Cylinder liner
During an engine overhaul on a cruise ship, a cylinder liner weighing 1200kg was being lifted using the overhead gantry crane in the engine room. However, the crane’s hoisting wire suddenly snapped, causing the cylinder liner to fall and damage both the engine and the liner. Additionally, it struck the foot of an engine room fitter, resulting in a broken toe. It was discovered that the hoisting wire had been recently replaced but was shorter than the length specified by the crane manufacturer. This shorter wire prevented the hoist limit switch from functioning properly, allowing the winch motor to overload the wire and cause it to fail. Subsequent tests revealed that all the limit switches on the engine room cranes failed to meet manufacturer requirements. The ship’s planned maintenance system also recorded an incorrect wire length. As a result, the cranes were taken out of service for repair, and the engineering team was instructed to conduct a thorough inspection of all hoisting devices and ensure compliance with manufacturer specifications. They were also reminded to test the hoist limit switches before using the cranes.
The Lessons
- Hazard → This incident serves as a reminder that crew members should never stand under or near suspended loads, regardless of the condition of the lifting equipment. The fortunate outcome for the crew member involved highlights the importance of being vigilant, as equipment failures can happen unexpectedly and carry serious consequences.
- Margin of safety → The reason behind the incorrect wire length recorded in the PMS remains unclear. However, it is important to note that relying solely on hoist limit switches to cut power to the winch electric motor is a risky practice, whether it pertains to cranes or lifeboat davits. The powerful torque generated by an electric winch motor can exert excessive stress on the hoist wire, leading to its failure. It is always safer to halt the lifting operation before reaching the maximum capacity overhead, even if the system is properly configured and the limit switch has undergone testing.
- Risk → To ensure safety and prevent accidents during lifting operations, it is crucial to conduct thorough risk assessments. The Code of Safe Working Practices for Merchant Seafarers (COSWP) Chapter 19 offers valuable guidance on the necessary control measures to implement both before and during these tasks. This resource provides essential information to help mitigate risks effectively.
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Source: MAIB
