Reliability assessment of a fault tolerant propulsion system for an electrical helicopter

The paper describes an approach and a methodology of quantitative reliability assessment of fault tolerant propulsion systems for an electrical helicopter. As a comprehensive parameter for the assessment of fault tolerance of the components with a number of degradation states, it is proposed to use the criterion “degree of fault tolerance”. On the basis of such a parameter the transition probabilities have been defined for the Multi-State System reliability Markov Models. The simulation and assessment results allow concluding, which power train topology complies best with the design requirements on the reliability and the future operational conditions of electrical helicopters.