Best Sealants for Fuel Access Panel Screws?

[MrRodgers]

Hi everyone,

I would like your suggestions (from personal experience preferably) on the best type of sealant to use on the screws in my fuel tank access panels on the bottom of my wing.  I have one screw in particular that has an ongoing minor leak that I would like to rectify.  Any suggestions on the best process in the use of the sealant would also be appreciated.

Thanks in advance for your assistance.  Note:  I have searched the MS site without finding anything.

Edited August 18 by MrRodgers

[Fly Boomer]

Just now, MrRodgers said:

Hi everyone,

I would like your suggestions (from personal experience preferably) on the best type of sealant to use on the screws in my fuel tank access panels on the bottom of my wing.  I have one screw in particular that has an ongoing minor leak that I would like to rectify.  Any suggestions on the best process to use the sealant would also be appreciated.

Thanks in advance for your assistance.  Note:  I have searched the MS site without finding anything.

Most people use Aviation Permatex.

[EricJ]

+1 for Permatex 3.   This is what Maxwells have recommended.

From the Wayback Machine:

https://web.archive.org/web/20180507232930/http://www.donmaxwell.com/publications/MAPA_TEXT/_overlay/Fuel Tank Repair_How We Fix Them 2-05.htm

It may help to have very little fuel in the tank, since if the cap is cracked or broken you can wind up with fuel coming out when you remove the screw (BTDT).   Otherwise just follow the instructions on the Permatex bottle.  Do clean any crap out of the screw hole before resealing, and don't use too much sealant.  Permatex isn't the only stuff that works, but it does work and isn't hard to use.
 

[MrRodgers]

25 minutes ago, EricJ said:

+1 for Permatex 3.   This is what Maxwells have recommended.

From the Wayback Machine:

https://web.archive.org/web/20180507232930/http://www.donmaxwell.com/publications/MAPA_TEXT/_overlay/Fuel Tank Repair_How We Fix Them 2-05.htm

It may help to have very little fuel in the tank, since if the cap is cracked or broken you can wind up with fuel coming out when you remove the screw (BTDT).   Otherwise just follow the instructions on the Permatex bottle.  Do clean any crap out of the screw hole before resealing, and don't use too much sealant.  Permatex isn't the only stuff that works, but it does work and isn't hard to use.
 

Eric,

Thanks for the info.  We will be emptying the tank before addressing the reseal of the screw.

 

 

[alextstone]

46 minutes ago, EricJ said:

+1 for Permatex 3.   This is what Maxwells have recommended.

From the Wayback Machine:

https://web.archive.org/web/20180507232930/http://www.donmaxwell.com/publications/MAPA_TEXT/_overlay/Fuel Tank Repair_How We Fix Them 2-05.htm

It may help to have very little fuel in the tank, since if the cap is cracked or broken you can wind up with fuel coming out when you remove the screw (BTDT).   Otherwise just follow the instructions on the Permatex bottle.  Do clean any crap out of the screw hole before resealing, and don't use too much sealant.  Permatex isn't the only stuff that works, but it does work and isn't hard to use.
 

I followed Don's instructions and I found a leak that others had attempted to find and seal three previous times.  Here's a few photos:

BTW, the external location of the leak was several inches away from the internal origin.

 

Alex

 

[N201MKTurbo]

That’s not the correct way to fix that leak. Per the service manual, you are supposed to remove the old sealant down to bare metal and apply new sealant. Once you are that far into the repair, doing it properly doesn’t take that long.

[Shadrach]

1 hour ago, alextstone said:

I followed Don's instructions and I found a leak that others had attempted to find and seal three previous times.  Here's a few photos:

BTW, the external location of the leak was several inches away from the internal origin.

 

Alex

 

FYI - Less is more regarding soapy water. It need not look “milky”.  Just capable of suds. 

[N201MKTurbo]

2 hours ago, Shadrach said:

FYI - Less is more regarding soapy water. It need not look “milky”.  Just capable of suds. 

I have found the toy bubble blowing liquid works best. You can get enough to do your tanks for $1 at Walmart. 

[N201MKTurbo]

BTW, I use a Hudson sprayer full of water to rinse out the soap.

[Shadrach]

7 hours ago, N201MKTurbo said:

BTW, I use a Hudson sprayer full of water to rinse out the soap.

I seal off the fuel pick up and tow it to the wash rack for a thorough flush. I think that when sealant fragments are found in a gascolator screen it is often from an old repair that was not thoroughly flushed.

[N201MKTurbo]

1 hour ago, Shadrach said:

I seal off the fuel pick up and tow it to the wash rack for a thorough flush. I think that when sealant fragments are found in a gascolator screen it is often from an old repair that was not thoroughly flushed.

That would work too. I usually use the shop vac to get all the bits up from scraping. I use a chip brush to knock loose the bits that have re-stuck themselves. And some times my fingernail. I use the water mostly for the soap. Then use the shop vac to get any residual water left in the tank. The water gives you an opportunity to see how the drain back holes are working. Even when they are working properly, some water gets trapped, so the shop vac will suck it up. Considering that the last step is a final leak check before closing them up, a water flush is always the last thing you do.

Either way, nothing replaces a thorough visual inspection before closing it up.

[OR75]

On 8/18/2024 at 4:22 PM, N201MKTurbo said:

That’s not the correct way to fix that leak. Per the service manual, you are supposed to remove the old sealant down to bare metal and apply new sealant. Once you are that far into the repair, doing it properly doesn’t take that long.

I wonder how many actually do that 

[N201MKTurbo]

1 hour ago, OR75 said:

I wonder how many actually do that 

Just the ones who want to do it right. Anything else is a “patch”. There is no approved procedure for doing a patch! There is a whole chapter in the service manual about how to do it right. It isn’t that hard.

[OR75]

28 minutes ago, N201MKTurbo said:

Just the ones who want to do it right. Anything else is a “patch”. There is no approved procedure for doing a patch! There is a whole chapter in the service manual about how to do it right. It isn’t that hard.

I get it. The leak repair in the MM is a recommendation. not called a patch but really the same thing. calls for removing old sealant around the leak (usually a rivet or nut)