What is Preventive Maintenance Optimization (PMO)?

You may be aware of a process called Preventive Maintenance Optimization or PMO AND and you may have heard it said that "PMO delivers the same results as RCM - only faster."


Well, that just isn't true and you'll learn why in this Advanced Concept.

PMO Process (1)

What is Preventive Maintenance Optimization (PMO)?

PMO is a process that is used to "optimize" a current maintenance schedule and/or manufacturer scheduled maintenance recommendations.  PMO includes only four of RCM's seven steps.

  • Identify the Failure Mode that the task is intended to manage (Step 3 of the RCM process)
  • Write the Failure Effect (Step 4 of the RCM process)
  • Determine the Consequences of Failure (Step 5 of the RCM process)
  • Decide if an On-Condition or Preventive Maintenance task is appropriate.  If so, what is the appropriate interval? (Step 6 of the RCM process)


When PMO is done, each maintenance task is "reverse-engineered" by applying the four RCM steps stated above.


BUT...it's very important to note that PMO is ONLY APPLIED to existing maintenance tasks and/or manufacturer recommendations.


So...when you apply PMO, you ONLY analyze those Failure Modes associated with the maintenance tasks that are being reverse-engineered.


Doing so allows you to determine the following for each current maintenance task:

  • Is the task technically appropriate?  Can it be eliminated?
  • If the task is technically appropriate, is the task frequency correct?
  • Should a different maintenance task be performed instead?

What is the significance of ONLY analyzing Failure Modes associated with current maintenance tasks?

Recall that when we do RCM, we include Failure Modes that:

  • Have happened before
  • Have not happened, but are real possibilities
  • Are unlikely to occur but have severe consequences
  • Are associated with current maintenance tasks.


So, when PMO is performed, a significant number of Failure Modes are NOT analyzed.


PMO Failure Mode Comparison

Is it okay NOT to analyze all Failure Modes?

You may hear some people say that PMO "meets the 80/20 rule."  That is, that 80% of failures come from 20% of the causes.


Even if that's true (but as responsible custodians, we really can't assume that for every situation), if you employ PMO (versus RCM) you'll never know what the Failure Effects and Consequences are of the "20%" of Failure Modes that you don't analyze...


If an organization is okay with taking that risk, and it's comfortable with the current level of risk and availability (for example) they are currently experiencing, then PMO may be an option. 


Remember, our Maintenance and Reliability goals should drive the programs and processes we put in place.


If an organization is experiencing (for example), chronic downtime, chronic unreliability, and increasing costs, then doing PMO is unlikely to uncover the problem BECAUSE not all Failure Modes are being analyzed.  In that case, PMO probably isn't the right choice.

With respect to results, what do you get with RCM that you don't get with PMO?

Because you analyze all Failure Modes that meet the four criteria set forth earlier, when you do RCM, you:

  • Formulate a robust Proactive Maintenance Program
  • Have the opportunity to identify any applicable Default Strategies including:  Operating Procedures, Equipment Redesigns, Technical Publication updates, Training Recommendations, Supply changes, etc.
  • Analyze Protective Devices


With PMO, you ONLY analyze your current maintenance tasks.  So your product is just an optimization of your current maintenance tasks.


The bottom line is this:  PMO does not achieve the same results as RCM.  Your Maintenance and Reliability goals should dictate how robust a process you apply.