Reliability Engineering

Reliability engineering is an engineering field that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. Reliability engineering is a sub-discipline within systems engineering. Reliability is theoretically defined as the probability of failure, the frequency of failures, or in terms of availability, a probability derived from reliability and maintainability. Maintainability and maintenance may be defined as a part of reliability engineering.

Reliability engineering for complex systems requires a different, more elaborate systems approach than for non-complex systems. Reliability analysis has important links with function analysis, requirements specification, systems design, hardware design, software design, manufacturing, testing, maintenance, transport, storage, spare parts, operations research, human factors, technical documentation, training and more. Effective reliability engineering requires experience, broad engineering skills and knowledge from many different fields of engineering.

Reliability engineering is closely related to safety engineering and system safety, in that they use common methods for their analysis and may require input from each other. Reliability engineering focuses on costs of failure caused by system downtime, cost of spares, repair equipment, personnel and cost of warranty claims. The focus of safety engineering is normally not on cost, but on preserving life and nature, and therefore deals only with particular dangerous system failure modes. High reliability (safety) levels are also here the result of good engineering, attention to detail and almost never the result of re-active failure management (Reliability Accounting / Statistics).

"Reliability is, after all, engineering in its most practical form" as once stated by James R. Schlesinger, Former US Secretary of State for Defense.