Fault -Tolerant System Reliability Modeling /Analysis
C. Johan Masreliez, Bo E. Bjurman · Journal of Aircraft · 1977
A formulation of a reliability analysis approach for a redundant channel system was a primary task of the NASA-sponsored Airborne Advanced Reconfigurable Computer System (ARCS) study. Major design objectives for the ARCS were to achieve two-fail-operational capability for the majority of failures in a triplex system by degradation from triplex to duplex to simplex operation, and to provide transient fault survivability. This paper presents the Markov model technique used for the reliability assessment of the application model flight control system, including sensors, computer system, servos, and hydraulic power. The application model included a flyby-wire control wheel steering mode and an ail-weather autoland mode. Primary reliability parameters evaluated were functional survivability and functional readiness as a function of time since last verification of a fault-free system.