This step covers the Strategy Decision in the RCM Analysis guided workflow.
Step 3 addresses the first part of RCM question six of the seven RCM questions: What can be done to predict or prevent each failure? Specifically, it covers the maintenance strategy. The remaining elements of this question — maintenance tasks, MEI economics, and risk reduction — are addressed in subsequent steps.
The Strategy Decision Tree determines the appropriate maintenance strategy for each Failure Mode. To work through the tree, you need to know whether the Failure Mode is age-related and whether the failure is revealed. This typically requires input from a maintenance craftsperson and a reliability engineer. The possible outcomes are:
Condition-Based Maintenance
Time-Based Maintenance
No Scheduled Maintenance
The Strategy Decision Tree involves four primary questions, each with sub-questions:
Is it possible to define a clear potential failure condition? Sub-questions: What is that failure condition? What is the P-F interval, and is it reasonably consistent? Can the task be performed at intervals shorter than the P-F interval? Is the residual risk acceptable?
If yes: Determine a technically feasible on-condition task and enter the P-F interval value.
Note
Click the Interval button to change the PF interval frequency.
If no: Continue to the next question.
Is there an age at which the conditional probability of failure increases rapidly? Sub-questions: What is that age? Will a restoration or discard task restore original functionality? Is the residual risk acceptable?
If yes: Determine a technically feasible scheduled restoration or discard task and enter a Safe Lifetime value.
If no: Continue to the next question.
Is the loss of function caused by this Failure Mode on its own, hidden?
If yes: Is it possible to check whether the item has failed? Is it practical to perform the task at the required intervals? Does the task secure sufficient availability to reduce the probability of a multiple failure to a tolerable level?
If yes: Determine a scheduled failure finding task that is technically feasible.
If no: Continue to the next question.
If no: Continue to the next question.
Is the risk of failure acceptable?
If yes: Apply a No Scheduled Maintenance strategy (Run to Failure).
If no: Redesign may be required.
Together with the information held in Failure Effects, these answers drive the maintenance task selection in the next step.
Once you are done, click Maintenance Task to continue to the next guided step.
If the triggering questions are not needed and the strategy result is already known, you can bypass the decision tree by selecting Overwrite strategy result.
Instruction video
For a walkthrough of the guided steps, see RCM Analysis Guided Steps - Episode 7.