Supportability of DoD weapon systems has become a national issue. The ability to perform diagnostic and maintenance tasks impacts our world position both through our efficiency and our effectiveness. The following statements indicate that current maintenance methods are not capable of performing as required: One-third to one-half of F-15/F-16 maintenance man-hours were expended on chasing problems where no defects were found. [AFSB86] 20% - 50% of avionics maintenance actions resulted in removal of items with no evidence of failures. [RIDD86] Nearly two thirds of the 900 responding technicians indicated they used Fault Isolation Manuals less than 50% of the time to troubleshoot faults. [WYNK91] These problems, coupled with characteristics of today's systems (e.g., highly sophisticated hardware/software designs and low-volume production) and emerging operational environments, (e.g., reduced manpower with high turnover rates, elimination of technician specialty groups, two-level maintenance, composite basing, etc.) will make the maintenance diagnostic job more difficult. This results in escalating supportability costs within a shrinking defense budget. Drastic new approaches are required to cost-effectively maintain DoD weapon system in an acceptable readiness mode.This report describes the Flight Control Maintenance Diagnostic System (FCMDS) which was developed for the Air Force to address these issues within the Flight Control System (FLCS) of the F-16 fleet. The paper includes the results of field testing of the FCMDS which indicates a potential for savings in manpower time to conduct fault isolation (25% time reduction), reduction in Re-Test OK (RTOK) and Can Not Duplicate (CND) incidents which lead to 42% reduction in spares requirements, and a 92% increase in diagnostic accuracy such that novice technician performance was raised to expert technician levels. Finally, the paper describes the future plans and recommended next steps for FCMDS.