Page 47 - RCM - A practical Guide_V1

RCM - A Practical Guide

Failure rate
Is the Functional Failure rate high?
This question is intended to identify functions that fail infrequently. If the answer is no it is a possibility
that the failure is being prevented by a scheduled task, therefore, a no answer directs the analysis to
consider the cost of this task before rejecting the modification.
Operational consequences
Does the failure involve major operational consequences?
A No answer here directs the Analyst to the same question about the cost of maintenance that the
previous question identified.
Cost of maintenance
Is the cost of scheduled and/or corrective maintenance high?
This question can be reached via one of the two questions identified above. With a No answer to the
question of high Failure Rate maintenance may be preventing Functional Failure but at great cost.
Failure may not affect operational consequences but the cost of repair may be excessively high.
Specific costs
Are there any specific costs which might be eliminated by modification?

This question relates to the cost of lost operational capability, due to poor design and the costs of
maintenance activities. If the problem can be narrowed down to a specific element then the cost
effectiveness of the modification will be high.
Probability of success
Is there a high probability that, with existing technology, the modification will be successful?
It is possible that although a modification may be very desirable it may well not be feasible. At this
stage if engineering judgement indicates that the probability of success is low, the proposed
modification is unlikely to be worthwhile. Care must be taken that in rectifying one problem by
modification, another is not created.
Cost effectiveness
Is the modification cost effective?
The cost effectiveness of the proposed modification will compare the expected reduction in costs
during the remaining life of the equipment with the overall cost of embodying the modification.
Considerations:
If the analysis is calling for a redesign action, whether mandatory or otherwise, it really should offer a
suggestion as to the solution.
Some examples of considerations:
Could we reduce the probability of failure by changing the asset in question by removing or changing
the failure mode by:
• modifying it?

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