Add to Mirror Group Window (FMRA)

By adding multiple cause records to a mirror group, you can place the same cause in more than one location in the FMRA hierarchy. This is useful when you need to consider common cause failures (i.e., single faults that result in the failure of multiple components) in your analysis. Typical examples of common cause failures include impact, vibration, temperature, contaminants, miscalibration, improper maintenance, and so forth.

Adding Causes to Mirror Groups

In the FMRA, mirroring is accomplished by adding causes to a mirror group via the Mirror Group window. To add a cause to a mirror group, select it in the FMRA and choose FMRA > Mirror Groups > Mirrors > Add Cause to Mirror Group.

To create a new mirror group for the cause, select Add to new in the Options area and enter a name for the group.
To add a cause to an existing group, select Add to existing in the Options area and then click the group in the Select Mirror Group area.

All cause records in a mirror group (i.e., "mirrored causes") are treated as representing the very same cause. To accommodate this, the use of mirror groups will change the properties of cause records in the following ways:

When a cause is added to a mirror group that already includes other causes, its properties (e.g., the short description, reliability policy, etc.) will be changed to match the other causes in the group.
If you change the properties of a mirrored cause, that change will also be applied to all other causes in the same mirror group.
If a cause is added to an empty mirror group (i.e., one that includes no other causes), the cause's properties will not change. However, the properties of causes you add later may be changed.

Removing Causes from Mirror Groups

To remove a cause from a mirror group, select it and choose FMRA > Mirror Groups > Mirrors > Remove Cause from Mirror Group.

To remove all causes from all mirror groups, choose FMRA > Mirror Groups > Mirrors > Clear All Mirror Groups.