Title: FMEDA: Quantitative Hardware Safety Analysis | ISO 26262 Academy URL: https://iso26262.academy/features/concepts/fmeda Description: FMEDA for ISO 26262-5: turn failure rates, failure-mode distributions and diagnostic coverage into the SPFM, LFM and PMHF of safety-related hardware. --- Concept guide · ISO 26262-5 §8-9 · 10 chapters # FMEDA: Quantitative Hardware Safety Analysis Build the worksheet behind the ISO 26262-5 hardware metrics row by row: failure rates, failure-mode shares, fault classes and diagnostic coverage, then the SPFM, LFM and PMHF they produce. 10 Chapters 21 Figures 1 End-to-end worked example Included in [Expert](https://iso26262.academy/pricing#plan-advanced) [Preview free](https://iso26262.academy/register?plan=free&from=%2Fconcepts%2Ffmeda&utm_source=website&utm_medium=cta&utm_campaign=features_concepts) See the chapters Inside the course 1. 01 **What an FMEDA Does** 2. 02 **Scoping the Worksheet** 3. 03 **Failure Rates per Row** 4. 04 **Failure Modes & Shares** 5. 05 **Classifying Each Row** The short version ## Quick answers What is FMEDA in ISO 26262? FMEDA (Failure Modes, Effects and Diagnostic Analysis) is the quantitative hardware safety analysis behind the metrics of ISO 26262-5. It extends FMEA with a failure rate for every part, split across its failure modes, and a diagnostic coverage for every safety mechanism that detects those modes. Each failure mode is classified against the safety goal in scope, and the results roll up into three numbers: SPFM and LFM for the architecture and the PMHF for random hardware failures. Together they show whether the hardware design meets the targets for its ASIL. What is the difference between FMEA and FMEDA? FMEA is qualitative: it asks how parts can fail and what that causes, and ranks actions. FMEDA is quantitative and coverage-aware: it assigns each failure mode a failure rate, classifies it into a fault class, credits the safety mechanisms that detect it, and sums everything into the hardware metrics. An FMEA tells you where to worry; an FMEDA tells you whether the design numerically meets the ISO 26262-5 targets. It is maintained from the hardware concept through verification. Keep going, free - [Article · 6 min read Why FMEDA Matters for ISO 26262: Five Practical Reasons](https://iso26262.academy/blog/why-fmeda-is-critical-for-iso-26262-hardware-safety) - [Demo exam · no account Test yourself with 7 exam-style questions](https://iso26262.academy/demo-exam) Why this course · ISO 26262, Part 5, Clause 8-9 ## Why it pays for itself ### Build the worksheet row by row Scope the analysis to a safety goal, give each row a documented failure rate and failure-mode share, and see how the rows add up to SPFM, LFM and PMHF on an illustrative circuit. ### Classify every fault correctly Trace each failure mode to the safety goal and sort it into safe, single-point, residual or multiple-point faults, the step where many FMEDAs quietly go wrong. ### Defend diagnostic coverage claims Map safety mechanisms to the rows they actually cover, account for overlapping mechanisms and latent faults, and back each claimed coverage with a reason a reviewer accepts. After the course ## What you’ll be able to do ### Scope and structure a worksheet Set up rows per safety goal with a sensible level of detail and clear column ownership. ### Justify rates and shares Document where each failure rate and failure-mode share comes from and how the mission profile affects it. ### Classify faults correctly Sort every row into safe, single-point, residual or multiple-point faults against the goal in scope. ### Defend coverage claims Tie each claimed coverage to a mechanism, a row and evidence, including latent-fault tests. ### Review a supplier FMEDA Read rows critically and spot the patterns that make metrics indefensible. The curriculum · 10 chapters ## Chapter by chapter 1. 01 **What an FMEDA Does** See how a parts list becomes classified failure rates and metrics, what the worksheet adds to an FMEA, and who fills which column. - Parts to classified rates - Five column groups - Who fills which column 2. 02 **Scoping the Worksheet** Scope the analysis to one safety goal at a time and decide which parts become rows and at what level of detail. - One safety goal at a time - Which parts become rows - Level of detail 3. 03 **Failure Rates per Row** Give each row a documented failure rate, adjust it for the mission profile, and handle permanent and transient faults. - One source per part family - Mission profile factor - Permanent and transient rows 4. 04 **Failure Modes & Shares** Split a part failure rate across its failure modes and decide what to do when no distribution data exists. - Rate per failure mode - Where shares come from - Current-sense shunt split 5. 05 **Classifying Each Row** Trace each failure mode to the safety goal and sort it into the right fault class, including rows that belong to safety mechanisms. - Tracing the effect - Two questions per row - Safety mechanism rows 6. 06 **Coverage in the Worksheet** Map safety mechanisms to rows, split each row by coverage, and make the claimed coverage defensible for both residual and latent faults. - Mapping mechanisms to rows - Defensible DC numbers - Start-up and periodic tests 7. 07 **From Rows to Results** Sum the columns into the hardware metrics, see what passes to the PMHF, and find the rows that dominate the result. - Summing the columns - What goes to PMHF - Levers and side effects 8. 08 **Worked Example** Build a complete illustrative worksheet for a brake-by-wire pedal travel sensing path and iterate the design once. - Pedal travel sensing circuit - One row step by step - One design iteration 9. 09 **The Worksheet in Practice** Plan build order and handoffs, integrate a supplier IC analysis, keep the worksheet alive, and relate it to the FMEDA simulator. - Build order and handoffs - Supplier IC analysis - Keeping it alive 10. 10 **Reviewing an FMEDA** Read rows like a reviewer, separate myths from reality, and spot red flags at worksheet level. - Reading a row - Myths and reality - Worksheet red flags Read all 10 chapters with Expert. Start with a free account: the complete Functional Safety Concept guide and 5 practice exams a month, then upgrade when you need this guide. [Expert](https://iso26262.academy/pricing#plan-advanced) [Preview free](https://iso26262.academy/register?plan=free&from=%2Fconcepts%2Ffmeda&utm_source=website&utm_medium=cta&utm_campaign=features_concepts) [Try the 7-question demo exam](https://iso26262.academy/demo-exam) Figures ## Not just text: the visual toolkit ### Five column groups The structure of the FMEDA worksheet at a glance. ### The failure-rate receipt How one part rate travels from its reference value to the value used in the row. ### Effect ladder Worksheet rows traced from the part pin to the safety goal. ### How one row splits A failure mode divided by coverage into the fault classes. ### Contributor Pareto Which rows dominate the result of the worked example. Worked example ## Pedal travel sensing for brake-by-wire An illustrative pedal travel sensing path with two sensor ICs on inverse slopes is analyzed end to end, then revised once to show how a design change moves the result. - The item, its safety goal and the sensing circuit - Building one worksheet row step by step - The complete example worksheet - Totals and the verdict against the goal - One design iteration and what it changes Example worksheet Why inverse sensor slopes make the same fault safe on one track and dangerous on the other Unlock in course Built for ## Who this guide is for - Hardware safety engineers building their first FMEDA from a bill of materials - Reliability engineers moving from qualitative FMEA into quantitative ISO 26262-5 analysis - Reviewers auditing a supplier FMEDA for optimistic coverage or under-counted latent faults - Engineers whose SPFM or PMHF misses its target and who need to find out why ## Frequently Asked Questions Common questions about FMEDA: Quantitative Hardware Safety Analysis ISO 26262-5 sets targets for ASIL B, C and D that tighten as the ASIL rises: higher single-point and latent fault metrics and a lower PMHF. ASIL A has no required metric targets. The metrics are evaluated per safety goal, and the target values can also be derived from a well-trusted similar design. The guide shows how the worksheet columns turn into these metrics and which rows usually dominate the result. One FIT is one failure per 10^9 device hours, the base unit for rates in an FMEDA. Base rates come from recognized reliability handbooks or supplier data, documented consistently per part family, and are then adjusted for the mission profile, because temperature and stress change them substantially. The part rate is apportioned across its failure modes, and each mode is classified against the safety goal being analyzed. Where no failure-mode distribution exists, the choice has to be justified and reviewed. The guide has 10 chapters: what an FMEDA does, scoping the worksheet, failure rates per row, failure modes and shares, classifying each row, coverage in the worksheet, from rows to results, a worked example, the worksheet in practice and reviewing an FMEDA. The worked example analyzes a brake-by-wire pedal travel sensing path end to end, supported by 21 figures. A free account starts you off, and the Pro and Expert plans unlock more of the library. ## Running this analysis on a real project? Have an engineer check it, or help you build it. You get written findings on method, coverage and results. From **$1,490** with a written quote before any charge [See how we can help](https://iso26262.academy/features/consulting?service=analysis#sample) ## Start the course today A free account unlocks one full concept guide, 3 work product templates, 1 guided process, the Markov and RBD simulators, and 5 practice exams per month. The Pro and Expert plans unlock more of the 93-guide library. No credit card required. [Preview free](https://iso26262.academy/register?plan=free&from=%2Fconcepts%2Ffmeda&utm_source=website&utm_medium=cta&utm_campaign=features_concepts) [View Pricing Plans](https://iso26262.academy/pricing) Continue with ## Where this topic leads next. [Browse all 93 guides](https://iso26262.academy/features/concepts#library) - Hardware [Hardware Element Evaluation](https://iso26262.academy/features/concepts/hardware-element-evaluation) Study ISO 26262-8:2018 Clause 13: element classes, evidence, evaluation scope and integration responsibilities. [Expert](https://iso26262.academy/pricing#plan-advanced) 10 chapters - Hardware [Soft Errors & Transient Faults](https://iso26262.academy/features/concepts/soft-errors) A cosmic ray hits a memory cell and your ASIL D function computes with a wrong value. This concept walks from the physics of radiation-induced bit flips through single event effects, ECC and hardened design, all the way to Part 11 quantification. 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