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The 10% Rule of Preventive Maintenance

Many organizations use the PM compliance metric as a measurement of their maintenance department’s performance. This metric is often viewed by professionals as a joke because if your PM compliance is high but you continue to have many reliability issues, then the metric has no meaning. There have been organizations with one hundred percent PM compliance, but over ten percent downtime due to reliability issues. Of course, many different issues could contribute to this problem.

  • 30-day PM - Must be completed within three days or PM is “Out of Compliance”
  • “Out of Compliance” means more equipment failures and higher maintenance costs because of variation in execution

Figure 2.1: A simple rule: you cannot perform preventive maintenance that continues to break down; something is wrong.

However, there is a solution to the PM compliance metric to make it believable and truly help you feel confident that it is a true measurement of compliance to your PM program. This solution, which has been tested and proven, requires you to manage your PM program as a controlled experiment. By doing so, you can control reliability with more reliable accuracy.

Now, in order to have a controlled experiment, you must control the variables, such as time. Most PMs are time based, therefore, controlling the variance in your PM schedule would allow you to control reliability better and help you make better decisions.

The 10% rule of preventive maintenance simply states that:

A time-based PM must be accomplished in ten percent of the time frequency or it is out of compliance.

Figure 2.2: This figure illustrates how many organizations perform a monthly (30-day) preventive maintenance strategy applied to a specific component.

Tip from Preventive Maintenance Made Simple by Doug Stangier and Ricky Smith