TOCICO

This presentation details the use of theory of constraints (TOC) critical chain (CC) at Warner Robins Air Force Base in planning and managing aircraft maintenance and repair operations. The C-5 aircraft maintenance operation is described. Warner Robins won both the Edelman and Shingo Awards for its achievements. The lean 'evolution' from 2001 to 2004 is described. Even after lean they still had many issues: priority given to lead aircraft; tendency to release work ASAP; task times buffered to account for uncertainties; and many milestones with date-driven mentality. Some of the remaining challenges included: competition for equipment, tools, manpower, facilities, etc.; parts shortages; inherent variability of repair work; discovery of unanticipated work; coordinating with support organizations; etc. Critical chain was implemented in 2005 which enabled resource pool formation; supplanted cell teams, which dedicate resources to their own task; one-piece flow (major lean precept). Resource pools allow application of skills against tasks consuming the most project buffer and ensure that best interest of the entire project is the foremost consideration. The C-5 process flow is described including the details of pre-dock, doc and post-dock. An overview of critical chain buffering, pipelining and buffer management is provided. With the use of lean over five years we got the number of aircraft down to 13. In 8 months of using critical chain we went from 13 to 6 aircraft in work in process. This put five more aircraft in action instead of down for maintenance. The dollar amount impact is discussed. In the Q & A, Percell discusses CC and lean integration with the high variability in work content. CC becomes the tact time for the line. It is a correct model for MRO. It was a revelation after the fact!