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Did I mention that I hate fuel tanks.....

didja

Active Member
So, I have both my left and right fuel tanks closed out. I am in the process of getting them ready to pressure test. I have inserted all of the fittings, including applying fuel resistant thread sealant...?. until I came across a problem...?

While inserting the filter, I got it about half way when it galled on me..... I attempted to remove it and it ended up snapping where the filter is attached at the threads (see pics below)?.

Any ideas on how to get the rest of the filter out? Or am I going to have to open the tank, drill out the threaded mount from the rib where the filter screws into and try to replace it all and then seal everything back up?

any guidance is much appreciated.....

Did I mention that I hate fuel tanks.....?

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Easy out

Maybe an EasyOut? Big box store or Ace. They are designed to grab left hand so the piece may back out.
 
NPT tap

If that fails, drill to just under thread size, then use an NPT tap to chase the threads.

I had a similar thing happen to me when trying to remove a leaky fuel tank fitting and was able to perform a successful surgery this way. The replacement fitting in the recut thread hasn't leaked in six years.
 
So, I was able to use an easy out to get the remnants out. Now, this is what is left of the threads.

20181018_013459.jpg


So, does anyone know the size tap to use to try to repair the threads?

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I appreciate the help......
 
Side benefit of getting pissed at my fuel tank adventures.... I was able to wash my piper finally! (sorry for the non RV related pic!)

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Never EVER try to insert a new part into boogered threads!

Well Scott, that is a little mess. First determine what size it is. You can get actual specs for the AN fitting - is it a 3/8" tube? If so it is likely a 1/4" NPT. Go to the hardware store, or order a pipe tap and carefully begin to chase these threads.

Never EVER, try to insert a new part into boogered threads!! It just makes the situation worse. Since you have gotten this far, you might need some expert assistance to recover what is left.

Now, back to the tap. This aluminum is soft, so be sure the tap is aligned with the hole and lubricated with some oil/grease before it touches the aluminum. Grease will contain the chips. Then with skill and care begin to twist it and do your best to get the tap into the original first thread. This is where the skill comes, push too lightly and it won't engage and will make the hole tapered with no threads. Wrong place and it will double the threads and half the material. Right place, right torque, good alignment, lubricant and proceed a little at a time and it should turnout alright.

The good news is a tapered thread allows some extra insertion length, but limited by the hex on the AN fitting. You can use a steel fitting. I would check the threads lubed, then clean and use some proseal to ensure a leak free fitting. No pressure i there so it is not going to blow out.


Wasn't all this in the -14 instructions?
 
Just checking - how much torque were you applying? These fittings should be tightened, not bottomed out.

I had the strainer only threaded in about half way before it galled. I was using a socket to insert so that it would have even torque but got galled. I tried to back it back out when it froze and then snapped off as I was trying to get it out.
 
Bill, thank you for your help. I will have to visit the local aviation aisle at ACE tomorrow and grab some taps!
 
Just checking - how much torque were you applying? These fittings should be tightened, not bottomed out.

I was thinking this, too. I've never seen a properly installed fitting snapped like that.

Remember that NPT threads should always get some lubricant. I've used FuelLube (now called EZ Turn) for years with great success.
 
To avoid galling use a steel fitting, alum-alum is bad juju.

Where does one get steel fittings for the fuel strainer? If there is a better way, I wanna do it! This aluminum fitting stuff is for the birds!!!
 
So, after much consternation and hand wringing..... I was able to shop the local harbor freight aviation department and find the correct easy out and 3/8 NPT tap...… I finally got the threads fixed and even managed to run the square plug in through the fitting and it worked like a champ.

Now..... I have to wait for the replacement strainer so I can close everything up and then do the pressure test...….


Here is the threads after they have been tapped.....
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Then I decided to test it with the square plug, which is the same size as the strainer...….
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Square plug is installed with fuel proof sealant..... now just have to wait for the strainer and run it in!

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What..... me worry?....

Again, thank you for all of your help! Always something new to learn in this project!
 
Where does one get steel fittings for the fuel strainer? If there is a better way, I wanna do it! This aluminum fitting stuff is for the birds!!!

Didn't realize this fitting was "special" from Van's, looks like Van's just took an AN fitting and made it to accept a finger screen, shouldn't be hard to duplicate using a steel fitting. Worth the effort, maybe.
 
Often metal remnants from the male thread break off and lodge in the female threads. It is best to pick these out, if they exist, before you run the tap through to improve your chances.

Good luck.

Larry
 
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