"Expert systems" are becoming an important maintainability tool, especially as industry downsizes with a concomitant loss of individual company
"maintainability experts." Expert systems are used to "capture" and codify the knowledge of one or more experts in a given field or area of study and to make this knowledge available to non-experts.
For maintainability, a major use of expert systems is in diagnostic tools. The diagnostic capability of expert systems has been successfully demonstrated in both the medical and maintainability fields. Whether the problem is to identify a specific illness afflicting a patient or to identify the cause of an observed system or equipment failure, expert systems have proved to be efficient and effective.
Another potential use of expert systems in the field of maintainability comes as a result of "downsizing" and the use of integrated product design teams (IPDTs). As companies have downsized, the number of individuals employed as "maintainability engineers" has decreased. Many years of corporate experience are being lost and the few remaining maintainability engineers are spread thin. Where IPDTs are used, an engineer who may know very little about maintainability, may very well be given the responsibility for that aspect of design. Expert systems can help "replace" the maintainability engineer and assist those given the responsibility for maintainability design. As part of a computer-aided design system, an expert system could guide the designer in equipment placement, selection of fasteners, design of access panels and hatches, and so forth.
Although no companies were found using expert systems
as a maintainability design tool at the time this handbook was published, many
were developing knowledge bases. McDonnell Douglas, for example, is
consolidating thousands of design "rules" that have been developed over the
years for a variety of products, including fixed-wing aircraft and
helicopters. Entered into a data base, these design rules will be available to
the engineers as part of the CAD system used by McDonnell Douglas. Such a
knowledge base, as will be discussed in 22.214.171.124.1.1 , is an essential part of a rule-based expert system.
Two distinct types of expert systems are used: rule-based and model-based.