The U.S. Navy has refused to accept new Freedom-class Littoral Combat Ships (LCS) built by Lockheed Martin until the company fixes a flaw the service found in its combining gear.
An engineering defect was found in the bearings system in USS Detroit (LCS-7) and USS Little Rock (LCS-9) ships. The system links the ship’s Rolls Royce MT30 gas turbines and Colt-Pielstick diesel engines, which power the main drive shaft to achieve 40-knot top speed, USNI News reported today.
The bearings would wear faster than anticipated over a period of time and result in a failure of the combining gear. A probable fix would be replacing the two high-speed clutch bearings with a different bearing version that would not fail as easily.
The Navy will have to operate at or under 35 knots until the problem is solved.
“We had in March of last year a combining gear failure on Little Rock LCS-9. That combining gear failure started with the high-speed clutch,” a senior Navy official said.
The service has notified Lockheed Martin it would not accept delivery of additional Freedom-class hulls until the design flaw is fixed. This could delay the commissioning of the Navy’s Minneapolis-Saint Paul (LCS-21) ship scheduled to take place in May.
“A joint Navy and Lockheed Martin team with RENK AG, the original equipment manufacturer, conducted a root cause analysis and determined a class design defect exists with the high-speed clutch bearings. A design fix has been developed and is in production, to be followed by factory and sea-based testing. The Navy is determining the plan to install this fix on ships in the fleet,” Naval Sea Systems Command said in a Tuesday statement to USNI News.
The cost to fix the issue across the class has yet to be determined.
Confirming the development, Lockheed Martin said in a Tuesday statement to USNI News: “In partnership with the U.S. Navy, Lockheed Martin is aggressively pursuing a resolution to the gear issue the Freedom-variant Littoral Combat Ship is currently experiencing.”
Repairs to Fix the Flaw Already Underway
Initial repairs on Detroit and Little Rock have shown that the repairs can happen without having to put the ships in a dry dock; instead, the repair yard could build a cofferdam around part of the hull that needs to be cut and then navigate through the piping and wiring to get to the gear.
The company is also testing a method the company developed internally that would allow the repair to occur without cutting into the hull of the ship and could save months on the process, said a source familiar with the ongoing repair process.
Lockheed Martin “developed a solution that actually allows you to jack up that gear so you could rotate it in place. And by doing that, you mitigate the need to dry dock, and you also mitigate the need to remove some interferences that are there,” said the source.
Saudi Arabia's Frigates based on LCS to Get Fixes Too
The land-based testing will be conducted on the four combining gears RENK has built for the four frigates based on LCS design for the Royal Saudi Navy. The fix will be in place on the gears, and the bearing problem won’t delay the construction of the four Saudi ships, the source said.
Previous Defects Found on LCS
A software glitch that resulted in the damage of the propulsion plant of USS Milwaukee (LCS-5) was found in 2015. Another LCS, USS Fort Worth (LCS-3) had suffered an operator error that led to the damage of a different combing in gear.