The Mean Time to Repair (MTTR), also known as the Mean Corrective Maintenance Time, is a measurement on the maintainability of equipment and repairable parts. It represents the average time needed to repair a failure until the equipment returns to a fully functional state.

 

A higher Mean Time to Repair may indicate that the replacement of a given asset is cheaper or preferable to repairing it. It may also suggest that you should store more spare parts for the equipment in question. Knowing how to reduce the MTTR is essential to avoid or minimise inactivity and the harm this may cause to your business.

 

How do you calculate the MTTR?

It can be mathematically expressed by the division of the total corrective maintenance time during a given period by the number of corrective maintenance actions performed. This can be seen by the following formula:

MTTR formula

It is worth noting that the total corrective maintenance time (and therefore, the Mean Time to Repair) can range from the discovery of the failure to the actual moment the reparation works start (this includes the time spent in identification, notification, acknowledgment and diagnostic of the failure). When it incorporates all of these other steps, it can also be referred to as Mean Time to Recovery. For this reason, an explicit definition of the MTTR in maintenance contracts is important so as to avoid confusion.

 

The lead time for parts that are not readily available or other Administrative or Logistic Downtime (ALDT) is not included in the calculation.

 

How can you reduce the MTTR

To reduce MTTR, you will have to evaluate and try to reduce both variables in the formula. Although, mathematically, reducing the number or repairs won’t reduce the MTTR in on itself (if the total corrective maintenance time stays the same), in reality, reducing the total number of repair will always result in a reduction of the maintenance time as well.

 

Reducing the total corrective maintenance time

The total maintenance time starts from the minute the malfunction is detected and only ends once it is resolved. This brings us onto our first big problem: too much time is spent between the malfunction being discovered and it being reported to a competent technician. If this is the case, implementing a more efficient facility management system could be the solution. If the technician cannot be physically present at the company, look for a partner that can provide remote assistance. You should also consider preparing your employees to do quick checks.



Equally, an excessively high repair time may be a warning sign that certain pieces of equipment should be replaced. If we combine the cost of repairing and losses/loss of productivity incurred during downtime, it’s very likely that replacing equipment will be more economical.

 

Reducing the number of repair actions

Once again, the secret may lie within your team. If an operator notices that a particular machine or equipment is under-performing, a service technician should be called immediately. Acting quickly can avert a total malfunctioning of the asset and could prevent a complete shutdown of production. In the case of an emergency, the technical operations manager should be available to give a prompt response and to review the protocol with the team.


Almost all equipment requires periodic revisions (learn everything you need to know about preventive maintenance in our ultimate guide). In the case of heavy-duty machines, actually replacing some mechanical components regularly (often annually) is highly recommended. What you may not know yet is that you can automate these notifications, ensure that all maintenance is up to date and therefore reduce the number of repair actions using a good CMMS.



In short, reducing the MTTR involves three factors — accelerating malfunction reporting, centralising and organising information and investing in equipment maintenance. Review these three items successfully and we’re pretty sure you’ll be able to reduce your company’s mean time to repair in time for 2019.

 

For an indicator of your equipment availability, learn more about the Mean Time Between Failures, or MTBF.