MTTR Calculation and MTTR Analysis Frequently Asked Questions (FAQ).
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Instant MTTR Report Frequently Asked Questions


Q: What is a "Instant Maintainability MTTR and Availability Prediction Report"?

 

A:  An "Instant Maintainability MTTR and Availability Prediction Report" is the Mean Time To Repair (MTTR) and Availability (Ai) of your equipment delivered instantly in a Maintainability and Availability Prediction Report. The report is prepared in accordance with Procedure V, Method A, of MIL-HDBK-472, Notice 1, "Maintainability Prediction"; and MIL-STD-470B, "Maintainability Program for Systems and Equipment", Task 203, "Maintainability Predictions". All you need to do is enter Average Corrective Maintenance Task Times for each replaceable assembly in your equipment.  It's that simple. We process your data, enter it into a Maintainability and Availability Prediction Report, and e-mail it to you within minutes.


The report you will receive is a complete Maintainability and Availability Prediction Report that includes a title page, table of contents, introduction and summary, resulting MTTR value, Maximum Corrective Maintenance Time (Mmaxct) value, Availability (Ai) value, mathematical models supporting these values, and a MIL-HDBK-472 and MIL-STD-470B methodology discussion. The Maintainability Prediction Report also contains an Appendix which presents the "Maintainability Analysis Worksheet" tabulations showing the Average Corrective Maintenance Task Times that support the MTTR and Availability calculations.

 

Q: How does one determine Average Corrective Maintenance Task Times (Repair Task Times)?

 

A: Have typical repairmen perform the indicated tasks while another records the task times using a stopwatch.  Typically, repairmen experienced in repairing the equipment can pull these times from their memory.  If feasible, refer to MIL-HDBK-472 Procedure V for default task times, as a guide.

 

Q: Why do you need to have a Reliability MTBF Prediction in order to perform a Maintainability MTTR Prediction?

A:  MTTR Prediction is a function of both sub-assembly failure rate and repair times.  See MTTR mathematical models in the examples section of our web page.

Q: What are definitions of the Corrective Maintenance Task Times?
 

A:

Localization:

Time associated with those tasks required to be performed before fault isolation can be executed.

 

Fault Isolation:

Time associated with those tasks required to isolate the fault to the level at which fault correction begins.

 

Disassembly:

Time associated with gaining access to the replaceable item or items identified during the fault isolation process.

 

Interchange:

Time associated with the removal and replacement of a faulty replaceable item or suspected faulty item.

 

Reassembly:

Time associated with closing up the equipment after interchange is performed.
 

 

Alignment:

Time associated with aligning the system or replaceable item after a fault has been corrected.

 

Checkout:

Time associated with the verification that a fault has been corrected and the system is operational.

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