Failure Modes and Effects Analysis

2 Failure Modes and Effects Analysis (FMEA) ● Purpose – Systematically, prospectively, identify ways in which a process (system) can fail: Failure Modes. – Also, prospectively identify problems that might occur and should be designed around. – Identify factors potentially contributing to failures. – Estimate risk of failure – Identify countermeasures – Develop requirements ● Method (WSE workbook) – Copy IDEF0 model nodelist into WSE [Process Model] worksheet – Select subprocess/task on which to perform FMEA – Prepare task FMEA worksheet from [FMEA template] worksheet ● copy [FMEA template] worksheet ● copy or type subprocess/task A# and name into upper left cell ● rename new task FMEA worksheet to task's A# – Perform FMEA

3 PRIS IDEF0 Model Nodes in WSE Workbook

4 PRIS FMEA in WSE Workbook

5 FMEA Fields ● Contributing Factors – Circumstances, conditions, events, factors,... anything that might make a failure mode more likely. ● Potential Failure Mode – A way in which the process/system can fail or a problem develop: ● human error ● acute injury (e.g., cut, broken bone) ● cumulative injury (e.g., carpal tunnel syndrome) ● equipment/tool failure ● etc. ● Potential Effects of Failure Mode – Consequences of the failure.

6 FMEA Fields (2) ● Severity – Numeric rating of the estimated severity of consequences, of the failure/problem, e.g., ● negligible ● minor ● moderate ● major ● catastrophic ● Probability – Numeric rating of the estimated probability that the failure/problem will occur, e.g., 1. Remote 2. Unlikely 3. Occasional 4. Common 5. Frequent

7 FMEA Fields (3) ● Nondetectability – Numeric rating of the difficulty of detecting the failure in time to prevent or mitigate its consequences, e.g., 1.Should the failure occur or problem develop, there is a virtual certainty that the existing controls will detect it. ● Should the failure occur or problem develop, there is a high probability that the existing controls will detect it. 1.Existing controls have difficulty detecting the failure/problem. 2.Controls are weak. Detection could depend on a lucky catch. 3.No controls for this failure mode exist. ● RPN: Risk Priority Number – RPN = Probability x Severity x Nondetectability

8 FMEA Fields (4) ● Potential Remediations – Design strategies that could reduce the likelihood of the failure mode. ● Design Requirements – Abbreviated requirements statements for remediations. – Requirement numbers ([Requirements] worksheet).

9 Example ● PRIS FMEA

IE WSE Project Assignment 1.FMEA on at least 3 Break Down Subsystem processes (3 of the most detailed IDEF0 diagrams) 2.Requirements Version 3 (including requirements from FMEA) 3.Progress Report 3 i.Cover: Memo Evaluation Form (provided by instructor) ii.Memo (see syllabus) iii.Separator page: Work Products Evaluation Form (provided by instructor) iv.Copies of work products (see above, plus final IDEF0 diagrams)