Using the Validated FMEA to Update Trouble Shooting Manuals: a Case Study of APU TSM Revision

Trouble Shooting Manuals (TSMs) provide useful information and guidelines for machinery maintenance, in particular, for fault isolation given a failure mode. TSMs produced by OEMs are usually updated based on feedback or requests from end users. Performing such update is very demanding as it requires collecting information from maintenance practices and integrating the new findings into the troubleshooting procedures. The process is also not fully reliable as some uncertainty could be introduced when collecting user information. In this report, we propose to update or enhance TSM by using validated FMEA (Failure Mode and Effects Analysis), which is a standard method to characterize product and process problems. The proposed approach includes two steps. First, we validate key FMEA parameters such as Failure Rate and Failure Mode Probability through an automated analysis of historical maintenance and operational data. Then, we update the TSM using information from the validated FMEA. Preliminary results from the application of the proposed approach to update the TSM for a commercial APU suggest that the revised TSM provides more accurate information and reliable procedures for fault isolation.