The U.S. Navy had to cut short the first extended underway in Singapore for the Littoral Combat Ship (LCS-1), the USS Freedom, apparently because of continuing issues with the ship’s coolant system, service officials say.

The problem appears to be a minor one, the Navy says, with the ship returning to the Singapore Changi Naval Base on its own power.

The Freedom is the first LCS to be deployed to Singapore, and the ship- lass is considered to be a vital part of the “small footprint” of U.S. Navy assets being sent to the region as part of the U.S. Pacific pivot and rebalance of resources to that part of the globe.

At the International Maritime and Defense Exhibition (Imdex) Asia 2013 earlier this month in Singapore, Navy officials said they were looking forward to the ship’s first underway and operations with regional Asian partners.

The ship did leave the pier for a few hours May 17 as part of the Republic of Singapore Navy-led Western Pacific Multilateral Sea Exercise and returned as planned the same day, Navy officials say.

However, “after getting underway on the morning of May 21 [local time], USS Freedom returned to Changi Naval Base approximately eight hours later after the crew detected sediment in the ship’s lube oil system,” Navy spokesman Capt. Darryn James says.

“USS Freedom returned to port under its own power and at no time was the crew in any danger,” James says. “The crew is now working with maintenance technicians in Singapore to determine the source of the problem and accomplish any needed repairs.”

The Navy cannot discuss “specific maintenance timelines or operational schedules,” James says, but “technicians are working to quickly address the problem.”

Navy officials say the problem appears to be related to coolant-leak issues reported in April shortly after the Freedom first arrived in Singapore. The system may not have flushed completely following repairs, they say.

Freedom appeared ship-shape when open for tours during Imdex.

On April 28 and 29, shortly after the ship arrived in Singapore, Freedom’s crew reported a problem with faulty seawater coolers, which are used to cool lube oil in the ship’s propulsion systems, Navy officials say. The vessel had been experiencing problems with water coolers designed to bring water into the ship, but there was no flooding, they note.

During transit through the Pacific, the ship also experienced power outages due to problems with diesel generators.

Navy officials say they expect to experience maintenance and operational challenges with Freedom during the Singapore “proof-of-concept LCS overseas deployment.”