Question 1

You are asked to explain the difference between "preventive" and "predictive" (condition-based) maintenance, and give an example of each as applied to a ship's machinery.

Accepted Answer

Preventive maintenance is performed at fixed intervals regardless of actual condition (e.g. changing lubricating oil filters every X running hours per manufacturer recommendation), while predictive/condition-based maintenance uses monitored data (e.g. vibration analysis, oil sample analysis, thermal imaging) to determine the actual condition of equipment and schedule maintenance based on need rather than a fixed interval Preventive (time-based) maintenance provides a reliable baseline but can result in either premature replacement of components still in good condition or, conversely, failure between intervals if degradation is faster than expected, while predictive maintenance uses actual condition data to optimise the timing of intervention. A practical example is vibration analysis on a generator bearing — trending vibration data can detect developing wear well before a fixed-interval inspection would have caught it, allowing planned replacement before failure, while oil analysis (detecting metal particles, contamination, or additive depletion) provides similar insight for lubrication systems.

Question 2

You're draining a thermal oil system that was running normally a short time ago. Before opening the drain point, what should you confirm?

Accepted Answer

That the system has cooled and depressurised, and you are positioned clear of the drain point's discharge path On the dredger MV Amazone, two crew members draining a thermal oil system after months of contamination were sprayed with hot oil, suffering severe burns. The investigation found company procedures lacked clear instructions for safe drainage — confirming the system has cooled and depressurised, and standing clear of the discharge path, are essential before opening any drain point on a hot oil system.

Question 3

A thermal oil system has been contaminated and needs draining for cleaning. The written procedure tells you to open the drain valve but doesn't specify a cooling-down period or PPE. What should you do?

Accepted Answer

Treat the gap as a hazard in its own right: apply a suitable cooling/depressurising period and full PPE before proceeding, and raise the procedure gap with the Chief Engineer The FEBIMA investigation into the MV Amazone incident found that although the crew followed company procedures, those procedures lacked clear instructions for safely draining a thermal oil system. A procedure that's silent on cooling time and PPE for a hazardous task is a gap to be closed before the job starts — not a green light to skip those precautions.