Bad Bolts in 4 U.S. Submarines
Assembly Glitch Could Disable Weapons Room
Weapon-handling gear aboard four Virginia-class attack submarines was improperly assembled by workers at Northrop Grumman's Newport News shipyard - the latest manufacturing problem at the Virginia facility.
The problem affects the submarines North Carolina (SSN 777), New Mexico (SSN 779), Missouri (SSN 780) and California (SSN 781), Naval Sea Systems Command (NAVSEA) confirmed for Defense News. Uncorrected, the problems could disable the weapons room, according to the Navy.
At issue are fasteners: the nuts and bolts that hold together the tracks for the sophisticated handling system in each submarine's weapons, or torpedo, room.
Yard workers at General Dynamics Electric Boat in Groton, Conn., discovered the mechanical quality issue in early August while working on the Missouri. After notifying Northrop Grumman Shipbuilding - which shares equally in building the Virginia-class submarines - GD, as the prime contractor for the program, notified the Navy on Aug. 6.
Of the four affected submarines, only one, the North Carolina, is in service, having been accepted by the Navy in February 2008 and commissioned in May of last year. The New Mexico is in the final stages of completion at Newport News. The Missouri is set to be launched later this year at Electric Boat, and Newport News held a keel-laying ceremony for the California this past May.
According to the Navy and Northrop Grumman, only minor problems were found on another submarine, New Hampshire (SSN 778), which was delivered by Electric Boat in August 2008.
Under the 50/50 work share agreement between Electric Boat and Newport News, each shipyard is responsible for building certain portions of each submarine. The sections are barged between the yards, and EB and Newport News alternate in assembling, launching and completing each sub.
Newport News builds the torpedo rooms of all the submarines.
The system in the Virginia class for handling weapons is different than on other submarines. Rather than moving each weapon individually, cradles are used to accommodate differently shaped torpedoes, mines, missiles, underwater vehicles and other items, and a track system is designed to enable sailors to smoothly shift weapons between the submarine's four torpedo tubes.
According to a written statement from NAVSEA, "during the final alignment of the forward and aft weapon cradle tracks aboard the Missouri, several bolts, bolt holes and fasteners were found that did not meet specifications. Specifically, the shipbuilders have found improperly drilled and machined bolt holes, bolts that had been improperly machined, and fasteners that were not installed and tightened properly."
The shipbuilders are continuing to investigate the problem and are to provide "a combined assessment of the issue to the Navy within two weeks," NAVSEA wrote.
Could Prevent Weapons' Movement
"The application of nonspecification bolts, bolt holes and fasteners could result in a misalignment of the weapons-handling equipment that could prevent the movement of weapon cradles within the torpedo room, and could compromise the integrity of the weapons handling system in a shock event," NAVSEA wrote.
Inappropriate use of Loctite, an adhesive product used to fix in place nuts and bolts, also is an issue. Northrop Grumman, in an e-mail, described the problem as including "use of the incorrect grade of Loctite; close tolerance bolts that were modified without the proper use of appropriate technical direction (certain shanks tapered, thread ends cut short); close tolerance bolts that did not meet the diametrical clearance requirements for the respective hole; truss tapped holes that were damaged and nonconforming threads."
Northrop Grumman wrote, "These fastener issues might, under certain conditions or circumstances, result in a misalignment of the weapons handling equipment that could prevent the movement of weapon cradles or the proper operation of the weapons handling system in a shock event."
Newport News had been moving along smartly in completing the New Mexico, the third Virginia-class submarine to be delivered by the shipyard. The crew moved aboard on July 28, sea trials were set to begin in early September, and the company was working toward a delivery date of Oct. 5 - well in advance of the contract delivery date of April 30.
"This will impact the New Mexico's sea trials," shipyard general manager Matt Mulherin said. "We'll have to get that sorted out."
But Mulherin and the Navy's officer in charge of the sub program expressed confidence the ship would be handed over ahead of schedule.
"I still have every confidence the ship will deliver before the contract delivery date," Capt. Michael Jabaley said Aug. 21.
No cost or repair time estimates for the fastener problem are as yet available, NAVSEA spokeswoman Pat Dolan said Aug. 20. Navy officials stressed that the ships remain safe and that the issue was identified by overall attention to quality. ■
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