Steps to Perform Failure Modes and Effects Analysis (FMEA)

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Sofema Online (SOL) considers the necessary steps to perform a Failure Modes Effect Analysis (FMEA)

Introduction - Establish the context and purpose

The purpose of FMEA is to take actions to eliminate or reduce failures, starting with the highest-priority ones. FMEA is a dynamic tool and should be revisited over time, especially after changes have been made in the design or process.

>> Define the system, subsystem, or process to be analyzed. Determine the scope, the reason for the analysis, and the team who will conduct the FMEA.

o This team should include a cross-section of experts from various fields such as design, manufacturing, quality, and reliability engineering.

Breakdown the system

Create a graphical representation of the system, subsystem, or process.

>> This could be in the form of a block diagram, flowchart, or process map, showing the relationship between components and steps.

Identify the Potential Failure Modes

List all possible ways that each component or step in the process could fail.

A failure mode refers to the way something might fail to perform its intended function.

Identify the Effects and Causes of each Failure Mode

For each failure mode, determine all possible effects and their potential causes.

>> An effect is the consequence of a failure mode on the system or process.
>> A cause is a deficiency or defect in design, process, quality, or part, which is the direct reason for the failure mode.

Assign Severity, Occurrence, and Detection ratings

For each failure mode, assign a rating for:

>> Severity (S): This measures the seriousness of the effect of a failure.
>> Occurrence (O): This measures the frequency of the cause leading to the failure.
>> Detection (D): This measures the likelihood of detecting the cause before the failure occurs.

Calculate the Risk Priority Number (RPN)

Multiply the three ratings: RPN = S x O x D.

>> The RPN provides a numeric assessment of risk associated with each potential failure mode and helps prioritize them.
>> Identify and prioritize actions: Based on the RPN and the team’s expertise, identify actions to eliminate or reduce the high-risk failure modes. Decide which actions should be carried out first based on the RPN, resources, and feasibility.

Take action

>> Implement the actions determined in the previous step and validate their effectiveness in reducing or eliminating the risk of failure.

Review and update the FMEA

>> Once the actions have been implemented, update the FMEA with new severity, occurrence, and detection ratings, and recalculate the RPNs.

o If the actions are not effective, you may need to revisit the analysis.

Next Steps

Sofema Aviation Services ( offers training to cover CS 25 System Safety Assessments – please see the following: Type Certification System Safety Assessment – 5 Days
For additional questions or comments – please email

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