Reliability assessment of vessel's main engine by combining Markov analysis integrated with time dependent failures

Safe operation of a merchant vessel is dependent on the reliability of the vessel’s main propulsion engine. Overall reliability of the main propulsion engine is interdependent on the reliability of a number of subsystems including lubricating oil system, fuel oil system, cooling water system and scavenge air system. The reliability of various components of certain system such as gear pumps in a fuel oil system or filters in a lubricating oil system, which exhibit constant failure rate (random failure) independent of their history of operation, therefore could be analysed using Markov modelling. Other vital component such as turbochargers exhibits time dependent failure rate (wearing out). The wearing out failure rate (increasing failure rates) can be analysed using Weibull analysis. This paper presents integration of Markov model (for constant failure components) and Weibull failure model (for wearing out components) to estimate the reliability of the main propulsion engine. This integrated model will provide more realistic and practical analysis. It will serve as a useful tool to estimate the reliability of the vessel’s main propulsion engine and make efficient and effective maintenance decisions.