Turning multiple PFMECA results into an optimal action plan

Failure modes effects and criticality analysis (FMECA) is a tool that fosters proactive thinking and action. Most process FMECAs (PFMECAs) are performed by teams to develop subjective conclusions with multiple viewpoints. When different teams evaluate different processes, the results may vary widely, due to differences in persons, processes, and criteria. Yet, one of the key features of FMECAs is their usefulness in ranking by use of a risk priority number (RPN). This paper offers an innovative method for cross-ranking multiple process steps, while accounting for differences in importance among the items analyzed. A simple natural-log transformation, combined with additional algebraic calculations allows the interlacing of the RPN results. The resulting ranking can be plotted vs. corresponding improvement costs to allow logical decision-making and planning. This method has been used on a defense industry program with multiple suppliers and equipment, resulting in a useful model for optimizing improvement actions. A simple example will be provided to help illustrate the points.