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genie(at)swissmail.org
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 Posted: Mon Oct 12, 2015 11:16 am Post subject: Sealing Fuel Connectors and Loctite |
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To my disappointment I noticed that fuel was leaking from my RV-6. On
closer look and analysis I could tell that this came from the starboard
fuel tank. That could be seen from paint being damaged. I removed the
fuel tank and noticed that the leak came from the wing root. Then I
tested and found no leak in the tank. Therefore it seems to me that the
leak originates in the fitting of the fuel pipe with the fuel tank.
What sealant can I use to ensure that no fuel leaks from the connection
between the fuel tank and the pipes? There are two pipes, one for fuel
to the cock and one for the fuel tank vent. Is there any possibility
that fuel can leak from the fuel tank vent? I contacted Loctite and was
told that none of their products was suited for sealing fuel. Is there
any suitable product or should I just screw tighter?
On another occasion when I was worried about fuel leaking from the
fittings of the fuel tank with the cock an aircraft mechanic
recommended that I use Loctite 603 and sold me some. I used it for the
fittings with the fuel cock. I did not notice any leaking (nor had I
noticed previously, as I used it for good measure). Now I wonder whether
that was a good idea. Would it be easy to unscrew the pipes from the
cock or is there a special procedure that I should follow.
Thanks for your replies.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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gyoung
Joined: 09 Jan 2006
Posts: 211
Location: Republic of Texas
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| Posted: Mon Oct 12, 2015 12:51 pm Post subject: Sealing Fuel Connectors and Loctite |
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The flared fittings should not have or need sealant on the flared surfaces. Check the flare to make sure it is smooth, burnished and proper width. If tightened too much the flare can crack and leak. Once unscrewed the crack will close and can be very hard to detect. If the flare is not cracked but a bit rough or uneven there are soft aluminum flared washers that can be inserted to promote the seal.
If you're referring to pipe thread connections then I use Fuel Lube or EZ Turn and crank down on them to seal. If they are angled fittings that need to be clocked you may need to try different ones that will clock differently when tight. Don't loosen to get to the proper position.
Greg Young
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ceengland7(at)gmail.com
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| Posted: Mon Oct 12, 2015 2:29 pm Post subject: Sealing Fuel Connectors and Loctite |
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On 10/12/2015 2:15 PM, George Nielsen wrote:
| Quote: |
To my disappointment I noticed that fuel was leaking from my RV-6. On
closer look and analysis I could tell that this came from the
starboard fuel tank. That could be seen from paint being damaged. I
removed the fuel tank and noticed that the leak came from the wing
root. Then I tested and found no leak in the tank. Therefore it seems
to me that the leak originates in the fitting of the fuel pipe with
the fuel tank.
What sealant can I use to ensure that no fuel leaks from the
connection between the fuel tank and the pipes? There are two pipes,
one for fuel to the cock and one for the fuel tank vent. Is there any
possibility that fuel can leak from the fuel tank vent? I contacted
Loctite and was told that none of their products was suited for
sealing fuel. Is there any suitable product or should I just screw
tighter?
On another occasion when I was worried about fuel leaking from the
fittings of the fuel tank with the cock an aircraft mechanic
recommended that I use Loctite 603 and sold me some. I used it for the
fittings with the fuel cock. I did not notice any leaking (nor had I
noticed previously, as I used it for good measure). Now I wonder
whether that was a good idea. Would it be easy to unscrew the pipes
from the cock or is there a special procedure that I should follow.
Thanks for your replies.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
I think that is the 'green loctite' that is frequently used to seal
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'weeping' rivets in fuel tanks. There's an STC'd product developed by
the Mooney crowd that is basically green loctite, IIRC.
Thread sealant should never be needed on an A/N flaired/tapered fitting;
the seal is between the tubing flair and the taper of the fitting. I'd
first check for proper alignment of the tubing flair and for proper
torque. If it still leaks, disassemble & check the flair for cracks
and/or deformities, and deformities on the taper of the fitting. If no
cracks but slight deformities, you can buy soft aluminum cone shaped
washers that are specifically designed to seal 'difficult' joints. Try here:
http://www.anplumbing.com/Extras/Washers+%7C+O-Rings-63.html
and scroll down until you see 'conical seals'.
Don't ignore the possibility that the prosealed hole where either
fitting enters the tank can develop a leak, and joints around the
aluminum angle in the nose of the root rib can also develop leaks (one
of mine is leaking now). Depending on where the leak is, it can be very
difficult to find the actual source; fuel will move all around along the
outside surface. The fix is to clean it up carefully with MEK or similar
solvent (be careful not to use too much, or you'll dissolve other, good,
joints) and re-seal with your choice of tank sealant. It's best to do it
on the inner side of the fitting (easy to do with the supply fitting,
since it's on the access cover). If you've got a leak around the nose
angle or vent fitting, you can try to reach inside the tank to repair
the leak, but it will be pretty tough to do. Working with mirrors and
reaching elbow - deep into the access hole just about guarantees
failure. Sealing from the outside can be done, usually successfully.
Charlie
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Sun Oct 18, 2015 4:17 pm Post subject: Sealing Fuel Connectors and Loctite |
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George,
Yes, start with the simple and easy first. Â
One huge area of leakage is the fuel quality sending unit. There are a few different makes, but most use simple rubber or cork gaskets. The HUGE issue with them is the installers OVER TIGHTEN THE MOUNTING SCREWS. Yes, over tightening will distort the shape and the WILL LEAK! Replace them. And tighten them to screw size torque specifications. My trick is also to coat the gasket with a very light smear of PRC (or equivalent) sealant. Don't Americanize it...  More is NOT better.
Hoses, inspect the quality of the hose, no cracks, splits, or uneven cuts. Make sure the ID of the hose fits the OD of the fitting. You should not have to force. Use good quality hose clamps. NOT Home Depot garbage. A good quality clamp is aircraft grade made by BREEZE CORP. SNUG UP THE CLAMP! Again over tightening will cause problems.
As you tighten the rubber of the hose should just squeeze through the openings in the strap. I use EZ TURN fuel lubricant to make sure the hose slips on easy. If you can't get a seal easy then something is wrong and or distorted.
Tank Sealant - I have done over three dozen tank sealing jobs. They require diligent cleaning... New sealant WILL NOT stick to old sealant. It requires a clean surface. Their are a few manufacturers of sealant, but chemically they are all EXECTLY the same. The name is not important, what is is the ASTM or MILL SPEC NUMBER. The first name that comes to mind is PRC SEALANTS. Look up their website and review the types and specs. Then find one that fits your budget. If you do not have any luck drop me a line. READ ALL the types and specs.
I do not believe you have leaks between fittings and hoses. Unless as I mentioned above there is something wrong. You DO NOT need, should not need sealant on hoses.
Can you take pictures?
If you have questions throw them at me.  Been their, Done that. Many Times.
BarryÂ
On Monday, October 12, 2015, George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)> wrote:
| Quote: | --> RV6-List message posted by: George Nielsen <genie(at)swissmail.org>
To my disappointment I noticed that fuel was leaking from my RV-6. On closer look and analysis I could tell that this came from the starboard fuel tank. That could be seen from paint being damaged. I removed the fuel tank and noticed that the leak came from the wing root. Then I tested and found no leak in the tank. Therefore it seems to me that the leak originates in the fitting of the fuel pipe with the fuel tank.
What sealant can I use to ensure that no fuel leaks from the connection between the fuel tank and the pipes? There are two pipes, one for fuel to the cock and one for the fuel tank vent. Is there any possibility that fuel can leak from the fuel tank vent? I contacted Loctite and was told that none of their products was suited for sealing fuel. Is there any suitable product or should I just screw tighter?
On another occasion when I was worried about fuel leaking from the fittings of the fuel tank with the cock an aircraft mechanic recommended that I use Loctite 603 and sold me some. I used it for the fittings with the fuel cock. I did not notice any leaking (nor had I noticed previously, as I used it for good measure). Now I wonder whether that was a good idea. Would it be easy to unscrew the pipes from the cock or is there a special procedure that I should follow.
Thanks for your replies.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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Doug Gray
Joined: 10 Jan 2006
Posts: 112
Location: Sydney, Australia
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| Posted: Sun Oct 18, 2015 6:55 pm Post subject: Sealing Fuel Connectors and Loctite |
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Google 'weepnomore' - a service that will repair problems like this. The company's founder Paul Beck has posted on various RV forums at various times.
Doug
Sent from my iPhone
On 19 Oct 2015, at 11:17 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
[quote]George,
Yes, start with the simple and easy first.
One huge area of leakage is the fuel quality sending unit. There are a few different makes, but most use simple rubber or cork gaskets. The HUGE issue with them is the installers OVER TIGHTEN THE MOUNTING SCREWS. Yes, over tightening will distort the shape and the WILL LEAK! Replace them. And tighten them to screw size torque specifications. My trick is also to coat the gasket with a very light smear of PRC (or equivalent) sealant. Don't Americanize it... More is NOT better.
Hoses, inspect the quality of the hose, no cracks, splits, or uneven cuts. Make sure the ID of the hose fits the OD of the fitting. You should not have to force. Use good quality hose clamps. NOT Home Depot garbage. A good quality clamp is aircraft grade made by BREEZE CORP. SNUG UP THE CLAMP! Again over tightening will cause problems.
As you tighten the rubber of the hose should just squeeze through the openings in the strap. I use EZ TURN fuel lubricant to make sure the hose slips on easy. If you can't get a seal easy then something is wrong and or distorted.
Tank Sealant - I have done over three dozen tank sealing jobs. They require diligent cleaning... New sealant WILL NOT stick to old sealant. It requires a clean surface. Their are a few manufacturers of sealant, but chemically they are all EXECTLY the same. The name is not important, what is is the ASTM or MILL SPEC NUMBER. The first name that comes to mind is PRC SEALANTS. Look up their website and review the types and specs. Then find one that fits your budget. If you do not have any luck drop me a line. READ ALL the types and specs.
I do not believe you have leaks between fittings and hoses. Unless as I mentioned above there is something wrong. You DO NOT need, should not need sealant on hoses.
Can you take pictures?
If you have questions throw them at me. Been their, Done that. Many Times.
Barry
On Monday, October 12, 2015, George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)> wrote:
| Quote: | --> RV6-List message posted by: George Nielsen <genie(at)swissmail.org>
To my disappointment I noticed that fuel was leaking from my RV-6. On closer look and analysis I could tell that this came from the starboard fuel tank. That could be seen from paint being damaged. I removed the fuel tank and noticed that the leak came from the wing root. Then I tested and found no leak in the tank. Therefore it seems to me that the leak originates in the fitting of the fuel pipe with the fuel tank.
What sealant can I use to ensure that no fuel leaks from the connection between the fuel tank and the pipes? There are two pipes, one for fuel to the cock and one for the fuel tank vent. Is there any possibility that fuel can leak from the fuel tank vent? I contacted Loctite and was told that none of their products was suited for sealing fuel. Is there any suitable product or should I just screw tighter?
On another occasion when I was worried about fuel leaking from the fittings of the fuel tank with the cock an aircraft mechanic recommended that I use Loctite 603 and sold me some. I used it for the fittings with the fuel cock. I did not notice any leaking (nor had I noticed previously, as I used it for good measure). Now I wonder whether that was a good idea. Would it be easy to unscrew the pipes from the cock or is there a special procedure that I should follow.
Thanks for your replies.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
===========
List" target="_blank">http://www.matronics.com/Navigator?RV6-List
===========
FORUMS -
_blank">http://forums.matronics.com
===========
b Site -
-Matt Dralle, List Admin.
target="_blank">http://www.matronics.com/contribution
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Tue Oct 20, 2015 12:28 pm Post subject: Sealing Fuel Connectors and Loctite |
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George,
I took a look at your pictures.
Just a few comments:
1- I do not see leakage around the hatch or the fuel sending unit.
BUT! There is way too much sealant and it looks like someone is trying to seal the tank from the OUTSIDE. The hatch and sending unit should have been removed, cleaned down to bare metal, new gasket installed on the sending unit.
2 - Just a very small safety issue... All electrical lines should be run OVER the TOP of fuel lines. This is done encase there is a fuel leak the fuel does not drip onto an electrical wire.
3 - Color of the sealant... The sealant should be LOW BOND / LOW ADHESION, which has a purple/pink tinge to it. The high bond sure will hold but will present some issues if you have to remove it.
4 - Fuel lines - If you look at that one picture where the aluminum tube comes out of the Blue Nut Fitting... Â The bend starts immediately as the tube exits. There should be a straight run of two to three tube diameters before the tube begins its bend.
5 - What is the BLACK stuff? Â
6 - RULE! New sealant will NOT stick to Old sealant. You can see the Black is over the top of the gray. Sure looks like you have TWO ISSUES here: a) Different Types of Sealants.  b) New sealant over the top of Old sealant.
7 - Screws - You now have a difficult job/situation. You globed up ALL the screw heads. This will make future maintenance a royal P.I.T.A.
8 - Screws - Again - I'm making blind judgement call here, but, if you removed the hatches and sealed on the inside... And only because of what the outside looks like.. I'd bet you got sealant on the screws. If you did that could cause the screw heads to strip or even brake off when you go to remove them. Yes, in the life of a plane yo will need access to the inside of gas tanks. Â
9 - Screws - still again - Now, this is my thing... I would make sure ALL the screws are Mil-Spec STEEL screws... NOT Stainless Steel. Why? Because Steel screws are TWICE the strength of stainless steel and the heads do not strip as easy. Want them to look pretty?  Put a light painting of chromate paint on them.
If you still have the wing open, I would remove everything and start from the beginning. Sorry, I know you don't want to hear that. But, in the long run it will be done right, you will be able to do future maintenance without any issues.
10 - Fuel Bulkhead Fitting - Take a look at the picture of the fitting. What is the YELLOW stuff around the fitting?
Once you remove the access hatch remove the bulkhead fitting, clean both inside and outside. Are their O Rings for sealing? Whether you have O Rings or not I would put a Very Light Smear of Sealant on the inside and outside. MORE IS NOT BETTER!
The sealant will do two things: 1 - Act as a lubricant so you do not distort the O Rings. 2 - And of course seal the fitting.
Side note:  It is getting cold here in NJ. Make sure you use the sealant within the temperature operating limits.
Side note:  Don't Guess!  Measure the mixture of the sealant to catalyst. The mixture is 100:10 which is the same as 10:1. You can get a very accurate digital scale from Harbor Freight for about $15.
Hope this helps,
Barry
Â
On Mon, Oct 19, 2015 at 1:51 AM, George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)> wrote:
[quote] Barry,
Thank you for your reply.
I had sealed both tanks at a professional motorcycle tank garage a few years ago. After dismounting the starboard tank I immersed the whole thing with sater, blocked the ventilator and used a hose to blow air into the tank. I noticed several leaks. I used tank sealant which I purchased from Aircraft Spruce and Speciality Shop. A week later I tried this again and noticed a minute leak. I applied sealant and then mounted the tank on the aircraft.
This seems to have helped for a while. But not for long. At the end the leak was horrendous. I removed the tank and tried again this procedure. I found no leak. Yet it seems obvious from the damage to the paint job that the leak is from the starboard wing root. I removed some previously applied tank sealant. Still no leak. I applied some more sealant. Again no leak can be found. I mounted once more the fuel tank on the wing and tightened the connections with the pipes which are out of aluminium.
For good measure I have ordered EZ TURN.
Attached you will find some pictures.
If you have any other ideas please let me know. Could the problem be the mounting of the pipes to the tank? EZ TURN should solve that. Could it be a ruptured pipe? I have not found any trace of that so far. Perhaps I should look again. At least now I cannot see any fuel dripping. but I can stall smell some when I open the canopy.
George
On 19/10/2015 02:17, FLYaDIVE wrote:
| Quote: | George,
Yes, start with the simple and easy first. Â
One huge area of leakage is the fuel quality sending unit. There are a few different makes, but most use simple rubber or cork gaskets. The HUGE issue with them is the installers OVER TIGHTEN THE MOUNTING SCREWS. Yes, over tightening will distort the shape and the WILL LEAK! Replace them. And tighten them to screw size torque specifications. My trick is also to coat the gasket with a very light smear of PRC (or equivalent) sealant. Don't Americanize it...  More is NOT better.
Hoses, inspect the quality of the hose, no cracks, splits, or uneven cuts. Make sure the ID of the hose fits the OD of the fitting. You should not have to force. Use good quality hose clamps. NOT Home Depot garbage. A good quality clamp is aircraft grade made by BREEZE CORP. SNUG UP THE CLAMP! Again over tightening will cause problems.
As you tighten the rubber of the hose should just squeeze through the openings in the strap. I use EZ TURN fuel lubricant to make sure the hose slips on easy. If you can't get a seal easy then something is wrong and or distorted.
Tank Sealant - I have done over three dozen tank sealing jobs. They require diligent cleaning... New sealant WILL NOT stick to old sealant. It requires a clean surface. Their are a few manufacturers of sealant, but chemically they are all EXECTLY the same. The name is not important, what is is the ASTM or MILL SPEC NUMBER. The first name that comes to mind is PRC SEALANTS. Look up their website and review the types and specs. Then find one that fits your budget. If you do not have any luck drop me a line. READ ALL the types and specs.
I do not believe you have leaks between fittings and hoses. Unless as I mentioned above there is something wrong. You DO NOT need, should not need sealant on hoses.
Can you take pictures?
If you have questions throw them at me.  Been their, Done that. Many Times.
BarryÂ
On Monday, October 12, 2015, George Nielsen <genie(at)swissmail.org (genie(at)swissmail.org)> wrote:
| Quote: | --> RV6-List message posted by: George Nielsen <genie(at)swissmail.org>
To my disappointment I noticed that fuel was leaking from my RV-6. On closer look and analysis I could tell that this came from the starboard fuel tank. That could be seen from paint being damaged. I removed the fuel tank and noticed that the leak came from the wing root. Then I tested and found no leak in the tank. Therefore it seems to me that the leak originates in the fitting of the fuel pipe with the fuel tank.
What sealant can I use to ensure that no fuel leaks from the connection between the fuel tank and the pipes? There are two pipes, one for fuel to the cock and one for the fuel tank vent. Is there any possibility that fuel can leak from the fuel tank vent? I contacted Loctite and was told that none of their products was suited for sealing fuel. Is there any suitable product or should I just screw tighter?
On another occasion when I was worried about fuel leaking from the fittings of the fuel tank with the cock an aircraft mechanic recommended that I use Loctite 603 and sold me some. I used it for the fittings with the fuel cock. I did not notice any leaking (nor had I noticed previously, as I used it for good measure). Now I wonder whether that was a good idea. Would it be easy to unscrew the pipes from the cock or is there a special procedure that I should follow.
Thanks for your replies.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
===========
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