Closed-loop, Simulation-based, Systems Engineering Approach to Life Cycle Management of Defense Systems

Assessing the life-cycle impacts of operations and maintenance decisions made for new or aging systems requires an accurate ability to measure and respond to uncertainty. Maintenance and parts requirements forecasts for fielded military systems are traditionally performed through historical repair and supply demand models. These models work well once several years of steady state weapon system operation has been accomplished, but tend to depend on a stable and somewhat regular operations and support structure. Predictions based on data that capture the cyclic trends that tend to occur as the fleet endures standard operations, scheduled maintenance, and average component failure rates work best when components are relatively new. Aging systems comprised of component populations of varying ages can be adversely affected by change or the failure to change the traditional maintenance and support concepts. The right action for a new system may result in adverse impacts when considering older systems. Further Explanation A Closed-Loop, Simulation-Based, Systems Engineering approach to Life Cycle Analysis (LCA) provides a method for integrating the time dependent relationships of a systems reliability and operations to the maintenance, and supply support structure that must sustain it. Actions taken over time in any of these categories will somehow affect and impact the throughput and response time of the others. Simulation-based analysis offers the flexibility and expandability to model complex systems and their operations, maintenance and supply environments. Clockwork Solutions is currently applying simulation based methods to develop LCA tools in order to aid the Department of Defense in its management of aging weapons systems. These tools are being used by the US Army, for example, to quantify time-dependent, life-cycle costs and impacts resulting from proposed aircraft and engine sustainment decisions, specifically, recapitalisation maintenance concepts. It provides a capability to assess decisions for the fleet prior to their implementation, enabling the US Army to achieve the best financial and readiness life cycle returns on their upgrade, acquisition and sustainment program investments. Life Cycle Management (LCM) and LCA are a set of tools and techniques which are utilized by defense decision makers to base programmatic decisions on the anticipated mission-related and economic benefits derived over the life of a weapon system. This paper presents three alternate approaches to LCM and LCA, distinguished by both the granularity and the frequency of feedback between the elements being modeled. The merits and pitfalls of the different approaches are discussed and several examples of applying the approaches to defense LCM are presented, concluding with a case study of a project applying closed-loop simulation to answer key Life Cycle Management questions. 1 LIFE CYCLE MANAGEMENT AND LIFE CYCLE ANALYSIS CONCEPTS 1.1 Life Cycle Management and Life Cycle Analysis Defined Life Cycle Management (LCM) is a management technique which bases programmatic decisions on the anticipated mission-related and economic benefits derived over the life of a weapon system. Knowing a system’s life cycle characteristics and future behavior in advance enables decision makers to assess the cost-effectiveness of utilization, logistic support and engineering improvements scenarios before they are implemented. Life Cycle Analysis (LCA) is a formal process for establishing a quantitative basis in support of LCM decisions. LCA consists of: (i) building a Connors, Gauldin, and Smith model representation of a real world system or process, (ii) obtaining data to populate or instantiate the model, (iii) using the populated model to predict future behavior – e.g. performance and costs – for a range of defined system design or use scenarios, (iv) validating the model predictions, and (v) presenting the analysis results to decision makers. 1.2 LCA Applications to LCM LCA can be used to support a range of LCM decisions during all stages of a system life. LCA provides program managers, item managers, and executive staff with rigorous quantitative support for strategic, tactical, and operational level decisions that previously had to be made based on crude approximations and intuition. During acquisition LCA is used in support of investment decisions, including: identification of potential performance and cost weaknesses; assessment of alternative design options; and, evaluation of the cost and impact on system performance of alternative maintenance concepts. During deployment LCA is used in support of change management, including: assessment of the effects of proposed engineering improvements on system performance and cost; changes in maintenance procedures and capacity; changes in supply practices to reflect component and system aging; and, determination of spare pool implications for technology refresh. Finally, as an asset approaches its end of life LCA is used in support of transition management, including: support investment allocation among the systems to be retired and their replacements; projected remaining life of end-of-life extensions; and, assessment of required support resources. 2 A SYSTEMS PERSPECTIVE ON LIFE CYCLE ANALYSIS OF DEFENSE SYSTEMS 2.1 LCA Components – Cost and Performance Drivers For the purpose of this discussion, we distinguish between the following major cost and performance drivers in the life cycle of a defense weapon system (Figure 1). • Operations & Unit Maintenance – Those front line activities involved in flying/operating the weapon system (e.g. aircraft/tank) and performing first level maintenance work. • Intermediate Maintenance – Performs intermediate level maintenance for weapon systems. Configuration and capabilities range depending on equipment, location, mission. • Depot Maintenance – Performs range of maintenance from minor repair through complete overhaul of equipment not reparable by unit/intermediate maintenance, due either to policy or the requirements of the specific maintenance action. OEM (Original Equipment Manufacturer) maintenance also falls into this category. • Management – Represents policy makers; management also balances requirements for support of multiple weapon systems. • Engineering – Provide technical analysis and guidance leading to policy & procedures for items such as safety inspections. • Supply/Logistics – Collective term for those activities which support the field and depot to ensure required spare parts are available when and where needed. In the U.S. Military, this function is typically performed both by DLA (Defense Logistics Agency) and the services themselves. Collectively, these elements form the system that LCA seeks to quantify and that LCM seeks to control and optimize. In this view, the system is broader than just the weapon system (i.e. hardware); encompassing all the operations, support, logistics, management, and engineering activities that occur throughout the life of the weapon system. 2.2 Segmented Life Cycle Analysis Stemming from the complex nature of DoD systems as well as constraints in available models and computing power, traditional methods of LCA for DoD weapon systems have sought to segment the problem into palatable pieces. Within the DoD there are numerous LCA models – supply models, LORA (Level of Repair Analysis) models, RAMS (Reliability Availability and Maintainability) models, LCC (Life Cycle Cost) models, and models for determining maintenance staffing levels (Clockwork Designs 2000). Many times these analyses are performed by completely separate groups within the organization. Thus, for example, spare parts optimization is performed in isolation from maintenance resource level planning. O p e ra tio n s & U n it M a in te n a n c e In te rm e d ia te M a in te n a n c e D e p o t M a in te n a n c e S u p p ly C loud M a n a g e m e n t L o g is t ic s