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  • Writer's pictureMorten N. Pettersen | Principal Consultant

The Ultimate Guide to FMEA, FMECA and FMEDA: Understanding the Key Differences

Updated: Jun 12, 2023

Answers to 7 FAQs about FMEA, FMECA, and FMEDA

Component or system failure is an occurrence dreaded by engineers, product designers, and consumers. Chances are, several engineers and industrial firms discover potential failure late in product/system development or launch. The impact can be devastating, and there have been numerous stories about product recalls extended system downtimes, and increased project costs.

Failure Modes and Effects Analysis (FMEA), Failure Modes Effects and Diagnostic Analysis (FMEDA), and Failure Modes Effects and Critical Analysis (FMECA analysis) are systematic methods used to analyze potential failures in systems. Although these methodologies are known to improve the quality, reliability, and safety of a product or system, few questions remain unanswered about these risk identification approaches.

This article presents answers to 7 common questions you might be asking about FMEA, FMECA, and FMEDA.

What is Failure Modes and Effects Analysis (FMEA)?

Failure Modes and Effects Analysis is an inductive or bottom-up risk analysis technique. In simple terms, it involves considering failures of individual components or processes one by one to determine their effect on the overall systems.

FMEA was first widely used by the defense industries in the 1940s to reduce the sources of variation and failures in munitions production. Since then, it has grown to become one of the most used approaches for risk identification. It is a vital tool in the chemical, petrochemical, manufacturing, transportation, and defense industries.

Although FMEA was one of the first systematic approaches to risk assessment, it has developed enhanced capability and suit several other applications. Two common extensions of FMEA are FMECA and FMEDA.

What is Failure Modes, Effects and Criticality Analysis (FMECA)?

Like the FMEA, Failure Modes Effects and Critical Analysis is a bottom-up approach to risk assessment. However, in addition to the risk assessment and failure analysis done using an FMEA tool, Failure Modes Effects, and Critical Analysis enables you to rank the identified failure modes in order of importance or severity.

This rank is described using a criticality (C) or risk priority number (RPN). Failure Modes Effects and Critical Analysis tools find applications in military and space applications. It played a significant role in some NASA programs like Voyager and Galileo. It allowed NASA’s reliability engineers to indicate the failure modes that were more likely to influence their spacecraft in a safe and reliable operation.

Read more about FMECA in this insight.

What is Fault Tree and Event Tree Analysis (FMEDA)?

Failure Modes Effects and Diagnostics Analysis is a further extension of FMEA and was first used in electronics in the early 1980s. You will typically find it in use for more complex systems, such as a group of processes or devices that perform a complex function.

In addition to the prediction of failure rates in FMEA, FMEDA provides two additional pieces of information:

  1. The failure rates and distribution of failure modes of a target system

  2. The probability of a system detecting internal failure using an online diagnostics technique

What is the process for FMEA, and how is it similar to FMECA and FMEDA?

Since FMECA and FMEDA are just extensions of FMEA, these all share the same basic concept-FMEA which is a starting point for both FMECA and FMEDA. So, let’s start by discussing the FMEA solution process:

  1. Identify all the individual components that make up your design, system, or process. This step typically involves breaking down your entire system and understanding the role of each element.

  2. Deduce all the possible ways that each of the components can potentially fail and analyze the failure modes’ effect at a local and system level.

  3. Rank each potential failure effect based on the risk criteria of your choosing. Two standard methods used to quantify risk levels are Risk Priority Number (RPN) and Criticality (C). While the RPN method involves measuring risk on a 1 -1000 scale, the criticality method is based on probability values.

  4. After quantifying and ranking the risk level, define a plan of action to detect, minimize, eliminate, or mitigate these risk levels.

  5. Finally, review and revise the risk levels until you are sure that the countermeasures will reduce the risks.

How is the FMECA process different from FMEA?

As the name implies, Failure Modes Effects and Criticality Analysis differs from FMEA due to a specific type of criticality assessment. FMECA enables reliability engineers to determine the severity level of each potential failure and its likelihood of occurrence. The risk is then evaluated using a graph of severity versus circumstance.

How is the FMEDA process different from FMEA?

FMEDA assessment involves the assessment of diagnostic coverage of a safety instrumented system design in addition to FMEA. This methodology enables reliability engineers to achieve high reliability via online diagnostic.


In conclusion, FMEA, FMECA and FMEDA are three powerful tools for identifying and preventing potential failures in products, systems and processes. By understanding the key differences between these approaches, you can make an informed decision about which one is best suited for your particular needs. Whether you are working on a small or simple system, or a large and complex one, these methods can help you reduce the risk of failure and ensure the success of your project.

How are FMEA, FMECA, and FMEDA best performed?

At ORS, we provide risk management advisory and system reliability services using tailor-made FMEA methods for complex systems.

We are a leading reliability solutions provider, and our methodology is implemented in a wide range of sectors and industries, including oil and gas, maritime, and aviation industries. Let us assist you with FMEA, FMECA, and FMEDA. Reach out to us!

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