Research On Technique Of Civil Aircraft Systems Safety Analysis Faced To Continuous Airworthiness

The goal of continuous airworthiness is to ensure that the level of safety of civil aircraft is consistent with its model design characteristics at all times throughout the entire life cycle.As a highly integrated complex system of aircraft,studying the technique of civil aircraft systems safety analysis faced to continuous airworthiness and establishing a feasible safety analysis process are of great significance whether from the point view of safe operation of aircraft or from the point view of airworthiness certification.Firstly,the paper studies the basic theory of civil aircraft systems safety analysis during the phase of continuous airworthiness.Based on international and domestic advanced airworthiness regulation and industry standards,the continuous airworthiness system of civil aircraft is determined preliminarily,as well as the continuous airworthiness requirements of civil aircraft systems;then elaborates the main contents and working process of risk assessment and safety risk management;discusses relevant concepts,properties,information sources,classification and judgment criteria of civil aircraft safety events deeply and further establishes the integrated processing flow of civil aircraft safety events.Afterwards,the paper studies the principle and mechanism of risk assessment and safety management and keeps up with safety risk management approach of foreign authorities and manufacturers(such as FAA/EASA,Boeing/Airbus and so on),then establishes a risk-based safety analysis system for civil aircraft systems faced to continuous airworthiness and clarifies the working process and implementation steps of the preparation of the plan,hazard identification,qualitative and quantitative risk analysis,safety evaluation and risk control as well as combs and summarizes the applicable safety analysis method and its selection principle in each stage.Finally,based on the establishment of the safety analysis system for civil aircraft systems faced to continuous airworthiness,the paper studies the semiquantitative and quantitative risk assessment methods for civil aircraft systems.For semiquantitative risk assessment,combines mathematical statistics,analytic hierarchy process and gray-fuzzy multi-level synthetic evaluation method to calculate the occurrence probability index and consequence severity index of unsafe events of civil aircraft systems and determines whether the risk level of the event can be accepted according to ALARP risk acceptance criteria and risk matrix method.For quantitative risk assessment,establishes the dynamic probabilistic safety assessment(DPSA)model based on event tree-dynamic fault tree(ET-DFT)and monte carlo simulation,makes a quantitative analysis of the unsafe events such as faults and failures that occur in different scenarios during the process of operation and maintenance of civil aircraft systems and then finds out the weaknesses and defects in the system.The safety analysis process and methods for civil aircraft systems faced to continuous airworthiness proposed in this paper have a certain reference value for ensuring continuous safe operation of civil aircraft.