Mean Downtime (MDT) [Suggest Change]

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Primary Functional Area : Life Cycle Logistics

Definition [Suggest Change]

Mean Downtime (MDT) is the average Total Downtime required to restore an asset to its full operational capabilities. MDT includes the time from reporting of an asset being down to the asset being given back to operations / production to operate. MDT includes administrative time of reporting, logistics and materials procurement and lock-out/tag-out of equipment, etc., for repair or preventive maintenance.

Source: http://www.acq.osd.mil/log/mr/mean_down_time.html

General Information/Narrative [Suggest Change]

The principal importance of Mean Downtime (MDT) as a life cycle sustainment metric lies in its relationship to the Operational Availability (A_O) formula. Operational Availability is one of the two components of the Availability Key Performance Parameter (KPP) defined in Appendix E, Enclosure B of the Joint Capabilities Integration and Development System (JCIDS) Manual.  Operational Availability is defined as Uptime divided by Uptime plus Downtime.
The Defense Acquisition Guidebook, Chapter 5.1.1.2 defines mean downtime as the average time an end item is unavailable to perform its assigned mission after it experiences unscheduled or scheduled maintenance actions. It includes all time where the system is not at the disposal of the Force Provider to initiate missions. In addition to the projected supply chain approach with its resultant logistics footprint, the impact of surge/deployment acceleration requirements should be determined for this and the Materiel Availability metric.
The JCIDS Manual further identifies "Reliability" as a mandatory Key System Attribute (KSA). If Reliability constitutes the "Uptime" part of the formula, Mean Downtime constitutes the "Downtime." While not a formal KPP or KSA, its importance in determining Operational Availability is paramount.

As with most other high-level sustainment metrics, Mean Downtime is generally broken down into lower order metrics. In this case, it is most often expressed as Mean Preventive Maintenance Time (or M_pt) plus Mean Corrective Maintenance Time (or Mct or M_ct ) plus Mean Logistics Delay Time (MLDT).
Examining these components of Mean Downtime, it should be noted that both M_pt and Mct are essentially characteristics of system design. In other words, the design of the system will determine how much preventive maintenance is required and how long it will take.  Similarly, system design will determine how much corrective maintenance is required (determined by the inherent Reliability of the system) and how long it will take. On the other hand, MLDT is a function of process, a process that is the result of product support planning.  MLDT is determined by such factors as adequacy and positioning of spare parts, transportation, operational issues—and many more.  For this reason, the Mean Downtime metric is seldom part of a performance-based life cycle product support—or PBL—arrangement, since it would be highly unusual for one entity to control all aspects of Mean Downtime.

As with many other metrics, particularly those used in a performance-based product support—or PBL—environment, care must be taken to appropriately define the parameters of the lower-order Mean Downtime metrics and achieve a common understanding of that definition among the various stakeholders.  As the Product Support Manager Guidebook says:

"Note that these metrics must be mathematically and qualitatively described before they are useful. Additionally, they should be:

• Linked to system level required sustainment metrics objectives
• Appropriate to scope and responsibility
• Specify unit of measure
• Specify acceptable range or threshold
• Motivate desired long-term behavior
• Understood and accepted
• Easy to collect data and verify
• Can be readily assessed
• Provide timely feedback"

Defense Acquisition Guidebook, Policies, Directives, Regulations, Laws [Suggest Change]

Policies:

• https://dap.dau.mil/policy/Documents/2015/CJCSI_3170_01I.pdf
• https://dap.dau.mil/policy/Documents/2015/JCIDS_Manual_-_Release_version_20150212.pdf
• OPNAVINST 3000.12a, "Operational Availability Handbook"
• http://www.acq.osd.mil/log/mr/mean_down_time.html
• Undersecretary of Defense (Acquisition, Technology and Logistics) "Implementing a Life Cycle Management Framework" of 31 July 2008
• Deputy Undersecretary of Defense (Logistics & Materiel Readiness) and the Director, Acquisition Resources and Analysis "Implementation of Life Cycle Sustainment Outcome Metrics Data Reporting" of 11 December 2008

Guidebooks:

• Defense Acquisition Guidebook, Chapter 5
• DoD Product Support Manager (PSM) Guidebook
• DoD Performance Based Logistics (PBL) Guidebook
• DoD RAM-C Manual
• DoD RAM and Cost Rationale Report Manual
• DoD Guide for Achieving Reliability, Availability, and Maintainability

Best Practices, Lessons Learned, Stories, Guides, Handbooks, Templates, Examples, Tools [Suggest Change]

Training Resources [Suggest Change]

• CLL 001 Life Cycle Management & Sustainment Metrics
• LOG 101: Acquisition Logistics Fundamentals
• LOG 200: Product Support Strategy Development, Part A
• LOG 201: Product Support Strategy Development, Part B

Communities [Suggest Change]

Life Cycle Logistics

Program Management

Reliability, Availability & Maintainability

Systems Engineering

Related Articles [Suggest Change]

Key Performance Parameters (KPPs)

Life Cycle Sustainment Outcome Metrics

Maintenance Levels

Readiness-Based Sparing (RBS)

Reliability Key System Attribute (KSA)

Sustainment Key Performance Parameter (KPP)

Integrated Product Support (IPS) Element - Support Equipment

Integrated Product Support (IPS) Element - Supply Support

Integrated Product Support (IPS) Element - Product Support Management

Attachments [Suggest Change]

Page Information Page Views 3,367 Created on 10/10/2012 Modified on 5/11/2016 Last Reviewed 5/11/2016