "full to the brim" during take-off.
Third.... I think, in the context, "over-filling" is an unfortunate expression that has caused unnecessary confusion.
It evokes images of "over-doing it" or "over-eating".... something that maybe should not have been done.
In reality, maybe a term like "manual topping-up" would have been better.
The procedure is perfectly normal, without any danger in normal operation, and was used regularly.
It's exactly like your car at the petrol station... the petrol pump will cut out automatically when the tank is about 95% full. You can squeeze in a few more litres if you want to.
For your car it's just a matter of getting the pump to show a round figure in pounds (or euros), for Concorde it was a matter of adding the few hundred litres that would be burned during taxy.
So, on Concorde, there was nothing wrong with "topping up" tank 5 "to the brim", whether done during refuelling or by the F/E during taxying.
What nobody could have foreseen was that it would become one of the primary items on that ghastly day in July 2000....
CJ
The fluid level in a fuel tank contibuting to this accident was in my view unforseen by the industry in general. It is easy to use hindsight and theories to propose how it might have contributed etc.
Both in the past and presumably in the future engineers and designers have been caught by surprise with a new lesson learned. Obviously lots of fuel tanks have been overfilled without ever seeing such a result.
The key to the recognition that in this specific event it might have been significant was the finding of the tank piece on the runway and its shape and fracture surfaces. To my eye they were unique and I have only seen them before associated with ballistic impacts in thick aluminum. Of course the more scentific evaluations would have to be made in a metalugical lab.
Both in the past and presumably in the future engineers and designers have been caught by surprise with a new lesson learned. Obviously lots of fuel tanks have been overfilled without ever seeing such a result.
The key to the recognition that in this specific event it might have been significant was the finding of the tank piece on the runway and its shape and fracture surfaces. To my eye they were unique and I have only seen them before associated with ballistic impacts in thick aluminum. Of course the more scentific evaluations would have to be made in a metalugical lab.