<p>The majority of Navy submarine maintenance has been conducted at public shipyards over the last decade, with a recent Government Accountability Office (GAO) report indicating that only 11% of maintenance was completed on schedule.</p>
<p>According to the GAO report, released on August 28, 2026, four public naval shipyards—Portsmouth Naval Shipyard, Norfolk Naval Shipyard, Puget Sound Naval Shipyard, and Pearl Harbor Naval Shipyard—are responsible for most maintenance on attack submarines and other nuclear-powered vessels. From fiscal 2016 through fiscal 2025, these facilities exceeded planned maintenance timelines 89% of the time.</p>
<p>The Navy experienced 3,040 days, or over eight years, of maintenance delays from fiscal 2016 to fiscal 2020, followed by an additional 3,454 days, or nearly 10 years, from fiscal 2021 to fiscal 2025. The average depot-level maintenance period for a submarine was 744 days from fiscal 2016 to fiscal 2020, increasing to 809 days from fiscal 2021 to fiscal 2025.</p>
<p>These delays have resulted in an estimated cost of $3.4 billion to sustain crews and submarines during the extended maintenance periods, with an additional projected cost of $3.1 billion over the next five years if no mitigation measures are implemented. The delays have also led to a loss of over 15,000 operational days, with a similar amount expected over the next five years.</p>
<p>The report noted that while the U.S. Navy has made some progress in reducing active idle time for attack submarines, inactive idle time is expected to increase due to upcoming inactivations of Los Angeles-class submarines over the next five years.</p>
<p>The Navy currently operates 44 attack submarines. The Fleet Response Training Plan outlines an 18-month operational cycle, including a 12-month training and certification period followed by a six-month deployment, with an additional 30-day stand-down period after deployment.</p>
<p>Submarines typically undergo this cycle three to four times before entering extensive depot maintenance, which can last between two and three years.</p>
<p>The maintenance delays have created situations where a submarine's deployment ends, but repairs cannot begin immediately, resulting in idle time for active submarines. Crews must remain at the pier since they are not certified for normal operations, although the submarines are still classified as active.</p>
<p>From fiscal 2016 to fiscal 2025, the Navy accumulated nearly 25 years of active idle time for submarines, peaking in 2022 with 1,518 days of idle time, before declining to 166 days in fiscal 2025.</p>
<p>Inactive attack submarines also experience idle time when they are designated for decommissioning but cannot be inducted into a dry dock. For instance, the USS Pasadena entered inactive idle status on January 1, 2025, but is not expected to be decommissioned until November 15, 2028, resulting in an estimated cost of over $300 million during this nearly four-year period.</p>
<p>There are two private shipyards—General Dynamics Electric Boat in Groton, Connecticut, and Huntington Ingalls Industries Newport News Shipbuilding in Newport News, Virginia—that build nuclear-powered ships and provide limited depot maintenance. However, an official familiar with the report stated that private yards have a poor track record with depot maintenance compared to public yards, as they are primarily designed for building submarines.</p>
<p>The GAO report includes two recommendations: the Navy Secretary should ensure the Chief of Naval Operations directs the Naval Sea Systems Command to evaluate alternative options for more efficient decommissioning of attack submarines and to develop a plan to reduce inactive idle time for crews during inactivations. Navy officials have verbally concurred with these recommendations but did not provide written comments.</p>