When a customer complaint lands, contain suspect stock first. Then define the problem with Is / Is Not, run the 8D to find both why it happened and why it escaped, and finish by updating the PFMEA and Control Plan so the fix is built into how the part is made and checked.
Start with
Contain suspect stock before you start investigating.
The path, in order
Containment
Find and isolate every suspect part: at the customer, in transit, in finished goods and in work in process. Sort it and record quantities inspected and rejected at each location. Protect the customer first, within 24 hours or whatever your customer requires.
Is / Is Not
Pin the problem down: which part, which defect, where it was found, when it started and how many. Compare what is affected with what is not. The differences point at the cause.
8D
Work D1 through D8: team, problem statement, containment, root cause, permanent corrective action, validation, systemic prevention and recognition. Find two root causes, why it happened and why it escaped.
PFMEA update
Re-rate the failure mode with what you now know. A real escape usually means the occurrence or detection rating was too optimistic.
Control Plan
Add or strengthen the control that would have caught it, with a reaction plan. Then verify the next production runs before you close.
Use these next
- How to write an 8D report
- Containment, correction and root cause
- Free 8D starter form
- PFMEA to Control Plan check
- ShopFloorOps workbooks on Etsy: The Root Cause & Corrective Action Bundle on Etsy covers the whole chain in connected workbooks.