Reliability analysis of redundant aircraft systems with possible latent failures

A methodology has been developed to calculate unreliability of redundant airplane systems containing latent failures with differing inspection intervals. The usual assumption that all components are unfailed at the start of a flight is not valid for the airplane systems investigated. The analysis method consists of representing a redundant system either as a fault tree or a reliability block diagram. The bottom-up approach is recommended for the fault-tree representation where one starts from the lowest AND gate and calculates failure probability. The number obtained for the top fault-tree gate would represent the system failure probability in which the system logic and latency have been appropriately considered. Alternatively, for a system represented by a reliability block diagram, the top-down approach is recommended.>