YOKOSUKA NAVAL BASE, Japan -- The Navy's three newest fast-attack submarines are on operational restrictions after a contractor found undocumented repairs made to critical components, service officials said.
USS John Warner, which was just commissioned Saturday, along with USS Minnesota and USS North Dakota, have been sidelined because of concerns over pipe elbows that help connect the steam generated by the nuclear power plant to the turbines.
"As part of an ongoing investigation into a quality control issue with a supplier, General Dynamics Electric Boat (GDEB) determined that three steam pipe elbows supplied by the vendor in question required additional testing and repair due to unauthorized and undocumented weld repairs having been performed on these elbows," said Rory O'Connor, a spokesman for the Naval Sea Systems Command, in a statement sent to Stars and Stripes on Wednesday evening from Washington.
GDEB and Huntington Ingalls Industries-Newport News Shipbuilding are performing additional inspections, O'Connor stated. The two contractors are the Navy's primary submarine builders.
Keeping up standards for the components is an important safety measure for the crews, O'Connor added.
The safety concerns are related to long-term wear on the elbow pipe joints, according to an unidentified Navy official quoted by Defense News, which first reported the story.
The elbows were supplied by a subcontractor and passed ultrasonic inspections but later failed upon further inspections using different methods, according to Defense News.
North Dakota was commissioned last year after a Navy investigation into substandard third-party contractor components delayed the boat's launch by five months. The Navy inspected 58 components and made multiple repairs to the $2.6 billion submarine.
North Dakota and John Warner are the first two Block III boats, which feature redesigned bows and replace 12 launch tubes with two larger tubes, each of which can hold up to six Tomahawk cruise missiles.