Model 4-1200 gas tank drain loose info needed.

[Bourneredi]

I recently bought a model 4-1200. I just replaced the CAV-110 quick drains in the wings. The left drain was weeping fuel prior to replacement. The old drain came out very easy but the new drain will not snug up and just keeps turning as I attempt to tighten it. I have not put hardly any pressure on it so I think this is why it was weeping. The new drain is not stripped and so I assume the fitting in the tank is stripped or has come loose and is spinning. I did not build my plane and do not have the original plans for it. I can't really see how/ what the tank attachment is without cutting the wing covering which I obviously don't want to do. Has anyone built one of these tanks or do you have plans which show this area? Any help on this would be greatly appreciated. Thanks!

Randy

[Oneninerwhiskey]

Search the forum for "stripped threads in fiberglass".

[Bourneredi]

Search the forum for "stripped threads in fiberglass".

Thanks for the heads up!

[Lion8]

I have never tried this, but there is a product from #M, called 5200. My son used it on his boat. I have never seen anything like this stuff. Toughest sealant I have ever seen. I would recommend testing this if you decide to try it. Drawback?, expensive.
While I have the floor, I just found out that Fastenal co. carries AN fasteners. Hope this helps someone.

[Paul Z]

Here is the way I have seen composite aircraft tanks built. It look like a pain in the rear, but you will not have it go bad. The Aluminum Flange is available at Aircraft Spruce, it is an aluminum welding flange and it comes with pipe threads tapped into it. Just a suggestion.

[Slyfox]

my thought is to get a step up reducer. meaning, go to a bigger size fitting with the center being the same size as the drain. once you find that, you just drill out the tank and cut new threads for the fitting.

[Northof49]

would it be possible to install a helicoil ? and when you reinstall the quick drain use PRC 1422 on the threads .
mike

[kmach]

my thought is to get a step up reducer. meaning, go to a bigger size fitting with the center being the same size as the drain. once you find that, you just drill out the tank and cut new threads for the fitting.

I like this idea, and if you have the tap it would be low $'s .

I originally thought of the thread repair methods, like my favorite the Time-sert , but it is fiberglass you would be trying to lock these thread repairs into and you still would need to drill and tap.

[HighWing]

Thinking about this, this is what I would try. I have been using Hysol 9430 extensively for many and varied purposes. I like the stuff a lot. First, I would clean a 1/8" tap with acetone to remove any cutting oils and freshen the threads to remove any thread sealent on the tank by snugging in the tap and taking the it a little deeper. Then I would paint a little PVA mold release - for fiberglass fabrication from molds - on the threads of a 1/8" pipe plug - maybe two thin coats. (Car wax might work - also a couple of coats and wipe carefully after drying. Then when the PVA is dry, coat the internal threads of the tank and the threads on the plug with the Hysol and screw it in place - not too snug as we are trying to make the hole smaller. When that is cured, unscrew the plug and try the valve for fit.
Typically there would be a small mushroom of the Hysol both inside and outside the tank that would give a mechanical lock in addition to the great adhesive strength. That stuff sticks to almost anything and stays forever.

About ten years ago, we had an old timers group - Empty Nesters - over for an evening get together. To play a trick on one of the old guys, I glued a quarter on our exposed agregate front porch with the 9430. 100° days in full sun and sometimes freezing temps and numerous kind souls trying to return our lost quarter by attempting to pry it loose and it is still there. I need to polish it.

[Bourneredi]

Thanks for the ideas everyone. Now that I know it's fiberglass and stripped, I think I will get a brass male/ female 1/8 fitting and glue it in somehow. That way I can still use the standard CAV-110 drain. Is JB Weld impervious to gasoline???

Thanks again!