Integrating the human factor in FMECA-based risk evaluation through Bayesian networks

The contribution of the present paper aims to develop the traditional Failure Modes, Effects and Criticality Analysis (FMECA) for quantitative risk analysis from a Bayesian Network (BN)-based perspective. The main purpose of research consists in providing a framework for analysing causal relationships for risk evaluation and deriving probabilistic inference among significant risk factors. These parameters will be represented by linguistic variables and will include the human factor as a key element of analysis. Traditional approaches for risk evaluation and management performed by FMECA [1] represent helpful tools to globally enhance systems and processes conditions [2]. However, such approaches require previous clarification of several assumptions/simplifications [3]. FMECA is a systematic procedure to identify and analyse all the failure modes potentially involving systems or their main components, through the definition of the related causes and effects. In particular, the method aims to prioritise the failure modes under analysis by calculating the index called Risk Priority Number (RPN) for each of them. The RPN is traditionally derived from the multiplication of three main factors, that are severity (S), occurrence (O) and detection (D), generally ranged within discrete intervals. Severity S measures the impact of a given failure mode with respect to the global performance; occurrence O estimates the frequency of a failure mode within a given time horizon; detection D expresses the probability of correct failure identification. The three risk factors are commonly assessed in a qualitative and subjective way, what may lead to imprecise results with the consequent adoption of ineffective decisions in terms of preventive and/or mitigation actions. This assumption represents one of the reasons why the traditional RPN has been widely criticized in the literature. Moreover, the RPN formula appears far too simplistic [4] [5], without taking into account the different importance of the three aforementioned ...