Disaster Stories, Part 3

The blame for the Airbus A380 delivery delay is being placed on the CAD software used to design the wiring:

Dominc Gates is the Seattle Times aerospace reporter:

* "One issue was that the CATIA computer tool used in the airplane's digital design was not sufficiently accurate when it came to designing electrical systems," said senior Airbus executive Tom Williams. "The problem was made worse by Airbus' switch to aluminum wiring when the model was designed for copper wiring, which has very different physical properties."

Airbus would have switched to aluminum to save weight. Designers and CAD operators perhaps did not realize that aluminum has different properties from copper -- that reminds me of NASA's imperial-metric mixup that caused a spacecraft to crash on Mars.

* "Williams said the complexities caused in A380 production by airlines requiring extensively customized interiors -- which can affect the wiring, some of which goes to the seats -- were indeed a big factor in what went wrong."

But don't blame politics:

* "The dual Franco-German leadership structure at the top is not at fault... and will stay because the French and German shareholders demand it."

An anonymous poster to WorldCAD Access stated that the wiring was designed by IGE+XAO. An anonymous reader disagrees:

"As a former automotive harness designer in a Japanese company, I suspect that that may just be partially true and wholly misleading. IGE+XAO is more of a logical electrical design tool, and it is CATIA that handles the physical routing that takes place inside the 3D model. The CATIA & IGE+XAO joint partnership says just that at softmarket.cz/Download/Dokument/Press%20release.pdf [PDF file]."

Anon adds:

"The physical properties of wiring -- copper or aluminum -- are going to affect minimum bend radii and wire lengths because of the different thermal properties. This has nothing to do with the schematic logical diagrams done in IGE+XAO."

With hundreds of miles of wiring in the world's largest passenger aircraft, even small changes have big effects.

Robert Wall writes for Aviation Week and Space Technology:

* "Airbus officials say poor design tools were a main cause of A380 delays. Problems with the Catia digital mock-up led to inaccuracies. [Airbus executive vice president for Programs Tom] Williams says the computer tool didn't represent the wiring harnesses well and, because there wasn't always good configuration control in the database, some design changes were not properly reflected and remained undiscovered until problems during wiring installation were encountered."

This makes it sound like the CAD operators didn't know how to change the material properties from copper to aluminum, or that Catia is unable to distinguish? Aluminum wiring is used so rarely today that perhaps the software assumes all wiring is copper. This could have implications for all other CAD software that does wiring design.

My son wonders if the design change was ordered but not passed on to everyone who needed to know.

* "Also up for review is Airbus's information management. The company has trailed some rivals in adapting the latest electronic design and enterprise management tools. Chief technical officer Jean J. Botti is undertaking a survey of Airbus's information technology approach. He says he will likely make recommendations for updates and harmonization of tools in a few months."

The CTO hadn't implemented the latest software for managing one of the world's most complex projects -- not that the "lastest" software is necessarily better, but it reads like Airbus's use trailed that of Boeing. It also sounds like Airbus suffered from translation problems between differing data systems.

Comments

[Billmce]

After reading the above it sounds like the internal processes used to control the project were not up to the task - bad management. When management is blaming the tools.......it is not a good sign either. The tools are what they are and Boeing, using the same CAD (CATIA) software seems to be able to make it work as do other airframers.

One must ask why aluminum wiring is used when it is no longer allowed for home contruction in many locals due to the increased potential for fire initiation. I would think this would have been an issue since in-flight fires is the biggest threat in aviation. But then again if one is desperate for weight savings bad decisions follow ......

[Evan Yares]

Regards aluminum wiring -- the problem isn't with the wiring, it's with the connections. In the context of an airplane, those connections are likely to be gas-tight, and not subject to the thermal cycling problems inherent in home wiring.

Still, it would seem to me that the use of aluminum wiring would introduce a lot more criticcal engineering issues than the use of copper. But I'm not an expert in these things.

The wiring in airplanes is subject to far more thermal cycling than in home wiring, since every take off and landing cycle goes from ground temps to 40k feet. Much of the wiring is not in the climate controlled part of the plane. The connection technology has to be completely different.

It is interesting to note Airbus' prediction that CATIA will be fixed, to Boeing's benefit; since Boeing is almost to the same phase in the design cycle this seems like an early explanation for why they won't have the same problem...a little too conveniently.

I was in Toulouse in June, one rumor at the time was that the harness issue had to do with hand-crimping the aluminum wires to connectors. There is something like 500K of wiring in each aircraft. However, there are the "usual" issues that emerge in flight test...why is everyone so convinced that 787 will not have a delay? 747 is before my time, but it had delays...there is an assumption that Boeing's mismanagement of commercial programs ended with Sonic Cruiser.

Why not use fiber?