What Is FMEA?
Failure Mode and Effects Analysis (FMEA) is a structured methodology primarily designed to identify and address potential failures in a system. The core idea of FMEA is to anticipate and mitigate failures. It involves a detailed examination of the components of a system to pinpoint where and how failures might happen, what their causes could be, and the potential effects on the overall system. FMEA helps ensure that every potential point of failure is accounted for, thereby bolstering the integrity and robustness of designs.
Learn the basics of FMEA, including:
- What is FMEA?
- Why is it used?
- How is FMEA performed?
- What tools are used?
Published: 28 Feb 2024
On May 25, 1979, American Airlines Flight 191 lost control immediately after takeoff at O'Hare International Airport in Chicago. The aircraft soon rolled hard to the left before crashing less than a mile from the end of the runway. All 271 occupants on the aircraft perished, as well as two people on the ground.
According to the National Transportation Safety Board, or NTSB, the root cause of the accident was improper maintenance conducted months earlier, which damaged a pylon assembly and eventually led to the left engine separating from the wing. This is just one painful example of the importance of safety in modern systems. Engineers who develop safety-critical systems need to account for many types of events and processes to ensure the end users of these systems are not put in peril.
Failure Mode and Effects Analysis, or FMEA, is a common analysis performed by teams developing safety critical systems. In this video, we will cover, what is FMEA? Why is it used? How is FMEA performed? And what tools are used?
First, what is FMEA? Failure Mode and Effects Analysis, or FMEA, is a structured methodology primarily designed to identify and address potential failures in a system. The core idea of FMEA is to anticipate and mitigate failures. It involves a detailed examination of the components of a system to pinpoint where and how failures might happen, what their causes could be, and the potential effects on the overall system.
Why is it used? At its heart, FMEA is a proactive approach. Engineers systematically analyze failure modes and their potential effects on the system. A failure mode is a specific way in which a process or product might function incorrectly. A potential effect might be a hazardous condition. FMEA helps ensure that every potential point of failure is accounted for, thereby bolstering the integrity and robustness of designs.
How is FMEA performed? FMEA involves several steps, including assembling a team of experts, conducting the analysis, and defining plans of action. In this video, we will focus on the analysis itself.
The analysis is typically comprised of the following steps. Step 1, identify the system or component to analyze. Step 2, identify potential failure modes. For each component or process step, identify all the ways it could malfunction.
Step 3, determine failure causes. For each failure mode, identify the potential causes. For example, a failure mode may be due to a system anomaly such as a fault. It may also be due to design flaws, material weaknesses, process shortcomings, or external factors.
Step 4, evaluate the effects of failures. Assess the potential consequences of each failure mode. This involves understanding the impact on the system, the end user, and related systems or processes. In many cases, an FMEA will include other data points. A few common metrics are the failure mode's severity, occurrence, or probability, and detectability. You can multiply these metrics to create a risk priority number to prioritize failure modes.
Here is a simple example FMEA using an everyday mode of transportation, a bicycle. The system or component under analysis is the bicycle front brake system. The potential failure mode-- the brake cable snapping. Potential failure causes include wear and tear, corrosion, improper installation, material defect, and more. The potential effects of the failure could include the inability to slow down or stop, increased stopping distance, the loss of rider balance, and more.
How would we prioritize this failure mode? Let's quickly calculate a risk priority number, or RPN. This is simply the product of the failure mode's severity, occurrence rate, and detectability. We will use a scale from 1 to 10 for all three. Let's say the severity is a 7, the occurrence or probability is a 2, and the detection score is a 3. That gives us an RPN of 42, which is moderately high.
This is just a simple example of one failure mode and a handful of data points associated with it. Most FMEAs will include many more data points, often columns in a spreadsheet. FMEA is an iterative process which needs to be performed throughout a product's life. It is a living document which needs to be reviewed and updated regularly.
So what tools are used? Some teams use a spreadsheet tool, like Microsoft Excel. Others use a dedicated safety analysis tool. Some teams start with a whiteboard. What is important is that the set of tools and processes provide flexibility, while encouraging team-based creativity and appropriate automation to augment engineering expertise.
You can use the power of Matlab and Simulink to validate assumptions and automate steps in your FMEA. To learn how, check out our video "How to Perform an FMEA in Matlab." See the link in the description below.