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Defense Sustainment Chain Operational Readiness Evaluator (D-SCORE)

Last Updated : 11/13/2013

D-SCORE (Defense Sustainment Chain Operational Readiness Evaluator) quantifies the effect changes in logistics policies and procedures have on weapon system availability. It is a simulation tool used for evaluating system readiness and cost performance of alternative logistics processes and constraints. Simulates DoD’s entire sustainment value stream, from the operational level through intermediate-level maintenance to wholesale supply and depot maintenance

The D-SCORE model is a stochastic event simulation model written in the SIMSCRIPT simulation language that provides a capability to quantify the impact on weapon system availability due to changes in logistics policies and procedures. It models the entire logistics support system from the retail echelon to the wholesale echelon. We have used the model to process spare part data at two indenture levels; LRUs and SRUs, through three echelons; organizational-level maintenance, intermediate-level maintenance, and depot-level procurement, repair, and distribution. Its recent application was to evaluate competing COTS packages for Navy inventory optimization of spare parts to achieve required materiel readiness for weapon systems, often referred to as Readiness-based Sparing.

The simulation can monitor the availability of up to 20 different types of weapon systems at an unlimited number of retail locations with a variety of retail and wholesale business processes, practices, and policies. For example, D-SCORE can assess the availability implications of alternative policies for lateral resupply, job routing spare parts at a depot, alternative distribution policies, alternative repair scheduling policies, cannibalization, and readiness-based sparing.

Input data consists of more than 100 different types of inputs. Depending on the size of the scenario to be simulated, thousands of input parameters can be used. The following major types of inputs are included: Transportation times, weapon system characteristics, retail and wholesale characteristics, individual item characteristics and some user-specified options.

Transportation times include standard shipments and priority shipments that consider flow times between supply and maintenance organizations at retail locations, order and ship times (OSTs) from wholesale to retail echelons, retrograde times, and lateral resupply times.

Characteristics of each weapon system (as many as 20 can be simulated) include operating hours per month, major LRUs used by the weapon system, and number of each LRU needed to be serviceable for the weapon system to be operational. Complete indenture structure for each LRU that provides up to four levels of indenture, although we have only used the top 2 levels (LRUs and SRUs) in our studies.

Characteristics of each retail location include the number of organizational units, number of weapon systems by type in each unit, availability requirements of each unit in peacetime and wartime, and level of repair capability.

Characteristics of each spare part include failure rate per operating hour, percentage repaired at each echelon, replacement percentages for each subcomponent at each echelon for failed components being repaired, name of depot and regional repair shop for reparable components, repair time, repair shop capacities, and use of batch processing.

User-provided options include developing priorities for distributing spare parts, establishing retrograde priorities, setting criteria for lateral resupply, setting spares levels at all echelons, and specifying depot repair budgets for weapon systems at several sources of supply and sources of repair.

Other information
The primary output is the weapon system availability. The simulation monitors the number of weapon systems that are non-operational each day and calculates the percentage of total weapon systems available. Other results include the type (standard or expedited) and number of shipments between retail and wholesale echelons and lateral shipments between retail locations. D-SCORE also shows the results for many secondary parameters, such as the number of repair actions at retail and wholesale echelons, and many secondary supply indicators, such as supply availability, carcass availability, repair shop utilization, and number of reparable spare parts awaiting parts (AWP) at the depot.

Many current analytic models cannot accurately reflect the many constraints of the logistics support system and have no capability to evaluate, in terms of weapon system readiness, the benefits of logistics process improvements, especially readiness based sparing. This tool enables the logistics community to adopt a "fly before buy" approach for logistics information systems and processes.

D-SCORE has been used to evaluate options for:

  • setting retail and wholesale supply levels
  • scheduling repair of reparables at the depot
  • conducting lateral supply
  • setting priorities for distribution when spares are in short supply at the wholesale level

According to LMI, the DoD functional classifications supported include:

  • Program Management
  • Logistics Management
  • Supply Chain Management
  • Engineering Management

D-SCORE was developed for Air Force management of logistics process simulation. It has been tailored for the Navy and can be tailored to meet the needs of other organizations.

Processes Supported

Departments Associated

  • Navy / Marine Corps
  • Air Force

Integrated Product Support Elements Addressed

For more information

Organization: Logistics Management Institute (LMI)
2000 Corporate Ridge 
McLean, VA 22102

Webpage: http://www.lmi.org/ 



This product support analytical tool was identified as part of a database provided solely to assist defense acquisition workforce professionals to identify best value product support solutions which optimize system readiness and life cycle cost. Neither the Department of Defense or the Defense Acquisition University provide any warranty of these tools whatsoever, whether express, implied, or statutory, including, but not limited to, any warranty of merchantability or fitness for a particular purpose or any warranty that the contents of the item will be error-free. This analytical tools database should under no circumstances be considered as being all-encompassing, and is in no-wise meant to endorse the capabilities or products of any particular individual, company, or organization.


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