Analytical Results in an FMRA

The analytical results in the FMRA may include reliability or probability of failure (which are available in both XFMEA/RCM++ and BlockSim), and criticality (which is available only in XFMEA/RCM++).

To perform analytical calculations, choose FMRA > Calculations > Calculate (Reliability).

In XFMEA/RCM++, if there are multiple systems (top-level items) or if the FMRA is synchronized with BlockSim, you will be prompted to specify a) which systems to calculate and/or b) whether to consider a more complex reliability-wise configuration that may have been modeled in the BlockSim diagrams. (See Calculation Options Window.)

In BlockSim, these calculations are available when you are using analytical FMRA diagrams. If there is only one system in the FMRA, this will calculate results for the entire FMRA. If there are multiple systems, you will be asked to choose whether you want to calculate the entire system hierarchy or just the currently selected system and its dependents.

Reliability and Probability of Failure

You can display the following FMRA columns in both XFMEA/RCM++ and BlockSim:

  • Analytical Results Status displays a green indicator light if the analytical results are based on the current inputs. It displays a red light if they are not.
  • Reliability (Analytical) displays the record's calculated reliability at the system's specified operating time. In XFMEA/RCM++, the reliability for each item will also be displayed in the Current Reliability field of the Properties tab when the item is selected. This value will be highlighted in red if it is below the specified target reliability.
  • Probability of Failure (Analytical) displays the record's probability of failure at the system's specified operating time. This is the complement of reliability (1-R).

Criticality Analysis

In XFMEA/RCM++ only, you can also display the following FMRA columns for quantitative criticality analysis:

  • Mode Ratio displays the probability that the item failure will be due to the failure mode under consideration.
  • Prob of Loss displays a factor from 0 to 1 that describes the probability that this failure mode would result in a system failure. By default, this is set to 1 (Actual Loss).
  • Criticality displays the calculated criticality value. This column must be displayed when the mode ratio or probability of loss is displayed.

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