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.
Ok. This combination is also used in windturbine blades of some manufacturers, it may have substantial impact if it is something structural involving the base material, less so if it is just a rare combination of process/chemicals.
Are they in a particular sequence or randomly distributed across the 53 hull numbers? If the former it might be a process change somewhere in the paint or resin/polymer formulation.
Are they losing money grounding them? They're probably operating fewer flights that pre covid so they could have more planes then needed and be using this opportunity to 'ground' planes with minor issues as a negotiation tactic to extract concessions from Airbus.
Given that the Qatari regulator ordered the grounding and that Qatar Airways is state owned that seems like a pretty big conflict of interest. Especially with Qatar Airways refusing delivery of any more a350s until the problem is fixed (in a time of extremely low levels of international air travel).
Qatar is bringing A330s out of storage and up-gauging some routes to 77Ws, which have significantly higher fuel-burn (due to more seats, and a older airframe). I doubt this is just a negotiating position.
Qatar has a population of over 2.5 million but only about 300,000 of those are native Qataris. Even if they have different last names, chances are they're somehow related.
This is true, briefly thought I was in manila when doing a hotel stop over, only the hotel manager seems to be a native. Horrible country, but I'll do the gov subsided stopover frequently when travelling back and forth.
Except that imagine the issue is non-safety related and the regulator which happens to be related to the Airline company grounded them on requests of the Airline during low traffic times to put more pressure on the manufacturer and maybe profit from higher damage payments.... (Purely speculative to give a point for the next argument.)
I.e. we can't say if the regulator acted correct with safety concern or corrupt until we know what is actually going one. Just because something seems to be "proper safety orientated acting" on the first sight doesn't mean it is and neither mean it's not corrupt...
I'd say this is correct. Qataris have one rule for them and another for everyone visiting or working ( the flippas, Nepalese etc), a friend is quite well connected as part of chemical supplies to oil industry, more like store at origin and broker nowadays, they live by different laws than the mere mortal (like me) passing through. You can live it large if you have the right connections - connection to above - one form of corruption doesn't exists it's systematic so yeah making the regulator act to protect a private contract condition is very plausible in qatar
I live in Qatar, and the Qataris are notorious for finding ways to avoid paying their bills, delaying payment for extremely long periods, or asking for unreasonable reductions. Claiming something is wrong or faulty is a common tactic, another one is to substantially expand the scope of a project, and then refuse to pay when the project inevitably runs over the original deadline.
Akbar Al Baker pulled similar cons with the construction of Doha airport, demanding the project be accelerated but refusing to pay for the extra work that would be involved. Bechtel and Lindner/ Depa Interiors are two companies that spring to mind. They also suffered due to the erratic and insanely inefficient bureaucracy that is endemic in Qatar - 60-70% of Qataris "Work" in government jobs.
Similar stories can be heard of tower construction in Qatar. Empty and unfinished towers littler the country due the Qataris failing to pay their dues to construction companies. This article superficially covers it: https://www.constructionweekonline.com/business/article-3775...
You don't know the half of it. When they held the Asian cup, they were so concerned with the stadiums looking empty, they forced laborers to go and fill the seats. Problem is that many legitimate ticket holders were then denied entry! Of course people got angry about that, so the police saw fit to start administering beatings to people.
Now image that scenario with drunken football hooligans instead!
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 material appears to be perfect but carbon has always felt to me to not be going in the right direction.
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.
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.
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?
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).
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.
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.
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.
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.
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.
To elaborate, carbon-fiber reinforced carbon, the expensive ceramic used for very heat-resistant lightweight structural members (like the leading edges of the space shuttle, and some jigs for use in metallurgy furnaces, where it's lack of deformation and low heat capacity is beneficial) can handle something around 20% of it's ultimate tensile strength for millions of full load cycles.
This is, going by fatigue-limited-strength to weight ratio, far better than steel or aluminium. The difference is mostly that it's a brittle ceramic and retains most of it's strength at temperatures where steel can be poured.
Which is why Aluminium drop-handlebars on bikes freak me out - when they fatigue they become brittle and can just snap one day if you put too much weight on them (e.g. out of the saddle sprinting).
The only time I've ever had aluminum drop bars go out on me was when the salt brine from sweat corroded the aluminum a lot.
I was on a hill in a mild rain riding next to a friend. I managed not to take her out and stay upright which was great. The cycling team I participated on in college said road bars need to have the tape off and inspected every year. They were right.
It's way to early to speculate about this, as we don't really have information from either side.
The fact that only Qatar Airways seem to have such problems (for now) is also interesting.
The reason could be anything from manufacturing errors with a specific batch of them which happened to have been bought by Qatar Airways to wrong maintenance by Qatar Airways or the planes having been to often exposed to to extreme weather conditions as they are not that unusual in Qatar. And even this "wide range" speculation is not really usable given the facts we (don't) have.
A likely reason for why only Qatar airways reports this is that they are notorious about regularly publicly complaining about “quality issues” in the press during commercial negotiations. It’s a trick to pressure the aircraft manufacturer.
That’s not to say that quality issues don’t happen, they certainly do. But QTR is known to be very quick to refuse to work with their supplier and publish the complaint in the press, instead of working it out like is the norm, especially if it’s near a time of contract negotiation.
Yeah I worked in NDT for a bit and it's very difficult to test carbon fibre for damage or delamination under the surface. There are techniques but not as good as for aluminium. And as you said they don't have a nice plastic region like metals.
Metals don’t have a “nice plastic region “ either. If the parts of your aircraft have been permanently elongated by plastic deformation, you’ve destroyed it.
If anyone is curious about material science, some keywords are "stress strain curve", "plastic vs elastic deformation", and "fatigue limit" (that last one is really cool).
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?
Fatigue is not a concept applicable to carbon fiber reinforced materials. Carbon is anisotropic, unlike bulk metals which can be modeled as isotropic. Carbon may suddenly delaminate or whatever, but it doesn’t have a cycling limit.
The 320s have had composite parts forever. So have virtually every plane since then, The 787, for all it's other faults, hasn't had this issue, and uses a more radical design for it's 787, versus the A350 which still uses stringers and panels, rather then put more load on the CFRP.
But that said, given that Lufthansa is also apparently pulling and repainting it's A350s, there may be some reaction here.
"A QR A350, A7-ALL MSN 036, a 4 year A350, was being prepped for paint removal from the standard QR livery and repaint into the Qatari World Cup 2022 livery at SNN when IAC engineering discovered that the airframe had premature cracks in the composite fuselage..."
I am aware of Airbus statement that is only surface related. It is surprising they took the airplane back to Toulouse. So its certainly something more than just a paint
issue.
Interesting. I'm curious what the eventual outcome of this will be but it is always very hard to keep track of such stories further down the line, especially if the result is non-spectacular.
On the assumption these panels are a component of the pressure vessel—and it would seem that they are—then they very much are structural components. Not in "the wing will fall off" kind of way but in "the whole cabin will explosively decompress" way.
Yes, they are structural components but as far as I understand the article they are not structurally damaged, though the company is - of course, and as they should - taking the proper precautions to ensure that it really is just a surface issue without affecting the structural integrity of the panels.
I'm quite interested in what the root cause here is, whether it is process related or some formulation issue or an un-anticipated reaction.
As a -small- point of order it is against HN convention to sign your comments.
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.