Optimization of Continuous Maintenance Availability Scheduling

Abstract

Every few months each United States submarine must return to a port to undergo major maintenance that cannot be conducted at sea. These maintenance periods are called Continuous Maintenance Availability (CMAV) periods. All CMAV scheduling aboard the two remaining submarine tenders in the United States fleet, the USS Emory S. Land (AS 39) and the USS Frank Cable (AS 40), is currently done manually. The schedulers rely on their experience and sound judgment with the goal of successfully completing the most maintenance as quickly and efficiently as possible for approximately 200 jobs, 50 maintenance shops and a host of other considerations. In this thesis, we develop a job-shop scheduling model, the CMAV Scheduler (CMAV-S). This is a large-scale, mixed-integer, linear program that accounts for a variety of scheduling inputs commonly used by planners: job priority, duration, allowed window of execution, prerequisites, mandatory character, workforce used and available (by shop), and special submarine conditions (active or inactive) needed to perform a job. CMAV-S produces near-optimal schedules that achieve maximum value for all scheduled jobs in about one minute. When compared to our own manual scheduling, we observe CMAV-S improves up to 25% the required CMAV length to schedule all maintenance.