A methodology for reliability and safety analysis of a certain class of repairable fault-tolerant systems is presented. The analysis leads to a closed-form approximation of the probability of an absorbing state in a state transition diagram. This expression can provide insight into the relationship between various system parameters and system reliability and/or safety. The approximation technique is based on the combination of results from the analysis of several failure mechanisms, each studied by itself, into an expression for the approximate reliability of a system. The resulting approximation error can be analyzed in order to evaluate whether or not the approximation is useful in a given situation.
