Ship maintenance

US Navy makes progress in maintaining coastal combat ships

File image courtesy of USN

Posted on November 18, 2021 at 10:46 p.m. by

The Maritime Executive

After a long series of controversies, the US Navy has good news regarding its fleet of Littoral Combat Ships. He accepted delivery of his first repair Freedom-LCS class, the final mark of approval for a class-wide solution for the vessel’s failure-prone suit gear.

The little Freedom-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% faster than a Arleigh Burke-class destroyer. The FreedomThe Class A’s thin armor, light armament, water-jet drive, and combined diesel and gas (CODAG) propulsion system were all selected with this goal of jetboat-like speed in mind.

The Freedom– the class’s propulsion system contains a sophisticated combined gear, which connects the final drive to one of three power options: its diesel engines for slow speeds, or its gas turbine engines for high speeds, or all its diesel and turbine engines for top speed. This is a common gearbox arrangement for a naval vessel, and it was selected as a practical way to achieve the speed requirement.

However, the combined gear design proved unreliable in service. In 2013, the first of her class USS Freedom suffered three mechanical failures while in transit to Singapore, then several more while deployed. In 2015, the USS Milwaukee suffered combination gear failure due to clutch slippage while sailing in the Atlantic, one month after delivery. The following year, the USS fort worth suffered a bearing failure related to human error in his suit gear.

In 2020, the Freedom-class LCS USS Detroit suffered a propulsion accident related to his gear combination en route, then lost all power. After this accident, the US Navy launched a root cause investigation with the gearbox OEM and with Lockheed Martin, the ship’s designer. They found a class-wide issue related to “premature high-speed clutch bearing failure.”

After discovering this “hardware 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 FreedomLCS-class hulls until its contractors find and implement a solution.

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

The first ship to receive the fix was the USS Minneapolis-St.Paul. Moton told Defense News it took six months to remove all unrelated parts and equipment to gain access to the gearbox, then complete the repair, reassemble everything and conduct sea trials. were satisfactory, said Rear Admiral Moton.

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

Operational success for the Independence-class LCS

The Freedom-class LCS has stayed 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 IndependenceThe LCS-class hulls are currently operating out of Singapore, conducting exercises with US forces throughout the region. Capt. Tom Ogden, the commodore of Destroyer Squadron 7, said the three ships are benefiting from new active-duty Navy “maintenance execution teams”, which bolster the private contractor teams that previously handled most overseas LCS maintenance operations.

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