Root Cause Analysis

Component Description
occurs. Severity applies to the effect only. Severity
should be estimated on a “1” to “10” scale.

Severity of Effect Ranking

Very High Very hwarning, 10 without warning)igh severity ranking (9 with 109

High

High degree of customer

dissatisfaction due to the nature of

the failure

8

7

Moderate

Moderate ranking because failure

causes some customer

dissatisfaction

6

5

4

Low Causing only a sligannoyance ht customer^32

Minor

Unreasonable to expect that the

minor nature of this failure would

cause any real effect

1

Classification This column may be used to classify (e.g. critical
key, major, significant) any component, subsystem,
or system characteristics that may require
additional process controls.
Potential
Cause(s)/Mechanism(s)
of Failure

Potential Cause of Failure is defined as an
indication of a design weakness, the consequence
of which is the failure mode.
Occurrence (O) Occurrence is the likelihood that a specific
cause/mechanism will occur. Estimate the
likelihood of occurrence of potential failure
cause/mechanism on a 1-10 scale.

Frequency of

Occurrence of

Failure Effect

Severity Levels
1
Insignificant
2
Marginal
3
Critical
4
Catastrophic
5: Frequent Undesirable Intolerable Intolerable Intolerable
4: Probable Tolerable Undesirable Intolerable Intolerable
3: Occasional Tolerable Undesirable Undesirable Intolerable
2: Remote Negligible Tolerable Undesirable Undesirable
1: Improbable^ Negligible^ Negligible^ Tolerable^ Tolerable^
Current Design
Controls

List the design validation/verification (DV),

prevention, or other activities which will assure the

design adequacy for the failure mode and/or

cause/mechanism under consideration.

Component Description

Detection (D) Detection is an assessment of the ability of the

proposed current design controls to identify a

potential cause (design weakness) before the

component, subsystem or system is released for

production. Rank on a scale of 1-10.

Likelihood of Detection Ranking

Absolute

Certainty

on Non-

Detection

DV Program will/can not detect a

potential design weakness, or there

is no DV Program. 10

Very Low

DV Program probably will not

detect a potential failure

cause/mechanism (design

weakness)

9

Low

DV Program not likely to detect a

potential failure cause/mechanism

(design weakness)

8

7

Moderate

DV Program may detect a potential

failure cause/mechanism (design

weakness)

6

5

High

DV Program has a good chance of

detecting a potential failure

cause/mechanism (design

weakness)

4

3

Very High

DV Program will almost certainly

detect a potential failure

cause/mechanism (design

weakness)

2

1

Risk Priority Number

(RPN)

RPN is the product of the Severity (S), Occurrence

(O), and Detection (D) ranking. RPN is a measure of

design risk. This value should be used to rank order

the concerns in the design. The RPN will be

between “1” and “1,000”. For higher RPNs, the

team must undertake efforts to reduce this

calculated risk through corrective action(s). In

general, regardless of the resultant RPN, special

attention should be given when severity is high.