Failure Mode and Effects Analysis is a structured, proactive technique for identifying potential failure modes in a process or product, assessing their impact, and prioritizing actions to prevent them — before they reach the customer.
Foundation
FMEA was originally developed by the US military in the 1940s and later adopted by the aerospace and automotive industries. Today it is a standard risk management tool used across manufacturing, healthcare, software, and service industries — and is widely used in Six Sigma and to support the risk-based thinking required by ISO 9001.
The fundamental question FMEA answers is: "What could go wrong, how bad would it be, and what can we do about it?" It converts subjective risk assessment into a quantified priority score — the Risk Priority Number (RPN) — so teams can focus their effort where it matters most.
Types of FMEA
There are three main types of FMEA — each focused on a different stage or aspect of product and process development.
Analyzes potential failure modes in a product design before it is released to manufacturing.
Analyzes potential failure modes in a manufacturing or service process — the most common type in Lean Six Sigma.
Analyzes interactions and interfaces between subsystems and components at the highest level.
Risk Priority Number
Each potential failure mode is scored on three dimensions. The product of these three scores gives the Risk Priority Number (RPN), which prioritizes which failures require action first.
How serious is the effect of the failure on the customer or process? Rated 1–10.
How likely is the failure mode to occur? Rated 1–10 based on frequency or probability.
How likely is the current control to detect the failure before it reaches the customer? Rated 1–10.
Risk Priority Number
RPN = Severity × Occurrence × Detection
Maximum RPN = 1,000 | Minimum RPN = 1 | Typical action threshold: RPN ≥ 100, or any Severity = 9–10
The Process
FMEA is a team exercise — it should involve people with direct knowledge of the process or design. Follow these steps in sequence.
Clearly define what process, product, or system is being analyzed. Break it into its component functions or process steps.
For each function or step, ask: "In what ways could this fail?" List every potential failure mode — do not filter at this stage.
For each failure mode, identify the effect on the customer, process, or next operation downstream.
Determine the root causes of each failure mode. Use tools like the 5 Whys or fishbone diagram to go beyond symptoms.
Rate Severity, Occurrence, and Detection (1–10 each) for each failure mode. Calculate RPN = S × O × D.
Focus on the highest RPN scores and any Severity 9–10 items. Assign owners, actions, and due dates.
Carry out the recommended actions — design changes, process controls, error-proofing, or additional testing.
After actions are implemented, re-score the RPN to verify improvement. FMEA is a living document — update it regularly.
For Process FMEA, ensure all critical controls identified are reflected in the process control plan and SOPs.
Worked Example
This simplified example shows how an FMEA table is structured for a transactional process. In practice, a full FMEA may contain many more rows and columns.
| Process Step | Potential Failure Mode | Effect of Failure | S | Potential Cause | O | Current Controls | D | RPN | Recommended Action |
|---|---|---|---|---|---|---|---|---|---|
| Data Entry | Incorrect invoice amount entered | Overpayment or underpayment to supplier | 7 | Manual entry error, no validation | 6 | Manager review before payment | 5 | 210 | Implement automated validation against PO |
| Approval | Invoice approved without authorization | Fraudulent or duplicate payment | 9 | Approval workflow bypassed | 4 | System access controls | 4 | 144 | Mandatory dual authorization for amounts above threshold |
| Payment Run | Duplicate payment issued | Financial loss, supplier reconciliation issues | 8 | No duplicate check before payment | 3 | Manual check by accounts team | 5 | 120 | Automate duplicate invoice detection in ERP |
| Filing | Invoice not archived correctly | Unable to retrieve for audit — compliance risk | 6 | No standard filing procedure | 5 | None | 7 | 210 | Create SOP for electronic filing and naming convention |
Reference Materials
Detailed FMEA examples with completed tables across various industries and processes.
Practical FMEA examples and templates for manufacturing and service processes.
FMEA sits within the Improve and Control phases of DMAIC. See the full Six Sigma tools reference.