The Navy has been unable to begin or complete the vast majority of its  attack submarine maintenance periods on time resulting in significant  maintenance delays and operating and support cost expenditures. Our  analysis of Navy maintenance data shows that between fiscal year 2008  and the end of fiscal year 2018, attack submarines will have incurred  10,363 days of idle time and maintenance delays as a result of delays in  getting into and out of the shipyards. Using historical daily cost data the Navy adjusted for inflation,  we estimated that since fiscal year 2008 the Navy has spent more than  $1.5 billion in fiscal year 2018 constant dollars on attack submarines  sitting idle while waiting to enter the shipyards, and on those delayed in  completing their maintenance at the shipyards (see table 1). For example:
The public shipyards have been hiring to address workforce  shortages. Navy Has Not Effectively Allocated Maintenance Periods among the Public and Private Shipyards to Limit Attack Submarine Idle Time

While the public shipyards have operated above capacity for the past  several years, attack submarine maintenance delays are getting longer  and idle time is increasing. The Navy may have options to mitigate idle time and maintenance delays. We believe that the Navy has not fully mitigated this challenge because it  has not completed a comprehensive business case analysis to inform  maintenance workload allocation across public and private shipyards, and  to proactively minimize attack submarine idle time and maintenance  delays. Navy leadership has  acknowledged that they need to be more proactive in leveraging private  shipyard repair capacity, but officials cautioned that maintenance could  cost more at a private shipyard than at a public shipyard. Conclusions

The nation’s investment in attack submarines provides the United States  an asymmetric advantage to gather intelligence undetected, attack enemy  targets, and insert special forces, among other capabilities. However, the  Navy’s attack submarine fleet has suffered from persistent and costly  maintenance delays. Without addressing this challenge,  the Navy will not achieve the full benefit of the nation’s investment in its  attack submarines, and it risks continued expenditure of operating and  support funding to crew, maintain, and support attack submarines that  provide no operational capability because they are delayed in getting into  and out of maintenance. Recommendation for Executive Action

The Secretary of the Navy should ensure that the Chief of Naval  Operations conducts a business case analysis to inform maintenance  workload allocation across public and private shipyards; this analysis  should include an assessment of private shipyard capacity to perform  attack submarine maintenance, and should incorporate a complete  accounting of both (a) the costs and risks associated with attack  submarines sitting idle, and (b) the qualitative benefits associated with  having the potential to both mitigate risk in new submarine construction  and provide additional availability to the combatant commanders. To assess the extent to which the Navy has addressed any challenges  and developed mitigation plans for any maintenance delays, we reviewed  the Navy’s plans to address attack submarine maintenance delays and  interviewed Navy headquarters, fleet, and squadron officials, attack  submarine crews, and public and private shipyard officials to understand  any plans to address attack submarine maintenance delays and idle time.
Why GAO Did This Study

According to the Navy, its 51 attack submarines provide the United States an asymmetric advantage to gather intelligence undetected, attack enemy targets, and insert special forces, among others. These capabilities make attack submarines some of the most–requested assets by the global combatant commanders.
GAO was asked to review the readiness of the Navy's attack submarine force. This report discusses the extent to which the Navy (1) has experienced maintenance delays in its attack submarine fleet and costs associated with any delays; and (2) has addressed any challenges and developed mitigation plans for any maintenance delays. GAO analyzed readiness information from fiscal years 2008-2018, operating and support costs, maintenance performance, and other data; visited attack submarines and squadrons; and interviewed public and private shipyard and fleet officials.
This is a public version of a classified report issued in October 2018. Information the Department of Defense deemed classified or sensitive, such as attack submarine force structure requirements and detailed data on attack submarine maintenance delays, has been omitted.

What GAO Found

The Navy has been unable to begin or complete the vast majority of its attack submarine maintenance periods on time resulting in significant maintenance delays and operating and support cost expenditures. GAO's analysis of Navy maintenance data shows that between fiscal year 2008 and 2018, attack submarines have incurred 10,363 days of idle time and maintenance delays as a result of delays in getting into and out of the shipyards. For example, the Navy originally scheduled the USS Boise to enter a shipyard for an extended maintenance period in 2013 but, due to heavy shipyard workload, the Navy delayed the start of the maintenance period. In June 2016, the USS Boise could no longer conduct normal operations and the boat has remained idle, pierside for over two years since then waiting to enter a shipyard (see figure). GAO estimated that since fiscal year 2008 the Navy has spent more than $1.5 billion in fiscal year 2018 constant dollars to support attack submarines that provide no operational capability—those sitting idle while waiting to enter the shipyards, and those delayed in completing their maintenance at the shipyards.
The Navy has started to address challenges related to workforce shortages and facilities needs at the public shipyards. However, it has not effectively allocated maintenance periods among public shipyards and private shipyards that may also be available to help minimize attack submarine idle time. GAO's analysis found that while the public shipyards have operated above capacity for the past several years, attack submarine maintenance delays are getting longer and idle time is increasing. The Navy may have options to mitigate this idle time and maintenance delays by leveraging private shipyard capacity for repair work. But the Navy has not completed a comprehensive business case analysis as recommended by Department of Defense guidelines to inform maintenance workload allocation across public and private shipyards. Navy leadership has acknowledged that they need to be more proactive in leveraging potential private shipyard repair capacity. Without addressing this challenge, the Navy risks continued expenditure of operating and support funding to crew, maintain, and support attack submarines that provide no operational capability because they are delayed in getting into and out of maintenance.

What GAO Recommends

GAO recommends that the Navy conduct a business case analysis to inform maintenance workload allocation across public and private shipyards. The Department of Defense concurred with GAO's recommendation.