Delamination prompts Boeing to inspect 787 fleet

[Fear_of_Flying]

And so the debate between Boeing and Airbus continues, only the distinctions between the two companies become less clear over time. Both are moving in similar directions in the manufacture of their products, and both are international firms, with parts and assembly taking place on both sides of the ocean. Now, instead of a Boeing versus Airbus debate, we seem to be sliding into an even less evolved argument, that things made in the U.S. are better than those made elsewhere, just because.

The debate over composite parts is a good example.

First it was that Airbus uses too many composite materials in the manufacture of its aircraft. But both companies continue to use an increased proportion of composite materials with each new line of aircraft. The 787 is 80% composite materials by volume, 50% by weight, much more than the A380. The 787 will be surpassed in its use of composites only by the A350, which will have both wings and fuselage made primarily from composite materials. But there seems to be no valid argument that Company A or Company B uses more composites than the other, since both are trending upwards, trying to reap the significant economic benefit of composite construction.

So then, the argument turned to the quality of the composite materials, with Boeing being touted as the producer of superior composites.

But now, well, it turns out that Boeing only would make superior composites, but in fact they outsource, so that's not actually the case, since many of the materials aren't made right here in the good ol' U.S. of A, an absolute imperative it seems in order for something to be made properly. But the fact remains, Boeing is left with sub-par composites, so its supposed leg up over Airbus in that respect is lagging.

So where does the argument go from here? The pens that the Boeing engineers use to draw up the specs for the parts are made in Taiwan?

[Highkeas]

.......................... The pens that the Boeing engineers use to draw up the specs for the parts are made in Taiwan?

I always thought it interesting that Boeing reportedly uses CATIA to design its aircraft - CATIA is CAD software developed and licensed by Dassault in France.

[snanceki]

I just love it!

@Highkeas. I just love the Catia/pens argument.

Surely the different viewpoints of composites are driven purely by the very different stages of technology maturity.
(Al vs composites)

Airbus saw the potential of composites and took the "risk". It's undoubtedly the superior technology for the current needs of the aviation industry, but its still in its infancy and I suspect that its achilles heel may lie "in service repair" when and if required for whatever reason.

[Alessandro]

Another quality issue now is cracks in the wings, http://www.chicagotribune.com/busine...,5114194.story

[Evan]

Here's the thing I don't get:

Boeing said it was recently informed by Mitsubishi Heavy Industries, which makes the carbon composite wings in Japan, that a change in their manufacturing process caused hairline cracks in a limited number of shear ties on a wing rib.

So, a manufacturer develops a wing, has it structurally load tested, puts it into service and proves it to be reliable, earns a certification, then changes the manufacturing process! Ok, maybe that's just bad reporting but I can't imagine a manufacturer can get a certification and then change the process to the point that it creates cracks in the structure. Somebody please say it ain't so.

[Gabriel]

Here's the thing I don't get:

So, a manufacturer develops a wing, has it structurally load tested, puts it into service and proves it to be reliable, earns a certification, then changes the manufacturing process! Ok, maybe that's just bad reporting but I can't imagine a manufacturer can get a certification and then change the process to the point that it creates cracks in the structure. Somebody please say it ain't so.

It ain't so, well, more or less.

To begin with, do you think that Boeing keeps making the wing of the 737 with the same process than 45 years ago? Wait a second... It's not even the same design, let alone the process!!!

When you said "change the process to the point that it creates cracks in the structure" it almost sound as if that was the object of the change, or at least that it was a big process change where such a thing was foreseeable.

It could have been a very minor and subtle process change.

And what is a process change after all? A subtle change in the order of the operations (Which goes first? Screw 234 or rivet 1853?). A change of tooling (even by one of identical design, different supposedly identical tooling do not always behave identically). Hell, even the output of different cavities of the same injection mold are often considered as coming from different processes. Even the change of the operator if the process is "skill" dependent (two operators with the same training and following the same set of instructions don't always behave identically, just as pilots). Or what about a different brand of the same chemical compound? Supposedly, if two compounds have the same chemical formula there should be no difference, and yet not all the brands of sugar are equally sweet. Every process that I knew needs adjustment from run to run, for example because all raw materials have variation even within the specification (among many other factors that introduce variation).

In the industry in general, typically, some "minor" process changes are just done (like change of operator, of lot of raw materials, adjustments). The process has normal quality controls and you just keep making them to verify that everything is still ok. There might be some additional quality checks at the beginning of a run or change a parameter.

Other major process changes need a re-qualification of the process, where you make not only a very thorough quality check but may also re-check the process stability and capability, and even make some performance and life tests on the product.

I don't know what the regulations say about process changes, but I'm sure that not every change requires a product re-certification, and not every process change can get away without one.

Now, a product re-certification doesn't mean that all the strength and fatigue test must be repeated. A wing can be certified with analysis, as long as that analysis is validated by test results (which can be partial test, a previous test, etc.)

For example, the wing of the 737s surely needed some re-certifications along its history, but I've never heard of a full scale flex test after the original one 45 years ago.

The problem is, some times, very minor process changes that nobody anticipates will have an impact on the product quality surprises us. And composites are quite good at doing these tricks.

We don't know what kind process change are we talking about here. But I would ask a question that is different from yours:

Cracks an delamination are two very critical and typical defects in composites and I'd expect that looking for these kinds of defects is part of the regular control plan of any composite product, let alone an airliner's wing!!! Process change or not.

So how is that Mitsubishi didn't note it until there were 40 wings in production planes at Boeing? (and there must be several more in transit and at Mitsubishi). What's that? Just a couple of months of production?

[BlueMax]

cracks found in wings

Hairline cracks in wings of "production planes" not yet in service, more bad news for the 787. Reliability has to be a concern with this new technology

http://money.cnn.com/2014/03/07/news/companies/boeing-dreamliner-cracks/index.html?source=cnn_bin