Fault Tree Evaluation Tool
The fault tree is a very useful tool to evaluate functional failure conditions, but the usefulness is dependent upon the quality of its inputs and usability of its outputs. Airplane certification requires verification of all data and analyses, and this includes the data used in the fault tree. The fault tree cut set tool can be used to look for single-point failures in a functional failure condition. However, an error in fault tree development may mask (a single-point failure is not shown in the cut set) when an item is modeled under two slightly different names. The problem of assuring the quality and usability of this data comes from the highly integrated nature of aircraft systems and the capabilities of fault tree tools. The size and complexity of fault trees for an aircraft system can become very large. Large fault trees lead to large numbers of cut sets. The analysis generates so much data that it is impractical for a human to manually review all of it to confirm it is correct. Automation is needed to process and prioritize that data into smaller elements to highlight issues only. Textron Aviation has developed a tool that highlights such issues by evaluating each basic event looking for missing verification data, confirming standardization of basic event and gate naming, and confirmation that gate descriptions match the gate type. The tool also evaluates each basic event against the other basic events looking for potential common-named events. The tool reduces and prioritizes a dataset of thousands of entries to a manageable list of issues for review.