MTTR: what is it and how to calculate the Mean Time To Repair metric

The MTTR (Mean Time To Repair) is the parameter that measures the average time it takes to repair a faulty system. Learn how to calculate it in this interesting guide.

The downtime of mechanical, technological or electronic equipment can have significant consequences within a company: from reduced productivity to increased costs, up to missed deadlines and delays in payments.

That’s why it’s important for an organization to quantify and track metrics related to system uptime and downtime, and how quickly and effectively maintenance teams solve problems.

In this article we will deal with Mean Time To Repair (MTTR), the parameter used to evaluate the average time needed to repair an asset, which, together with MTBF (Mean Time Between Failure) and MTTF (Mean Time To Failure), is one of the most used metrics in the maintenance sector.

To calculate and track all these parameters in the simplest and most effective way possible, rely on a facility management software, the system that allows you to monitor the operation and performance of your assets, and helps you document, manage and solve any problems related to maintenance.

What is the MTTR (Mean Time to Repair) metric

The Mean Time To Repair (MTTR) is an evaluation metric used as part of Facility Management to measure the maintainability of repairable systems. It’s used to assess the average time necessary to repair, troubleshoot, and restore the functionality of faulty equipment.

The MTTR parameter reflects the ability and speed with which an organization is able to respond to unforeseen events. This parameter, in fact, measures the period that elapses between the detection of a fault and the moment in which the system returns to being fully operational. For the calculation, the timing required for:

• diagnose problems;
• carry out repair activities;
• assemble, align and calibrate the asset;
• configure, test, and restart the system for production.

The MTTR does not take into account delivery times for spare parts, and is used to evaluate the efficiency of unscheduled maintenance activities, i.e., all those operations aimed at solving unforeseen problems.

Mean Time To Repair-Technicians at work

What MTTR means and how it is used

MTTR means the average time to repair a fault. This metric helps identify inefficiencies in asset management and maintenance processes, and is used by organizations and Facility Managers to

• understand the reasons why repairs take longer than expected;
• develop strategies to reduce unplanned downtime;
• make more informed decisions (relating, for example, to the convenience of repairing or replacing an obsolete asset);
• improve preventive maintenance programs to ensure that all activities are as effective and efficient as possible;
• inform the purchasing and design process, predicting the life cycle costs of the new systems;
• optimize MRO (Maintenance, Repair, and Operations) inventory management, which includes all the resources needed for asset maintenance and repair.

How to calculate MTTR

The Mean Time To Repair (MTTR) is calculated by dividing the total unplanned maintenance time spent on an asset in a given period by the total number of repairs performed in the same time interval, according to the following formula:

Although some repairs may take minutes or days to complete, depending on the severity of the failure, the Mean Time To Repair is typically measured in hours. If we consider, for example, a system that suffers 8 failures in the course of a year, and we take a total of 60 hours to perform the necessary repairs, the MTTR will be equal to:

According to a common rule of thumb, it is good that the Mean Time To Repair assumes a value of less than 5 hours. In fact, it is almost impossible to compare this parameter with a given value under different operating conditions due to the high number of variables. In fact, the calculation of the MTTR is influenced by several factors, including the type of resource analyzed, its age, critical issues, the training of the maintenance team, etc.

Mean Time To Repair vs. Mean Time to Recovery

MTTR may also refer to an additional parameter called Mean Time to Recovery, which is mainly used in digitized environments to determine the average time a computing device (such as a cloud system) will take to recover from a total or partial failure.

The Mean Time to Recovery is very similar to the Mean Time to Repair but differs from it because it is calculated from the exact moment in which the malfunction occurs and corresponds, consequently, to the overall period of interruption of the system.

Contrary to what we might think, the average time required to perform a repair does not always equal the asset’s downtime. In some cases, repairs begin immediately after the failure has occurred; other times, however, it takes time before starting to solve the problem (for example, to notify and mobilize the technicians), therefore, there may be an interval between the moment in which the failure occurs, the moment in which the problem is actually detected and the start of the actual repair operations.

Mean Time To Repair vs Mean Time to Recovery

How to Reduce MTTR and Improve Asset Productivity

The MTTR parameter measures the average time required for troubleshooting and repairing equipment, so the smaller its value, the higher a company’s ability to cope with unforeseen problems as quickly as possible.

Among the strategies that contribute to reducing the value of Mean Time To Repair we find, for example:

• the use of technology, in the form of wireless sensors and alarm systems that allow shortening the time needed to identify a fault;
• training and education of staff, to increase skills and increase the ability to understand and diagnose problems in the shortest possible time;
• the development of standardised procedures and action plans, which simplify the processes and define precisely the methods of intervention and the parties involved;
• using tracking systems, such as Computerized Maintenance Management System (CMMS)software, that help monitor repair progress and analyze asset performance in real time.

What is the role of a CMMS in monitoring and reducing MTTR?

Monitoring maintenance metrics requires a CMMS software to gather valuable information on the aspects that contribute to the calculation of metrics such as MTTR, MTBF and MTTF. These software play an essential role in the entire maintenance process of an asset and help in quick troubleshooting and reducing downtime.

Modern systems for the management and maintenance of resources offer, in fact, the possibility of:

• get continuous real-time data on asset performance;
• notify technicians when malfunctions or unforeseen events occur;
• improve communication between the parties involved;
• simplify the creation of work orders;
• automate the processes of management and resolution of problems;
• produce reports that show the results of the different operations;
• plan preventive maintenance actions.

The use of a CMMS system is therefore the optimal solution for all companies and professionals who want to improve efficiency and reduce response times to more or less complex problems that occur in the field of maintenance.

If you think it is too complicated or tiring to collect consistent and complete data for the MTTR calculation, rely on the potential of an Facility Management software, the only tool that provides you with up-to-date and reliable information on the operation of your assets, and allows you to have full control of any aspect related to maintenance.