Platform Case Study

Crane Control System FMECA

Failure Mode Effects and Criticality Analysis


MDL was awarded a contract by an operator to update the control system on their platform’s two electro-hydraulic offshore mast cranes. This work would involve removing the outdated electrical controls and replacing them with a PLC-based control system. As part of the crane control system upgrade, MDL conducted a Failure Mode Effects and Criticality Analysis (FMECA) on the components.

MDL Solution

MDL Engineering recognised that many third-party FMECAs do not cover electronics, with the control system considered a “black box”. This leaves the operators in the dark on how often PLC/control faults lead to the crane’s outage or downtime. By performing the FMECA at the early stages of the awarded scope, MDL was able to incorporate the findings into the control system design to enable continued but safe operation during a PLC fault. It also identified the required contingency spares, allowing for the issues to be resolved at the most optimal time.


The FMECA identified the maintenance routines, included within the Maintenance Schedule, which minimises or eliminates the chance of potential failures on the crane’s control system. Besides the control system upgrade, the complete scope also covered replacement of the operator cabs and main hydraulic pumps. These modifications will allow the cranes to operate safely with the integrated equipment for another 20 years.

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