A Sequential Inspection Model based on Risk Quantitative Constraint and Component Importance

Due to aerospace equipment’s need to maintain a certain degree of safety and reduce the system risk of operation, relevant maintenance and inspection strategies should be developed to meet the requirements of risk quantitative indicators. The inertial navigation system commonly used in aerospace products is taken as an example, and a sequential inspection and maintenance model based on quantitative risk constraints and component importance is proposed in this paper. Firstly, based on the quantitative constraints of the system risk and the importance of the components, the reliability constraints of the components in the inertial navigation system are determined by the fault tree analysis method. Secondly, the Wiener process is used to establish a performance degradation model for a key component of the inertial navigation system, and the expression of real-time reliability distribution is obtained with close form by use of the first-hitting time theory. The adaptive estimation method is used to estimate the unknown parameters of the model. Once the new degradation information is available, the parameters should be updated with a Bayesian equation. Thirdly, a sequential inspection model is discussed to determine the optimal intervals to satisfy the requirements for the real-time reliability at a certain time. Finally, an example of the drift data of the gyroscopes in the inertial navigation system is given to illustrate the validity of the proposed method.