AIAA S-102.2.18

Abstract

This standard establishes uniform requirements and criteria for a performance-based fault tree analysis (FTA), including the modeling components, symbols, and analytical objectives. The performance-based aspect of this standard requires that the organization&#700;s FTA capability be rated according to predetermined criteria for process capability and data maturity. Although it is a common industry practice for FTA to be performed using computerized tools, this standard does not mandate that any particular computerized methodology be used. <br><strong>Purpose</strong> <br>The primary purpose of FTA is to examine systematically a potential system failure and create a graphical representation of the system logic. The fault tree represents system relationships and fault paths and provides a means for qualitative or quantitative system evaluation. Fault tree analysis is a deductive, topdown method used to determine how a given system failure can occur. A system top undesired event is either identified or postulated and the analysis attempts to find out what contributes to this undesirable event. The FTA begins with a top event, establishes the component-level to which each system-level fault is examined, and determines the immediate causes for each fault at progressively lower levels until a component-level fault is reached. The FTA determines the various ways in which a particular type of top event or failure could occur. All of the possible system contributing factors and their relationships shall be established and, if possible, a top probability of occurrence calculated. <br>The primary output of FTA is the fault tree structure, which allows for qualitative or quantitative evaluation of a system failure. FTA is particularly useful in the examination of functional paths of high complexity, in which the outcome of one or more combinations of non-critical basic events may produce an undesirable system failure. Typical candidates for FTA are functional paths or interfaces that could have impact on flight safety, munitions handling safety, safety of operating and maintenance personnel, and probability of error-free command in automated systems in which a multiplicity of redundant and overlapping outputs may be involved. Fault tree is an analysis tool that provides a way to combine all contributing failures, events, and conditions that can lead to the occurrence of an undesired top event.