The Research On Safety Analysis Method Of Aircraft Environmental Control System

Cabin environmental control system(ECS)plays an important part on high-flying and occupants health. According to the statistics of ECS-related accidents/incidents and airworthiness safety requirements, as a complex system, it's necessary for ECS to do safety analysis. So the research on safety analysis method of ECS has been done in this paper.For ECS, its basic working principle, components and cabin environmental control parameter requirement have been studied. Because the most important subsystem of ECS are pressure and temperature control subsystem, so the composition structure and the control logic of these two subsystems of some aircraft type have been focused on.For safety issues, airworthiness standard and industry standards related to aircraft system safety have been analyzed. And the process and objective of system safety assessment have been studied. In addition, the modeling principles, the analysis processes, their interrelation,the advantages and disadvantages of 9 kinds of safety analysis methods, which included Failure Modes and Effects Analysis/Summary(FMEA / FMES), Fault Tree Analysis(FTA),Dependence diagram(DD), Markov Analysis(MA), Common Cause Analysis(CCA),Dynamic Fault Tree Analysis(DFTA), Petri Net Analysis, GO Analysis and Monte Carlo Simulation, have been studied.According to airworthiness regulatory requirements, the typical system failure conditions of cabin pressure and temperature control system have been selected as research object. Then,based on system characteristics, DFTA and FTA have been selected respectively for safety modeling. From the process of model calculation and analysis, the following conclusions can be got: the top event's probability of the two systems is less than their safety objective respectively, so the systems are considered to be safety for the two failure conditions; the conclusion of the minimum cut sets' importance analysis are matched with the conclusion of the bottom events' sensitivity analysis, and they all meet the actual. So DFTA and FTA are applicable to the safety modeling and analysis of cabin pressure and temperature control system respectively, and they can describe the respective system architecture accurately.