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Identify Failure Modes
Discover and document system-level failure modes linked to system functions.
Score Risk Factors
Assign severity, occurrence, and detection ratings to calculate Risk Priority Numbers.
Mitigate Risks
Document design changes and mitigation actions to reduce failure mode risk.
Evaluate Effectiveness
Recalculate post-mitigation RPN and verify risk reduction targets are met.
SFMEA Workflow Overview
The system-level FMEA (SFMEA) process follows a four-phase cycle aligned with ARP 4761 and MIL-STD-882E safety assessment methodology:
When to Use SFMEA
SFMEA is performed when:- Analyzing failure modes of system-level functions defined in your Functional Hazard Assessment (FHA)
- Evaluating the design’s ability to mitigate failure mode effects before detailed component analysis
- Assessing compliance with DO-178C, ARP 4754A, and ARP 4761 safety requirements
- Tracking risk reduction activities across the development lifecycle
Key Concepts
| Concept | Definition | Example |
|---|---|---|
| Failure Mode | The manner in which a system function fails (loss, degradation, or intermittent behavior) | Loss of roll control signal |
| Severity (S) | Impact of the failure on aircraft/crew safety (Catastrophic, Critical, Major, Minor, No Effect) | Critical = crew cannot maintain aircraft control |
| Occurrence (O) | Likelihood that the failure will occur (1–10 scale: Remote to Frequent) | 3 = unlikely during aircraft service life |
| Detection (D) | Likelihood that built-in diagnostics or verification will catch the failure before hazard manifests (1–10 scale: Remote to Not Detectable) | 2 = easy to detect via functional test |
| Risk Priority Number (RPN) | Product of S × O × D; drives mitigation priority (scale 1–1000) | 3 × 3 × 2 = 18 (low priority) |
| Mitigation Action | Design change, built-in test, procedural control, or requirement to reduce S, O, or D | Add dual-channel sensor with cross-check logic |
| Post-Mitigation RPN | Recalculated RPN after implementing mitigation, showing risk reduction | 3 × 1 × 1 = 3 (acceptable) |
Documentation Structure
| Page | Purpose | When to Use |
|---|---|---|
| Identify System-Level Failure Modes | Record failure modes and effects | At the start of SFMEA; document every potential failure |
| Score Severity, Occurrence, and Detection | Assign S, O, D ratings and calculate RPN | After all failure modes are identified |
| Add Mitigation Actions | Propose design/procedural changes to reduce risk | When RPN exceeds acceptable threshold |
| Evaluate Post-Mitigation RPN | Verify mitigation effectiveness and close items | Before baseline release or certification review |
Common Tasks
- Start a new SFMEA: Create a system FMEA risksheet linked to your system’s failure conditions from the FHA
- Copy an existing SFMEA: Use the template to baseline a subsystem or updated SFMEA variant
- Assign severity and occurrence: Follow ARP 4761 classification mapping to severity ratings
- Track open risk items: Use workflow state (In Progress → Review → Closed) to manage mitigation priority
- Generate RPN summary report: Export pre- and post-mitigation RPN metrics for certification evidence
See Also
- Identify Failure Conditions — FHA background for failure mode identification
- Create PSSA and SSA Documents — How SFMEA results feed into higher-level safety assessments
- Read the FMEA Summary Report — Generate metrics and compliance evidence from SFMEA data
Source References (dev)
Source References (dev)
Code:
modules/RiskTemplates/DFMEATemplate/attachments/risksheet.json (0.52) · modules/Risks/COMPLIANCE-001/module.xml, modules/Risks/MIL-STD-882E-HTS-001/module.xml, modules/Risks/SEC-THREAT-001/module.xml, modules/Risks/SFMEA-SUB-001/module.xml, modules/Risks/SFMEA-SUB-002/module.xml, modules/Risks/SFMEA-SUB-003/module.xml (0.51) · datasets/sol-aero-ui-walkthrough/summary.md, navigation.md, dashboards/home-dashboard.md, dashboards/role-dashboards.md, dashboards/standards-compliance.md, risksheet-views/risksheet-views.md, work-item-types/data-model.md (0.47) · .polarion/pages/spaces/Requirements/Home/page.xml, Design/Home/page.xml, Risks/Home/page.xml, Testing/Home/page.xml, Risks/FMEA Reports/page.xml, Documentation/Home/page.xml, Documentation/Powersheet Help Redirect/page.xml, RiskTemplates/Home/page.xml (0.43) · modules/RiskTemplates/SubSystem-FMEATemplate/attachments/risksheet.json (0.41) · modules/RiskTemplates/System-FMEATemplate/attachments/risksheet.json (0.41) · .polarion/documents/workflow/riskSpecification-workflow.xml (0.41) · .polarion/nextedy/sheet-configurations/DO-160G Environmental Qualification.yaml, Component RTM.yaml, Configuration Index.yaml, Design Verification Sheet.yaml, Interface Control Matrix.yaml, Problem Report Tracker.yaml, Process Steps.yaml, Review Action Item Tracker.yaml, SOI Stage Gate Dashboard.yaml, Use Steps Specification.yaml, User Need Validation Sheet.yaml, characteristics.yaml, component-characteristics.yaml, customer-requirements.yaml, design-requirements.yaml, subsystem-functions.yaml, subsystem-verification.yaml, system-elements.yaml, test-verification.yaml (0.40) · .polarion/nextedy/models/rtm.yaml (0.39) · modules/RiskTemplates/DFMEATemplate/module.xml, modules/Risks/DFMEA-CMP-PSU/module.xml, modules/_default/WholeRTMSheet/module.xml, modules/Requirements/CUSTOMER-REQS/module.xml (representative of ~50 module.xml files across all spaces and templates) (0.39)