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Qatar Airways grounds 13 Airbus A350s as fuselage degrading

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Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#41

Post by yread »

JKCalhoun wrote: post #6

I've been a long time carbon-fiber skeptic. Only an armchair materials enthusiast but carbon fiber construction seems to lack the margin for fatigue that aluminum has. It seems to me that when carbon fails it fails catastrophically, while aluminum allows some "give". Now it seems carbon fiber doesn't have the longevity either? I am aware the aluminum can "work harden" over time and become more brittle as well. No mat…

I am more worried about fire safety. Fire in CF is difficult to extinguish. How well and for how long does it protect occupants from fire, does it produce poisonous gases and lose structural integrity as it heats up?

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#42

Post by throwawayboise »

EMM_386 wrote: post #8
JKCalhoun wrote: post #6

I've been a long time carbon-fiber skeptic. Only an armchair materials enthusiast but carbon fiber construction seems to lack the margin for fatigue that aluminum has. It seems to me that when carbon fails it fails catastrophically, while aluminum allows some "give". Now it seems carbon fiber doesn't have the longevity either? I am aware the aluminum can "work harden" over time and become more brittle as well. No mat…

Keep in mind we have 30-year old A320s flying around using carbon-fiber, so we would seem to be out of the trial-period phase. This issue appears to be a cosmetic one with regards to the paint layers, not structural (see my other comment).

If it's cosmetic only, why the grounding?

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#43

Post by jacquesm »

InTheArena wrote: post #20
EMM_386 wrote: post #5

This was first reported back in January when a Qatar Airways Airbus A350 was in Shannon for a repaint. When the paint was stripped they found surface coating irregularities. This is apparently cosmetic and not structural. This was one of the first A350s to be repainted. Qatar has 53 Airbus A350 aircraft, so why these particular 13 is the question now.

The rumor is that some combination of paint, stripper and CFRP led to the actual mesh being exposed. If so, that goes considerably further then cosmetic.

Is there a link or some other substantiation to the rumor? I'm quite interested in this (but for an entirely unrelated field).

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#44

Post by jacquesm »

walrus01 wrote: post #27
EMM_386 wrote: post #8

Earlier quoted context omitted.

Keep in mind we have 30-year old A320s flying around using carbon-fiber, so we would seem to be out of the trial-period phase. This issue appears to be a cosmetic one with regards to the paint layers, not structural (see my other comment).

there are also a number of enthusiastic road cyclists riding 20, 25 year old carbon fiber frames - if not crashed or mechanically damaged (in a way that would also total beyond repair a thin walled aluminum frame like a cannondale CAAD8), they last quite a while.

I had one of these until very recently, a first generation CADEX frame (1987, so now a good 35 years old), still as good as new, it went to Germany and is now plying the streets of Berlin.

Unless you smash them up just keep them clean and they seem to last quite long, at least as long as comparable steel or aluminum frames.

The weak points are where aluminum is bonded to the carbon, those spots you need to monitor and if there is any damage at all you should count the frame as lost.

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#45

Post by rorykoehler »

jacquesm wrote: post #44
walrus01 wrote: post #27

Earlier quoted context omitted.

there are also a number of enthusiastic road cyclists riding 20, 25 year old carbon fiber frames - if not crashed or mechanically damaged (in a way that would also total beyond repair a thin walled aluminum frame like a cannondale CAAD8), they last quite a while.

I had one of these until very recently, a first generation CADEX frame (1987, so now a good 35 years old), still as good as new, it went to Germany and is now plying the streets of Berlin. Unless you smash them up just keep them clean and they seem to last quite long, at least as long as comparable steel or aluminum frames. The weak points are where aluminum is bonded to the carbon, those spots you need to monitor an…

When I raced mountain bikes I always found the feel of aluminium frames to deaden after a few years. They would be super responsive at first and then slowly lose that snappiness and with it trail feel as the years went by.

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#46

Post by danuker »

> Qatar

Could it be the Qatar weather, typically over 40°C (100°F)?

How much time do planes spend parked there? I would assume more, since the pandemic.

Keeping them in the sun would make them even hotter than the air temperature (which is measured in the shade).

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#47

Post by chiph »

dylan604 wrote: post #33
jacquesm wrote: post #16

Earlier quoted context omitted.

Yes, and quite possibly they did not factor in the long term differences between interaction of paint and materials.

Is the paint for anything more than cosmetics/branding purposes? Does it provide a benefit like UV shielding etc? In otherwords, do we use the paint for anything other than ego of corps owning them?

You want your plane to be mostly white in color to reflect solar heat and reduce the load on the air conditioning packs.

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#48

Post by sandworm101 »

chiph wrote: post #47
dylan604 wrote: post #33

Earlier quoted context omitted.

Is the paint for anything more than cosmetics/branding purposes? Does it provide a benefit like UV shielding etc? In otherwords, do we use the paint for anything other than ego of corps owning them?

You want your plane to be mostly white in color to reflect solar heat and reduce the load on the air conditioning packs.

White paint also weighs slightly less which, across a fleet, adds up to an economically relevant fuel cost.

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#49

Post by danmaz74 »

himinlomax wrote: post #23
JKCalhoun wrote: post #6

I've been a long time carbon-fiber skeptic. Only an armchair materials enthusiast but carbon fiber construction seems to lack the margin for fatigue that aluminum has. It seems to me that when carbon fails it fails catastrophically, while aluminum allows some "give". Now it seems carbon fiber doesn't have the longevity either? I am aware the aluminum can "work harden" over time and become more brittle as well. No mat…

Carbon fiber and other composites are actually much better wrt fatigue than aluminium. In fact they are pretty much immune to it, if you mean the word in the sense it's used in metallurgy. They are however much worse for impact resistance.

Does the impact resistance degrade during the expected lifetime of those composites?

Re: Qatar Airways grounds 13 Airbus A350s as fuselage degrading

#50

Post by himinlomax »

danmaz74 wrote: post #49
himinlomax wrote: post #23

Earlier quoted context omitted.

Carbon fiber and other composites are actually much better wrt fatigue than aluminium. In fact they are pretty much immune to it, if you mean the word in the sense it's used in metallurgy. They are however much worse for impact resistance.

Does the impact resistance degrade during the expected lifetime of those composites?

No, except inasmuch as the resin may degrade over time, but that's not just an issue for impact resistance.
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