Implementing risk based maintenance in the naval context: review and directions

Summary: Rising maintenance costs due to the complexity of naval vessel systems have empha¬sised the importance of cost-effective maintenance practises. The current preventative mainte¬nance approach schedules maintenance based on fixed-time intervals, leading to excess cost and time spent on maintenance. Therefore, there is a need to develop alternative maintenance practises. Challenges exist due to both the naval context and implementation of an alternative maintenance strategy. While reliability-based approaches are popular, they do not include a measure of severity of failure. This is necessary to produce a more-informed maintenance schedule. Risk-based maintenance (RBM) approaches use the product of severity and failure probability as an estimate of risk to schedule maintenance. Such an approach provides greater flexibility in maintenance intervals, allowing maintenance to be performed 'on-condition'. RBM had existed since the 1970s when it was developed for the nuclear power industry, though it had not been widely adopted for naval vessels to date. The present paper aims to describe the history of RBM for mobile maritime assets such as naval ships; by determining when RBM methodologies were developed. Eight RBM methodologies were identified, seven of which focused on components and one on a subsystem. Research focus on the development of RBM for mobile maritime assets had been found follow an increasing trend since the 1980s. Future research directions are proposed for the development of RBM for naval vessels.