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NASA Space Science

Low Quality Alloy Cause of Shuttle Main Tank Issue 118

BJ_Covert_Action writes "NASA engineers have finally discovered the root cause of the cracks that have been found on space shuttle Discovery's main external tank. The main tank, one of the 'Super Lightweight Tank' models developed by Lockheed-Martin, employs an aluminum-lithium alloy developed by Lockheed-Martin specifically for this application. The new alloy is used in various structural stringers throughout the SLWT design. Unfortunately, the batch of this alloy used in the tank that is currently mated with the Discovery shuttle appears to be of low quality. The alloy used in the stringers has a 'mottled' appearance, compared to the nominal appearance typically used in the main tank stringers (see picture in article). This appearance is indicative of a fracture threshold that is significantly lower than typical. NASA has determined, through testing, that this low grade alloy has only 65% of the fracture strength of the nominal alloy typically used. NASA engineers have devised a potential fix to the problem that they are currently testing to ensure the repair will cause no unintended consequences. NASA plans to have the Discovery shuttle ready to launch again by February 24th, 2011."
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Low Quality Alloy Cause of Shuttle Main Tank Issue

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  • That is surprising (Score:5, Insightful)

    by vadim_t ( 324782 ) on Friday January 14, 2011 @01:47PM (#34880232) Homepage

    The bad alloy is distinct enough from the good one to tell at a glance from a low res photo.

    And it even seems that they had records of the unusual appearance. So the materials came in, somebody noticed and documented that this batch looked funny, but nobody thought to investigate if they might have got something other than what was specified?

  • by jd ( 1658 ) <imipak@@@yahoo...com> on Friday January 14, 2011 @01:49PM (#34880268) Homepage Journal

    The problem is, the fuel tank production facility has already closed. There aren't any spare parts. It could well be that the last production cycle was done on the cheap for just that reason - there's nobody to complain to, there can't be any penalties placed on those responsible, they get their last paycheck, and if they walk away with the difference in costs, well who'se going to even notice?

  • by Rosco P. Coltrane ( 209368 ) on Friday January 14, 2011 @02:02PM (#34880470)

    That's the Government's stupidity for not putting a performance clause into the contract

    And you know that because...?

    I work as a QA engineer for a large defense contractor. One thing I can tell you is that we issue a lot of documents requiring our plants and our suppliers to follow a metric shitload of MIL, ISO, EN and whatnot standards, for the very purpose of meeting stringent quality requirements set forth in the contracts. It takes months, sometimes years for our products just to pass qualification and type-approval tests, and our products don't even go in space.

    In short, you're talking out of your ass.

  • by geekoid ( 135745 ) <dadinportland AT yahoo DOT com> on Friday January 14, 2011 @02:03PM (#34880488) Homepage Journal


    Quality has been a part of every government requirement I have ever seen.
    Price is another factor as well.

    But hey, lets not let facts stand in the way of urban myths and hyperbole.

    NASA quality has had a very demanding view on quality. No, it's not perfect. Unfortunately, when it's not perfect and something fails, it's a big deal. When that happens, no one seem to remember all the success.

    The singles biggest point of quality failure is no bid contracts.

  • by llung ( 1841162 ) on Friday January 14, 2011 @02:08PM (#34880546)
    Blame the government? They didn't build the tank, the contractor did. The idea is for the contractor to build the item they bid upon to the specifications. How would the engineers know that these are at 65% of the expected fracture strength? Because they have specs.
  • by smooth wombat ( 796938 ) on Friday January 14, 2011 @02:10PM (#34880586) Journal
    They build things that barely get by the predefined margins of acceptability with the lowest cost.

    Like Spirit and Opportunity, right?

    Or did you mean Deep Impact (not the movie)?

    Voyager 1 and 2? Cassini?
  • by BJ_Covert_Action ( 1499847 ) on Friday January 14, 2011 @02:34PM (#34880884) Homepage Journal
    Or, alternatively, back in November when Discovery was being fueled, an on-pad engineer could have noticed a crack along the main tank that looked large enough to be suspicious and reported it. As a result, NASA delayed a launch multiple months (something which causes a hassle for other launch platforms preparing to launch, as shuttle almost always takes precedence) to figure out what was causing the main tank, a gigantic bubble filled with cryogenic, highly flammable liquid explosives, to crack since, you know, they don't want that toxic shit spraying all over their personnel on launch. Then, after performing three months of rigorous analysis to model, simulate, and test a highly complex system with hundreds of thousands of stress focal points that are subjected to extreme temperatures throughout a mission, the people that NASA pays a cubic assload of money to for being smarter than you and I finally figured out the problem, and proposed a solution.

    There are dozens of ways low-quality material could have made it through the QA process at Lockheed that don't require some sort of communist-conspiracy, "OMG we need jobs," to explain. For instance, it could be that, since production on this particular tank model has stopped, the remaining work force was simply trying to make due with what they had, materials wise, and produce their product (the tank) as quickly as possible without giving a particular two-shits to the wind as to how sound it was since, you know, their program was getting canceled anyways. Or, yeah, it could be a jobs program. Sure.
  • by Thelasko ( 1196535 ) on Friday January 14, 2011 @02:51PM (#34881084) Journal
    I'm also willing to bet that the best and the brightest at the tank manufacturing facility left shortly after they heard the shuttle program was canceled.
  • by Dunbal ( 464142 ) * on Friday January 14, 2011 @03:08PM (#34881318)

    A contractor provides inferior quality alloy for a lightweight fuel tank. So NASA engineers come up with a system to brace said fuel tank, reinforcing it and fixing the problem.

    The lightweight fuel tank now weighs as much as a regular fuel tank, when you include the reinforcement, but at 3 times the cost. But don't worry, people stayed employed at your expense, and that's all that matters. Yay!

  • by timeOday ( 582209 ) on Friday January 14, 2011 @03:19PM (#34881470)
    It would take some actual evidence to convince me anybody did this knowingly. Your assumption of, "oh well, it's our last batch, I don't care if the shuttle blows up" doesn't sound very likely to me.

Statistics are no substitute for judgement. -- Henry Clay