A repeat defect starts in the filing cabinet. Pull the old 8D and read it as evidence: was the root cause proven or only stated, did the action change the process or the person, did anyone look at detection, and what did the effectiveness check test? Mark each answer proven, stated or missing. Keep the old report open and link the new corrective action to it.
Monday, week 16. The customer's quality contact calls about sensor bracket BK-6139. Lot 6471, 120 pieces, and 7 of them have the two mounting holes too far apart. The bracket will not seat on the sensor. It is the same defect you closed 11 weeks ago.
Before anyone walks out to the floor, go to the filing cabinet and pull the old 8D. The theory people are about to offer is usually in there, and it is the same one that did not hold.
Read it as evidence
The old report records what the team believed at the time. Nobody wrote it to mislead you. Read it the way you would read a witness statement, and ask five things:
- Was the root cause proven or only stated? Proven means someone turned the cause on and off and watched the defect follow it. This one says "operator did not check the first piece". Nobody ran a test.
- Did the action change the process or the person? The action was to retrain the operators and add a first piece reminder. Six people sat through a session. The die, the press and the gage stayed as they were.
- Did anyone look at detection? The report asks why the defect happened. It never asks why nobody caught it.
- What did the effectiveness check actually test? It says no complaints for 30 days. Hold that thought until step 8.
- When did it close? It closed in week 5, on the day the training ended. A fix that is closed the day it goes in has not been tested by anything.
Write each answer next to the old text in two words: proven, stated, missing. Most repeat defects show the same pattern. The cause was stated, the fix depended on people remembering, and the check was too short to see the failure come back.
Keep the old 8D open, not closed
Do not start a clean sheet and do not edit the old report. The old one stays exactly as it was, because it is part of the evidence. Open a new corrective action, link it to the old one by number, and say in the first line that this is a repeat. Your corrective action log should show the two as a pair. If it does not, that is a finding too, because nobody searching the log next year will know there was a first one.
Read more: how to write an 8D report. The old report is also a good test for the free 8D report checker. If the checker flags a missing verification, that is the same gap you just found by hand.
The mistake to avoid
Starting from the old root cause. It is tempting to say the operator missed the check again and go straight to a stronger reminder. If the first answer had been right, the defect would not be back. Treat the stated cause as a guess until you have seen it proven.
- Pull the last closed action that came back.
- Mark each cause proven, stated or missing.
- Link the repeat to the original this week.
Open the printable Monday Board
Related on ShopFloorOps
The part, the die, the lots and every number in this book (sensor bracket BK-6139) 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.