An equation to calculate the availability for the k-out-of-n system

Reliability and availability (R&A) analyses are primary phases in management of complex systems and play a fundamental role in products and services quality. Management of maintenance activities has to be based on optimisation to simultaneously improve the operative conditions of the system. Maintenance optimization can be effeectively pursued by the RCM (Reliability-centered maintenance) approach. The authors demonstrate the global improvement of R&A by applying the RCM to the results derived by the FMECA (Failure Modes Effects and Criticality Analysis). Many efforts have been made to improve traditional methodologies of analysis, mainly tending to reduce the imprecision on data related to the occurrence of failures. Gargs underlines how to investigate the behavior of a reparable system by using a combined measure of RAM (Reliability, Availability and Maintainability) R&A analyses help the analyst to improve the operative conditions to achieve higher levels of technical and economic performance. About industrial systems with reparable components, it is known that the more interesting parameter used to drive the maintenance management is the stationary availability (SA). The present research is to investigate this parameter for a k-out-of-n system by suggesting a mathematical expression for the exact value of AS(n;k)