RPN results are calculated for every failure mode in the FMEA Worksheet table. For these calculations to make sense, Severity, Occurrence, and Detection must each be at a FMEA data level above or equal to the level of the RPN. If any of the three fields for calculation results (RPN, RPN Results, and RPN Improvement Percentage) are not defined in the Project’s FMEA Design file, then they are assumed to be at the item level. For more information, see FMEA Design Files,

Examples follow to show how the data structure affects RPN calculations. In these examples, data levels are noted in parentheses in the table header.

The FMEA data structure is item>mode. This is a valid case because all three input fields are at the same level as the RPN (mode).

The FMEA data structure is item>mode. This is a valid case because all three input fields are at either the same level as the RPN (mode) or a higher level than the RPN (item).

The FMEA data structure is item>mode>cause. This is a valid case because all three input fields are at either the same level as the RPN (cause) or at a higher level than the RPN (mode or item).

The FMEA data structure is item>mode>cause. This is an invalid case because an input field (Detection) is at a lower level (cause) than the level for the RPN (mode). You should not have inputs at a level lower than the level for the RPN. In this case, the last cause for each mode value wins.

The FMEA data structure is item>mode>cause>effect. This is a bad case because two input fields (Occurrence and Detection) are at lower levels (cause and effect) than the level for the RPN (mode). You should not have inputs at levels lower than the level for the RPN. In this case, the cause and effect for the last mode wins. If the row containing the last effect has no cause, then its Occurrence value is assumed to be 0. If the row that contains the last cause has no effect, then its Detection value is assumed to be 0.