ABSTRACT
The economic success of any system depends on its availability for the intended use. The overall availability has two components: reliability and maintainability. System reliability is defined as the probability of numerous components working together to deliver the specified performance over the mission duration. Failure of any one component in a chain of many components renders the assembly useless. The failure rate of a given component is derived from tests on a large number of identical components under actual operating conditions. Sometimes in practice actual failure rate data may be available for only a few components to make any meaningful statistical inferences with high confidence. This may make the reliability estimate difficult, sometimes debatable or even questionable. However, the estimate is extremely useful, at least on a relative basis, in identifying and correcting weak links in the chain of reliability. The perspective of system reliability developed during the reliability analysis is perhaps more important than the final reliability number.
