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