SSN-688 Los Angeles-class Engineered Refueling Overhaul (ERO)
At about 2/3 the way through its life, the submarine undergoes a large and comprehensive overhaul that includes periodic maintenance, system upgrades, and alteration. For the earliest built Los Angeles Class submarines, the work also includes refueling the ship's reactor plant. These availabilities are called Engineered Refueling Overhauls (EROs). For the later Los Angeles Class submarines, the reactor doesn't need to be refueled. For these vessels the overhaul is called an Engineered Overhaul.
Submarine Engineered Refueling Overhauls (EROs) are complex, short duration availabilities performed to extend the useful life of the vessel. Average duration of an ERO is 24 months with a production period of less than 15 months. Unlike ships under construction EROs are performed on assembled hulls with limited access. The unique sensitive and safety (SUBSAFE) nature of submarine repair and refueling efforts dictates that the availability must be thoroughly and carefully integrated in advance to minimize disruptions and delays. The production period at the beginning of the ERO is extraordinarily labor intensive.
SSN-688 class submarines could operate for much longer than 30 years; one of the shipbuilders stated that 10 to 20 years of additional service would not be unreasonable. Past Navy actions indicated that extending a submarine's service life may be feasible. After a 5-year study was completed on the SSN-637 class submarine--the predecessor of the SSN-688 class--the design life was extended from 20 years to 30 years, with a possible extension to 33 years on a case-by-case basis. By the end of 1999 the Navy had determined that it could safely extend the service lives of all its Los Angeles and Improved Los Angeles class submarines by 3 years, to 33 years. This reduced somewhat the steady-state procurement rate needed to maintain an SSN force of a given size, and delayed the point at which the size of the SSN force might bottom out due to rapid retirements.
Between 1998 and 2001 the US retired 11 Los Angeles class submarines that had an average of 13 years left on their 30-year service lives. The 18 SSN-688 class submarines that will be refueled at their mid-life made good candidates for a service life extension because they could operate for nearly 30 years after the refueling. After these submarines serve for 30 years, they could undergo a 2-year overhaul and serve for one more 10-year operating cycle, for a total service life of 42 years. The cost for the additional overhaul of SSN-688 class submarines would be about $406 million per boat.
Eight older Los Angeles-class submarines, without a vertical launch system, could be refueled at a cost of $210 million more than it would cost to inactivate them.
FY2000 - SSN 713 Houston
FY2001 - SSN 698 Bremerton
FY2001 - SSN 699 Jacksonville
FY2001 - SSN 714 Norfolk
FY2005 - SSN 716 Salt Lake City
FY2006 - SSN 717 Olympia
FY2007 - SSN 718 Honolulu
FY2008 - SSN 710 Augusta
These submarines can still be used in strike missions, however, by firing Tomahawk land attack missiles through their torpedo tubes.
In late 1999 the Clinton Administration decided to add $1.1 billion in funding to the shipbuilding plan in the period FY2002-FY2005 for submarine refuelings beyond those previously programmed. The money is to be used either for refuelings of 688-class submarines scheduled for early retirement, or conversion of Ohio-class Trident ballistic missile submarines into cruise missile submarines (SSGNs). A total of 7 older 688s would require refueling to avoid early retirement. Their refueling was not previously funded, and the $1.1 billion would be enough to refuel 4 of them. Alternately, the $1.1 billion would be enough to convert 2 older Trident SSBNs into SSGNs.
The Clinton Administration's DOD guidance called for a force of 50 attack submarines, although some studies called for raising the number of subs to as many as 72. Existing plans were sufficient to meet the goal of 50 boats, although higher numbers would require modification to these plans. According to Navy secretary Richard Danzig, as of October 1999 the Joint Chiefs of Staff were studying options for increasing the size and capability of the submarine force. The three options under review include by converting older Ohio-class SSBN submarines to so-called SSGNs at a cost of $420 million; refueling and extending by 12 years the service life of perhaps eight Los Angeles-class (SSN 688) subs at a cost per copy of $200 million; or building new Virginia-class (SSN 774) subs at a rate of at least four over the next five years, at a cost of roughly $2 billion per boat. The FY2000 Defense Authorization bill requires the Navy to study converting four of the oldest Tridents to the new SSGN configuration.
The JCS Submarine Force Structure Study, completed in November 1999, concluded that the optimal force structure would be 68 attack submarines by 2015 and 76 by 2025, with the minimum being at least 55 by 2015 and 62 by 2025. The first would be to refuel some Los Angeles-class submarines previously scheduled to be decommissioned.
The Portsmouth Naval Shipyard conducts maintenance and refueling of nuclear submarines at its facilities on the Piscataqua River. Depot modernization maintenance requires less than a year in port, and an engineered refueling overhaul is a 2-year operation. The Navy canceled two Engineered Refueling Overhaul projects that had been scheduled -- SSN 716 Salt Lake City and SSN 710 Augusta.
Salt Lake City
Engineered Overhaul (EO)
The Attack Submarine (SSN) Engineered Overhaul (EO) program modernizes, and upgrades SSNs for extended service in the fleet. SSN-719 USS Providence entered Portsmouth Naval Shipyard on 29 October 2003 for the Navy's first-ever Engineered Overhaul for an attack submarine. For these later Los Angeles Class submarines, the reactor doesn't need to be refueled. For these vessels the overhaul is called an Engineered Overhaul, versus the Engineered Refueling Overhaul (ERO) of earlier boats. This included maintenance and several system upgrades with an estimated total cost of $160 million.