5 ms·

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 cosme

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).

numpad0 5y ago
Apparently A350 are built with Teijin Tenax thermoplastic carbon. Brochures say it cures in one minute, eliminating autoclave. Could be different from normal resin based carbons.
- jacquesm 5y ago
  Yes, and quite possibly they did not factor in the long term differences between interaction of paint and materials.
  - avs733 5y ago
    Why would you think that? You think these aerospace engineers are a bunch of goof offs?
    - jacquesm 5y ago
      Because sometimes process optimizations have complex downstream effects. Aerospace engineers are anything but a bunch of goof offs, which is why flying is as safe as it is. And that's why they pulled the aircraft from service even though it is 'just a surface issue' they want to make sure that it really is just that before releasing them - freshly painted - back into service again. The history of aerospace quality control is written in blood, not because they are goof offs but because materials science is complex and sometimes the only warning you get that something is wrong is a crash. Avoiding those is what this sort of action is all about, in any other industry they would have slapped some new paint on it and kept going.
  - dylan604 5y ago
    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?
    - jacquesm 5y ago
      Some paint is more slippery than the substrate it is painted on for lower air resistance: https://www.skybrary.aero/index.php/Surface_Coatings_and_Drag_Reduction https://www.skybrary.aero/index.php/Surface_Coatings_and_Dra... Then there is corrosion protection, protection from ablation (especially on leading edges which usually have other protection against this as well), ice adherence and so on. So it is far from just cosmetic, and given the weight of a single coat of paint (500+ pounds on a 777 for instance) airlines make sure they optimize for fuel consumption because just hauling 500+ pounds along for the lifetime of the aircraft costs a pretty penny. Aircraft are fairly regularly stripped and re-painted too (I lived near a special purpose facility in Canada that did this, pretty weird to see a widebody come down in a location that is not near any major airfield, the first time I saw that I thought it was about to crash, but it turned out it was there for a paint job).
    - chiph 5y ago
      You want your plane to be mostly white in color to reflect solar heat and reduce the load on the air conditioning packs.
      - sandworm101 5y ago
        White paint also weighs slightly less which, across a fleet, adds up to an economically relevant fuel cost.
  - numpad0 5y ago
    Sounds plausible, if someone told me that this can of paint designed for that epoxy destroys this thermoplastic, I’d just believe it.
    - jacquesm 5y ago
      That could be, or it could be a process related issue, or a change in formulation of a paint that performed well, or a change in formulation of the polymer that the fiber is embedded in, there are a very large number of options to choose from.
walrus01 5y ago
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.
- jacquesm 5y ago
  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.
  - rorykoehler 5y ago
    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.
- bobthepanda 5y ago
  road cycling is probably less harsh than a plane cycling through 0 to 30k+ feet multiple times a day, though.
- mihaaly 5y ago
  The loads and operating conditions are quite different for bicycles and airplanes. As I wouldn't use the characteristics of my steel coffemaker to predict the behaviour of an LNG vessel I wouldn't do the same with bicycles and airliners.
throwawayboise 5y ago
If it's cosmetic only, why the grounding?

numpad0 5y ago

Apparently A350 are built with Teijin Tenax thermoplastic carbon. Brochures say it cures in one minute, eliminating autoclave. Could be different from normal resin based carbons.

jacquesm 5y ago
Yes, and quite possibly they did not factor in the long term differences between interaction of paint and materials.
- avs733 5y ago
  Why would you think that? You think these aerospace engineers are a bunch of goof offs?
  - jacquesm 5y ago
    Because sometimes process optimizations have complex downstream effects. Aerospace engineers are anything but a bunch of goof offs, which is why flying is as safe as it is. And that's why they pulled the aircraft from service even though it is 'just a surface issue' they want to make sure that it really is just that before releasing them - freshly painted - back into service again. The history of aerospace quality control is written in blood, not because they are goof offs but because materials science is complex and sometimes the only warning you get that something is wrong is a crash. Avoiding those is what this sort of action is all about, in any other industry they would have slapped some new paint on it and kept going.
- dylan604 5y ago
  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?
  - jacquesm 5y ago
    Some paint is more slippery than the substrate it is painted on for lower air resistance: https://www.skybrary.aero/index.php/Surface_Coatings_and_Drag_Reduction https://www.skybrary.aero/index.php/Surface_Coatings_and_Dra... Then there is corrosion protection, protection from ablation (especially on leading edges which usually have other protection against this as well), ice adherence and so on. So it is far from just cosmetic, and given the weight of a single coat of paint (500+ pounds on a 777 for instance) airlines make sure they optimize for fuel consumption because just hauling 500+ pounds along for the lifetime of the aircraft costs a pretty penny. Aircraft are fairly regularly stripped and re-painted too (I lived near a special purpose facility in Canada that did this, pretty weird to see a widebody come down in a location that is not near any major airfield, the first time I saw that I thought it was about to crash, but it turned out it was there for a paint job).
  - chiph 5y ago
    You want your plane to be mostly white in color to reflect solar heat and reduce the load on the air conditioning packs.
    - sandworm101 5y ago
      White paint also weighs slightly less which, across a fleet, adds up to an economically relevant fuel cost.
- numpad0 5y ago
  Sounds plausible, if someone told me that this can of paint designed for that epoxy destroys this thermoplastic, I’d just believe it.
  - jacquesm 5y ago
    That could be, or it could be a process related issue, or a change in formulation of a paint that performed well, or a change in formulation of the polymer that the fiber is embedded in, there are a very large number of options to choose from.

walrus01 5y ago

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.

jacquesm 5y ago
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.
- rorykoehler 5y ago
  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.
bobthepanda 5y ago
road cycling is probably less harsh than a plane cycling through 0 to 30k+ feet multiple times a day, though.
mihaaly 5y ago
The loads and operating conditions are quite different for bicycles and airplanes. As I wouldn't use the characteristics of my steel coffemaker to predict the behaviour of an LNG vessel I wouldn't do the same with bicycles and airliners.

throwawayboise 5y ago

If it's cosmetic only, why the grounding?