Weapon System Sustainment: DOD Identified Critical Cost Growth, and the Army Should Take Action to Yield Cost Savings

What GAO Found

Operating and support (O&S) costs are comprised of costs for repair parts, maintenance activities, contract services, and personnel. The Department of Defense (DOD) identified 14 systems with critical O&S cost growth out of 36 weapon system sustainment reviews it conducted for fiscal years 2023 and 2024. This critical O&S cost growth represents at least a 25 percent increase in the cost estimate for the remainder of a system's life cycle compared with its most recent independent cost estimate, or at least a 50 percent increase compared with the original baseline cost estimate. GAO identified common causes DOD reported for the critical O&S cost growth for the 14 systems, such as extensions to operational life.

Weapon System Sustainment Reviews with Reported Critical Operating and Support Cost Growth and Causes, Fiscal Years 2023 and 20224

Note: Weapon systems experienced critical O&S cost growth in either Category A (growth is at least 25 percent more than the estimate documented in the most recent independent cost estimate for the system) or Category B (growth is at least 50 percent more than the original baseline cost estimate for the system).

DOD has taken some actions to address critical O&S cost growth identified in fiscal year 2021 and fiscal year 2022. However, GAO found the Army has not fully completed a software update that it reported would remediate a top maintenance issue for its Common Remotely Operated Weapons Station (CROWS). Doing so would yield cost savings that GAO estimates would be more than $130 million over the program's remaining approximately 30 years of life. Without ensuring that its units implement the software update identified in the CROWS remediation plan on a timely basis, the Army is missing an opportunity to address a top maintenance issue affecting this weapon system and to achieve a cost savings of more than $130 million over the remaining life of the program.

DOD identified challenges in conducting sustainment reviews and determining O&S cost growth. GAO found that DOD has taken steps to address challenges, such as revising guidance to correct cost estimating data deficiencies.

Why GAO Did This Study

DOD spends tens of billions of dollars to sustain its weapon systems. O&S costs are about 70 percent of a system's total life-cycle cost. In response to a statutory provision, DOD has been required to annually submit sustainment reviews that include O&S cost estimates and the reasons for any critical cost growth, although the National Defense Authorization Act for Fiscal Year 2026 eliminated the requirement for DOD to include the O&S cost growth information in its sustainment reports.

The National Defense Authorization Act for Fiscal Year 2021 included a provision for GAO to review DOD's annual sustainment reviews and O&S cost estimates through 2025. This report, the final one to be submitted under this statutory requirement, evaluates the extent to which DOD (1) identified critical O&S cost growth in its fiscal years 2023 and 2024 weapon system sustainment reviews and the causes of that growth, (2) has taken actions to address the critical O&S cost growth identified in the fiscal years 2021 and 2022 sustainment reviews, and (3) has taken steps to identify challenges and improve the sustainment review process.

GAO analyzed DOD guidance and weapon system sustainment reviews DOD conducted in fiscal years 2023 and 2024 and cost savings initiatives identified in the fiscal years 2021 and 2022 reviews and interviewed DOD officials who conducted the reviews.