How to use this template — S, O, D and Action Priority

FMEA (Failure Mode and Effects Analysis) is a structured method for identifying potential failures, assessing their risk and taking preventive action before the failure occurs. Each failure mode is scored on three factors: severity (S), occurrence (O) and detectability (D). Together they decide the Action Priority — high, medium or low.

S — Severity

10 = safety hazard or legal requirement
9 = product unusable
7-8 = significant loss of function
4-6 = partial loss
1-3 = cosmetic or no effect

Scale: 1–10

O — Occurrence

10 = happens almost always (>1 per 10 units)
7-9 = frequent
4-6 = occasional
2-3 = rare
1 = extremely unlikely (<1 per 1,000,000)

Scale: 1–10

D — Detectability

10 = no control / cannot be detected
7-9 = unlikely to be caught before delivery
4-6 = can be detected
2-3 = likely to be detected
1 = always caught before the customer

Scale: 1–10

AP high (H)

Action required. Find an improvement, or document why the current control is sufficient.

AP medium (M)

An action should be found. If it is not, the reason is written down.

AP low (L)

Action may be omitted. The risk is accepted and monitored.

Watch out

RPN is a prioritisation number, not an absolute risk score — two failures with the same RPN can have very different profiles (e.g. S=10, O=1, D=1 vs. S=3, O=3, D=3).
High S (severity) must always be acted on, regardless of RPN — a rare but catastrophic failure is not accepted.
An FMEA that is never updated loses its value — review it on process changes and after serious deviations.

Example

Failure mode: wrong torque on a screw. Effect: product comes loose (S=8). Cause: operator uses the wrong wrench (O=4). Control: no visible control (D=7). RPN = 8×4×7 = 224 — STOP. Action: introduce a click torque wrench and mark the correct wrench with colour.

Method: AIAG & VDA FMEA Handbook, 1st edition (2019), which superseded AIAG FMEA 4th Edition and VDA Volume 4. Used in IATF 16949, ISO 9001 and general risk management. The full AP table covers all 1,000 S/O/D combinations and is in the handbook.

FMEA analysis

Process step / Function	Failure mode	Effect of failure	S	Cause of failure	O	Current control	D	RPN S×O×D	Recommended action	Owner / Due

Action follow-up — top RPN priorities

Failure mode (from analysis)	Current RPN	Action implemented	New RPN	Owner	Closed?
					Y N
					Y N
					Y N
					Y N
					Y N

FMEA risk analysis

How to use this template — S, O, D and Action Priority

FMEA analysis

Action follow-up — top RPN priorities