Failure Modes and Effects Analysis

Abstract

The inductive tabular system analysis method, failure modes and effects analysis (FMEA), and its variants are the most often used system analysis method type. The chapter presents the classical definitions of the FMEA method as well as application domains on system (functional) concept, system design, and the production process level. Such distinctions are by now often considered as application cases only. The steps to conduct successful FMEAs are provided and discussed: analysis aim formulation, preparation, structural analysis, functional analysis, failure analysis, measure analysis, optimization, and executive summary. It is emphasized that modern FMEAs take up many elements of similar tabular analysis such as hazard analysis and classical extensions such as asking for root causes, immediate consequences of failures, or criticality assessment of failures on system level (FMECA). Some templates even ask for potential additional failures leading to catastrophic events pointing toward approaches like double failure matrix. Modern extensions such as FMEDA are introduced, which assesses the diagnostic coverage (DC) and safe failure fraction (SFF) of failures as required for functional safety approaches. In all cases, an emphasis is on applicable evaluation options of obtained results sufficient for decision-making regarding system improvements: semi-quantitative and quantitative assessment of risks, including risk priority number (RPN); consideration or neglection of detection options, avoidance options, frequency and severity within risk maps; and efficiency of improvement measures. Advantages, disadvantages, and limitations of FEMEAs are discussed. Several FMEA templates are provided including sample column entries, compared and applied within worked-out examples.