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  #1  
Old 06-05-2018, 07:07 PM
asw20c asw20c is offline
 
Join Date: Jun 2010
Location: Edgewood, NM
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Default Stuck AN913-3D

I finally finished my fuel tanks and leak tested them this past weekend. No leaks!!!!!!!! However I discovered that the AN913-3D plug, that's the blue aluminum plug that goes in the top opening on the inside rib of the fuel tank(s) intended for a fuel return line if your powerplant uses one, is hopelessly stuck. I've tried hard enough to back it out that I have rounded the corners. Obviously there was some gorilla snot contaminating the threads. My choices are to either simply put a glob of snot over the plug and call it good, or to try again to remove the plug so I can use some proper thread sealant making this fitting usable for a future fuel return line should one ever be needed.
My fear is causing damage; either shearing the rivets of the flange into which it is screwed (and stuck), buckling the rib, or causing separation between the rib and the skin. I surely don't want to make things worse, but at the same time it drives me crazy that after all the effort and care that went into building the tanks that now I have a stuck plug. Any thoughts on how to remove it? I've tried WD-40 hoping it would seep into the threads, but no joy. I have a bottle of CRC Freeze Off on order hoping I might be able to shrink it just enough with cold temps to break the bond. I'd appreciate thoughts from others who have run into something similar.
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  #2  
Old 06-05-2018, 07:57 PM
VA Maule VA Maule is offline
 
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Location: Bucking ham, Virginia
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If you're not going to use it for a return and the tank passed the test why worry about it?
If you're dead set determined to take it apart two pair of Vicegrip brand locking pliers (not the harbor fright junk) one pair on the 3/8" plug second pair on the base and lock the pliers tight, but be forwarned the threads may be seized/gauld together and the female threads may come out with the plug thence you get to try your hand at taping it out to1/2" and getting chips in the tank
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  #3  
Old 06-06-2018, 09:44 AM
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Raymo Raymo is offline
 
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If it was installed with something like thread locker, a heat gun will break it down for removal.
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  #4  
Old 06-06-2018, 09:55 AM
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az_gila az_gila is offline
 
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Quote:
Originally Posted by Raymo View Post
If it was installed with something like thread locker, a heat gun will break it down for removal.
Heat would probably not be good for the proseal on the inside of the tank.
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  #5  
Old 06-06-2018, 11:51 AM
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kbalch kbalch is offline
 
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Location: Clermont, FL
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Changing over to a fuel-return system isn't something that, having decided against it on initial construction, one is likely to implement in future. If it doesn't leak, leave it alone; you can only make things worse at this point.
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  #6  
Old 06-06-2018, 12:07 PM
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Raymo Raymo is offline
 
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Quote:
Originally Posted by az_gila View Post
Heat would probably not be good for the proseal on the inside of the tank.
Good point. Specs say it is okay up to 250 F with short excursions to 275, which might be enough.
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  #7  
Old 06-06-2018, 02:09 PM
asw20c asw20c is offline
 
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Thanks all for the replies so far. The plug was not installed with thread-locker. It was installed dry with the expectation that I would go back and reinstall later with a thread sealant. I even made a conscious effort with flashlight and dental pick to clean the threads before installing the plug but obviously there was something there I couldn't see which has now seemingly welded the plug in-place.
I've ordered some of that CRC freeze off in a can thinking I could put a collar of silicon insulation (like a kitchen hot pad) around the fitting and impinge the cold gas directly on the plug in hopes of shrinking it a bit, and maybe breaking the seal that is holding it. As mentioned above, I don't want to make things worse but I do want to try once more to remove the plug. However as someone already said, if the threads have galled then nothing will work. My plan is to freeze it, shock it lightly with a light hammer, then attempt to remove it again with less force than I applied previously. If that doesn't work I'm just going to put a big glob of snot on it and cut my losses.
What a letdown after working so hard to build leak-free tanks!
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  #8  
Old 06-06-2018, 03:51 PM
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kbalch kbalch is offline
 
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Quote:
Originally Posted by asw20c View Post
What a letdown after working so hard to build leak-free tanks!
You did build a leak-free tank. This unused return line pseudo-glitch is irrelevant. Stop fussing with it and move on...
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  #9  
Old 06-06-2018, 04:53 PM
mturnerb mturnerb is offline
 
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Quote:
Originally Posted by kbalch View Post
You did build a leak-free tank. This unused return line pseudo-glitch is irrelevant. Stop fussing with it and move on...
“Let it Go” needs to be the theme song for airplane building. We all tend to obsess over stuff like this.
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  #10  
Old 06-06-2018, 05:10 PM
David Paule David Paule is offline
 
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Quote:
Originally Posted by az_gila View Post
Heat would probably not be good for the proseal on the inside of the tank.
I can confirm that. See this thread about removing Pro-Sealed parts.

Dave
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