Understanding FMEA Detection Risk:
Problems and Solutions
Can you find this common error in detection ranking in the intermediate problem in this article? In the advanced problem, the topic of an in-service detection scale will challenge the most experienced readers.
If you haven’t already read the article Understanding FMEA Detection Risk – Part 1, this may be a good time to read about the underlying fundamentals of assessing detection risk in FMEAs.
You are doing a Design FMEA and it is time to identify the detection ranking for a given failure mode/cause. One of your team members asks you to clarify the definition of detection. Identify which of the following are correct or incorrect responses to this question?
1. Detection ranking considers the likelihood that the current detection-type design controls will detect the failure mode/cause.
2. Detection ranking is associated with prevention-type design controls.
3. Detection is the likelihood that the effect of the failure mode will manifest sometime during the product life cycle.
4. Detection ranking is associated with detection-type design controls.
1. Detection ranking considers the likelihood that the current detection-type design controls will detect the failure mode/cause. Correct
2. Detection ranking is associated with prevention-type design controls. Incorrect.
3. Detection is the likelihood that the effect of the failure mode will manifest sometime during the product life cycle. Incorrect.
4. Detection ranking is associated with detection-type design controls. Correct
You are doing a Design FMEA on the hand brake subsystem of an all-terrain bicycle. Review the following excerpt from this FMEA and determine the error in detection ranking.
The team has assigned a detection ranking of “2” for the cause “cable binds due to inadequate lubrication.” Remember, the definition of detection is “a ranking number associated with the best control from the list of detection-type controls, based on the criteria from the detection scale.” Since there is no detection-type control for this cause, the detection risk would be very high.
Company X is developing a next generation sub-sea drilling system. Although it is important to detect failure modes and their causes before the new system goes into operation, it is even more important that failures be detected once the system is operating, so that mitigating action can be taken to avoid a potential catastrophe. How can a detection scale be configured to assess detection risk during operation?
In-service detection techniques can be designed-in to system operations. An example is a warning system in a nuclear power plant in which sensors detect an emerging problem, alerting personnel who can then prevent the problem or avert it before an accident or serious consequence occurs.
It is possible to define criteria for the detection scale that assesses the likelihood of the monitoring-type control to detect the problem during system operation. The nature of the application should determine the specific criteria of this unique detection scale.
Figure 2 is an example of an in-service detection scale. This scale can be configured to the unique circumstances of the operations being assessed.
What if a production worker uses a different cleaning method for an assembly operation than was outlined in the operation work instructions, and the result is customer complaints and field issues. How could this be addressed in a Process FMEA? This question is discussed and answered in the next FMEA Q and A article.
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