Why a Planned Maintenance System Does Not Guarantee Maintenance Control

Every managed vessel runs a planned maintenance system. The jobs are listed, the intervals set against calendar days or running hours, the work signed off as it falls due. The dashboard turns green. The superintendent reports from it, the auditor opens it first, and the office reads a vessel's condition off the percentage of jobs closed on time.

A green PMS tells you one thing with certainty: the work was scheduled and recorded as done. It does not tell you the work was done well, that it addressed the actual condition of the equipment, or that anyone would have noticed if it hadn't been. The system records activity. Whether that activity kept the vessel under control is a different question, and the PMS was never built to answer it.

Most people in ship management know this, in the way you know something you have stopped looking at directly. What is worth setting down plainly is why the gap exists, and why it does not close on its own.

A signature closes a task, not a risk

Start with the signature. A sign-off closes a task. It is a record that someone attended to a job by the date it was due. It is not evidence that the failure the job exists to prevent is now less likely. Those are two different claims, and the PMS only makes the first one. On a well-run vessel they usually travel together. The problem is that nothing in the system requires them to, and when they come apart, the record still reads green.

The interval is a proxy, not the condition

Then there is the interval itself. Most PMS jobs are timed - every 500 hours, every three months, at every dry dock. Time is a proxy for condition, and usually a reasonable one, set by manufacturers or by statutory requirements. But a proxy met on schedule is not the same as a machine that is actually sound, and the system cannot tell the difference. It knows the job was raised and closed. It does not know whether the bearing it covered was worn, or whether the same defect has now come back three scheduled maintenance intervals later.

The deepest part of the gap is knowledge

The deepest part of the gap is knowledge, and the analysis of the history of occurrences with one part of the equipment or another. The person who carries out a job and the person who understands why it matters on this particular part are often not the same person, and the PMS holds neither of them. It holds the task and the date. It does not hold the reasoning - why an interval was shortened after a bad experience, which supplier's part failed early last time, why the previous chief engineer never trusted a particular reading. That retained knowledge is key to the assessment of the technical condition of equipment, and to planning preventive maintenance accordingly. Each job is closed in isolation, so a similar but different fault that has appeared four times in two years is treated as new on the fifth, because nobody links them together behind the task - only its status.

Compliance is not control

None of this is an argument against planned maintenance. A PMS is necessary, and a vessel without one is worse off in every respect. The argument is narrower and, I would say, more useful: a completed PMS is a record of compliance, not a demonstration of control, and running an operation as though the two are identical is how management teams are surprised by failures their own dashboards told them were handled.

Control looks different from compliance. It means seeing the history behind a job and not only its status - a historical analysis showing that this defect has recurred, that the last three sign-offs changed nothing, that the reasoning behind an interval is still held somewhere other than in one person's memory. It means the recurrence is visible before it becomes a detention, an off-hire, or a serious breakdown - not after. It is the difference between a system that records what was done and a system that "thinks" whether the work is actually holding.

That distinction is not expensive to make. It mostly requires deciding that the record should carry the reasoning as the work happens, rather than assuming the reasoning will still be there when it is needed.

In a lot of instances, being on board as a Captain or Chief Engineer, we keep our notebooks with records of our findings and "to do" lists, and we keep them alongside the PMS - keeping in mind that apart from the jobs raised in the system, there are a number of things we need to remember.