VAF Forums - Loctite on AN fitting B nut

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- - Loctite on AN fitting B nut (https://vansairforce.net/community/showthread.php?t=181208)

In the 70's, during my A&P school, I saw some B-nuts with safety wire holes and they were safety wired.

For me, I am planning to torque to spec and then torque stripping.

What about EZ Turn lube on flair fittings. The product sold through Aircraft Spruce is supposed to be, I thought, specifically for this purpose.

Quote:

Originally Posted by Tankerpilot75 (Post 1420956)

What about EZ Turn lube on flair fittings. The product sold through Aircraft Spruce is supposed to be, I thought, specifically for this purpose.

NO. The torque spec is for clean, dry threads. Adding a lubricant will result in the loss of the expected friction, so the threads will be over-torqued.
EZ turn is for pipe threads, where the seal is within the threads, and ideally metal to metal. Most people add a sealant/lubricant to the threads to ?help?. There is considerable debate as to how well EZ works as a sealant in fuel lines.

I use no loctite but triple torque.

1. tighten to torque value, then loosen.
2. tighten to torque value, then loosen.
3. tighten to torque value, final.

Quote:

Originally Posted by Tankerpilot75 (Post 1420956)

What about EZ Turn lube on flair fittings. The product sold through Aircraft Spruce is supposed to be, I thought, specifically for this purpose.

EZ Turn is a lube to be used very sparingly in a fuel valve...and it's arguably not the best choice for even that limited use.

Remember, EZ Turn is thick, sticky, and insoluble in fuel. A little dab loose in the fuel system can plug a carb jet and either kind of fuel injection.

Quote:

Originally Posted by fixnflyguy (Post 1420899)

As your building, or re-building, a good practice is to apply torque seal which is a great visual inspection aid that will validate 2 things..one, that you have torqued it for final time, and second, it will visually let you know if it is loose, or has been loosened during inspection or maintenance. I torque seal mine at the B-nut and the ferrule /tube. I prefer bright orange, but lots of colors available. In fact, I do the same for every bolt on the plane.

When I do a tech inspection, if it doesn't have torque seal on it, it isn't torqued.

Quote:

Originally Posted by N941WR (Post 1420993)

When I do a tech inspection, if it doesn't have torque seal on it, it isn't torqued.

Excellent. It means you would pick up a wrench and check them for real.

I’ve had mixed results with Torque Seal. When checking some B nuts in my fuel system I discovered a few were loose after a few years, even though the Torque Seal looked perfect. What I found was that the hardened Torque Seal was slipping around the threads. So I don’t trust it much anymore and always put a wrench on these fittings to make sure they are tight.

Quote:

Originally Posted by F1 Rocket (Post 1421279)

There was a recent article in Sport Aviation or Kitplanes showing torque seal applied but was kind of messy. I never do it this way, neatness counts. To avoid the torque seal slipping and giving a false positive torque reading, I run a very nice bead all the way along a line from the hose barrel to the flange nut on the fitting. This way, if the b nut rotates, it will break the torque seal on the flange nut. Here I found neatness counts. It the torque seal is messy, it is hard to tell if it broke loose. And if the torque seal does not have good adherence to the flange, it wont break when rotated.