Ship maintenance

US Navy advances maintenance of littoral combat ships

File image courtesy of USN

Posted on November 18, 2021 at 10:46 PM by

The maritime executive

After a long series of controversies, the US Navy has good news regarding its Littoral combat ship fleet. He accepted delivery of his first repair Freedom-class LCS, the final mark of approval for a class-wide fix for the vessel failure-prone combination gear.

The little Freedom-The class surface fighter is intended for high speed operations in shallow coastal waters. From top to bottom, the LCS was designed around a Navy speed requirement of over 40 knots, approximately 30 percent faster than a Arleigh Burke– destroyer class. The FreedomThin armor, light armament, waterjet drive, and class-class Combined Diesel and Gas Propulsion System (CODAG) – have all been selected with this jetboat-like speed target in mind.

The Freedom-The class propulsion system contains a sophisticated combined gear, which connects the final transmission to one of three power options: its diesel engines for low speeds, or its gas turbine engines for high speeds, or all its diesel and turbine engines for maximum speed. This is a common gearbox arrangement for a warship, and it was selected as a convenient way to achieve the speed requirement.

However, the design of the combination gear has proven to be unreliable in service. In 2013, the first USS in its class Freedom suffered three mechanical failures while in transit to Singapore, followed by several more during deployment. In 2015, the USS Milwaukee suffered a combination gear failure due to clutch slip while en route in the Atlantic, one month after delivery. The following year, the USS Fort worth suffered a bearing failure related to human error in his combine gearing.

In 2020, the USS Freedom-class LCS Detroit suffered a loss of propulsion related to his gear combination while underway, then lost all power. After this accident, the US Navy launched a root cause investigation with the gearbox supplier and with Lockheed Martin, the designer of the ship. They found a class wide problem related to “high speed clutch bearings failing prematurely”.

After discovering this “material defect”, the Navy limited its current FreedomLCS class fleet at a maximum speed of 34 knots until the problem is resolved. It also suspended all deliveries of new Freedom-class LCS hulls until its subcontractors can find and implement a solution.

This week, the leadership of the Navy announced that the fix had been found. It will be a big class-wide effort, but the service is confident it will work, according to PEO Unmanned and Small Combatants Commander Rear Admiral Casey Moton.

The first ship to receive the patch was the USS Minneapolis-St. Paul. Moton told Defense News that it took six months to remove all unrelated parts and equipment in order to access the gearbox, then perform the repair, reassemble everything, and conduct sea trials. The results have been satisfactory, said Rear Admiral Moton.

Next, the Navy and Lockheed will need to repair four other ships in the construction pipeline – LCS 23, 25, 27 and 29 – and develop a repair plan for ships already in service. They will also need to reach an agreement on cost sharing, according to Defense News.

Operational success for Independence class LCS

The Freedom-class LCS has remained closer to home in recent years, but the Independence-class – an entirely different ship – enjoys extensive service in the Indo-Pacific, where the Navy needs it most.

Three IndependenceLCS-class hulls currently operate out of Singapore, conducting exercises with U.S. forces throughout the region. Captain Tom Ogden, Commodore of Destroyer Squadron 7, said all three ships are benefiting from new active-duty Navy “maintenance execution teams”, which bolster the private contractor teams who previously managed most of the work. LCS maintenance operations abroad.

“With the same amount of time spent on maintenance, we have increased LCS operational readiness in the Pacific more than ever before,” Ogden told USNI.