Recessed fuel drain install

[airlina]

Years ago, I had a wizzened old A&P tell me to get some stuff called Fuel Lube.I bought a small can of the stuff that will last a lifetime and use it for thread sealant and such. Has out performed anything else I tried and i am sold on it. Its the consistency of peanut butter and never gets hard and is fuel resistant. I checked aircraft spruce by searching for fuel lube but all that came up is a product called "EZ Turn lubricant " which it says is the functional equivalent of Fuel Lube. Bruce N199CL

[896tr]

Sorry to post non aviation related but never use white Teflon "tape" on natural gas or propane fittings either.

[efwd]

I just bought Fuel Lube. Thought I got it here at the local AS&S. Anyhow, I stated previously on my thread that after my brake line fittings were found to be leaking 5606 hydraulic fluid I got this stuff and it seemed to be working. Not any longer. My brake fittings at all four points on the grove gear leak. The permatex product that was recommended has sealed the fittings where they enter the brake cylinders but neither products has stopped leaking at the aluminum gear. I called Grove. They use Permatex and had no recommendation. My only thought is that I will have to use brand new fittings and try again. I have these tight enough to make me nervous to tighten further. Im hoping that new ones will be a better fit. Any other ideas would be appreciated.

[rv9ralph]

Not to hijack the thread. But what I have used to seal leaky brake fittings on my gear legs was this product.

80017.jpg

I also used it to seal the access to the fuel tank on my RV9 project. Follow directions, install and leave for a few days for it to set before you add any fluids.

Ralph

[GuppyWN]

Thanks all. Loctite 565 is the plan but I saw a mention on the super cub forum of adding thread tape. Wanted to see what you thought.

[Floog]

ANY product you use can clog a system if applied wrong. Love that teflon tape!

[jrevens]

ANY product you use can clog a system if applied wrong. Love that teflon tape!

I agree with you, Doug. My favorite thread sealant with metallic tapered pipe threads is the high-temp Loctite, but I have used teflon tape for literally thousands of connections during my career, including aircraft and natural gas. You can read all kinds of silly things on the internet about “regular” teflon tape being unsuitable for natural gas because it will eventually degrade from it. Teflon is teflon for all practical purposes when it comes to thread sealant tape. The only difference between the white and the colored (“for natural gas”) is the color and supposedly the thickness. I say supposedly because I’ve seen & measured the thickness of tape from China (found everywhere now) and have found some very nice thick white and some yellow that was crazy thin, & vice versa. The yellow stuff is supposed to be thicker, which makes it a little more durable when applying and less likely to shred & shed little pieces (which is bad on airplanes, and gas valves & orifices). I always look for a good mil-spec’d tape, preferably made in the USA. If good tape is applied properly it is reliable, and under certain circumstances (like female threads that may be contaminated with oil and difficult to clean for some reason for instance) can be better than any paste sealant. I welcome any disagreement with these statements... I’m not done learning yet.

[Delta Whisky]

It really depends on what material the joint in made of and what thread is involved. If we are talking about NPT threads:


National Pipe Thread (NPT)

This type of thread when mated, may contain slight gaps between the major and minor diameter of the threads. Because of this, a thread seal agent may be required. However, this type of thread is tapered at a rate of 1/16 (3/4"/foot), which often allows a seal to be made without a sealing agent. (https://diy.stackexchange.com/questi...-be-used#21137)



Note that there is often, by design, a gap between the major and minor diameter of the threads.


And, teflon tape is not designed to be a gap sealer:


Teflon tape:
The purpose of this white, non-sticking tape is to serve as a lubricant when threaded parts of a piping system are being assembled. The inherent slipperiness of the material makes assembly easier.
Strictly speaking, Teflon tape is not a thread sealant (Fig. 1). The tape may have the effect of clogging the thread path, but it does not actually adhere to surfaces as a true sealant should. During installation, the tape must be carefully wrapped in the direction of the threads or it unravels and tears. (https://www.plantengineering.com/sin...46dd34156.html)



Now-a-days, there is a third degree of movement available: the anaerobic resin compound/sealer. But, I digress.



The above italicized paragraphs were SELECTIVELY chosen by little ol me because they match reference material I can't locate right now but have been my guiding light (wow, really getting heady now) for a long time. What is interesting, because I couldn't find my old material I went nosing around on the good ol internet and found that you can read gobs (a scientific term) of entries matching whatever you'd like to do and, I discovered, there are now several colors of TFE tape for all kinds of applications. But, be careful, it is the internet and most are not written for vehicles that get very high.



Obviously, if your tape seals the difference between the minor and major diameter differences (if there are any in your parts) then you have a winner. But, it wasn't necessary designed to do that and if the joint has to be opened for any reason in the future, getting the threads cleaned up again for reassembly could be more of an issue if you used tape. This might be an problem if there are tiny orifices downstream of the joint.

[efwd]

You have named my very situation John. My brake line leaks developed on initial install. I think maybe the replacement of the sealant with the new stuff, and its failure, may have been due to my inability to really clean the female threads in the grove gear the second time around since it had hydraulic fluid in
it.