What Is Mean Time to Repair (MTTR)? Definition, Calculation, Reduction Techniques, Benefits

MTTR, or mean time to repair, is the average time it takes for a system, machine or asset to be repaired due to a variety of failures, which can potentially include technical or mechanical faults.

The meaning of MTTR extends to the identification and diagnosis of the fault. It also includes the time it takes to repair and test. In short, it is only when the machine is fully functional once again that the MTTR metric can be considered to have run its duration. MTTR is usually associated with unplanned downtime, as this is when a machine is down due to the need for emergency repairs or corrective maintenance efforts.

In addition, MTTR is often closely associated with mean time between failure (MTBF) or mean time to failure.  Looking at the definition of mean time between failure, it becomes evident that MTTR and MTBF are not the same.  However, these two metrics are typically looked at in tandem with each other.

Often, mean time to repair is also used interchangeably with mean time to recovery or mean time to resolve. Whichever option your organisation uses, the ultimate aim is to reduce MTTR values, expressed in hours, keeping them as low as possible. Also worth noting is that the MTTR generally excludes any delays caused by waiting for spare parts to arrive or other external factors. Instead, it typically focuses on the actual time spent on repair activities.

The less time your technicians spend repairing faulty machines, the better your organisational performance and operations will be, without sacrificing downtime. Therefore, work towards reducing high MTTR incident metrics to ensure your incident management process is smooth.

MTTR Steps

When looking at MTTR—mean time to repair—we already noted that the process starts from fault diagnosis to repair work and includes testing before bringing the machine online again. Below, we discuss the four simple steps that are encompassed by the mean time to repair metric.

1. Problem detection: The clock starts ticking on the calculation of MTTR metrics when a problem is detected. This can be identified by a person within the organisation who notices a malfunction, a fault, a breakdown, etc., causing poor equipment performance. Once the problem has been detected, a work request is submitted and the maintenance manager will convert the work request into a work order, schedule it and then assign it to the right technician for corrective repairs.
2. Root cause diagnosis: The technician assigned to the repair job will carry out a root cause diagnosis. In short, this means that they will determine where the fault with the machine lies before carrying out repair work. The diagnosis is one of the most important aspects of determining the source of the fault in question because repairing something else can lead to wasted time, money and organisational resources. This is why it is so crucial to ensure accuracy in the diagnosis, where specialist technician skills play a key role.
3. Repair work: When the fault has been accurately diagnosed by the technician, they will start doing the repair work. In some cases, there may be a need for calibration, while in other cases, the technician will need to add new spare parts to the asset so that the broken or faulty part can be replaced.
4. System operability verification: The final step in the MTTR metric involves verifying system operability. In simple terms, this means testing the asset for proper functioning and ensuring that it is fully operational as part of the broader system of assets before the MTTR metric clock can stop running. In short, the quicker the repair and testing work done by the technician, the faster the organisation’s operations will be up and running again, restoring normal levels of production.

As part of the broader scope of maintenance KPI metrics, maintenance managers need to keep a close eye on mean time to repair and calculate MTTR with accuracy. If you are wondering, “How is a system-level mean time to repair calculated?” or, in other words, how to calculate MTTR, the mean time to repair formula appears below:

MTTR = Total time spent on repairs or total maintenance time / Number of repairs

Basically, to calculate mean time to repair, a maintenance manager would take the total time spent on repairs and divide this by the number of repairs to get the MTTR value, expressed in hours. We put this into practice with a brief mean time to repair example.

Say that several machines broke down and that the total time spent on the repairs of these machines was 8 hours. In addition, say that there were four machines in question. We would take the total maintenance or repair time spent (8 hours) and divide this by the number of repairs (4). This would give us an average value of 2 hours per repair job carried out.

Now that we’ve covered how to calculate mean time to repair and with a clear understanding that the average time taken to do repair work should be kept to a minimum, it’s essential to understand exactly how maintenance managers can achieve this objective. Below, we offer some tools and techniques that will help streamline your processes.

Standardising repair processes

As a starting point, maintenance managers should look to adopt a standardised set of procedures and protocols to streamline repair activities and minimise variability. This means that every repair job should begin and end in the same way. Namely, by identifying and reporting a fault, receiving a work request, converting it into a work order, scheduling and assigning it and monitoring how long it takes technicians to complete the repair and maintenance work on a given asset. The more standardised your protocols are, the more accurate your MTTR readings will be.

Enhancing troubleshooting procedures

We would also like to emphasise the importance of introducing systematic troubleshooting methodologies and training programmes to improve diagnostic accuracy and efficiency. By having your entire team of technicians on board with clear expectations about the procedures they need to follow, you will ensure that your organisational equipment operations are running smoothly and more accurately. You will also ensure that you’re able to diagnose problems and faults much faster, leading to greater efficiency.

Ensuring access to spare parts and inventory management

As we mentioned before, the mean time to repair calculation does not include external factors or time spent waiting for spare parts to arrive. In fact, some research points out that many technicians spend in the region of 10% to 25% of their repair time waiting for spare parts availability. For this reason, your spare parts inventory needs to be handled and managed in the most efficient way possible so that you can ensure quick access to them as and when needed. This optimisation of spare parts management, in turn, can help speed up repair work and minimise delays in repair activities.

Utilising predictive and preventative maintenance techniques

The role of predictive maintenance technologies in anticipating and preventing equipment failures should also be taken into account to reduce the MTTR rate. By following a proactive approach to maintenance activities, maintenance teams can take small preventative actions now to prevent bigger, system-wide equipment failures in the future. When these techniques are implemented and applied properly, it leads to reduced costly downtime and greater organisational efficiency.

Performing Root Cause Analysis (RCA)

Root cause analysis (RCA) methodologies can also be applied to identify and address the underlying causes of failures. This can ultimately lead to long-term improvements in system reliability and MTTR reduction. In essence, this involves looking at the symptoms of failure and tracing them back to where the problem initially began. Once symptoms showcase where the primary cause of the failure is, diagnostics can become more efficient, which then leads to faster repair work because the assigned technician would be working on the right problem instead of the wrong one.

Implementing a Computerised Maintenance Management System (CMMS)

In addition, it is highly encouraged that manufacturing organisations implement the right computerised maintenance management system (CMMS) to ensure that they’re able to take full advantage of an intelligent platform that streamlines their maintenance operations. Some of the key benefits of CMMS software or platforms are that they can help centralise maintenance data, track repair activities and facilitate proactive maintenance planning.

With the right CMMS platform at your fingertips, your maintenance team can track repairs in a unified maintenance management system. Through digitalisation, maintenance processes in a manufacturing plant can be streamlined, offering all types of reports and calculations immediately and automatically.

This means that whether you are looking at how to calculate idle time or perform a MTTR calculation, the CMMS automatically does this for you, saving you a lot of time and effort doing manual calculations on outdated and archaic paper-based systems.

Whether you are doing preventive maintenance or emergency repairs, using a CMMS system can introduce incredible efficiencies in your organisation and the assets and teams under your control.

To find out how Fabrico’s CMMS can help you achieve this, get in touch with us for your free demo today!

Measuring and tracking MTTR is crucial in maintenance management. MTTR is a significant CMMS key performance indicator (KPI) for assessing maintenance effectiveness and system reliability.

We encourage you to use a CMMS platform at your organisation to introduce greater efficiencies, help keep unnecessary costs down while facilitating a well-functioning asset base that works to your advantage.