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Revelation
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 3:05 pm

sxf24 wrote:
I’m surprised it’s taken this long for the issue to get press attention. Operators are not pleased, since this was not discussed when the airplane was marketed, and there’s not a clear path forward. The cold feet issue is real: without insulation it would feel like your feet are on an ice pack.

I think it is upsetting, but is pretty typical of the kind of issue one finds on the path from concept to delivery. Yet I think the level of snark on this thread shows people aren't treating this seriously, whereas the people who will have to deal with passengers on what will be 8+ hour flights in many cases are treating it seriously. It's not just the fuel "getting" cold, for operators in cold climates any fuel being put into the aircraft will start out cold enough to be uncomfortable and take long enough to burn off to be a problem.

mxaxai wrote:
Nobody in the general public discusses finer details of aircraft fuel systems; most don't know or care about the fuel tanks at all. It is good that the regulators have an eye on potential hazards but I expect this problem to be solvable. Worst case, Airbus has to shrink the tank a little to make room for thermal insulation and fire protection.

I'm in the "they will solve it" camp too, but it seems pretty late in the game to have something like this unresolved. From what I understand they've already begun detailed manufacturing so a lot of metal has been cut already. https://www.flightglobal.com/production ... 26.article suggests the first tank was in production in August 2020.

It sounds like shrinking the tank would be viable to add thermal insulation and fire and crash resistance but their response does not offer that as a solution:

This means insulation panels will need to be fitted between the tank and the cabin floor, and these would have to meet burn-through criteria. But Airbus has informed EASA that this is “technically not feasible”, for various reasons.

Lack of space prevents fitting of compliant panels, while burn-through protection of the cabin floor cannot be comprehensive because decompression panels either side of the fuselage must remain free of insulation panels.

Installation of compliant materials would also “jeopardise” the provision of sufficient ventilation around the tank, says EASA.

I wonder if some commercial concerns are at play. The customers were promised a certain fuel volume with a certain amount of added weight, and the vendor does not want to reduce the volume or increase the weight.
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keesje
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 3:10 pm

sxf24 wrote:
zeke wrote:
Tiredofhumanity wrote:
Are they allowed to put those types of floor panels over fuel tanks by the regulators?

Honest question from my experience.


As far as I am aware they have been used in a variety of aircraft from business jets to airliners before without restriction. My understanding it is like a heated blanket between the floor covering and the floor surface inside the cabin.

http://www.goodrich.com/cap/systems/sis ... Panels.pdf


Heated floors have not been used over/around fuel tanks.

JerseyFlyer wrote:
I am not clear if this is an issue that has arisen late in the design process or was always anticipated but has just been published.


It arose later and is just being published.


I think heated floor panels are used above center tanks. Of all requirements must be met.
It seems like a major change, so lots of testing and certification.

Image
https://www.airbus.com/content/dam/corp ... C-A321.pdf

It's a much bigger center tank than currently installed on the A321's.
"Never mistake motion for action." Ernest Hemingway
 
sxf24
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 3:27 pm

Revelation wrote:
sxf24 wrote:
I’m surprised it’s taken this long for the issue to get press attention. Operators are not pleased, since this was not discussed when the airplane was marketed, and there’s not a clear path forward. The cold feet issue is real: without insulation it would feel like your feet are on an ice pack.

I think it is upsetting, but is pretty typical of the kind of issue one finds on the path from concept to delivery. Yet I think the level of snark on this thread shows people aren't treating this seriously, whereas the people who will have to deal with passengers on what will be 8+ hour flights in many cases are treating it seriously. It's not just the fuel "getting" cold, for operators in cold climates any fuel being put into the aircraft will start out cold enough to be uncomfortable and take long enough to burn off to be a problem.


It is normal to encounter technical issues related to capabilities that were sold, but not yet designed. You’re also correct this is a significant issue for the commercial teams at airlines, which must deal with passenger satisfaction and revenue generation.

keesje wrote:
sxf24 wrote:
zeke wrote:

As far as I am aware they have been used in a variety of aircraft from business jets to airliners before without restriction. My understanding it is like a heated blanket between the floor covering and the floor surface inside the cabin.

http://www.goodrich.com/cap/systems/sis ... Panels.pdf


Heated floors have not been used over/around fuel tanks.

JerseyFlyer wrote:
I am not clear if this is an issue that has arisen late in the design process or was always anticipated but has just been published.


It arose later and is just being published.


I think heated floor panels are used above center tanks. Of all requirements must be met.
It seems like a major change, so lots of testing and certification.

Image
https://www.airbus.com/content/dam/corp ... C-A321.pdf

It's a much bigger center tank than currently installed on the A321's.


I don’t think your beliefs are correct. Or at least Airbus has not informed the commercial teams at A321xlr operators of such facts.
 
majano
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 5:27 pm

sxf24 wrote:
Revelation wrote:
sxf24 wrote:
I’m surprised it’s taken this long for the issue to get press attention. Operators are not pleased, since this was not discussed when the airplane was marketed, and there’s not a clear path forward. The cold feet issue is real: without insulation it would feel like your feet are on an ice pack.

I think it is upsetting, but is pretty typical of the kind of issue one finds on the path from concept to delivery. Yet I think the level of snark on this thread shows people aren't treating this seriously, whereas the people who will have to deal with passengers on what will be 8+ hour flights in many cases are treating it seriously. It's not just the fuel "getting" cold, for operators in cold climates any fuel being put into the aircraft will start out cold enough to be uncomfortable and take long enough to burn off to be a problem.


It is normal to encounter technical issues related to capabilities that were sold, but not yet designed. You’re also correct this is a significant issue for the commercial teams at airlines, which must deal with passenger satisfaction and revenue generation.

keesje wrote:
sxf24 wrote:

Heated floors have not been used over/around fuel tanks.



It arose later and is just being published.


I think heated floor panels are used above center tanks. Of all requirements must be met.
It seems like a major change, so lots of testing and certification.

Image
https://www.airbus.com/content/dam/corp ... C-A321.pdf

It's a much bigger center tank than currently installed on the A321's.


I don’t think your beliefs are correct. Or at least Airbus has not informed the commercial teams at A321xlr operators of such facts.

What "beliefs" are you referring to?
 
wjcandee
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 5:56 pm

mxaxai wrote:
I don't think anyone except perhaps some enthusiasts and engineers cares.


Until someone like Scary Mary calls it the "Next Hindenburg", some program like Dateline runs a piece on exploding airliners and asks, "Could TWA800 happen again with the new Airbus?", or someone at MSNBC says, "It's like flying across the ocean sitting on or under a leaky gasoline truck."

Then that's all they know.
Last edited by wjcandee on Sun Feb 28, 2021 5:56 pm, edited 1 time in total.
 
tomcat
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 5:56 pm

sxf24 wrote:
I’m surprised it’s taken this long for the issue to get press attention. Operators are not pleased, since this was not discussed when the airplane was marketed, and there’s not a clear path forward.


This is a pretty strong assertion. Can you please provide a link to support it? Or are you sharing with us your insider information?
 
MIflyer12
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 5:58 pm

If this issue was shared with operators leading up to firm orders Airbus would have outlined a solution that meets regulatory requirements.

'We don't have a solution that meets requirements and won't impede range or fuel efficiency, so just give us your money' is not a strong sales pitch.
 
hayzel777
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 6:08 pm

zeke wrote:
Tiredofhumanity wrote:
Are they allowed to put those types of floor panels over fuel tanks by the regulators?

Honest question from my experience.


As far as I am aware they have been used in a variety of aircraft from business jets to airliners before without restriction. My understanding it is like a heated blanket between the floor covering and the floor surface inside the cabin.

http://www.goodrich.com/cap/systems/sis ... Panels.pdf

Can they put carpet down if they put heated panels? It would look awfully weird if there is an area of plastic flooring in the middle of the plane. Most, if not all, airlines don’t have carpet in any of the heated areas mentioned in the link.
 
sxf24
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 6:38 pm

tomcat wrote:
sxf24 wrote:
I’m surprised it’s taken this long for the issue to get press attention. Operators are not pleased, since this was not discussed when the airplane was marketed, and there’s not a clear path forward.


This is a pretty strong assertion. Can you please provide a link to support it? Or are you sharing with us your insider information?


I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.

MIflyer12 wrote:
If this issue was shared with operators leading up to firm orders Airbus would have outlined a solution that meets regulatory requirements.

'We don't have a solution that meets requirements and won't impede range or fuel efficiency, so just give us your money' is not a strong sales pitch.


Airbus and Boeing sell uncertified designs and features all the time. Most of the sales for the currently available single and twin aisles came before the airplanes flew! Boeing has its own certification issues with cabin visibility on some MAX configurations that have been sold, and even built.
 
mxaxai
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 7:38 pm

wjcandee wrote:
Then that's all they know.

Yeah, and the following week some politician is gonna say something stupid and they'll forget about the A321 as quickly as it popped up.

The MAX is a unique situation because there were 2 crashes to the same cause in a short timespan, with over 300 fatalities. The Concorde crash was a unique situation because Concorde simply is an iconic aircraft and there were some impressive pictures. MH370 is a unique situation because the aircraft hasn't been found after many years, with continuous news coverage.

Nothing about the A321 is unique, and people get bored of technical details quickly. There's no excitement, no emotions, no mystery, no photos.
 
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keesje
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 7:49 pm

If there would be an issue with the new tank configurations and floor heating, it must be solved, by a different design, new requirements , testing and certification. Whatever it takes. If that is not the case, it might be a "you too" effort by a competing manufacturer. To win time, divert attention and play public perceptions with half truths and incorrect generalization.
"Never mistake motion for action." Ernest Hemingway
 
tomcat
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 8:13 pm

sxf24 wrote:

MIflyer12 wrote:
If this issue was shared with operators leading up to firm orders Airbus would have outlined a solution that meets regulatory requirements.

'We don't have a solution that meets requirements and won't impede range or fuel efficiency, so just give us your money' is not a strong sales pitch.


Airbus and Boeing sell uncertified designs and features all the time. Most of the sales for the currently available single and twin aisles came before the airplanes flew! Boeing has its own certification issues with cabin visibility on some MAX configurations that have been sold, and even built.


True, they initially sell uncertified designs but given their experience, they have a high degree of confidence that they will manage to certify the product they have sold. This case is interesting because if Airbus has to resort to significant compromises to certify this new tank, the XLR might end up loosing its unique selling point. Worst case would be to resort to offer a 101t LR instead of the XLR. This would surely re-open the game in the middle of the market. I'm curious to discover how Airbus is going to address this engineering challenge.
 
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Polot
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 8:30 pm

tomcat wrote:
sxf24 wrote:

MIflyer12 wrote:
If this issue was shared with operators leading up to firm orders Airbus would have outlined a solution that meets regulatory requirements.

'We don't have a solution that meets requirements and won't impede range or fuel efficiency, so just give us your money' is not a strong sales pitch.


Airbus and Boeing sell uncertified designs and features all the time. Most of the sales for the currently available single and twin aisles came before the airplanes flew! Boeing has its own certification issues with cabin visibility on some MAX configurations that have been sold, and even built.


True, they initially sell uncertified designs but given their experience, they have a high degree of confidence that they will manage to certify the product they have sold. This case is interesting because if Airbus has to resort to significant compromises to certify this new tank, the XLR might end up loosing its unique selling point. Worst case would be to resort to offer a 101t LR instead of the XLR. This would surely re-open the game in the middle of the market. I'm curious to discover how Airbus is going to address this engineering challenge.

It could be a situation where Airbus thought at time of launch (which was a few months after Max grounding) that they would have no issue on getting their solution/exception through certification but now the FAA and EASA are scrutinizing derivative products much more.
 
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Revelation
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 8:49 pm

keesje wrote:
If there would be an issue with the new tank configurations and floor heating, it must be solved, by a different design, new requirements , testing and certification. Whatever it takes. If that is not the case, it might be a "you too" effort by a competing manufacturer. To win time, divert attention and play public perceptions with half truths and incorrect generalization.

Seems the excuses are ready well in advance in case they are needed. Good job. Now, who is diverting attention?
Wake up to find out that you are the eyes of the world
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Wake now, discover that you are the song that the morning brings
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sxf24
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 9:55 pm

Polot wrote:
tomcat wrote:
sxf24 wrote:



Airbus and Boeing sell uncertified designs and features all the time. Most of the sales for the currently available single and twin aisles came before the airplanes flew! Boeing has its own certification issues with cabin visibility on some MAX configurations that have been sold, and even built.


True, they initially sell uncertified designs but given their experience, they have a high degree of confidence that they will manage to certify the product they have sold. This case is interesting because if Airbus has to resort to significant compromises to certify this new tank, the XLR might end up loosing its unique selling point. Worst case would be to resort to offer a 101t LR instead of the XLR. This would surely re-open the game in the middle of the market. I'm curious to discover how Airbus is going to address this engineering challenge.

It could be a situation where Airbus thought at time of launch (which was a few months after Max grounding) that they would have no issue on getting their solution/exception through certification but now the FAA and EASA are scrutinizing derivative products much more.


I think this is the case. Happening with 777X as well.
 
FLYBY72
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 10:18 pm

SEU wrote:
Revelation wrote:
Seems like it's Airbus's turn to walk the regulatory tight rope.

I was able to read the FG article w/o being a premium member, FWIW...


At least they are being up front and not hiding it from regulators......... :duck:

I am sure there would be work arounds and this shouldnt really delay anything, but there is a potential this could completely mess up the XLR before it even gets built.


Boeing didn't hide anything it says so in the DOJ report. 2 employees drunk texting said they hid something but then the DOJ states clearly, "others in Boeing disclosed MCAS’s expanded operational scope to different FAA personnel who were responsible for determining whether the 737 MAX met U.S. federal airworthiness standards"


If only the FAA knew how to talk to their own people.


(ii) although two of Boeing’s 737 MAX Flight Technical Pilots deceived the FAA AEG about MCAS by way of misleading statements, half-truths, and omissions, others in Boeing disclosed MCAS’s expanded operational scope to different FAA personnel who were responsible for determining whether the 737 MAX met U.S. federal airworthiness standards
 
Weatherwatcher1
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 10:44 pm

keesje wrote:
If there would be an issue with the new tank configurations and floor heating, it must be solved, by a different design, new requirements , testing and certification. Whatever it takes.If that is not the case, it might be a "you too" effort by a competing manufacturer. To win time, divert attention and play public perceptions with half truths and incorrect generalization.


Huh? Sounds like we have a difficult to resolve technical issue to address insulation, decompression panel functionality, fire risk, etc. I have no idea what you mean by “you too” by a competing manufacturer.

https://travelandaviation.com/a321xlrs- ... ions-news/

Lack of space prevents fitting of compliant panels, while burn-through protection of the cabin floor cannot be comprehensive because decompression panels either side of the fuselage must remain free of insulation panels.

Installation of compliant materials would also “jeopardise” the provision of sufficient ventilation around the tank, says EASA.

It adds that the tank is also potentially vulnerable if exposed to penetration by external fire and, if not adequately protected, might not provide enough time for passengers to evacuate. Although aluminium alloys have fire-resistant properties – at a certain thickness – the fire-protection function is mainly provided by insulation material.
 
flipdewaf
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 11:20 pm

Integral fuel tanks with insulation to meet fire regs don’t have rupture characteristics to meet over pressure regs.

Integral fuel tank without insulation lack burn through performance that meet fire regs.

Is it a fundamental issue that rupture design and failure mode required cannot meet regs or that the current technology implemented is unable to satisfy both?

There’s lots of noise around the issue but I still don’t think anyone appears to show what the issue actually is.

Fred


Sent from my iPhone using Tapatalk
Image
 
CRJockey
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Sun Feb 28, 2021 11:23 pm

sxf24 wrote:
I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.


Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...
 
sxf24
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 12:04 am

CRJockey wrote:
sxf24 wrote:
I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.


Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...


Airlines are planning networks and hanging their future on specific capabilities delivered at a set time. Delays in the XLR EIS to solve this issue, inferior passenger experience or reduced fuel capacity will hurt airlines. They care. Today.
 
Antarius
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 12:54 am

CRJockey wrote:
sxf24 wrote:
I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.


Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...


I didn't read this as anyone getting cold feet. Just that fleet planning occurs years in advance and if this does cause a redesign that shrinks the tank, it could cause impacts on aforementioned fleet planning.

I think calling this a "design hiccup" is intentionally downplaying the significance. It's not a deal breaker or anything, but it appears to be a significant hurdle to overcome.
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Weatherwatcher1
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 1:31 am

flipdewaf wrote:
Integral fuel tanks with insulation to meet fire regs don’t have rupture characteristics to meet over pressure regs.

Integral fuel tank without insulation lack burn through performance that meet fire regs.

Is it a fundamental issue that rupture design and failure mode required cannot meet regs or that the current technology implemented is unable to satisfy both?

There’s lots of noise around the issue but I still don’t think anyone appears to show what the issue actually is.

Fred


Sent from my iPhone using Tapatalk


It sounds like Airbus is trying to squeeze in a fuel tank into a pressurized section of the fuselage that doesn’t have enough space for proper fire resistant insulation and blow out decompression panels, which are both required in pressurized sections of the fuselage. Am I wrong?
 
sxf24
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 1:50 am

Antarius wrote:
CRJockey wrote:
sxf24 wrote:
I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.


Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...


I didn't read this as anyone getting cold feet. Just that fleet planning occurs years in advance and if this does cause a redesign that shrinks the tank, it could cause impacts on aforementioned fleet planning.

I think calling this a "design hiccup" is intentionally downplaying the significance. It's not a deal breaker or anything, but it appears to be a significant hurdle to overcome.


I was referring to the literal cold feet of passengers! Do you think B6 would accept a plane that had such a poor passenger experience?

I would also disagree that something increasing risk to the aircraft structure, passengers and their ability to safely evacuate as more than a design hiccup. Maybe the airframe is being pushed too far?
 
SRJ94AB
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:20 am

Reading the EASA document is quite interesting as it states the special condition is purely to address burn through properties of the RCT. To my interpretation of what the document is saying that EASA wants actual evidence on the burn through properties of the design before signing off on it. I’d be surprised if airbus didn’t already have a test or demonstration planned for this at this stage of the development. Otherwise this could mean a redesign.

In terms of the cold feet issue, would this hold back certification? I know the airlines and passengers will of course be concerned for passenger comfort but as this special condition is only looking at burn through protection then is the cold feet issue really that important for safety?

https://www.easa.europa.eu/sites/defaul ... tion_0.pdf

https://www.easa.europa.eu/sites/defaul ... e-01_0.pdf
 
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seahawk
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 6:15 am

If it does not meet the specs, it must not be certified.
 
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Polot
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:12 am

sxf24 wrote:
CRJockey wrote:
sxf24 wrote:
I’m sharing direct feedback from customers of the XLR. They’re a bit frustrated and one of them (not sure which one) leaked to Flight Global.


Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...


Airlines are planning networks and hanging their future on specific capabilities delivered at a set time. Delays in the XLR EIS to solve this issue, inferior passenger experience or reduced fuel capacity will hurt airlines. They care. Today.

Aside from that these are “design hiccups” that must be figured out now if you want to plane to enter service in 2023/2024. Airlines in 2023/2024 would not be happy to learn their jet is delayed because back in 2020/2021 Airbus decided to spare airlines of bad news because of covid and ignored the issue.
 
CRJockey
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:22 am

Polot wrote:
sxf24 wrote:
CRJockey wrote:

Yeah, I am sure of all the frustrations of the aviation years 2020 and 2021, a design hiccup on a plane not to enter service prior 2023/2024, is high on the list of the customers executives. I picture hopping mad managers running in cirles, heads red with anger.

Annoying for Airbus? For sure. And it will be additional money spent. A real problem for the customers at this point? Are they getting...cold feet? No, I don't buy that drama...


Airlines are planning networks and hanging their future on specific capabilities delivered at a set time. Delays in the XLR EIS to solve this issue, inferior passenger experience or reduced fuel capacity will hurt airlines. They care. Today.

Aside from that these are “design hiccups” that must be figured out now if you want to plane to enter service in 2023/2024. Airlines in 2023/2024 would not be happy to learn their jet is delayed because back in 2020/2021 Airbus decided to spare airlines of bad news because of covid and ignored the issue.


Nobody is sparring anyone from anything. Thats exactly my point. There is a design hiccup (or did they realize they are missing one wing?!) and they need to solve it. Like in every other airplane design and/or improvement process. And yes, now is the time to solve it to enter 2023/2024. Not the time to be super nervous about it.
 
Tristarsteve
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:25 am

I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.
 
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Polot
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:29 am

CRJockey wrote:
Polot wrote:
sxf24 wrote:

Airlines are planning networks and hanging their future on specific capabilities delivered at a set time. Delays in the XLR EIS to solve this issue, inferior passenger experience or reduced fuel capacity will hurt airlines. They care. Today.

Aside from that these are “design hiccups” that must be figured out now if you want to plane to enter service in 2023/2024. Airlines in 2023/2024 would not be happy to learn their jet is delayed because back in 2020/2021 Airbus decided to spare airlines of bad news because of covid and ignored the issue.


Nobody is sparring anyone from anything. Thats exactly my point. There is a design hiccup (or did they realize they are missing one wing?!) and they need to solve it. Like in every other airplane design and/or improvement process. And yes, now is the time to solve it to enter 2023/2024. Not the time to be super nervous about it.

If airlines are nervous now that is an indication that they are not fully buying into Airbus’s proposed solution and its ability to pass the regulators.

Tristarsteve wrote:
I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.


As someone pointed out yesterday the center tank of most aircraft is made of very thick and heavy gauge material, as it is typically part of the wing structure- fuel is just in the gaps in the wing box. That likely provides the necessary protections. Making the RCF like that would add too much weight, and rob fuel capacity or rob more cargo capacity, as they would have to increase size of tank along aircraft to get necessary fuel capacity.
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:38 am

keesje wrote:
If there would be an issue with the new tank configurations and floor heating, it must be solved, by a different design, new requirements , testing and certification. Whatever it takes. .
And hopefully the airplane will still meet the promises to customers. Airbus has concerns it would seem.

keesje wrote:
If that is not the case, it might be a "you too" effort by a competing manufacturer. To win time, divert attention and play public perceptions with half truths and incorrect generalization.

Wait what? Are all those posters lauding Airbus and EASA for their transparency mere dupes to an ingenious Boeing scheme to disparage the A321XLR? This strikes me as bizarre even by the standards of prior assertions.
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 11:57 am

Polot wrote:
If airlines are nervous now that is an indication that they are not fully buying into Airbus’s proposed solution and its ability to pass the regulators.


Do we have any indication that any customer is "nervous" about this?
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 12:37 pm

The special conditions regarding the A321XLR rear center tank installation were drafted by EASA (and not by Boeing) , because it's a novel design feature.
The normal SOP is that everybody (airlines, OEM's etc) can give a substantiated, detailed comment on these special conditions, positive or negative.
EASA then has to decide if the comments are included in the final draft of the special conditions.
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Astronage
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 12:43 pm

Could this be solved with the use of fancy insulation materials like aerogel?
 
Weatherwatcher1
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 1:17 pm

Tristarsteve wrote:
I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.


It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 1:26 pm

Weatherwatcher1 wrote:
Tristarsteve wrote:
I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.


It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?

The acts are also inside the pressure vessel and they don’t struggle, I think the issue might be that the wall of the fuel tank is also the wall of the pressure vessel. It needs to handle both functions.

Fred


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flipdewaf
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:04 pm

morrisond wrote:
This seems rather serious.

Would they really grant an exception for this?

What kind of special conditions could they allow it to operate under?

Who would feel comfortable flying on it without enough protection between the fuel and passengers? I know I wouldn't.

https://travelandaviation.com/a321xlrs- ... ions-news/

It's in Flight Global as well if you have premium access.


As far as I know airbus will solve this with Carbon fiber and major computing power. Fire doesn't exist with those things. :bigthumbsup:

:banghead:

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ILNFlyer
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:06 pm

armagnac2010 wrote:
The A321XLR rear center tank is an unusual design feature, as per part 21. It means the part 25 material (CS-25 for EASA) does not have the provisions for such design. Material is available for smaller tanks in the fuselage contour (common on business jets) or auxiliary tanks in cargo holds (AC 25-8), but not for large integral fuel tanks in the fuselage. The only other example coming to my mind is the A340-500 RCT.

Such tanks in the fuselage raise several safety concerns, including fuel tank safety, external fire, crashworthiness and possibly others. None of them are unsurmountable but the level of required design precautions needs to be defined and this is the purpose of the EASA Special Condition(s). The final material will drive design features, for instance the need for ventilation, insulation, etc. The dialogue between Airbus and EASA is being given some visibility which allows for constructive inputs that will be taken into account in some manner, and also helps diffusing liability: if something happens that nobody predicted, both manufacturer and regulator are in much better position.


Thank you for restating the issue so that we are not talking about cold feet.
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:11 pm

why manufacturers dont make fuel tank at sides from LDs?
 
tomcat
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:13 pm

flipdewaf wrote:
Weatherwatcher1 wrote:
Tristarsteve wrote:
I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.


It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?

The acts are also inside the pressure vessel and they don’t struggle, I think the issue might be that the wall of the fuel tank is also the wall of the pressure vessel. It needs to handle both functions.

Fred


Sent from my iPhone using Tapatalk


The new tank is definitely inside the pressure vessel. In terms of certification convenience, it is probably better to keep the current aft bulkhead unchanged in terms of structural function, ie it should remain a pressure bulkhead and not become a fuel tank boundary as well which would add a new set of load cases that would need to be combined with its original load cases. At worst, some support brackets and some fuel pipe penetrations would be added to the pressure bulkhead but that's it. The Airbus news release that I posted upthread seems to indicate that the new tank is an independent assembly that is then inserted in the fuselage during its assembly (*). Of course, it is possible that the new tank would integrate the aft pressure bulkhead as its front boundary and still be viewed as an independent assembly being 'inserted in the fuselage' but that's not my take at this stage. In terms of structural design, it's much easier to retain the current airframe as it is and to view the new tank just as an independent component (so not exactly an integral fuel tank) permanently installed inside the fuselage. An additional reason to proceed like this it to retain as much commonality as possible with the non-XLR models.

(*):
Premium AEROTEC, which was commissioned by Airbus in September 2019 to manufacture the RCT, will complete the structure’s sub-assembly over the next few months at its factory in Augsburg, Germany. This phase involves production of the other RCT parts, followed by structural assembly, systems equipping and testing prior to delivery to Airbus’ major component assembly (MCA) facility in Hamburg early next year, where the tank will be integrated into the aircraft’s rear fuselage.
 
flipdewaf
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:18 pm

tomcat wrote:
flipdewaf wrote:
Weatherwatcher1 wrote:

It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?

The acts are also inside the pressure vessel and they don’t struggle, I think the issue might be that the wall of the fuel tank is also the wall of the pressure vessel. It needs to handle both functions.

Fred


Sent from my iPhone using Tapatalk


The new tank is definitely inside the pressure vessel. In terms of certification convenience, it is probably better to keep the current aft bulkhead unchanged in terms of structural function, ie it should remain a pressure bulkhead and not become a fuel tank boundary as well which would add a new set of load cases that would need to be combined with its original load cases. At worst, some support brackets and some fuel pipe penetrations would be added to the pressure bulkhead but that's it. The Airbus news release that I posted upthread seems to indicate that the new tank is an independent assembly that is then inserted in the fuselage during its assembly (*). Of course, it is possible that the new tank would integrate the aft pressure bulkhead as its front boundary and still be viewed as an independent assembly being 'inserted in the fuselage' but that's not my take at this stage. In terms of structural design, it's much easier to retain the current airframe as it is and to view the new tank just as an independent component (so not exactly an integral fuel tank) permanently installed inside the fuselage. An additional reason to proceed like this it to retain as much commonality as possible with the non-XLR models.

(*):
Premium AEROTEC, which was commissioned by Airbus in September 2019 to manufacture the RCT, will complete the structure’s sub-assembly over the next few months at its factory in Augsburg, Germany. This phase involves production of the other RCT parts, followed by structural assembly, systems equipping and testing prior to delivery to Airbus’ major component assembly (MCA) facility in Hamburg early next year, where the tank will be integrated into the aircraft’s rear fuselage.

Thanks! I had though it was integral so that’s my ignorance there.

Fred


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Weatherwatcher1
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:34 pm

flipdewaf wrote:
Weatherwatcher1 wrote:
Tristarsteve wrote:
I am a bit confused here.
Many years ago when I worked on a B737 C check hangar, we used to lift the floor panels over the centre tank for inspections. Beneath the floor panels were the floor beams that held up the floor, and below the beams was the top of the centre tank. Very close at its highest point .
Cabin exhaust air passes through the gap and keeps the floor warm.
So whats the difference here. Have they eliminated the floor beams and floor panels?
Can't see what is different from a B737 centre tank 15 cm under the passengers feet, and an A321 centre tank under their feet.


It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?

The acts are also inside the pressure vessel and they don’t struggle, I think the issue might be that the wall of the fuel tank is also the wall of the pressure vessel. It needs to handle both functions.

Fred


Sent from my iPhone using Tapatalk


The cargo holds have insulation outside the sidewalls and liners as well as having decompression panels built in to the design. I think you are right since Airbus doesn’t have those design features right between the pressure bulkhead and fuel tank.

Giving how strict regulatory agencies are being nowadays and avoiding deviations to requirements, I can see a scenario where Airbus has to redesign the fuel tank to accommodate for burn through insulation and decompression panels which results in a smaller fuel tank.
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 2:50 pm

CRJockey wrote:
Polot wrote:
sxf24 wrote:
Airlines are planning networks and hanging their future on specific capabilities delivered at a set time. Delays in the XLR EIS to solve this issue, inferior passenger experience or reduced fuel capacity will hurt airlines. They care. Today.

Aside from that these are “design hiccups” that must be figured out now if you want to plane to enter service in 2023/2024. Airlines in 2023/2024 would not be happy to learn their jet is delayed because back in 2020/2021 Airbus decided to spare airlines of bad news because of covid and ignored the issue.

Nobody is sparring anyone from anything. Thats exactly my point. There is a design hiccup (or did they realize they are missing one wing?!) and they need to solve it. Like in every other airplane design and/or improvement process. And yes, now is the time to solve it to enter 2023/2024. Not the time to be super nervous about it.

Yet it is being suggested in another thread that the 77x stress test result of 149% was significant even though we have no evidence it was any part of the current delay attributed to increased regulatory scrutiny. Seems like a double standard is being applied.
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astuteman
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 4:15 pm

Weatherwatcher1 wrote:
flipdewaf wrote:
Weatherwatcher1 wrote:

It is my understanding that the center fuel tank is outside the pressure vessel of the fuselage. It is my understanding that the A321XLR tank is behind the wheel well. The aft bulkhead of the wheel well is the pressure wall. Am I wrong that the fuel tank being inside the pressure vessel on the A321XLR is what is resulting in additional certification requirements?

The acts are also inside the pressure vessel and they don’t struggle, I think the issue might be that the wall of the fuel tank is also the wall of the pressure vessel. It needs to handle both functions.

Fred


Sent from my iPhone using Tapatalk


The cargo holds have insulation outside the sidewalls and liners as well as having decompression panels built in to the design. I think you are right since Airbus doesn’t have those design features right between the pressure bulkhead and fuel tank.

Giving how strict regulatory agencies are being nowadays and avoiding deviations to requirements, I can see a scenario where Airbus has to redesign the fuel tank to accommodate for burn through insulation and decompression panels which results in a smaller fuel tank.


Depending on how much smaller "smaller" is, I wonder if the biggest concern is added weight?
In most cases I feel that the XLR is unlikely to be fuel volume limited...

Rgds
 
FluidFlow
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 5:07 pm

So if I understand this correctly, Airlines do not want cold feet for the passengers, but this would happen because the current design can not have any insulation between the tank and the floor because this insulation would jeopardise security:

1)An integral (structural) rear centre tank (RCT) located behind the wheel bay is introduced to the aeroplane in the lower section of the fuselage, partially replacing the aft cargo compartment. The RCT creates a ‘cold feet’ effect for the passengers located above it, and insulation panels will have to be installed between the RCT and the cabin floor for comfort reasons. As per CS 25.856(b), these panels will have to be compliant with the burnthrough specifications. The aircraft manufacturer studied this strategy and concluded that, for the proposed design, compliance with CS 25.856(b) is technically not feasible due to the following reasons:
a.It is not possible to install insulation panels between the RCT and the cabin floor that would be compliant with the installation requirements as expressed in FAA AC 25.856 2A, due to the lack of space.
b.Burnthrough protection of the cabin floor would leave the decompression panels located on each side of the fuselage unprotected, as they cannot be blocked by any insulation panels. The total area of discontinuities above the RCT in terms of burnthrough protection would be around 10 %.
c.Due to the Fire, Explosion and Smoke Risk Assessment (FESRA) conclusions around the RCT, a certain level of ventilation must always be ensured, and any attempt to install burnthrough-compliant material would jeopardize this ventilation.


So the design of the tank is actually safe but it is not comfortable, except for one risk that is an external fire:

2)The integration of a fuselage integral fuel tank located behind the wheel bay, under the passenger cabin, brings additional risks (explosion, penetration by fire, vapor migration, etc) if it is exposed to an external fire. While the other risks are addressed separately, this proposed Special Condition intend to address the risk of penetration by fire only. Even though paragraph 25.856(b) focuses on the insulation material, the intent of the rule is to provide enough time for the occupants to evacuate the aircraft in case of an external pool fire. An integral fuselage fuel tank exposed to an external fire, if not adequately protected, may not provide enough time for the passengers to safely evacuate the aircraft. From a fuel tank fire protection perspective, aluminium alloys are indeed recognised to have fire resistant properties, when of a thickness that is appropriate to the function to be performed. This minimum thickness is, unfortunately, not specified. Moreover, from a fuselage burnthrough point of view, it is also acknowledged that an aluminium skin provides very limited protection, hence the fire protection function is mainly provided by the insulation material.


So to adress this risk, EASA proposes, that the whole fuselage around the RCT has to be resistant to fire penetration:

In order to protect the cabin occupants from an external pool fire, the lower half of the fuselage in the longitudinal location of the rear centre tank shall be resistant to fire penetration.


To achieve this Airbus has to prove to EASA that their design can handle the following criteria:

In showing compliance to SC-E25.856-01the following may be considered:
1. The strategy for protection of the fuselage against external pool fire effects for a fuselage structural centre tank installation may be demonstrated to be at least as safe as the previous design of the basic aircraft, for which the burnthrough protection was found compliant with CS 25.856(b).
2.The demonstration can be achieved either through the design features of the RCT itself, or through additional design features.
3.The demonstration can be based on tests, analysis supported by test evidence, or design similarity.
4.When flame penetration testing is performed on materials other than insulation blankets that would be compliant to 25.856(b), the test should be carried out in accordance with the test conditions prescribed in Appendix F Part VII with regards to the fire threat with an exposure time of 5 minutes to the flame. There should be no flame penetration during these 5 minutes.




On top of that Boeing raised a two concern upon crash worthiness of the RCT but that was dismissed by EASA as the RCT design already proved to be meet criteria:

Fuel tanks integral to the airframe structure inherently provide less redundancy than structurally separate fuel tanks. Such integral fuel tanks located within the fuselage volume can foreseeably result in more hazardous outcomes when exposed to threats such as an external pool-fed fire.


The protection of the RCT against an external pool-fire resulting in explosion or ignition of flammable vapors due to heat transfer will be covered by a separate Special Condition. The text of the proposed Special Condition has not been changed based on this comment.


oeing notes there are additional concerns presented by integral fuel tanks located within the fuselage volume due to threats other than the external pool-fed fire 25.865(b) is to protect against. The location of such an integral fuel tank immediately aft of the main landing gear presents the most extensive range of threats to be considered. EASA states the following in the reference SC Item 2) of the “Identification of Issue”: 2) The integration of a fuselage integral fuel tank located behind the wheel bay, under the passenger cabin, brings additional risks (explosion, penetration by fire, vapor migration, etc) if it is exposed to an external fire. While the other risks are addressed separately, this proposed Special Condition intend to address the risk of penetration by fire only. Boeing is concerned about other risks as identified in this paragraph. The inclusion of an auxiliary fuel tank integral to the fuselage presents many potential hazards, particularly the protection against structural disruption due to an otherwise survivable off-runway or landing gear failure event. Many of these hazards have been addressed in the past per the advisory material in FAA Advisory Circular (AC) 25-8 or other equivalent guidance.


The RCT design is being thoroughly reviewed with regards structural crashworthiness, taking into consideration the level of safety provided by the FAA AC25-8. Appropriate means of compliance will be defined. The text of the proposed Special Condition has not been changed based on this comment.



So simply said, Airbus knows what they have to do to make the design compliant to certification. Know we will see if they can do that.

We will also see if the airlines will be OK with the cold feet as this can not be addressed. So take it as it is or order a different NB with 4500nm range.
 
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Francoflier
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 5:18 pm

FluidFlow wrote:
We will also see if the airlines will be OK with the cold feet as this can not be addressed. So take it as it is or order a different NB with 4500nm range.


I'm not convinced that there's no way around the 'cold feet' problem. EASA has refused the proposed thermal insulation solution that Airbus offered, but I can't see why they couldn't work something else out, such as heated mats in the floor or a blown air solution.
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Bricktop
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 5:24 pm

Francoflier wrote:
FluidFlow wrote:
We will also see if the airlines will be OK with the cold feet as this can not be addressed. So take it as it is or order a different NB with 4500nm range.


I'm not convinced that there's no way around the 'cold feet' problem. EASA has refused the proposed thermal insulation solution that Airbus offered, but I can't see why they couldn't work something else out, such as heated mats in the floor or a blown air solution.

Or issue passengers with Uggs with an embroidered Airbus and airline logos on them.
 
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 5:31 pm

Having to make changes late in the process is just the cost of putting safety first.

Boeing is taking 2 year slips on MAX10 and 77X due to regulatory pushback, yet they already built the first MAX10 and many 779s.

It's always a risk to build things before you have a clear path towards regulatory approval, but it's pretty normal in aviation to have to take the risk of doing so and having to do rework if/when you find issues.
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madpropsyo
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 6:15 pm

I mean it's not just going to be cold feet, right? Those rows in the cabin over and near the RCT will be very cold in general if there's an icebox on the floor. So either the passengers in those rows will be very cold or the rest of the cabin will have to be overly hot to compensate. That is a pretty significant lose/lose comfort issue to work out and it's no wonder the airlines with orders are unhappy.

FluidFlow wrote:
So the design of the tank is actually safe but it is not comfortable, except for one risk that is an external fire:


Lol, yeah it's totally safe... except for the fire.
 
Tristarsteve
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 6:22 pm

madpropsyo wrote:
I mean it's not just going to be cold feet, right? Those rows in the cabin over and near the RCT will be very cold in general if there's an icebox on the floor. So either the passengers in those rows will be very cold or the rest of the cabin will have to be overly hot to compensate. That is a pretty significant lose/lose comfort issue to work out and it's no wonder the airlines with orders are unhappy.

FluidFlow wrote:
So the design of the tank is actually safe but it is not comfortable, except for one risk that is an external fire:


Lol, yeah it's totally safe... except for the fire.


Why should there be an icebox on the floor.?
The fuel in that tank is inside the pressure hull. It is loaded at around 5 degC or more, and is then warmed up by the cabin air flowing around it. Depends how they vent it , but current tanks are pressurised with cabin air, not vented to ambient
 
SRJ94AB
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Re: A321XLR’s rear fuel tank demands special fire-protection conditions

Mon Mar 01, 2021 6:36 pm

madpropsyo wrote:
I mean it's not just going to be cold feet, right? Those rows in the cabin over and near the RCT will be very cold in general if there's an icebox on the floor. So either the passengers in those rows will be very cold or the rest of the cabin will have to be overly hot to compensate. That is a pretty significant lose/lose comfort issue to work out and it's no wonder the airlines with orders are unhappy.

FluidFlow wrote:
So the design of the tank is actually safe but it is not comfortable, except for one risk that is an external fire:


Lol, yeah it's totally safe... except for the fire.


No one has provided evidence to say the airlines are “unhappy”. I’m sure they are watching how the certification process will unfold especially as there seems to be extra scrutiny going on with derivatives. (And rightly so) but ultimately it’s down to airbus/EASA to work out what needs to be done to meet regulations that EASA/faa set. I’m sure there’s issues like this that crop up all the time with certifications, and something airbus and Boeing have the resources to solve. This to me doesn’t seem like a show stopper just EASA and others discussing how they are gong to certify the a321xlr. I’m sure easa will want to demonstrate they are just as hard on airbus as they have been with Boeing since the max crashes.

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Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos