Study On Determining The Maintenance Interval Of Civil Aircraft System Based On Reliability

As the ARJ-21 regional jet received airworthiness certificates, and the development of C919 large aircraft project, our country has stepped onto the road of independent design and development of civil aircraft. The maintenance review board report(MRBR) is an important assurance file for the aircraft continuous airworthiness, its core content is to determine the maintenance task types and intervals for significant items of aircraft. Because maintenance intervals of civil aircraft system maintenance task mainly depend on performance characteristics, failure modes and reliability of system parts. But the domestic supply of civil aircraft system components almost depend on imports entirely, unable to get the relevant test data of system components. At the same time, domestic new developed models have not yet been put into operation, lacking the used reliability data adds difficulty to the determination of system task intervals. Therefore, most of domestic manufacturers usually determine the maintenance intervals based on engineering experience or use the intervals recommended by suppliers directly, have not mastered the principle of determining maintenance intervals from the source.To solve the above problem, this paper studies a method of identifying maintenance interval of new aircraft based on reliability analysis, analyzes the principles and methods of civil system to determine maintenance interval under the framework of MSG-3, and the reliability maintenance theory are analyzed in detail, then puts forward the method of reliability analysis and maintenance modeling used in this paper.Firstly, the reliability of the system is analyzed, the maintenance tasks related failure mode is clear through the analysis of the function fault and the failure mechanism of system, and builds up the fault tree with maintenance items as the top event, the failure rate data of bottom event in the design phase is used as input information, then the predict life data of maintenance item is obtained by Monte Carlo simulation, thus the life distribution of maintenance item is statistically deduced.Then select hidden fault as the study object, study the model of unavailability and maintenance cost rate of hidden function on the basis of its life distribution, establish the maintenance interval model and proposed the method of solving model, to obtain more economic and efficient maintenance intervals under the premise of reliability.Finally, the method which is proposed to determine maintenance intervals in this paper is applied to the civil aircraft fuel vent system. Failure modes which are related to maintenance tasks are determined by system reliability analysis, and a typical maintenance task named operation check for pressure relief valve is selected to determine maintenance interval. Then the method is verified based on data of similar models, indicating its rationality.