Building a Fault Tree from a FMEA
When both the FTA and FMEA modules are in use, you can build a fault tree from a FMEA after you have calculated FMEA results. The Build Fault Tree from FMEA command is available when a FMEA or FTA pane is active if both modules are in use. Building the tree inserts a new top gate and the OR gates and basic events that represent the failure modes in the FMEA.
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If you want to build a Lambda Tau fault from the FMEA, Lambda Tau must be selected as the FTA calculation type in the System file properties prior to performing the following procedure. For Lambda Tau trees, all events generated from the FMEA have Lambda Tau selected as the model. If an event is linked to a repairable item, MTTR is stored as the τ parameter. If an event is linked to a non-repairable item, mission time is stored as the τ parameter.
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1. Depending on the module in use, select either > or > . The Build Fault Tree from FMEA window opens.
2. Complete this window. For more information, see Build Fault Tree from FMEA Window.
3. When finished, click OK to build the tree.
If no records have the specified end effect, a window opens, indicating this. Once you click OK, you can repeat this procedure, selecting a different end effect.
If records do have the specified effect, a window opens, indicating that it is adding gates and events to a new tree.
Once the tree is built, the data link to the FMEA is removed. From this point forward, changes made to the tree do not affect the FMEA. Similarly, changes made to the FMEA do not affect the tree.
In the newly created tree, the description for the top gate is automatically populated with the system tree identifier followed by a dash and the end effect. This allows you to easily identify the System file and end effect from which the tree was created.