Failure Mode and Effects Analysis (FMEA): Examples

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When to use it | How to understand it | Example | How to use it | Practical variations

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Example

A developer of a wordprocessor package received a number of complaints from its customer base about some specific features. On further investigation, it found that there were a limited number of effects that particularly annoyed customers. Working with their customers, they allocated severity ratings to these, as in the table below.

An FMEA table was used to record the results of failures found in user trace logs. Only modes that resulted in the target effects were recorded. Criticality calculations were weighted with the severity ratings to take account of the customer priorities. A part of one table is shown in the illustration.

The analysis found that the mode with the highest weighted criticality score was when the disk became full. Further investigation found the actual cause was an uncurbed temporary file. The simple measure of putting limitations on the size of this file significantly reduced the defect rate.

Fig. 1. FMEA table

Other examples

• A new toaster design team uses FMEA to identify flaws in the design. This highlights ways in which the handle can stick and cause the toast to catch fire. This is prevented by adding a specific thermostatic safety release to the design.
• A boilermaker improvement team use FMEA to identify the failure modes that have caused certain pressure vessels to split. The result is the design of an effective and lasting solution.
• A secretary uses FMEA to highlight the possible undesirable effects of a room booking system not working properly, and consequently includes checks to reduce the chance of key effects of overbooking and key staff not being able to find rooms.

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