Failure Mode and Effects Analysis (FMEA) is a structured, bottom-up risk analysis technique used to identify potential failure modes of a system or process, analyze their causes and effects, and prioritize them for corrective action. Each failure mode is assigned a Risk Priority Number (RPN) = Severity × Occurrence × Detection. High-RPN items receive design changes, additional controls, or additional testing to reduce risk. FMEA is both a design tool (Design FMEA, or DFMEA) and a manufacturing process tool (Process FMEA, or PFMEA).
DFMEA focuses on how a design can fail and what the effect would be on the customer. For each component or assembly, engineers ask: what are all the ways this could fail to perform its function? What causes each failure mode? What is the effect on the system or user if it fails? How often is each cause expected to occur? How likely is the failure to be detected before reaching the customer? Answering these questions systematically surfaces risks that are not apparent from functional requirements alone.
FMEA is required by IATF 16949 (automotive), AS9100 (aerospace), and ISO 13485 (medical devices). Even outside regulated industries, FMEA provides value by forcing engineers to think about failure before committing to a design. The AIAG-VDA FMEA handbook (2019) is the current industry reference, replacing the earlier AIAG 4th edition with a more structured Action Priority (AP) system that replaces the traditional RPN ranking with High/Medium/Low priority categories.
Practical Example
DFMEA entry for a connector: Failure mode: Intermittent connection. Cause: Fretting corrosion from vibration. Effect: System reset, data loss, potential safety hazard. Severity: 8. Occurrence: 5 (vibration environment expected). Detection: 3 (detected in environmental test). RPN: 120 — above threshold. Corrective action: Change to gold-plated contacts, add connector lock. New RPN: 48.
How SpecZero handles this
FMEA findings translate directly into SpecZero requirements: a high-RPN failure mode should drive a requirement to address its root cause. For example, an FMEA finding that vibration causes connector failure might generate a requirement: 'All connectors shall pass IEC 60068-2-6 vibration testing at 10-500 Hz, 2g.'
Related terms
Risk Priority Number(RPN)
A calculated score in FMEA (Severity × Occurrence × Detection) used to prioritize failure modes for corrective action.
Verification and Validation(V&V)
Verification confirms a design meets its specifications; validation confirms the product meets user needs.
Design Verification Test(DVT)
The second prototype phase — verifying the design meets all specifications with production-representative builds.
Acceptance Criteria
The measurable conditions a system or component must meet to be considered complete and accepted.