The US Navy says parts on its Virginia-class attack submarines are breaking sooner than expected

• The US Navy has a parts problem with some of its Virginia-class submarines.
• Some parts "are failing more quickly than we originally envisioned," the acting Navy secretary said.
• His comments follow a report revealing the Navy has cannibalized hundreds of subs for working parts.

US Navy leaders acknowledged a problem with the service's Virginia-class fast-attack submarines on Tuesday, telling lawmakers that parts are failing much sooner than expected.

"The Navy is aware there are some challenges with some of the Virginia-class supply chains," acting Secretary of the Navy Thomas Harker told the Senate Armed Services Committee.

"There are parts on the Virginia class that we thought were going to be life-of-the-submarine parts, and they are failing more quickly than we originally envisioned," Harker said, adding that the service's sub crews and parts support are having to go back in and find replacement parts.

Questions about the parts problem follows a report from Bloomberg on how that spare parts problem is crippling the $166 billion fleet of four dozen nuclear-powered Virginia-class submarines.

The report cited a Congressional Budget Office report noting "significant delays" in submarine maintenance at Navy shipyards, as well as difficulties securing necessary parts.

The CBO said that in situations where parts are not readily available, a shipyard may choose to "cannibalize," or borrow, parts from another submarine, typically one that has just entered the shipyard for maintenance.

Between 2013 and 2019, the number of submarine parts the Navy had to swap out jumped from around 100 to 450, though the number has since started to decline. In total, the service has had to swap over 1,600 parts since 2013, Bloomberg reported.

Asked Tuesday why some parts on the Virginia-class submarines are failing sooner than expected, Harker responded, "I'll have to get back to you on that."

In a statement to Bloomberg, the Navy said that engineering analysis and testing indicated that parts on the submarines that first entered service in 2004 would last several decades.

But, the service said, unexpected "degradation," like "corrosion caused by complex galvanic interactions," has caused some parts to break sooner than anticipated.

Naval Sea Systems Command said that the design of the Virginia-class submarines was "revolutionary and forward-thinking," even if some parts "have failed sooner than expected." The command explained that the procurement approach offers the Navy the ability "to make reliability improvements in later blocks."

Most, around 70%, of the submarine spare parts problems were in the first two blocks, or development models, that were first delivered to the Navy in 2004 and 2008.

The naval command, which oversees naval maintenance activity, told Bloomberg that it is "not satisfied with any material cannibalization that limits our submarine fleet's ability to respond to national tasking and is taking all steps necessary to avoid these scenarios."

The Department of the Navy's fiscal year 2022 budget proposal requests funds for two new Block V Virginia-class submarines. It is unclear if the parts problems that affected earlier designs will affect the newer models.

The Navy's Virginia-class submarines are stealthy underwater warfighting platforms armed with torpedoes for anti-submarine and anti-ship combat, as well as cruise missiles for strikes on land-based targets. The submarines are also equipped with high-end sensors for intelligence, reconnaissance, and surveillance missions.