Research On Safety Analysis Approach Of Flight Control System Based On Bayesian Network

Safety analysis is the main method to improve the system safety level in the progress of civil aircraft system development, is also the important airworthiness compliance verification method. The automation and the integration degree of modern flight control system is high, and the cross-linked relationship between the units is complex, leading its failure with multi-state property. The traditional Safety analysis on the fault tree analysis method as the representative is not fully applicable to the multi-state system. This paper analyzes the failure property of typical components of the flight control system; the prediction method of component failure data is given, on this basis, the safety analysis approach of flight control system based on Bayesian network is proposed.The fault property and reliability of the typical subsystems of the flight control system is studied. Analysis and determine the fault property of typical subsystems of the flight control system, construct reliability model for typical subsystems with multi-state fault property, and the Universal Generating Function(UGF) is used to describe the multi-state fault characteristics. The failure data prediction method for flight control system components was studied. The method of reliability prediction for electronic, electrical and mechanical components is analyzed. This method can be used to get the basic failure data of components for the system safety analysis. To construct the model of system reliability based on Bayesian network are studied. In this paper, a Bayesian Network based multi-state safety model of flight control system is built according to the state relationship between the system and its constituting components. Universal Generating Function(UGF) is used to build the Conditional Probability Table(CPT) of the non-root nodes. Based on the variable elimination, a method of computing the system failure state's probability is proposed. The algorithm of the importance of each component in the system is inferred. Combined with the aileron control system of an aircraft an example is given.The result shows that this method in this paper provides a simple and intuitive measure to deal with the safety analysis of flight control system with multi-state and common cause property. And the flight control system safety level can be evaluated and the affection of each component to the system safety can be confirmed effectively.