Ask a drilling supervisor when the next service is due on a particular rig, and you'll usually get one of two answers. Either they know it off the top of their head, or there's a long pause while someone goes digging through spreadsheets and old Plods.

I've spent enough time around rigs to know that servicing is one of those jobs everyone agrees matters, right up until the rig's booked solid and the service can wait another shift. Then it waits another one, and another, and that's usually when an engine reminds you who's boss.

Here's why service schedules drift on drilling rigs, and a few simple ways to keep every engine on track.

Why engine hours are the number that matters

Most engine and compressor manufacturers set service intervals in engine hours rather than calendar days. That's because wear follows how hard and how long an engine runs. A rig that's flat out on double shifts racks up hours far faster than one sitting on standby waiting for a pad to be cleared, so two rigs serviced on the same day can be in very different shape a month later.

The catch is that engine hours are only useful if they're accurate, and on a lot of fleets they aren't.

Where service schedules drift

Servicing by the calendar

Booking a service every few weeks is easy to plan, but it ignores how hard each rig has been working. Busy rigs get serviced late, and quiet ones get serviced early, which wastes parts and a mechanic's time.

Hours copied off the Plod

When the hours come from the Plod, they're only as good as what got written down at the end of a long shift. A missed entry or a typo carries straight into the service schedule, and nobody notices until a rig is well past its interval. It's one reason digitising the Plod was only ever step one.

The kit isn't where the rig is

Remote jobs make timing tricky. If the service kit and the mechanic aren't on site when the hours come due, the rig either runs on or stands down while everything gets trucked out. Send the kit too early and it sits in a container for weeks. Send it too late and you've got a rig waiting on parts.

Small warnings slip past

Low oil pressure or a high coolant temperature often shows up on a gauge well before anything breaks. On a busy shift, with the crew focused on the hole, those early signs are easy to miss.

Nobody owns the whole fleet view

Each supervisor tends to know their own rigs. Across a whole fleet, though, the picture usually lives in someone's head or a spreadsheet that's a week out of date, so overdue services only surface when something goes wrong.

What a missed service really costs

An unplanned breakdown on a remote site costs more than the repair bill. There's the downtime while parts and a mechanic make their way out, and depending on your contract, the client may not pay standby for time lost to your own equipment. A rig that falls behind can also push back the next job, which is a much harder conversation.

One number worth watching is the ratio of planned to unplanned maintenance. If unplanned work keeps creeping up, servicing is falling behind. It's easy to track once your downtime is coded properly, and our guide to time usage models explains how.

How to keep every engine serviced on time

None of this needs fancy tech to get started.

Read hours straight off the engine. Get the crew to record the hour meter at the start and end of every shift, as its own entry, separate from drilling time.
Keep one service schedule for the whole fleet. List every engine and compressor with the hours at its last service and the hours its next one is due, so anyone can answer "when's it due?" in seconds.
Set a trigger before the service is due. Pick a point ahead of each service that suits how far your sites are from the workshop, and use it to send the kit and book the mechanic.
Check the Plod against the meter. If the engine hours on a Plod don't line up with the hours the rig was actually working, find out why before it goes to the client. It catches service drift and unrecorded activity at the same time.
Make the daily checks count. Pre-start checks are the cheapest maintenance you'll ever do. Get your offsiders involved, and make it normal for anyone to flag a gauge that looks off. Crews who feel listened to tend to stick around, too.
Track planned against unplanned. Review the ratio every month. It's the quickest way to tell whether your schedule is keeping up with how hard the rigs are working.

Where tech can help

Plenty of contractors run this well with a whiteboard and a spreadsheet, and that's a great place to start. As a fleet grows, though, keeping every hour meter honest gets harder.

In CorePlan's Drilling Hub, Plods flag when engine hours don't match active hours, so gaps get caught before submission. For rigs with sensors, the Drilling Command Centre reads engine hours straight from the machine and sends alerts for things like low oil pressure or engine fault codes, so your service schedule runs off the engine instead of someone's memory. If you're weighing up sensors, here's how to make live rig sensor data useful once it's flowing.

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