基于动态故障树分析的民用飞机辅助动力装置系统安全性评估

摘要

Traditional fault tree analysis method is widely used for system safety assessment in civil aviation indus-try , but dynamic characteristics of systems/subsystems, including operational sequencing interpretation, spare and redundancy expression cannot be represented by traditional fault trees. On the other hand, civil aircraft auxiliary power unit ( APU) often operates as a redundant system and its behavior can be described by using dynamic fault tree appropriately. As a result, the interest of DFTA application is focused on APU system safety assessment. In this paper, two kinds of dynamic gates ( PAND and CSP) were introduced firstly. Their quantitative calculations were presented by applying Markov model. Then two typical cases with auxiliary power unit ( APU) system safety assess-ment were analyzed by traditional fault tree and dynamic fault tree respectively. Finally the comparison between two kinds of Fault Tree Analysis ( FTA ) was provided and the result indicates that Dynamic Fault Tree Analysis ( DFTA) method based on proper application reaches remarkable accuracy ,and the calculation cost is acceptable when second-order approximation of exponential distribution function is applied.%在民用航空工业领域，传统的故障树分析方法广泛运用于系统安全性评估。然而，包含系统/子系统运行的时序阐述以及备份、冗余表达在内的动态特性不能通过传统故障树呈现。另一方面，民用飞机辅助动力装置( APU)经常作为一个冗余系统运作，因而其行为可以通过运用动态故障树进行适当的描述。所以APU的这种特性激发了动态故障树分析在APU系统安全性评估上应用的关注。首先介绍了两种动态门(优先与门和冷备件门)，其定量计算通过施用马尔可夫模型来呈现；然后分别通过传统故障树以及动态故障树分析了APU系统安全性评估的两个典型案例；最后进行了两种故障树分析( FTA )的比较，其结果显示出通过合理的应用，动态故障树( DFTA)方法达到了对于真实情况来说相当高的精度，并且对指数分布函数施用二阶近似后，其运算成本也是可以接受的。