In traditional aircraft design, many engineers and draftspersons work individually and in team on various parts and subsystems of the plane. As explained in detail by Petroski (1996), there were over 130,000 unique individual parts to be engineered in the 777, and when rivets and other fasteners were counted, over 3,000,000 parts were to be assembled in each plane. The 747, which had a total of 4,500,000 parts, required about 75,000 individual drawings to specify. This great number of drawings all had to be internally consistent if the various parts and subassemblies were to fit. This required a lot of interface work between engineers. Whenever a design change occurred, all drawings had to be checked in order to assess its impact and to adapt the existing design to the new one. This obviously was a slow and tedious process.

Even with lots of checking, cross-checking, and double-checking, human error could never be totally excluded and as a consequence, mismatches occurred frequently. In order to trace incompatibilities across parts, subsystems and systems, physical prototypes were built. This approach was of course expensive and time-consuming. In the past, Boeing had tried to minimize these problems through an intensive quality management approach emphasizing the need for intensive co-operation throughout the design process.

In order to remedy the aforementioned drawbacks, Boeing opted for a paperless design of the 777. Computers would be used in the design, testing and manufacturing process to a greater extent than ever before. Three-dimensional CAD systems would prove to be the solution to this challenge, enabling Boeing to achieve maximum concurrency during the design of the new plane while at the same time aiming at a high-quality robust design.
Boeing already developed some experience with CAD when designing engine parts of the 767. Both from a cost and throughput time perspective, the CAD approach proved a significant improvement over the traditional ‘drawing’ and ‘interfacing’ approach. Also, Boeing had experienced a sharp decline in Engineering Change Orders once the 767 CAD designs were released. The CAD system used during this pilot was the Computer Aided Three-dimensional Interactive Application (CATIA) developed by the French software firm Dassault Systèmes.

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Design Management
VIZO Workshop

“Design makes the Difference”
Brussels, Belgium - 29/30 November 2002

 
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