Full definition
A structured, systematic methodology for identifying all potential failure modes of a component, system, or process, evaluating the effects of each failure on system performance and safety, and prioritizing corrective actions. Each failure mode is scored on three criteria (1-10 scale): Severity (S, impact of failure on safety/production/quality), Occurrence (O, likelihood/frequency of the failure mode), and Detection (D, probability that current controls will detect the failure before it reaches the customer/end user). Risk Priority Number: RPN = S × O × D (range 1-1,000). High RPN items (typically >200, or any with S ≥ 8) are prioritized for corrective action. Types: Design FMEA (DFMEA — during product design) and Process FMEA (PFMEA — during manufacturing/maintenance process design). Per SAE J1739, AIAG 4th Edition (automotive industry standard), and IEC 60812 (international). FMEA is a core tool in: IATF 16949 (automotive quality), RCM (reliability-centered maintenance), and ISO 14224 (petroleum/petrochemical reliability data). Example in belt drive context: failure mode "belt breaks during operation," effect "production line stops," S=8, O=3 (with PM program), D=5, RPN=120 — corrective action: add vibration monitoring.