EVALUATION OF MECHANICAL SYSTEMS SERVICE EXPERIENCE AND ITS APPLICATION TO RELIABILITY IN PRELIMINARY DESIGN

Simple approximating methods for numerical reliability analysis are presented to promote their use on an equal basis with weight, stress and performance analyses by preliminary designers of mechanical systems. Supporting service data is presented in a form that provides through the designer's own analysis a useful approximation of future service reliability growth as a function of system maturity. The effectiveness of failure mode tradeoffs and “back-up” provisions are readily shown along with the price to be paid in maintenance. The data and methods of analysis presented cover the range of mechanical energy conversion, control, transmission and actuation of the type and quality presently used in safety-of-flight applications in manned aircraft systems.

The simplified methods of analyzing reliability potential and growth described in this paper have been mastered easily by engineers and designers with experience in mechanical design. The new system awareness that the failure mode logic diagrams supply has overcome reluctance on the part of designers to accept numerical reliability analysis for their own use as an everyday working tool. Management, sales personnel and customers alike in their monitoring of new programs find it easy to understand and appreciate the inherent reliability considerations that can be incorporated in even the most preliminary of designs.