SAD: Problemi sa podmornicama klase "Virginia"

[Dreadnought]

Novi problemi za Američku mornaricu. Oprema za rukovanje naoružanjem koja je ukracana na četri podmornice klase "Virginia" pogrešno sastavljena od strane radnika u brodogradilištu Northrop Grumman. Problemima su zahvaćene podmornice "North Carolina" (SSN 777), "New Mexico" (SSN 779), "Missouri" (SSN 780) i "California" (SSN 781).

U nastavku cela vest ....


New Sub Construction Problem Found at Northrop Grumman


Weapons-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 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.

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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's crew moved aboard for the first time July 28 and the submarine 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, no 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 shipbuilders are responsible for building 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 more easily accommodate differently shaped torpedoes, mines, missiles, underwater vehicles or 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," according to the NAVSEA statement.


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 to Defense News, 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."

Asked what problems the improper work could lead to, 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."

The problems are another embarrassment for Northrop Grumman's submarine builders. In May, the Navy revealed that a welding inspector falsified records. He was dismissed by the company, which was forced to re-inspect thousands of welds. Another problem came to light in December 2007, when inspectors found that improper welding filler had been used on a number of welds. The company has made a number of changes in light of those issues.

Northrop insists there is no connection between the three problems.

"It's important to note that the inspector issue was not one of process and therefore is totally separate," the company said Thursday in an e-mail to Defense News. "That being said, the quality of our work and our product quality is something we take very seriously. We have instituted improvements in our engineering, production and quality systems across Northrop Grumman Shipbuilding. The changes we are making begin with an absolute commitment to the quality of ships we are delivering from all of our shipyards. We have instituted process changes and improvements for the short-term, mid-term and long-term. These cover inspecting and evaluating our work to ensure it adheres to the Navy's strict requirements. When issues arise, it's something we address in an immediate and methodical way."

No cost or repair time estimates for the fastener problem are as yet available, NAVSEA spokeswoman Pat Dolan said Thursday. Navy officials stressed that the ships remain safe and that the issue was identified by the overall attention to quality.

Izvor: defensenews.com

[duje]

Nekoliko dana poslije primanja u flotu, USS John Warner upučena na tehnički pregled....(pojavile se teškoče na koljenima parovoda...)

Vir: "Obramba"
http://www.obramba.com/
07/08/2015

Tehnične okvare najnovejših ameriških podmornic razreda virginia?

PO LE NEKAJ DNEH SLUŽBOVANJA MORA PODMORNICA USS JOHN WARNER NA TEHNIČEN PREGLED

Ameriška mornarica je prvo soboto v avgustu 2015 v operacije vključila novo jurišno podmornico USS John Warner (SSN-785) na jedrski pogon, ki pa so jo že po nekaj dneh poslali na pregled, skupaj s še dvema najnovejšima podmornicama razreda virginia.

Ameriška mornarica (US Navy) je v zadnjih dveh letih operativno začela uporabljati tri nove jedrske podmornice razreda virginia – od septembra 2013 podmornico USS Minnesota (SSN-783), od oktobra 2014 podmornico USS North Dakota (SSN-784) in avgusta 2015 še USS John Warner (SSN-785). V začetku tedna so vse tri zaradi morebitnih tehničnih okvar poslali na tehnični pregled.

Ugotovili so namreč, da bi pri kolenih parnih cevi lahko pojavile težave. Dobavitelj le teh, General Dynamics Electric Boat (GDEB), je namreč sporočil, da je kolena potrebno dodatno testirati in popraviti zaradi nepooblaščenih in nedokumentiranih popravil (varjenje). Ta “kolena” so ključnega pomena za prenos pare iz motorjev do turbine, je dejal predstavnik mornarice Rory O’Connor in dodal, da so izredno veseli, da jih je dobavitelj vnaprej opozoril na morebitno pomanjkljivost.

Pentagon je jedrsko podmornico USS John Warner (SSN-785) (block III) ob začetku službovanja opisal kot najnovejšo hitro jurišno podmornico, ki bo “pokazala” najnovejše stealth, vzdržljive in bojne zmogljivosti.

Pripravil: A. Knific, foto: US Navy