Study On System Safety Analysis Methods Of Nose Landing Gear System

Safety is the condition in which there is no accident. System safety is a subject in which system analysis methods and engineering management principles are used to analyze, identify and control the hazards to get the high safety of aircrafts. System safety assessment is an important part of system safety. The application of system safety analysis is essential to the improvements of aircraft safety and the solution to the problems of safety requirements in the airworthiness certification. Therefore, it is very significative to research the analysis methods of the system safety assessment.Firstly, the concept of system safety assessment is explained, and system safety assessment process is researched. Then the characters and the relations of every step of assessment process (Functional Hazard Assessment, Preliminary System Safety Assessment and System Safety Assessment) are summarized.Secondly, in many system safety assessment analysis methods, Fault Tree Analysis (FTA) is introduced, and GO method which is used in system reliability assessment is tried to use in system safety assessment. Compared advantages and disadvantages of FTA and GO method, them are combined to a compositive assessment method, and the process of this compositive assessment method is given. To show that this method can be applied in the system safety assessment, it is simply used to assess a nose landing gear system.On the last step of the compostive assessment method, to calculate the failure probability of the top event of the complex fault trees, the Monte Carlo method is introduced. Applied it, the simulation model of a nose landing gear system is set up, after the calculation, the numerical solutions are gotten. Compared the numerical solutions and the analytic solutions, it proves that Monte Carlo method can be applied in the system safety assessment.At last, the summary of this paper is made, and the prospect of the future research is given.