The 787 - What happens in a fire?
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The 787 - What happens in a fire?
With the new 787, and the amount of non metal in it, what effect is that going to have in case of a crash landing, and a resulting fire?
Also what would happen because of the way that this thing is manufactured if there was a side impact from the food delivery van? I assume that the skin would crack, rather than bend like metal would.
Also what would happen because of the way that this thing is manufactured if there was a side impact from the food delivery van? I assume that the skin would crack, rather than bend like metal would.
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Yeah, I would hope that they have done their research that is for sure. But it does concern me none the less. All I can hear is that it is going to save 20% on fuel. It is defintely going to be interesting to see how the aircraft goes. Metal doesn't generally combust, but wonder if what the 787 is made of is. I mean OK, planes are meant to fly the majority of them do, but unfortunately some do. Would this new one be safer or more dangerous than using existing materials.
When a little SNUF crashed at Laarburch in the late 90's (I think it was the very last before LBH closed) - the runway was closed for two weeks while several dinky little hangar sweepers were written-off gathering all the Carbon Fibres from the floor.
That was just one single seat Harrier!
Notably - all groundcrew ran away from the crash site and site guards had to have medical tests afterwards.
The resin in the structure is the flammable substance with regard to fires - The Fibres that float up with the smoke just clog your lungs for life.
That was just one single seat Harrier!
Notably - all groundcrew ran away from the crash site and site guards had to have medical tests afterwards.
The resin in the structure is the flammable substance with regard to fires - The Fibres that float up with the smoke just clog your lungs for life.
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All Boeing aircraft built from 2008 onward will have this system.
The 787 will utilise a nitrogen inerting system for the fuel tanks. With this system, the chances of a deadly fire are greatly reduced as evidenced by the recent C-5 crash in Dover (DE) to name just one example.
Carbon Fibre can be recycled. More info here. < 2003 PDF from Boeing.
Carbon Fibre can be recycled. More info here. < 2003 PDF from Boeing.
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How the aircraft will burn depends on the matrix used in the composite. I think with the 787 the matrix isn't flammable. When exposed to a flame it will just decompose (maybe it'll also release some nasty gases? not sure) As far as I'm aware the only commonly used matrix that will burn is polyester but flame retardent can be added to it to stop combustion). Polyester isn't really used in aircraft. As for recycling a thermoset composite like that used in the 787 can only be recyled by grinding it down and using it in lower grade products (with current technology anyway). Thermoplastic composites on the other hand can be heated until the matrix melts and so you could possible separate the fibres and matrix for reuse. Thermoplastics are used alot less then thermosetting because they're harder to manufacture but their use is increasing. I think the leading edge of the A380 is thermoplastic composite. As for what will happen when something drives into the side of the fuselage, well with engine nacelles which are made of composites you can patch the hole if it is small enough. With primary structures such as the fuselage things could get a lot more complicated possibly you might have to replace the entire damaged part. Composites are hazardous waste and if the fibres get onto your skin they itch like crazy
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Re bgc post, this is in error and 787 uses epoxies throughout which are indeed flammable and also have smoke and toxicity issues. The whole subject can be researched under FST(Fire,Smoke and Toxicity) and FST issue of epoxies is why there are banned on all aircraft interiors being replaced by phenolics back in 1970's due to many fatalities.
In summary, there is a major problem which needs FST full scale testing prior to any certification or EIS.
In summary, there is a major problem which needs FST full scale testing prior to any certification or EIS.
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The key differences between epoxy composites and metallic components are far lower ignition temperature levels for epoxies and accompanying high lateral rate of fire spread, high peak heat release rates and high smoke and toxicity levels as is well established in the literature over several decades. In terms of ignition temperatures, you are talking factors of three to four higher for aluminum and magnesium versus composites and the smoke and toxicity from epoxy composites are very high.
So the danger is present and needs to be addressed prior to certification via FST full scale tests and not ducked around in my opinion.
So the danger is present and needs to be addressed prior to certification via FST full scale tests and not ducked around in my opinion.
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Re: Amicus
As far as I am aware cured epoxy is not flammable as a flammable material is something that will easily catch fire at commonly found temperatures. So for example petrol is flammable and uncured epoxy is flammable because of the solvents in it. The flash point of cured epoxy is approx. 200 Celsius so I don't think it can be classed flammable, I made that point incase someone was worried that the 787 would burn like the Hindenburg if it were to come into contact with a cigarette or something similiar, it won't. However in a crash there could be alot of burning jet fuel with temperatures building to >1000 celsius. In this situation epoxy would stand no chance - Not many materials would. So its not a question of if the composite will burn but how long the structure could resist the advancing fire to give passengers time to get to safety. You're correct about epoxy not being allowed within the cabin and it isn't found within the cabin of the 787, regulations forbid it. PEI composites are to be found instead. Don't forget that alu alloy found in current airliners isn't exactly excellent at resisting fire, indeed firewalls in aircraft aren't made of aluminium alloy, commonly stainless steel is used. I think that the structure should be able to resist the fire for long enough to allow for an evacuation which also means keeping dangerous fumes out of the cabin which would be the biggest killer of passengers who survive the impact. The composite structure will burn in an aviation fuel fire eventually - by the time that happens I don't think there would be anybody left alive anyway regardless of whether the aircraft is made of aluminium or composites.
As far as I am aware cured epoxy is not flammable as a flammable material is something that will easily catch fire at commonly found temperatures. So for example petrol is flammable and uncured epoxy is flammable because of the solvents in it. The flash point of cured epoxy is approx. 200 Celsius so I don't think it can be classed flammable, I made that point incase someone was worried that the 787 would burn like the Hindenburg if it were to come into contact with a cigarette or something similiar, it won't. However in a crash there could be alot of burning jet fuel with temperatures building to >1000 celsius. In this situation epoxy would stand no chance - Not many materials would. So its not a question of if the composite will burn but how long the structure could resist the advancing fire to give passengers time to get to safety. You're correct about epoxy not being allowed within the cabin and it isn't found within the cabin of the 787, regulations forbid it. PEI composites are to be found instead. Don't forget that alu alloy found in current airliners isn't exactly excellent at resisting fire, indeed firewalls in aircraft aren't made of aluminium alloy, commonly stainless steel is used. I think that the structure should be able to resist the fire for long enough to allow for an evacuation which also means keeping dangerous fumes out of the cabin which would be the biggest killer of passengers who survive the impact. The composite structure will burn in an aviation fuel fire eventually - by the time that happens I don't think there would be anybody left alive anyway regardless of whether the aircraft is made of aluminium or composites.
Last edited by bgc; 31st Jul 2007 at 13:43.
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Rigga
When a little SNUF crashed at Laarburch in the late 90's (I think it was the very last before LBH closed) - the runway was closed for two weeks while several dinky little hangar sweepers were written-off gathering all the Carbon Fibres from the floor.
That was just one single seat Harrier!
Notably - all groundcrew ran away from the crash site and site guards had to have medical tests afterwards.
The resin in the structure is the flammable substance with regard to fires - The Fibres that float up with the smoke just clog your lungs for life.
When a little SNUF crashed at Laarburch in the late 90's (I think it was the very last before LBH closed) - the runway was closed for two weeks while several dinky little hangar sweepers were written-off gathering all the Carbon Fibres from the floor.
That was just one single seat Harrier!
Notably - all groundcrew ran away from the crash site and site guards had to have medical tests afterwards.
The resin in the structure is the flammable substance with regard to fires - The Fibres that float up with the smoke just clog your lungs for life.
Indeed no one had, they walked around collecting parts and kicking up dust unprotected....The fibres do not just clog your lungs, they are not degradable they are hard, sharp and unremovable, they literally shred your lungs from the inside out with their movement........
I seem to remember if memory serves me correctly ( I could be wrong, its a long time ago) the SGT in charge lost something like 40% lung capacity over 6 months and the rest of the poor beggars faired no better...after that it was full suits and masks to prevent it happening again.....
That is why they RAN AWAY... they are better informed than your average Airman, if you see them running away from another accident, join em, they know what they are doing.
As a footnote, an Airline I know near me had a tail incident with a catering truck that resulted in the horizontal stab being written off, they donated it to a well known University...... A friend worked there and in passing mentioned they were going to section it as a training aid...... Luckily I was able to warn him in time and it was stopped until full protection was obtain, information gathered and it could be carried out safely, I hope that I may have saved some other unfortunates suffering the same fate as that RAF team.......... Nasty stuff, stay well away from it if it's damaged in a crash.. I look on it as 10% worse than asbestos.
Much more should be published to warn people dealing with it.
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Re BGC
Again, it is the low ignition levels of epoxies and the heavy concentration of smoke, possibility of flash-over fires and toxic gases which are of concern. Bringing in stainless firewalls and that aluminum catches fire evenually is only ducking the problem to me. Frictional heating alone in wheels up landing will ignite the fuselage epoxies as cited earlier. It is not a question of eventually, but initially or why were epoxies banned from interiors decades ago as you now admit? There is a window of time for escape in survivable crashes mandated by FAA and a 787 FST test is required to see if that existing standard is met or not and that means a full up test.
My opinion is do the fuel fed fuselage FST test on the 787 and A-350XWB and assess results prior to certification, simple to me and I don't think any rational engineer would think otherwise. Problems don't go away from wishing them away. The epoxy FST issue clearly exists or why not use them on interiors?
Equally clearly, we need a full up FST 787 fuel fed fire fuselage test. I think I have now said my piece and hope it is clear to all.
Again, it is the low ignition levels of epoxies and the heavy concentration of smoke, possibility of flash-over fires and toxic gases which are of concern. Bringing in stainless firewalls and that aluminum catches fire evenually is only ducking the problem to me. Frictional heating alone in wheels up landing will ignite the fuselage epoxies as cited earlier. It is not a question of eventually, but initially or why were epoxies banned from interiors decades ago as you now admit? There is a window of time for escape in survivable crashes mandated by FAA and a 787 FST test is required to see if that existing standard is met or not and that means a full up test.
My opinion is do the fuel fed fuselage FST test on the 787 and A-350XWB and assess results prior to certification, simple to me and I don't think any rational engineer would think otherwise. Problems don't go away from wishing them away. The epoxy FST issue clearly exists or why not use them on interiors?
Equally clearly, we need a full up FST 787 fuel fed fire fuselage test. I think I have now said my piece and hope it is clear to all.
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Amicus,
It seems you are more into your agenda then the cert requirements for test (FST or any other).
It would be inadvisable to think that Boeing's M&P as well as FAA (and EASA) were not having a detailed look into the topic.
(Un) Fortunately this info is still not publicly available and therefore prone to guess-work and free interpretation.
Regards,
It seems you are more into your agenda then the cert requirements for test (FST or any other).
It would be inadvisable to think that Boeing's M&P as well as FAA (and EASA) were not having a detailed look into the topic.
(Un) Fortunately this info is still not publicly available and therefore prone to guess-work and free interpretation.
Regards,
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It is potentially a huge issue and not just relating to the 787.
Some thoughts on fibre structures - There are techniques avaliable for working on fire/crash damaged bonded fibre componants. Positive pressure breathing masks and goon suits are a start, but massively reduce the ammount of time you can work for. Fixative sprays to hold down fibres are also usable though the duration is indeterminate. A pal recommends wrapping the damaged component in industrial cling film while it is transported.
I cant remember where I read some of this - will have to dig it out. There are a wide range of fibres not just "carbon". however in terms of acting like "asbestos" initial reaserch suggests that they don't have the same toxic properties as asbestos. That is not to say that you want a lung full of them due to all the other nasty qualtities.
more when I get time.
As fro the field repair of minor bumps - we shall have to wait for the Boeing Maint Manual and see what it says.
Some thoughts on fibre structures - There are techniques avaliable for working on fire/crash damaged bonded fibre componants. Positive pressure breathing masks and goon suits are a start, but massively reduce the ammount of time you can work for. Fixative sprays to hold down fibres are also usable though the duration is indeterminate. A pal recommends wrapping the damaged component in industrial cling film while it is transported.
I cant remember where I read some of this - will have to dig it out. There are a wide range of fibres not just "carbon". however in terms of acting like "asbestos" initial reaserch suggests that they don't have the same toxic properties as asbestos. That is not to say that you want a lung full of them due to all the other nasty qualtities.
more when I get time.
As fro the field repair of minor bumps - we shall have to wait for the Boeing Maint Manual and see what it says.
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Re Amicus,
Its well known that epoxy and most other plastics aren't allowed within the cabin due to the dangerous gasses that they emit in a fire, I never denied that so I'm not sure what you think I'm admitting to? My argument so far has been in relation to the primary structure of the aircraft. Whilst I acknowledge that there are risks involved I'm just a bit concerned that the dangers are being sensationalised here - its easy to do because information on advanced composite materials is not common knowledge.
Its well known that epoxy and most other plastics aren't allowed within the cabin due to the dangerous gasses that they emit in a fire, I never denied that so I'm not sure what you think I'm admitting to? My argument so far has been in relation to the primary structure of the aircraft. Whilst I acknowledge that there are risks involved I'm just a bit concerned that the dangers are being sensationalised here - its easy to do because information on advanced composite materials is not common knowledge.
Last edited by bgc; 1st Aug 2007 at 09:04.
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Lightening & Carbon Fibre
So how does the new 787 cope with lightening strikes?
Normally when carbon fibre get hit by lightening as on the B744 thrust reverser cowls on the GE CF6 and RR RB211 it burns the resin out and all your left with is a blacken burnt carbon fibre matt.
So if the whole aircraft is made of carbon fibre - a severe lightening strike does what to the fuselage? How do you test or check for that, man made lightening is no where near what nature can produce...
Normally when carbon fibre get hit by lightening as on the B744 thrust reverser cowls on the GE CF6 and RR RB211 it burns the resin out and all your left with is a blacken burnt carbon fibre matt.
So if the whole aircraft is made of carbon fibre - a severe lightening strike does what to the fuselage? How do you test or check for that, man made lightening is no where near what nature can produce...