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  #1  
Old 09-05-2012, 05:53 PM
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Ironflight Ironflight is offline
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Default A Little Maintenance Issue....

So we have this bolt that jams up going into a long threaded tube – it’s not like a regular nut that just has a few threads to go through – more like a Van’s wing tie-down receptacle. The bolt goes in about 4 turns, then binds up – torque gets higher than allowed.

Rather than damage anything further, we backed it all out and waited a few days to think about it (always good practice) and fabricate a few tools. The first tool was a tiny wire gun-barrel brush – we put this in a power driver and SLOWLY ran it into the female threads, then back out. This generated a bunch of small metal debris. Did this a couple of times until it came out without any more FOD. We then blew out the hole using a littel nozzle. Next came a cut-down toothbrush with lube on it to get lubricant deep into the threads. We followed that up with a bolt (not the one we were going to use in final assembly – it was a sacrificial bolt) to test the (hopefully) now cleaned threads. This was carefully driven in with a “T” Handle and a ratchet wrench when it got harder. Frankly, this was a bit of a “re-tapping” exercise. It got just a little tight at the same place as before, then smoothed out – I think we found the damaged thread area! Since the fastener isn’t going to really see a lot of load in use, having a slightly damaged interface probably isn’t a serious issue – so long as we could get it tightened down.

Sounded like it could very well have been done in your own workshop, doesn’t it? Oh, did I mention that this was all done today in low earth orbit, outside, on the International Space Station by two astronauts? Doing this on an EVA has been described as trying to “fix your roof at night while wearing diapers, ski clothes, and SCUBA gear over your pajamas”. Or installing -3 rivets while wearing oven mitts. But truthfully, it’s just routine troubleshooting of hardware…isn’t it?

Hopefully, this will make you feel proud the next time you screw up a hole on your very expensive Lycoming. Might not make you feel any better of course…but at least you’ll know that you have distinguished company! Even in space, it is not always “Rocket Science”, and we can get by with something less than “perfect”. As long as your fix is “good enough”, well…that should be good enough….

Paul
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Last edited by Ironflight : 09-05-2012 at 07:39 PM.
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  #2  
Old 09-05-2012, 06:06 PM
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Jerry Cochran Jerry Cochran is offline
 
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Default Fix some threads? Check...

Paul,

In that case, I bet most of us here could be astronauts?

.
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  #3  
Old 09-05-2012, 06:09 PM
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RV6_flyer RV6_flyer is offline
 
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Default

Too bad a tap was not available to clean the threads out. That is what I would have used in my hangar.
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  #4  
Old 09-05-2012, 07:12 PM
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Russians were doing it or it's classified?
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  #5  
Old 09-05-2012, 07:37 PM
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Default

Quote:
Originally Posted by RV6_flyer View Post
Too bad a tap was not available to clean the threads out. That is what I would have used in my hangar.
Yeah...you'd think! We have a tool kit onboard that is essentially the Snap-On demo catalog...but no taps!!


Quote:
Originally Posted by Vlad View Post
Russians were doing it or it's classified?
American Boxes on American Truss....American astronauts!!
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  #6  
Old 09-05-2012, 07:45 PM
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Quote:
Originally Posted by Ironflight View Post





American Boxes on American Truss....American astronauts!!


Proud to be an American!
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  #7  
Old 09-05-2012, 07:46 PM
Alex Alex is offline
 
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Default

Quote:
Originally Posted by Ironflight View Post
Next came a cut-down toothbrush with lube on it to get lubricant deep into the threads.
What kind of lubricant do they use? I'd assume the usual terrestrial stuff wouldn't work exo-atmospheric.
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  #8  
Old 09-05-2012, 07:57 PM
Wayne Gillispie Wayne Gillispie is offline
 
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Default Let me guess...

Was it aluminum-aluminum galling due to not using anti-sieze compound? How about trying to install a 120*C bolt in sunlight into a shaded hole at -100*C?? Sorry to speculate. If only they had checked the weather.

Time to ship a tap/die set up there now.
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  #9  
Old 09-05-2012, 08:22 PM
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Quote:
Originally Posted by Alex View Post
What kind of lubricant do they use? I'd assume the usual terrestrial stuff wouldn't work exo-atmospheric.
Surely Boelube of course?
I spent a good chunk of my day watching these intricacies and was completely enthralled with every quarter turn as any good mechanic/engineer would be.
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  #10  
Old 09-05-2012, 08:29 PM
David Paule David Paule is offline
 
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Default

Didn't they have a probe that would let them look into the hole and see what was going on?

Dave
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