The Navy wants to retire the Pearl Harbor-based USS Port Royal, the youngest Ticonderoga-class cruiser in the fleet and a ship with prized ballistic missile defense capability.

Congress wants to know why, and it wants to know in 180 days.

“You are talking about a billion-dollar asset. I mean, what would it cost to fix the ship? Or, what are the issues that are unrepairable?” said Wes Battle, a spokesman for U.S. Rep. J. Randy Forbes, R-Va., who fights to save cruisers the Navy wants to retire early to save money.

The $633 billion National Defense Authorization Act of 2013, signed by President Barack Obama Jan. 2, preserves, for now, four of those cruisers.

The Vicksburg, Anzio, Cowpens and Port Royal were scheduled to be inactivated on March 31. Only the Port Royal is based in Hawaii.

Three other cruisers, including the Pearl Harbor-based USS Chosin, are on the chopping block for fiscal 2014.

It is well-known that the Port Royal sustained extensive damage when it ran aground in shallow water off Honolulu Airport in 2009 and remained stuck for four days.

Less well-known, at least to Congress, is what lingering problems afflict the Port Royal to a degree that the Navy wants to ditch a ship that was commissioned in 1994 and is not that old, relatively.

“Although the Navy indicates that the ship never completely recovered from the grounding, the Navy has not provided adequate analysis and cost data on the structural condition of the ship,” the defense bill’s conference report states.

Conferees directed the secretary of the Navy to conduct a “detailed material condition assessment” of the Port Royal, including:

>> A comprehensive inspection of the ship’s major structural, machinery, electrical, combat and weapons systems.

>> Identification of necessary repairs and modernization, including costs, that would be required for the ship to meet its expected service life, consistent with other Ticonderoga-class cruisers.

>> A review of the results by an independent board of subject matter experts, from industry and the Department of Defense.

Congress called for a status update in 120 days, the results of the assessment in 180 days, and a Government Accountability Office review of the sufficiency of the report. Congress has not asked for similar assessments of the other cruisers the Navy wants to remove from service.

“Here’s a Navy that’s having budget problems and they are saying, ‘OK, the ship’s gone, we want to cut it,’ and so I think Congress is providing oversight to (ask), ‘What is specifically wrong with the ship?’ so they can make the best decisions with regards to it,” Battle said.

The Navy “already poured all that money into trying to repair it,” Battle added. “We’re not necessarily disagreeing with the Navy. We just want to make sure that that full analysis of the ship has been completed.”

The Navy spent more than $20 million in 2010 and 2011 to address cracks in the Port Royal’s aluminum alloy superstructure, a problem endemic to all 22 Ticonderoga-class cruisers.

That was on top of $40 million in fixes required by the 2009 grounding, and an $18 million refurbishment just before the warship ran aground.

Efforts to save existing cruisers come amid conflicting priorities caused by budget shortfalls, longer deployments, a maintenance backlog, and growing needs for Navy ships around the world — particularly in the Pacific and Middle East.

The Port Royal was among seven cruisers and two amphibious ships the Navy said it wanted to retire early in fiscal 2013 and 2014 to save about $4 billion over five years.

Retiring the cruisers was “a terribly difficult choice to make” that would sacrifice a few ships for the good of the rest, Vice Adm. William Burke, then deputy chief of Naval operations for fleet readiness and logistics, told the House Armed Service’s subcommittee on readiness in March.

The operating cost for cruisers is about $40 million a year and several hundred million a year for maintenance, repairs and modernization, Burke said.

“(If) we didn’t do this, if we kept too many ships, we would be undermaintaining all of them, and so we would end up down the road having a bigger problem than we have today,” Burke said.

However, Vice Adm. Kevin McCoy, commander of Naval Sea Systems Command, said in 2011 that “the cheapest way to afford our Navy with the force structure that we need is to maintain the ships that we already have.”

The Navy has 288 ships with a goal of 300 by 2019.

Forbes, the Virginia congressman, said in March that the defense budget sought to cut “perfectly good ships.”

The missile firepower of four U.S. cruisers exceeds that of the entire United Kingdom Royal Navy fleet, he said.

Forbes said six of the seven cruisers proposed for cuts in 2013 and 2014 — a list that presumably excluded the Port Royal because of ongoing condition concerns with the grounding — had 13 to 15 years of service life left.

Some of the “significant amount” of maintenance and modernization that Burke talked about with the cruisers relates to upgrades for ballistic missile defense — something the Port Royal already possesses.

The defense bill authorizes more than $628 million for the “retention” of the cruisers Vicksburg, Anzio and Cowpens, and none for Port Royal, the Navy said.

The 567-foot Port Royal ran aground on Feb. 5, 2009, on coral and sand in 14 to 22 feet of shoal water a half-mile off Honolulu Airport’s Reef Runway. It was stuck for four days as wave action rocked the vessel on the reef.

Needed repairs included replacement of the bow-mounted sonar dome; refurbishment of the shafting, running gear and propellers; painting of the underwater hull; structural repairs to the ship’s tanks; and fixes to cracks in the superstructure, the Navy said at the time.

Lt. Courtney Hillson, a Navy spokeswoman at the Pentagon, said the “Navy will comply with the law and conduct a material condition assessment on Port Royal. This report will be useful in determining the future of Port Royal.”

The Port Royal and its crew of about 330 returned Feb. 13 from a nearly eight-month deployment that included the handover of the Al Basrah and Khawr Al Amaya offshore oil terminals at the end of the Iraq War, the Navy said.

Before the deployment, the Port Royal’s commander, Capt. Eric Weilenman, told the Navy Times there were no lingering problems with the ship.

“She is absolutely rock solid. Structurally, she is sound,” Weilenman said of the ship. “We ran her at flank bells (top speed, with) hard rudder turns. No issue, whatsoever.”

The Port Royal remains fully manned and operationally ready, Navy Region Hawaii said.