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NASA Finds Critical Assembly Fault in Shuttle
mzs writes "During corrosion inspection on Discovery, technicians noticed that one of the gears in a rudder actuator had been installed backwards. This particular actuator was the top-most of four that control the air brakes on the tail. As luck turns out, if it had been the bottom-most actuator, loss of the shuttle and crew would have been nearly inevitable. Plans are in place to have four spares by the time Shuttle missions resume next year."
Could they not stamp "THIS SIDE UP" or whatever on the components?
Trolling is a art,
I thought they even checked Airplanes more thoroughly
Nothing to see here
...and I'm sure there will be lots of negative posts about NASA here...
It'd be nice to give some credit for the people that have put in layer upon layer upon layer of safeguards to check for exactly this sort of thing and the dilligent people that find this stuff. And caught it.
The awful thing is that this is going to be just another reason for Congress to loot the NASA money bag.
May we never see th
I'm quite surprised they're being quite so upfront about this. Kudos to them... On the other hand, I believe it to be a part of the healing process to convince the general public that they are, in fact taking the Columbia disaster extremely seriously, and want to show progress in the inspection and faliure-cathing procedures that obviously did not work for Columbia.
It was, however, just a matter of time before a Columbia-type disaster occured. The suttle program has a remarkable safety record, Challenger and Columbia no matter.
Come on NASA, it's not rocket science! Oh wait...
...I'll be running Duke Nukem: Forever on Microsoft Longhorn before the next shuttle launches.
NASA Finds Critical Assembly Fault in Shuttle
I know NASA is conservative with technology, but using assembly in this day and age is way backwards!
They should really do some double checking on this stuff. It's hard to imagine mistakes like this happen when dealing with something that holds the fate of a handfull of people's lives; not to mention all the millions of dollars put into these projects that would go down the drain. When dealing with people's lives and huge sums of money it's worth it to go over _everything_, and put in for better training so these thing don't happen again. They caught it this time, but if they don't take enough precaution, they might not be so lucky in the future.
Buckethead
And if you read the article, you realize that NASA installed defective actuators not once, but twice! The first being the one that was successfully flown 30 times, and the second in the spare actuators.
Given the complexity of a system like the shuttle, it is not surprising that out of 1000s of components there could be a mistake in one of them (and given some redundancy and robustness, it is not surprising that the shuttle could fly 30 times with one or more poorly installed components, though one would not normally want to bet on that...).
However, two errors out of 8 actuators checked implies some serious quality control issues.
-Marcus
Discovery flew safely 30 times with the defective actuator
When does a defect become a problem? I wonder if this was really a Critical problem because shouldn't some indication have already been seen by now?
I mean since they have fixed this problem will two other problems surface that are more critical and maybe they should have left it alone?
In engineering, it's usually good practice to design somthing that only assembles one way. That way, whoever is assembling it (no matter how intelligent they are) can only install the component the way it was meant to be.
It's strange and somewhat disconcerting that this was not the case for this shuttle component, but I haven't seen the part in question.
The important lesson here is about the design of critical parts. Nothing important should be made asymetrical and reversable. Even labeling it "THIS SIDE UP" on one side and "WRONG! DANGER! WRONG!" on the other isn't good enough. The part should either be symetrical, so it doesn't matter which way it goes, or non-reversable, so it wont fit upside down/backwards. Important thing to remember in mechanical engineering (gears|levers|*) or even eletrical parts specifications (connectors should be keyed to mate only one way: the right way).
Conclusion: the Empire squashes the Federation like a bug. Accept it.
The same basic thing happened with the F-111 program in the 60s. The drawing had a piece that was installed upside down, but the technician installing them said, this ALWAYS goes right side up and installed it that way. A couple crashes and the grounding of the whole F-111 fleet later, and the trouble was found. I don't know what happened to the installer, but I can't imagine it was any good. Check twice, install once :)
In this case nobody died and several lessons were learned, including something about fault-tolerance in actuators. I think two of the most valuable space flights from this point of view were Apollo 13 and the Mir mission that caught fire.
Things will go wrong. Learning how to cope when the evil wind blows is critical. In this case, we now know that the thing can be flown with one actuator in upside down. If the bottom one malfs, swap it out in orbit with the top one, and you still might get home. People are going to get killed doing this. People got killed learning to sail the Mediterranean. It's still worth doing.
Some mornings it's hardly worth chewing through the restraints to get out of bed.
I can imagine the guy that noticed this first. Probably went something like: looks at actuators. looks at diagram of how they're to be installed. looks at diagram again. looks at actuators. turns diagram around; notices that the legend is now upside down, so concludes that can't be it. checks other pages of diagram to see if this page is unusual--different view, maybe. finds that it isn't. checks back for errata. finds none.
Looks around. "Hey Bob, what do you make of this?" Thinks about all the work that day that isn't going to get done, because now management and, if he's lucky, congressional inspectors are going to crawl up his ass. At least he knows that he didn't *install* the things.
--
$tar -xvf
I work in New England, contracting for a jet engine manufacturer (and you can get it in two if you know the aero industry). Things like this happen frequently in manufacturing, especially with development hardware, before the kinks have been worked out of the assembly process and parts are ready to go to production. Assembly mistakes range from things that are easy to do but also easy to fix, like cut or cracked O-rings and tool knicks on non-critical parts, to things that are real screw-ups and result in major headaches, like parts left out entirely or vital parts being installed incorrectly and badly damaged because of it. You could consider the entire shuttle program to still be development-phase engineering, since only a few shuttles were ever built.
An example: a while back, we had a test engine spewing fuel all over the test cell for no readily apparent reason, prompting a panic that an entire compartment of the engine would have to be redesigned from scratch--until one of the test engineers found a fuel line seal that had not been reinstalled in the engine after the last teardown and reassembly. How do you miss something like this when there's a careful set of instructions to follow for every step of the assembly? I don't know, but I do know that humans are fallible, so we are constantly dealing with a stream of lost, damaged, and defective parts. Anyway, they put the seal back in, and the engine worked fine. (I have an NDA, so this is not what actually happened, but it is analogous.)
When I was in school, the more I learned about the environment the shuttle operates in, the more I was impressed by the fact that it worked at all, and now that I'm learning more about manufacturing engineering (not what I studied for; stupid job market), I'm surprised that the shuttles have as few problems as they do.
-Carolyn
Like Daddy always said: if you can't dazzle 'em with brilliance, baffle 'em with bullshit.
On a side-note, the reason Nasa is stuck in the proverbial hard-place between multi-billion dollar budgets and missions that nobody cares about is that we've all started over-valuing human-life. It's ridiculous that space exploration all but stopped because of the 2 shuttle disasters. Certainly, the loss of those crews was tragic, but the best way to honor those crews is to relentlessly pursue the dream that they died for, not hamstring ourselves being overly cautious.
Call me old-fashioned, but I still believe there are things more important than one or a dozen human lives. IMO, exploring the universe is one of them.
The meek shall inherit the earth, in 3 by 6 plots. - Lazerus Long
When the Mars Climate Orbiter was lost due to a mixup between NASA and Lockheed Martin concerning imperial vs. metric units, I recall Dan Goldin, the then-head of NASA, being asked by a reporter if heads would roll. He replied something like, "sure we could do that, but then we'd have to replace those engineers. Now we already hired the best ones we could find in the world, so where are we to get better ones?"
d perfectly without flaw. I would, however, expect it to be designed to work well in the face of such problems, as does seem to be the case here. Discovery had 30 successful flights despite a part on a major control surface being installed backwards? Everyone landed safely? Tons of good science, too? Doesn't mean the problem shouldn't be fixed, but kudos to NASA for what sounds to me like a job well done.
The Shuttle is one of the (if not *the*) most complex bits of engineering we, as a world-wide society, have achieved. I would never expect any shuttle to be manufactured/assembled/flown/controlled/maintaine
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.