D5–D7: Corrective Actions & Prevention

Once the root causes are proven, the team moves to eliminating them permanently and updating quality documentation.

D5: Permanent Corrective Actions (PCA) Selection

• Evaluation Matrix: Score candidate solutions based on technical feasibility, tooling costs, lead times, and potential side-effects.
• Risk Assessment: Confirm that the proposed action introduces no new failure modes.
• "Red Rabbit" Validation: For detection actions, document the challenge test strategy using known defective samples (Red Rabbit) used to validate the control.

D6: Implementation & Validation

• Action Plan: Define exact implementation tasks, responsibilities, target completion dates, and tracking milestones.
• Effectiveness Proof: Collect production data over a representative period (e.g. 3 consecutive batches or 30 days of production).
• Containment Removal: Once statistical verification proves 0% defect recurrence, dismantle interim containment (D3) to avoid ongoing operational costs.

D7: Systemic Recurrence Prevention

True continuous improvement ensures similar lines or products benefit from lessons learned:

• FMEA Updates: Revise Process / Design Failure Mode and Effects Analysis (PFMEA/DFMEA) severity, occurrence, and detection rankings.
• Control Plans: Amend inspection frequencies and error-proofing (Poka-Yoke) controls.
• Standard Operating Procedures (SOP): Update work instructions and retrain operators.