This article and presentation discuss the application of critical chain methodology to master scheduling for repair of complex military aircraft, a task considered by some to be a daunting challenge within even a sophisticated project management system. The application of critical chain to master scheduling of other complex industrial sectors would appear to offer similar benefits as appear in this case study in the remanufacturing sector. Experience with this approach within less than a year suggests the potential to reduce repair cycle rime by as much as 50 percent or more. The history of the implementation and use of critical chain in this maintenance, repair, and overhaul environment is described and observations drawn as they relate to using this approach for master scheduling. The roles of training, software and critical chain methodology are described. Critical chain may profoundly impact on standards, bills of material structures, and routers when implemented and used with an MRP II/ERP solution.
THE CASE STUDY ENVIRONMENT
This case study takes place in a complex, project-oriented repair and overhaul environment. Elements of the facility's repair processes include job shop, process, and project-oriented operations. The DoD repair facility described is under increasing pressure to deliver superior value in terms of quality, cost, delivery, and service to its customers on a global basis.
Many repair-aiid-overhaul-oriented organizations have traditionally used relatively simple operational planning and control methods along with home-grown software programs to manage repair operations. MRP II and now ERP software developers have tended to favor the manufacturing environment, where a larger market appeared to be available and has tended to fall short of meeting the specific needs of repair and overhaul operations. In particular, the aspect of uncertainty as relates to probability of use of materials and operations to be performed is a contrast to the relatively predictable consumption of materials and the straightforward assembly sequence in most manufacturing organizations. This complication provides additional difficulty to the master planning and scheduling of resources. Project management tools have
been applied to master planning of remanufacturing operations with varying degrees of success, but tend to fall short in the area of managing capacity and priorities while scheduling across projects in process that share the same resources. Other emerging methodologies, such as theory of constraints, critical chain, and advanced planning systems, have tended to be applied elsewhere and are just commencing to be applied to remanufacturing activities, such as maintenance, repair, and overhaul.
This paper points out how an organization can take a step-by-step approach to implementing critical chain as a master scheduling tool through an actual case study. The case study takes place at the Naval Aviation Depot Maintenance Facility at Cherry Point, North Carolina. NADEP Cherry Point has over 4,000 employees and a budget in excess of $500 million. It is a primary repair and overhaul location for complex Navy and Marine fixed and rotary wing aircraft, and to a lesser extent provides remanufacturing support to other U.S. Department of Defense and international military organizations. The items in repair can be so complex that often this has been considered and managed as a project management environment. Often the aircraft, treated as separate projects, have been launched into the mainstream of repair and reassembly operations without recognition of impossible conflicts of interest for attention at work centers. This
overload condition can easily result in extended lead times in the repair cycle and negative impacts on productivity.
NADEP Cherry Point, like other military repair facilities, is under increasing pressure to reduce costs, cut lead times, and constantly improve quality. The number of Naval Aviation Repair Depots was cut in half in the 1990s, and survival of any one depot is not guaranteed, as budgets continue to tighten and commercial sector competition takes aim at portions of their workload. Both public and private sector organizations tend to be led to progressive concepts and tools by the pull of the felt need to improve and survive, as in this case. The live case study in progress is used to illustrate how and what can be accomplished. Additional nongovernment organizations are commencing to use a similar approach to master scheduling.
Critical chain project management (CCPM) has the potential to substitute for both critical path and earned-value project management for project environments and may become a valuable tool for master scheduling in a larger marketplace. It may be the next logical improvement step beyond earlier methods for ensuring resource capacity and proper allocation where multiple projects share the same material and labor resources. In a single phrase, CCPM causes you to focus on project success. CCPM software is now available in the market and can schedule projects using the critical path methodology and also combine the schedule for multiple projects (items), respecting conflict of capacity for the same resource considerations. The concept of critical chain will be described as its methodology unfolds during the implementation sequence in the following real step-by-step implementation case study narrative.
To Be Continued