Research On Safety Analysis Methods Based On Environment Control System

The safety and airworthiness of Environment Control System(ECS) is the guarantee for both flight crew and passenger, it also creates the necessary working condition for airborne electronic equipment. Therefore, it is necessary to work on safety analysis of ECS and establish the method applicable to the safety analysis of the ECS,which could provide a reference for the airworthiness compliance verification of ECS of civil aircraft in China.Based on the research of current situation of safety assessment and safety analysis of the ECS used in the civil aviation, it was shown that the safety analysis of cabin ECS is extremely important. ECS is a powerful system which contains many components. This paper describes the working principle of ECS fully to prove the necessity of the general and effective research, which could help to design the better ECS on airworthiness and safety. In this paper, we focus on the Cabin Pressure Control System(CPCS) of a aircraft. The control program and the fault reasons to lead to accident were illustrated. The typical safety analysis method, Fault Tree, Dynamic Fault Tree and Markov methods were used to analysis two certain events, the difference could be seen from the modeling process and the calculation, so as the advantages and disadvantages of these three methods. To make further research and discussion of the safety methods applicable to the ECS, the Monte Carlo method based on the structure function of Fault Tree was put forward for the safety analysis of the Environment Control System. It came from the combination of the Fault Tree Analysis and the Monte Carlo method. It was used to analysis the more complex top event of the CPCS which contains 36 bottom events.The overall simulation and stratified analysis methods based on the Fault Tree were used to analyze this top event. The results show that the overall Monte Carlo simulation method could overcome the difficulty to calculate the overall structure function and error-prone of the calculation result. The Monte Carlo simulation method achieves the effective analysis of the Cabin Pressure Control System. At last, a software was designed based on this analysis method. This simple software could achieve the drawn of Fault Tree, the display of the structure formula, the possibility of top event and the simulation of the structure formula of Fault Tree.Over all, the research can provide special theoretical basis and reference method for the airworthiness compliance verification technology of ECS, and it can also provides an effective method assessing the performance of the ECS.