1. RPN / RISK PRIORITY NUMBER
Analysis Of Risk
RPN / RISK PRIORITY NUMBER
What Is Risk?
Probability of danger
Severity/Occurrence/Cause

2. WHICH ONE IS WORSE? Evaluation by RPN Only Case 1 Case 2 Case 3 Case 4
S=5, O=5, D=2 RPN = 50
Case 2
S=3, O=3, D=6 RPN = 54
Case 3
S=2, O=10, D=10 RPN = 200
Case 4
S=9, O=2, D=3 RPN = 54
WHICH ONE IS WORSE?

3. Example Extreme Safety/Regulatory Risk = 9 & 10 Severity
High Risk to Customer Satisfaction
Severity ≥ 5 and Occurrence ≥ 4
Consider Detection only as a measure of Test Capability.

4. Example of Significant/ Critical Threshold

5. 2) Potentially Significant
Evaluation by RPN Only
Case 1
S=5, O=5, D=2 RPN = 50
Case 2
S=3, O=3, D=6 RPN = 54
Case 3
S=2, O=10, D=10 RPN = 200
Case 4
S=9, O=2, D=3 RPN = 54
2) Potentially Significant
4) Low Risk
WHICH ONE IS WORSE?
3) Potential
Annoyance
1) Potentially
Critical

6. Re-rating RPN After Actions Have Occurred
Severity typically stays the same.
Occurrence is the primary item to reduce / focus on.
Detection is reduced only as a last resort.
Do not plan to REDUCE RPN with detection actions!!!
100% inspection is only 80% effective!
Reducing RPN with detection does not eliminate failure mode, or reduce probability of causes
Detection of 10 is not bad if occurrence is 1

7. RPNinitial - RPNrevised % Reduction in RPN = RPNinitial
Good Use of RPN’s
Effectiveness of Recommended Action(s)
Report percentage reduction in RPN as
Cause Risk Reduction.
RPNinitial - RPNrevised
% Reduction in RPN =
RPNinitial