Evaluating the operating dependability of a complex system

摘要

Evaluating the operating dependability of a system formed of hardware components and/or software components such as a system for displaying flight information on an aircraft instrument panel. Dependability evaluation can consider reliability, availability and maintainability of the system. Decomposing the components of the system into interconnected functions and defining associated functional failures for each function. Defining a logical expression of a feared event of the system whose terms are inputs and/or outputs of the functions. Determining a set of minimal combination of failures of functions causing the feared event of the system called minimal functional cuts. Further reducing the set of minimal combination of failures of functions to a set of hardware component minimal cuts. Computing for each component failure intervening in a component cut a failure rate and an exposure time. The exposure time may be duration of a mission for visible failures or duration separating two maintenance tests for failures which are not detectable by visual inspection or during normal operation. Computing a probability of occurrence of the feared event as a function of the failure rates and exposure times.