The Freedom is the third ship in the Freedom class of LCS, built by Lockheed Martin Corp., to suffer an engine casualty in the last year. The news of the incident, which happened July 11, was announced by the Navy on Sunday night.
The Freedom, the first ship in its class, returned to its homeport at Naval Base San Diego, California, on July 13 under its own power to conduct repairs on an unrelated issue, officials with Naval Surface Force, U.S. Pacific Fleet, said in a release.
While in port, personnel examined the leak, which happened at the seawater pump mechanical seal, allowing seawater to enter the engine lube oil system and damage the ship's second main propulsion diesel engine, officials said.
The crew performed seawater contamination procedures, but opted to return to sea to participate in the Rim of the Pacific multinational exercise, from July 19 to 28, using its gas turbine engines rather than its main diesel engines.
During RIMPAC, Freedom operated off the coast of southern California, training in mine interdiction warfare with American and allied ships.
Following the exercise, the ship returned to port. An Aug. 3 inspection of the number 2 diesel engine, conducted by Southwest Regional Maintenance Center's Diesel Engine Inspector, determined that rust and seawater had caused significant permanent damage to the engine.
"Based on initial assessments from the inspection, Freedom's #2 [main propulsion diesel engine] will need to be removed and rebuilt or replaced," officials said in the release.
Navy officials say the cost of the repair and the timeline for getting the work done remain unknown. Also unknown, they said, is whether crew error or mechanical failure, or both, are responsible for the casualty. The commander of Naval Surface Forces, Vice Adm. Tom Rowden, is overseeing an investigation into the incident.
In a statement, Rowden said this engineering casualty, which happened eight months after the USS Fort Worth was sidelined in Singapore due to a crew-caused engine casualty, indicated a need for "improvements in engineering oversight and training."
"The recently completed LCS Review of manning, design, and training looked at a number of sailor performance and ownership factors, to include crew rotation, size and proficiency," he said. "From this work, I believe we will be able to make immediate changes to help reduce chance for future operator error. I am fully committed to ensuring that our ships and the Sailors who man them have the proper tools and training they need to safely and effectively operate these ships."
Rowden will determine any needed corrective actions after the investigation is complete, officials said.
The Fort Worth, the second Freedom-class LCS, recently departed for its San Diego homeport after eight months in Singapore following an engine casualty that resulted when lubrication oil was not appropriately applied to the ship's combining gears during startup. The results of the investigation into that incident have not been made public, but the ship's commanding officer, Cmdr. Michael Atwell, was relieved of his post in March in connection with the incident.
The third ship of the class, the Milwaukee, also underwent engine repairs after it broke down during a transit from San Diego to Halifax, Nova Scotia, in December and was towed to Joint Base Little Creek, Virginia. According to officials, a clutch failed to disengage when the ship was switching from its gas turbine to its diesel engine system, resulting in damage to the clutch gears. The ship was repaired in Virginia, officials said.
The Navy has yet to make public the results of its LCS review, which studied the crewing approach for the new class of ships as well as operations, training and maintenance practices.
The review was initially ordered in February by Chief of Naval Operations Adm. John Richardson, then extended in May when Richardson asked for additional details on several topics.