Quantitative risk assessment of cruise ship turbochargers using type-2 fuzzy-FMECA and dynamic Bayesian network approach

Abstract

Marine propulsion systems, both traditional and modern electric, face significant risks associated with turbocharger and lubrication system failures. The failure outcomes can be severe, with accidents leading to deaths onboard, damage to machinery causing operational disruption, environmental pollution, and financial losses. While traditional Failure mode, effect, and criticality analysis (FMECA) methods excel in identifying system failures, their reliance on single-point estimates for severity, occurrence, and non-detection may prove limiting. Moreover, employing multiple experts in assessments can introduce biases. Integrating type-2 Fuzzy-FMECA with the linear opinion pool method is a robust approach to address these limitations. Leveraging the collective expertise of multiple experts, this framework enhances risk assessment comprehensiveness and accuracy. Focusing on the Carnival Freedom cruise ship incident near the Cayman Islands in October 2019, this study aims to develop a comprehensive risk assessment framework for assessing marine engine turbocharger and lubrication system risks. This study showed a strong positive correlation of 0.99 between the traditional risk prioritization number and the proposed type-2 fuzzy logic method, demonstrating its validity as a reliable alternative. This method effectively identified critical machinery failures, such as low-pressure switch and pressure control valve malfunctions, consistently aligning with the results of Traditional methods. It combines a dynamic Bayesian network for handling uncertainty with an interval type-2 fuzzy expert system and a bow-tie model. This framework enables both qualitative hazard identification and quantitative risk assessment. This risk analysis approach holds practical applicability in real-world scenarios, and its outcomes significantly provide actionable insights to mitigate and eliminate potential failures. Ultimately, it reduces the risk and improves the safety and reliability of cruise ship operations, providing a tangible solution to a pressing problem in the field.