Phase 5: sustain and improve APQP results

The final APQP phase turns launch and production performance into action. It uses actual evidence—not opinions—to confirm that controls work, correct problems, and prevent recurrence.

Useful sources of feedback

Production performance

Review scrap, rework, downtime, defects, process audits, layered process audits where used, measurement-system results, and control-plan records.

Customer experience

Use customer complaints, returns, scorecards, field failures, and warranty information when available. Contain customer risk first, then investigate cause.

Change and lessons learned

Record what changed, why it changed, what documents and validations were affected, and what should be reused in future design and process planning.

A disciplined corrective-action loop

  1. Contain the nonconforming product and protect the customer.
  2. Define the problem with facts, including where and when it occurs.
  3. Determine and verify the root cause and the reason the existing system did not prevent or detect it.
  4. Implement corrective action, update affected APQP documents, and train affected people.
  5. Verify effectiveness over an appropriate period and share the lesson with similar products and processes.
Close the loop: a corrective action is incomplete if it changes the shop floor but not the process flow, PFMEA, control plan, work instruction, training, or change record when those documents are affected.