Mean Time to Repair (MTTR)

Mean Time to Repair (MTTR) is an important maintenance measure that helps engineers and managers compare asset performance across time and category.

Mean time to Repair (MTTR)

Mean time to Repair refers to the average time it takes to repair a system. This could be a technical or mechanical issue that is resolved. MTTR includes both the planning, repair and testing time to give a full scope of how long the equipment is out of commission for. 

How to calculate Mean Time to Repair (MTTR)

MTTR is calculated by summing all time spent on repairs and dividing it by the number of repairs completed. This can be done across different time periods and asset classes to help managers identify the problematic maintenance operations areas. 

MTTR = All time Spent on Repairs / Total Number of Repairs Completed

Limitations of Mean Time to Repair (MTTR)

Relying on an overall MTTR can present an unbalanced view of maintenance operations. For example, if there are 18 system outages in a week that take 30 hours of labor, you would have an overall MTTR of 1 hour and 40 minutes. However, if 5 out of the 18 system outages were for a more complex system, say HVAC, which took a total of 20 hours of labor, then the MTTR will be skewed by these events. In this example, the HVAC MTTR would be 4 hours, while the remaining outages would have an MTTR of around 45 minutes.

It is important for managers to correctly separate their assets and time periods so that the metrics present an accurate picture of the organization. From there, the manager will hav the ability to make accurate decisions.