The sad saga of the Littoral Combat Ships (LCS) continues. The USS Fort Worth, the third Freedom Class LCS delivered, was testing its engines at dockside in Singapore and seriously damaged the ship’s combining gear. The LCS have both diesel and gas turbine engines. The combining gear is a complex set of gears which “combines” the output from the ship’s Rolls Royce MT-30 gas turbines and Colt-Pielstick diesel engines to the ship’s water jets. Initial reports say that the casualty was caused by the crew allowing the gear to run dry without adequate lubrication, leading to overheating. Whether the casualty was indeed due to operator error or a class-wide problem remains to be seen.
This is not the first combining gear casualty with a Freedom Class LCS. In December, the USS Milwaukee, the second ship of the class, which had been delivered from the shipyard only the month before, had a combining gear failure while in the Atlantic on its way to a deployment in San Diego. The ship was towed to a Navy base in Virginia for repairs, which are expected to take until February. The casualty has been blamed on slipping clutches which may have been caused by a software error. The clutch slippage caused fine metallic debris to clog and cut off the lube system on the gear. As reported by USNI News, Lockheed Martin and the Navy have still not determined if the failure on the USS Milwaukee is a class-wide issue.
The USS Fort Worth is also not the first LCS to break down in Singapore. On a deployment in 2013, USS Freedom, the first of the class, broke down three times on the way to Singapore then suffered repeated mechanical failures forcing the cutting short of several planned exercises. A GAO report from July of 2014 notes that changes have been made to the Freedom‘s starboard splitter gear and port combining gear to “improve maintainability on LCS 1 [USS Freedom] and 3 [USS Milwaukee.] The design will be changed on LCS 5 [USS Fort Worth] and follow-on ships to further improve maintainability.”
Thanks to Miroslav for contributing to this post.
‘Teething’ [as in tooth] troubles?
Grease Monkey as in yesteryear not doing his job.
Of course he would now be known as a Marine Engineer or similar.
Better training required?
Given that this is the second gear failure in just over a month and that all three of the ships of the class have had some sort of gear problems, I wouldn’t blame the crew yet.
As I understand:
Each 6500 shaft-kW Diesel engine (port/starboard) drives an associated combining gear at 1050 RPM engine speed through a “two-speed drive” … I assume it maybe an enlarged planetary gear drive, similar to an automotive transmission. This type of transmission was first used on the Ford Model T, one-hundred years ago which had two forward speeds and reverse, actuated by transmission “bands” locking/unlocking the sun and planetary gears
I assume the low speed gearing is used for long-distance trans-ocean transport at perhaps 18 knots, and the high speed gear used in the CODAG drive high-speed at the 47 knot cruise speed, with each port/ starboard associated 36000 Shaft-kW Gas-turbine driving its Combining gear at 3300 RPM.
Further, each combining gear has a single output shaft, that transmits power to its associated “splitter gear”; which drives two of the four total water jet drive pumps. The axial-water-pump jet drives most likely have variable vane angle blading for efficient speed change.
The more basic question is:
Why did the Littoral ship design use multi-stage gear-sets when most civilian high-speed ferry’s and cruise ships use generators and electric drive motors in the same 85000 shaft-KW output class of ship?
John,
Interesting question. The multi-stage gear sets seem to be expensive and vulnerable. far easier to swap out sen-sets or an electric motor is damaged, I wonder if weight and/or space are an issue with the LCS. The Independence class is already coming in too heavy.
The Freedom LCS ships have had the gear problems and weight more than the Independence variant.
Freedom LCS has larger Gas-Turbines: RR MTU 30’s at 36,000 kW, each, Vs the Independence class GE LM2500’s at 25,000 kW each.
Total Propulsion is 85,000 Shaft-kW for Freedom Class vs approximately 65,000 Shaft-kW for Independence……could the gearing problems be related to the the additional power?
You guys need to get your facts straight, starting with the original post. The Fort Worth is the second Freedom Class ship. Navy operator error is a true statement. I am not at liberty to discuss the rest but you are all way off. Look up the ship on Wikipedia or Jane’s if you want to know more of what you are talking about.
Just an old fluid power guy and a bit of a gearhead. This is the same problem area as the USS Milwaukee.
This has the appearance of a system problem.
I am not sure I believe the report as these ships are all being built under the Lockheed-Martin umbrella. We can look at the record on F-22 and F-35 as well.
Perhaps Senator McCain has a point and perhaps this boat is a mistake all the way around. Too light, and can’t do the work of a destroyer which will be very necessary in the China Seas.
A maintenance oversight smacks of any of a bunch of problems so I won’t comment. Maybe it is time for fast boats and PT’s. I don’t know.