The part you need isn't on the shelf: what to do at 2am

It's 2am. The gearbox on the infeed conveyor has let go. Your fitter has the cover off and the output shaft has play you can feel by hand. They walk to stores.

The CMMS says one in stock. The bin is empty. There's a pick note from three months ago and no sign of a reorder. The supplier's trade counter opens at eight.

Now you have six hours of decisions to make with half the information. Most of the risk sits in the next 20 minutes, when someone tired starts looking for something that will fit.

Make sure it's really not there

Before anyone starts improvising, do a proper search. Parts go missing in the same few places on every site.

• The quarantine shelf, the returns bench and the "awaiting inspection" cage
• The workshop, where someone stripped the last failed one and left the good parts
• An identical machine on another line that isn't running tonight
• Your sister site, if you have one, and someone there with a van
• The old unit in the scrap bin, if it's only a seal or a bearing that's gone

Robbing a part from a machine that's stood is a fair call at 2am. Tag both machines when you do it, and log it, so nobody tries to start the donor in the morning.

Who's open at 2am

Some suppliers run out-of-hours lines for bearings, motors, belts and drives. Some motor repairers will open up for a rewind or an exchange unit. If you don't know which of yours do, you'll find out the hard way. Get the numbers now and put them on the wall in the maintenance office.

For some kit, hire is the answer. A hired compressor, chiller or generator can keep a site going while you wait for parts. If you go that way, sort out who maintains it. HSE's code of practice says the hire firm and the hirer should agree who does the safety-related maintenance, and "the terms of the agreement should be set out or recorded in writing" (L22, paragraph 77).

Close enough is where it goes wrong

This is the part of the night that needs a clear head. The shelf has something that nearly fits. A gearbox with a different ratio. A motor with the same kW but a different frame. A sensor that's PNP where the old one was NPN. A drive from a different range. A fuse the next size up.

Some of those will be fine. Some will run for a week and then cause a worse failure. Some will make the machine unsafe without anyone noticing. A different ratio changes conveyor speed, which can upset every timing downstream. A drive swap needs its parameters set for the motor, or you'll be back to the trips you started with. A bigger fuse takes away protection. The Electricity at Work Regulations require "efficient means" of protection from excess current (regulation 11), and a fuse that won't blow before the cable cooks doesn't give that.

The rules here are simple. Work equipment has to be suitable for the purpose it's used for (PUWER, regulation 4). If it's adapted, "it must still be suitable for its intended purpose" (L22, paragraph 53). The code of practice also expects maintenance to follow the maker's recommendations, including the "replacement and adjustment of parts" (L22, paragraph 74).

So the question at 2am is who can judge whether the substitute is suitable. That takes someone with the right knowledge for that kit. The Electricity at Work Regulations ban work where technical knowledge or experience is needed to prevent danger unless the person has it, or is properly supervised (regulation 16). A good fitter can judge a coupling. Plenty of good fitters can't safely set up a different drive.

The cost of the wrong person

Here's where most of the money goes. If the person on shift can't judge the substitute, you have two bad choices. Wait until eight for the supplier and lose six hours. Or fit something close, hope, and risk a bigger failure later.

The third choice is to get someone in who can make the call. A controls engineer who can set up a different drive in an hour turns a six-hour wait into a two-hour stop. Put your own cost of an hour of downtime against those hours and the callout often pays for itself several times over. If you're not sure where your team's gaps are, fitters, electricians and controls engineers is a good place to start.

Whatever goes in, write it down

If a substitute goes in, it's a temporary fix until the right part is fitted. Tag it on the machine. Put it in the log with what was fitted, what settings changed, and who decided. Give it an owner and a date. Without that, tonight's stand-in becomes next year's mystery. We've covered how that happens in breakdown or bodge.

Then reorder the right part before you go home, and mark the empty bin. A count that says one when the bin is empty is worse than no count at all.

Fix the shelf in daylight

A 2am parts hunt nearly always traces back to a spares list nobody has looked at in a while. Go back over it on a quiet afternoon. Start with the machines that stop the whole site, using a criticality ranking. Then decide what's worth holding, using critical spares: what to hold and what to stop hoarding.

For anything the maker no longer supplies, start now. Don't wait for it to fail. Our post on obsolete parts walks through the options.

What to do on Monday

1. Check the stock count against the bin for the parts on your three most critical machines.
2. Get the out-of-hours numbers for your main suppliers and repairers, and put them on the wall.
3. Agree who on each shift can sign off a substitute part, and for which kit. Line up help for the rest.
4. Start a temporary fix register so every stand-in part has an owner and a date.

* Paragraph numbers refer to L22, fourth edition (2014, amended 2018).