The US Navy (USN) plans to subject the Littoral Combat Ship (LCS) combining gear fix to a much greater degree of normal propulsion-plant testing to ensure the new equipment works, said Howard Berkof, LCS deputy programme manager.
Combining-gear issues have plagued the LCS Freedom-variant vessels since they were first put to sea. The USN recently halted their delivery as the service and industry looked for a cause and a solution.
The combining gear “is a pretty complex gear” that is used to integrate LCS gas turbines and diesel engines, Berkof noted.
Following analysis from late 2020, it was determined that the bearings on the high-speed clutch could not sufficiently handle the loads required, he said. A design change was required to replace those bearings. That change had been validated by the technical community, he added.
The bearing change is being installed on USS Minneapolis-Saint Paul (LCS-21) in Escanaba, Michigan, he said. The USN is now scheduled to begin testing the new system in September.
“The testing will be double what you would normally test for a propulsion system on a ship like that,” Berkof said. “We are going to go through very vigorous testing, to make sure those gears test out in the many different modes – diesel-engine mode, gas-turbine mode, CODAG [combined diesel and gas turbine] mode, full power diesel and gas turbine – at varying speeds.”
“LCS 23 [USS Cooperstown ] also will go to Escanaba for combining-gear replacement shortly,” Berkof said. Other new-construction ships will follow, he added.
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