Root Cause

Friday, 10:00, a small meeting room. The stockroom lead, the receiving clerk, an assembly supervisor and quality sit with the report. The first answer in the room arrives in under a minute: operators should have checked the date.

That answer describes what happened. It is also where a finding goes to die. An audit finding is a system failure found in a sample. If the cause ends at a person, nothing in the system changes, and the next person makes the same mistake. Ask why until the chain ends at a process, a responsibility or a check that was missing.

Ask why, with evidence

1. Why was expired adhesive in use? The operator had no way to see the expiry date at the station. The container label showed the date it was received.
2. Why? The stockroom puts its own label on each container at receiving. The manufacturer's expiry date is on the outer carton, and the carton is thrown away.
3. Why is the expiry date not on the label? The label template has no field for it, and the receiving steps for consumables do not mention shelf life.
4. Why? Consumables are not in the receiving inspection plan. The plan covers product material.
5. Why? Nobody owns shelf life for consumables. Quality checks product. The stockroom lead issues stock and assumes the supplier's date is being watched. That is a missing responsibility and a missing check.

Write beside each answer how you know it: the label template, the receiving procedure, the inspection plan, an interview. An answer with no evidence is a guess. Stop at the fifth answer. You can control it and you can prove it.

Test the cause

Ask three questions of it. If every person involved were replaced tomorrow, would the gap come back? Yes, so it is a system cause. Does it explain all three stations? Yes, none of them could see a date. Does it explain the 3 expired containers on the shelf? Yes, nothing sweeps the shelf, because nobody owns it. It also explains why the 4 other shelf life materials have the same gap, even though none has expired yet.

The chain gives you 3 causes to fix: the label shows the received date, receiving has no shelf life check, and nobody owns it. Step 6 needs an action for each.

Why not the operator

This is the second reason a response comes back: it stops at a person or at training. "The operator did not check the date" gets flagged by the free audit finding response builder for exactly that. The operator is one step in the chain, and the cause sits behind it: the reason they could not see what mattered.

Read more: how to do a 5 Why, a worked 5 Why example, how to make a fishbone diagram and the free 5 Why helper.

The mistake to avoid

Stopping at the first answer that sounds reasonable. If your answer contains a person's name or the word forgot, ask one more why.

Open the printable Monday Board

The plant, the audit, the finding and every number in this book (finding CAR-0417) are a made-up example. The tool sidebars show ShopFloorOps tools, which I make and sell. Every chapter teaches the step itself, so you can use your own forms. New to a term? See the quality glossary.