A hybrid risk analysis method for a yacht fuel system safety

Many current risk assessment methods are used to evaluate, eliminate or mitigate potential risks in an engineering design process. One technique that has been widely used in the design process is known as Failure Mode and Effects Analysis (FMEA). The method assumes failure modes which occur in a system and effects of failures are subsequently evaluated. A risk priority number (RPN) is employed to assess the influence of failures in FMEA. The RPN is a product of three indicators (severity, occurrence and detection) on a numerical scale from 1 to 10. However, the RPN approach has been criticized for its several shortcomings. The assumption that the RPN factors are equally weighted leads to over simplification. Furthermore, the RPN has high duplication rates and does not consider ordered weight rules. An integrated methodology based on ordered weighted geometric averaging (OWGA) and generalized mixture operators (GMOs) is proposed to overcome the inherent shortcomings of RPN and improve design safety. A case study, which assesses the critical causes of failures of a motor yacht fuel system, is presented to demonstrate the applicability of the proposed approach. Obtained results showed that the methodology overcomes duplicated RPN values, and gets a more accurate, reasonable risk assessment in engineering design phases.