Failure Mode nodes exist on the second level of the tree, under the Failure Event node. Multiple Failure Mode nodes can be linked to the Failure Event node. The following image shows an example of how a Failure Mode node will look in the Logic Tree.
A given failure event can have multiple failure modes. For example, the image shows the failure modes from our Cooling Water Pump failure example. The Failure Event node (i.e., the overheated pump) is associated with the following Failure Mode nodes:
- No Spare Parts: There were no spare parts when the pump overheated, which caused the pump to be down for a longer amount of time and a greater loss of production. This failure mode did not cause the failure, so there are no hypotheses associated with it, but it is included as part of the failure event.
- Motor tripped due to high temperature: This failure was the cause of the overheated pump event. There are additional hypotheses associated with this node so that the cause of the event can be determined.