Chapter 13: Root Cause Analysis (RCA) & CAPA (Corrective and Preventive Actions)
📘 Overview:
In Quality Assurance and Control (QA/QC), defects, failures, and non-conformances are inevitable. What sets successful companies apart is how they analyze the root cause and prevent recurrence. This is where Root Cause Analysis (RCA) and Corrective and Preventive Actions (CAPA) play a crucial role.
🧠 What is Root Cause Analysis (RCA)?
Root Cause Analysis is a structured approach used to identify the fundamental reason for a problem or defect.
🔍 Key Tools Used:
| Tool | Description |
|---|---|
| 5 Whys | Ask “Why?” repeatedly until the root cause is found |
| Fishbone Diagram (Ishikawa) | Identifies potential causes in categories like Machine, Man, Method, Material, etc. |
| Fault Tree Analysis | Uses logic diagrams to trace failure back to the root |
| Pareto Chart | Focuses on the most frequent causes of problems (80/20 Rule) |
⚙️ CAPA: Corrective and Preventive Action
📌 Corrective Action
Action taken after a problem has occurred to eliminate its root cause and prevent recurrence.
✅ Example: A welding defect was found → Re-train the welder and revise WPS.
📌 Preventive Action
Proactive steps taken before a defect occurs to eliminate potential causes.
✅ Example: Quality trend shows paint defects → Introduce surface cleanliness audit before painting.
📂 Structure of a CAPA Report:
| Section | Description |
|---|---|
| Problem Description | Clear and detailed issue statement |
| Immediate Action Taken | What was done immediately to stop damage |
| Root Cause Identified | Based on RCA |
| Corrective Action | Elimination of root cause |
| Preventive Action | Measures to prevent future occurrence |
| Responsibility | Who will do what |
| Target Completion Date | Timeline for implementation |
| Verification | Evidence that actions were effective |
🏭 Real-World Industrial Example:
🧯 Problem: Frequent flange leaks in a steam piping system.
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Root Cause Analysis (5 Whys):
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Why did the leak happen? → Gasket failed.
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Why did gasket fail? → It was not suitable for temperature.
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Why was unsuitable gasket used? → Procurement used wrong specs.
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Why wrong specs? → Drawing lacked material code.
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Why no code? → QA/QC checklist was not followed.
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Corrective Action: Update drawing with proper spec, retrain team.
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Preventive Action: Introduce drawing review checklist before release.
🧰 Field Application Tips for Engineers:
Always investigate a failure beyond the symptoms.
Involve cross-functional teams in RCA.Document findings clearly and follow up CAPA actions.
Ensure that lessons learned are shared across departments.
Include RCA outcomes in weekly QA/QC meetings.
⚠️ Common Mistakes to Avoid in RCA/CAPA:
Jumping to conclusions without evidence.
Blaming personnel instead of analyzing process flaws.Not verifying the effectiveness of actions.
Ignoring trends of minor issues that could escalate.
Quiz: RCA & CAPA
Q1. What is the main goal of Root Cause Analysis?
A) To assign blame
B) To hide defects from clients
C) To identify and eliminate the origin of a problem
D) To reduce production costs
🟩 Correct Answer: C
Q2. In the 5 Whys technique, what is repeated to find the root cause?
A) What
B) Where
C) Why
D) When
🟩 Correct Answer: C
Q3. Which of the following is a visual tool for categorizing possible causes of a problem?
A) Scatter Plot
B) Flow Chart
C) Ishikawa (Fishbone) Diagram
D) Venn Diagram
🟩 Correct Answer: C
Q4. What does CAPA stand for?
A) Computer-Aided Production Analysis
B) Corrective and Preventive Actions
C) Certified Approved Project Audit
D) Common Action and Preventive Analysis
🟩 Correct Answer: B
Q5. Corrective action is:
A) Taken before a problem happens
B) Taken during shutdown only
C) Taken after a non-conformance is observed
D) Never documented
🟩 Correct Answer: C
Q6. Preventive action is meant to:
A) Reduce worker salary
B) Fix a defect that already happened
C) Stop future problems from occurring
D) Replace quality inspectors
🟩 Correct Answer: C
Q7. Which of the following is not part of a typical CAPA report?
A) Root cause analysis
B) Immediate action
C) Blame statement
D) Corrective and preventive measures
🟩 Correct Answer: C
Q8. A Pareto Chart is used to:
A) Display machine settings
B) Track non-conformity costs
C) Identify the few causes contributing to most problems
D) Allocate employee tasks
🟩 Correct Answer: C
Q9. A failure in a heat exchanger tube bundle repeatedly occurs. What should be done?
A) Just replace it again
B) Issue an NCR and close it
C) Perform RCA to prevent recurrence
D) Paint over the crack
🟩 Correct Answer: C
Q10. Why is verification important in CAPA?
A) To delay implementation
B) To ensure that actions taken are effective
C) To increase file size
D) To satisfy procurement
🟩 Correct Answer: B