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Hi, Gustavo
MTTR is a good KPI for Maintainability, showing how easy it is to maintain an asset or equipment. As you mentioned, skilled maintenance personnel will contribute to reduce the time spent during the actual maintenance, improving MTTR.
In terms of Reliability KPI's, some of the most common used are MTBF (Mean Time Between Failures), NPT (Non-productive time), JBI (Jobs Between Incidents) etc. The most suitable one will depend on your specifc application/activity.
Best regards,
Edson.

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Edson Amorim
Clamart
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo

Hello Gustavo,

MTTR is a KPI for asset maintainability because it does measure the average time needed to restore asset to its operational capabilities post failure.

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Ohuns Iboi
Halifax NS
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo

Hi Gustavo,

MTTR is certainly a lagging Reliability KPI, which indicates the efficiency of work planning and execution process. As we can see from the formula:
MTTR = Total repair or replacement time (hours)/Number of repairs or replacement events, the goal is to have as shorter MTTR (in hours) as possible. To achieve that goal you should address factors that directly impact MTTR such as:
- skills of resources (engineers, planners, technicians), improve the skills through training and on-the job coaching
- quality of work (adherence to repair procedures)
- Planning and scheduling of repair work (right materials and parts, tools, kitting etc.)
- Availability of materials, parts and tools for repair or replacement.

As for your goal as Rel. Engineer I agree that you have to work in avoiding failures, but is that enough? 


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Ardian Shala
T.A. Cook Consultants Inc.
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo

Gustavo,

I think that the definition of reliability is important here both for your argument and for your goal as reliability engineer. Reliability is "the probablity that an asset or item will perform its intended function for a specific period of time under stated conditions" (MIL-STD-721C).

Is MTTR a good KPI for reliability?
MTTR is simply the hours from starting a job to ending it and does not include other down time like the time before operations notices the failure, time between maintenance and startup, or delays due to other things like shift change. So MTTR is a lagging indicator for training, planning, and engineering as related to maintenance (@Ardian Shala explained this well in his reply). But none of this means MTTR does not contribute to reliability (technically availability I believe). MTTR is a part of MDT (mean downtime) and availability= uptime / (uptime + downtime). Broken down the formula becomes availability = MTBF / (MTBF + MTTR + other delays). This doesn't match what Gulati lists in M&R Best Practices because he says downtime = MTTR.

Should you, as a reliability engineer be focused on MTTR?
I think this one probably depends on your org structure and what responsibilities you may/may not have.​ If you are directly responsible for getting the equipment back online then of course you already care. If you are not a part of that effort, then you should still care because MTTR affects availability.

Hope this helps and that it's not too rambly.

Regards,
Noah

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Noah Wright
Duke Energy
Edwardsport IN
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo

In My opinion, MTTR is a good KPI to identify the maintainability of an equipment and its a design parameter; for reliability MTBF is an appropriate KPI that measure the mean time between failure.

Skill of maintenance craft and availability of right tools/materials/spares does play a role in reducing the MTTR; but, beyond a point its the inbuilt design that decides MTTR.

Thanks

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SUMIT KUMAR
SAIPEM
Mangaluru
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo

Gustavo,

As many of the other posts have suggested MTTR is a measure of maintainability not reliability.

I encourage you to use the SMRP Best Practice Metrics Compendium (available for free to SMRP members) to guide your KPI needs.  It is an extensive and thorough document with very clear definitions, calculations, examples, etc. and it offers other advice as well.

Paul Casto

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Paul Casto
Gray Matter Systems
Buchanan VA
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Original Message:
Sent: 02-09-2021 06:40 PM
From: Gustavo Soto
Subject: Does MTTR measures my reliability?

Sometimes I argue with my coworkers regarding MTTR as a kpi for reliability. I think that MTTR is a good kpi for maintenance guys skills, but not too sure if it is a good kpi for reliability. I think that if I design strong preventive maintenance I´ll avoid or minimize failures to occur. As far as I see, my goal as a Reliability Engineer is to avoid failures to occur and maintenance technicians is to solve as soon as possible when they occur (if they occur).

Any comment will be appreciated!

Regards

Gustavo