What is the highest score assigned for a failure mode that is impossible to detect in FMECA?

In Failure Mode, Effects, and Criticality Analysis (FMECA), each failure mode is assessed based on its detectability, severity, and occurrence. The highest score typically indicates a failure mode that is undetectable, meaning that it has a significant risk of going unnoticed until it results in a failure.

When a failure mode is deemed impossible to detect, it essentially reflects an extremely high level of risk because there are no means to identify the issue before it leads to a failure. Accordingly, in the scoring system used in FMECA, the most severe situation—where detection is not possible—corresponds to the highest score assigned, which is a 10. This score emphasizes the critical nature of such undetectable failure modes, as they can lead to significant consequences if they occur without warning.

The lower scores represent varying degrees of detectability, severity, or occurrence. Therefore, the highest score is reserved for failure modes that present the most severe risk regarding detection, which aligns with the score of 10 reflecting an impossibility of detection in FMECA.