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teamgrumman(at)YAHOO.COM
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 Posted: Thu Jun 17, 2010 8:01 pm Post subject: Fuel leak |
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So, I got under the wing again, opened the inspection panels, and nothing. Still no stains anywhere. I pressurized the tank through the vent line. Since I had to hold pressure I couldn't actually feel around and look for a leak while the tank was pressurized. Nothing. No leaks.
I removed the strap around the wing. Nothing. No stains at all. There was, however, fuel tank sealant applied to the outside. It looks post wing completion. I pressurized the tank again and after 30 seconds or so, went to look for leaks. Nothing. What a pain in the ass. I needed to look for leaks with the tank pressurized.
Then I thought, if I could plug the vent line, how could I pressurize the tank? Well, the solution was to pressurize through the sump fuel drain. I plugged the vent, then applied pressure at the drain, pushed it in as if to drain (but with air pressure on it) and I could hear bubbles going into the sump. Good first start. I waited about a 15 seconds, then, removed pressure. No leaks. I went to the vent line and removed the plug. A small mount of air escaped. Good. It works. So, plug back in, I pressurized the tank and waited about 30-45 seconds. Keep in mind I'm using 120 psi. I'll bet that got your attention. No, I'm using about 1 or 2 psi. Then I went looking for leaks.
Guess what. On the very bottom of the spar, at the edge of the wing skin, where the sealant was applied, a very tiny wet spot. I got a paper towel and put it on it. It was that hard to see. There it was; the little bugger. Under pressure, at the rate it was leaking, it would take forever to drain the tank. If I had to estimate the hole size, I'd say about 100 microns.
Is it worth trying to seal from the outside?
[quote][b]
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pitts_pilot(at)bellsouth.
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| Posted: Fri Jun 18, 2010 2:39 am Post subject: Fuel leak |
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Gary Vogt wrote: | Quote: | So, I got under the wing again, opened the inspection panels, and nothing. Still no stains anywhere. I pressurized the tank through the vent line. Since I had to hold pressure I couldn't actually feel around and look for a leak while the tank was pressurized. Nothing. No leaks.
I removed the strap around the wing. Nothing. No stains at all. There was, however, fuel tank sealant applied to the outside. It looks post wing completion. I pressurized the tank again and after 30 seconds or so, went to look for leaks. Nothing. What a pain in the ass. I needed to look for leaks with the tank pressurized.
Then I thought, if I could plug the vent line, how could I pressurize the tank? Well, the solution was to pressurize through the sump fuel drain. I plugged the vent, then applied pressure at the drain, pushed it in as if to drain (but with air pressure on it) and I could hear bubbles going into the sump. Good first start. I waited about a 15 seconds, then, removed pressure. No leaks. I went to the vent line and removed the plug. A small mount of air escaped. Good. It works. So, plug back in, I pressurized the tank and waited about 30-45 seconds. Keep in mind I'm using 120 psi. I'll bet that got your attention. No, I'm using about 1 or 2 psi. Then I went looking for leaks.
Guess what. On the very bottom of the spar, at the edge of the wing skin, where the sealant was applied, a very tiny wet spot. I got a paper towel and put it on it. It was that hard to see. There it was; the little bugger. Under pressure, at the rate it was leaking, it would take forever to drain the tank. If I had to estimate the hole size, I'd say about 100 microns.
Is it worth trying to seal from the outside?
|
I'd say yes ..... the resulting stain would be aggravating. Get some green Loctite, clean the hole: draw a vacuum on the tank and feed some MEK through the hole ...... make take a lot of patience. Keeping the vacuum on the tank, feed the hole some of the green Loctite. Remove the vacuum once you feel the Loctite has gone through whole passage. Should now stop the leak.
With the hole that small, getting fluid through the hole may be problematic ..... the hole may seal under vacuum ..... use the MEK to clean the external area real good and apply some proseal over the exterior where the hole is.
Linn
PS .... the green Loctite trick came from the RV group.
[quote]
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href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
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flyv35b(at)minetfiber.com
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| Posted: Fri Jun 18, 2010 5:09 am Post subject: Fuel leak |
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Yes. What have you got to loose? I'd pick away any sealant that wasn't attached well and maybe some of the externally applied sealant, add new sealant and try and blow it inward with some air pressure to "fill" any void then cover the whole area with sealant and see what happens. If that doesn't work you will have to go inside again.
Cliff
[quote] ---
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flyv35b(at)minetfiber.com
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| Posted: Fri Jun 18, 2010 5:54 am Post subject: Fuel leak |
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That might be a good idea, Linn. What is the number of the Loctite as their are scores of different types. Is just "Green" that definitive?
Cliff
[quote] ---
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flyadive(at)gmail.com
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| Posted: Fri Jun 18, 2010 5:55 am Post subject: Fuel leak |
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Gary:
You got a conundrum...
You know where the leak is but you have to make the leak BIGGER.
The leak/hole is so small that there is no surface area for the
sealant to adhere to.
And it very well could be corrosion that caused the leak.
Sealant has a difficult time sticking to corrosion. Especially when
the hole is so small.
If it is accessible from the inside:
Drill out the hole - small - about 1/32" dia. - You have to give it
some area to adhere to.
Press & smear the sealant in and around the hole.
Verify that it comes through to the outside.
LET IT CURE - For at least 72 Hours.
Take a new razor blade and slice it off flush with the wing.
I do not know if PAINT will stick to the sealant?
If it is not accessible from the inside:
Drill out the hole as above - 1/32" dia.
Remove some paint around the hole. 1/4" Dia.
Chem-Film the bare aluminum.
Make a mask around the hole - masking tape.
Press & smear the sealant in and around the hole.
LET IT CURE - For at least 72 hours.
Use an X-Acto knife to make a nice clean circle around the hole
removing the excess sealant - 1/4" dia.
And in both cases - PRAY.
Of course there are the illegal chemicals...
Barry
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pitts_pilot(at)bellsouth.
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| Posted: Fri Jun 18, 2010 11:58 am Post subject: Fuel leak |
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flyv35b wrote: | Quote: | That might be a good idea, Linn. What is the number of the Loctite as their are scores of different types. Is just "Green" that definitive?
Cliff
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' Green' would suffice .... all the different ones have different colors ..... green, blue, red ..... but the green is #290 ..... wicking locktite
Linn
[quote][b]
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teamgrumman(at)YAHOO.COM
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| Posted: Fri Jun 18, 2010 1:42 pm Post subject: Fuel leak |
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Well, now, there is something I hadn't thought of. I can draw a vacuum on the tank and try the MEK to see if it pulls it through. Cool. Good place to start.
From: Linn Walters <pitts_pilot(at)bellsouth.net>
To: teamgrumman-list(at)matronics.com
Sent: Fri, June 18, 2010 3:18:58 AM
Subject: Re: Fuel leak
Gary Vogt wrote: | Quote: | So, I got under the wing again, opened the inspection panels, and nothing. Still no stains anywhere. I pressurized the tank through the vent line. Since I had to hold pressure I couldn't actually feel around and look for a leak while the tank was pressurized. Nothing. No leaks.
I removed the strap around the wing. Nothing. No stains at all. There was, however, fuel tank sealant applied to the outside. It looks post wing completion. I pressurized the tank again and after 30 seconds or so, went to look for leaks. Nothing. What a pain in the ass. I needed to look for leaks with the tank pressurized.
Then I thought, if I could plug the vent line, how could I pressurize the tank? Well, the solution was to pressurize through the sump fuel drain. I plugged the vent, then applied pressure at the drain, pushed it in as if to drain (but with air pressure on it) and I could hear bubbles going into the sump. Good first start. I waited about a 15 seconds, then, removed pressure. No leaks. I went to the vent line and removed the plug. A small mount of air escaped. Good. It works. So, plug back in, I pressurized the tank and waited about 30-45 seconds. Keep in mind I'm using 120 psi. I'll bet that got your attention. No, I'm using about 1 or 2 psi. Then I went looking for leaks.
Guess what. On the very bottom of the spar, at the edge of the wing skin, where the sealant was applied, a very tiny wet spot. I got a paper towel and put it on it. It was that hard to see. There it was; the little bugger. Under pressure, at the rate it was leaking, it would take forever to drain the tank. If I had to estimate the hole size, I'd say about 100 microns.
Is it worth trying to seal from the outside?
|
I'd say yes ..... the resulting stain would be aggravating. Get some green Loctite, clean the hole: draw a vacuum on the tank and feed some MEK through the hole ...... make take a lot of patience. Keeping the vacuum on the tank, feed the hole some of the green Loctite. Remove the vacuum once you feel the Loctite has gone through whole passage. Should now stop the leak.
With the hole that small, getting fluid through the hole may be problematic ..... the hole may seal under vacuum ..... use the MEK to clean the external area real good and apply some proseal over the exterior where the hole is.
Linn
PS .... the green Loctite trick came from the RV group.
[quote][b]
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teamgrumman(at)YAHOO.COM
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| Posted: Fri Jun 18, 2010 1:54 pm Post subject: Fuel leak |
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The hole, where it's leaking, is at the very bottom of the spar in the middle. It's leaking at the sealant on the bottom of the spar and not the wing skin. On the 2005 AG5B, the gap at the bottom of the rib (normally just left open on the AA5B and then filled with fuel tank sealant) is filled with an epoxy that improves sealing. For all practical purposes, the wing is sealed without sealant.
I can't tell right now just exactly where the hole is. It's that small. I should know more later today.
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Fri, June 18, 2010 6:49:05 AM
Subject: Re: Fuel leak
--> TeamGrumman-List message posted by: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
Gary:
You got a conundrum...
You know where the leak is but you have to make the leak BIGGER.
The leak/hole is so small that there is no surface area for the
sealant to adhere to.
And it very well could be corrosion that caused the leak.
Sealant has a difficult time sticking to corrosion. Especially when
the hole is so small.
If it is accessible from the inside:
Drill out the hole - small - about 1/32" dia. - You have to give it
some area to adhere to.
Press & smear the sealant in and around the hole.
Verify that it comes through to the outside.
LET IT CURE - For at least 72 Hours.
Take a new razor blade and slice it off flush with the wing.
I do not know if PAINT will stick to the sealant?
If it is not
[quote][b]
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pitts_pilot(at)bellsouth.
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| Posted: Fri Jun 18, 2010 2:53 pm Post subject: Fuel leak |
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Be careful. I use a shop-vac in the fuel filler and a rag to loosely seal the opening. I've demonstrated PSI using a gallon can and a shop-vac.
MEK may not be the best .... hard to tell if it's evaporating or going in the hole!!! You might use food coloring ..... after the vacuum's been there for a while and you wipe the outside there may still be enough color in the hole to be seen. Good luck!!!
Linn
Gary Vogt wrote: [quote] Well, now, there is something I hadn't thought of. I can draw a vacuum on the tank and try the MEK to see if it pulls it through. Cool. Good place to start.
From: Linn Walters <pitts_pilot(at)bellsouth.net> (pitts_pilot(at)bellsouth.net)
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Fri, June 18, 2010 3:18:58 AM
Subject: Re: Fuel leak
Gary Vogt wrote: | Quote: | So, I got under the wing again, opened the inspection panels, and nothing. Still no stains anywhere. I pressurized the tank through the vent line. Since I had to hold pressure I couldn't actually feel around and look for a leak while the tank was pressurized. Nothing. No leaks.
I removed the strap around the wing. Nothing. No stains at all. There was, however, fuel tank sealant applied to the outside. It looks post wing completion. I pressurized the tank again and after 30 seconds or so, went to look for leaks. Nothing. What a pain in the ass. I needed to look for leaks with the tank pressurized.
Then I thought, if I could plug the vent line, how could I pressurize the tank? Well, the solution was to pressurize through the sump fuel drain. I plugged the vent, then applied pressure at the drain, pushed it in as if to drain (but with air pressure on it) and I could hear bubbles going into the sump. Good first start. I waited about a 15 seconds, then, removed pressure. No leaks. I went to the vent line and removed the plug. A small mount of air escaped. Good. It works. So, plug back in, I pressurized the tank and waited about 30-45 seconds. Keep in mind I'm using 120 psi. I'll bet that got your attention. No, I'm using about 1 or 2 psi. Then I went looking for leaks.
Guess what. On the very bottom of the spar, at the edge of the wing skin, where the sealant was applied, a very tiny wet spot. I got a paper towel and put it on it. It was that hard to see. There it was; the little bugger. Under pressure, at the rate it was leaking, it would take forever to drain the tank. If I had to estimate the hole size, I'd say about 100 microns.
Is it worth trying to seal from the outside?
|
I'd say yes ..... the resulting stain would be aggravating. Get some green Loctite, clean the hole: draw a vacuum on the tank and feed some MEK through the hole ...... make take a lot of patience. Keeping the vacuum on the tank, feed the hole some of the green Loctite. Remove the vacuum once you feel the Loctite has gone through whole passage. Should now stop the leak.
With the hole that small, getting fluid through the hole may be problematic ..... the hole may seal under vacuum ..... use the MEK to clean the external area real good and apply some proseal over the exterior where the hole is.
Linn
PS .... the green Loctite trick came from the RV group.
| Quote: |
| Quote: |
href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
|
href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
|
[b]
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teamgrumman(at)YAHOO.COM
Guest
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| Posted: Fri Jun 18, 2010 5:48 pm Post subject: Fuel leak |
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After I cleaned out all of the sealant on the OUTSIDE of the tank, I pressurized and squirted on soapy water. You can see it in pic 1359. The other side of the leak looks like this: 1258. About the only ay I can see that it would still be leaking is if it is coming in at the top and running down the inside between the rib and any doublers. What a pain.
From: Linn Walters <pitts_pilot(at)bellsouth.net>
To: teamgrumman-list(at)matronics.com
Sent: Fri, June 18, 2010 3:53:07 PM
Subject: Re: Fuel leak
Be careful. I use a shop-vac in the fuel filler and a rag to loosely seal the opening. I've demonstrated PSI using a gallon can and a shop-vac.
MEK may not be the best .... hard to tell if it's evaporating or going in the hole!!! You might use food coloring ..... after the vacuum's been there for a while and you wipe the outside there may still be enough color in the hole to be seen. Good luck!!!
Linn
Gary Vogt wrote: | Quote: | Well, now, there is something I hadn't thought of. I can draw a vacuum on the tank and try the MEK to see if it pulls it through. Cool. Good place to start.
From: Linn Walters <pitts_pilot(at)bellsouth.net> (pitts_pilot(at)bellsouth.net)
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Fri, June 18, 2010 3:18:58 AM
Subject: Re: Fuel leak
Gary Vogt wrote: | Quote: | So, I got under the wing again, opened the inspection panels, and nothing. Still no stains anywhere. I pressurized the tank through the vent line. Since I had to hold pressure I couldn't actually feel around and look for a leak while the tank was pressurized. Nothing. No leaks.
I removed the strap around the wing. Nothing. No stains at all. There was, however, fuel tank sealant applied to the outside. It looks post wing completion. I pressurized the tank again and after 30 seconds or so, went to look for leaks. Nothing. What a pain in the ass. I needed to look for leaks with the tank pressurized.
Then I thought, if I could plug the vent line, how could I pressurize the tank? Well, the solution was to pressurize through the sump fuel drain. I plugged the vent, then applied pressure at the drain, pushed it in as if to drain (but with air pressure on it) and I could hear bubbles going into the sump. Good first start. I waited about a 15 seconds, then, removed pressure. No leaks. I went to the vent line and removed the plug. A small mount of air escaped. Good. It works. So, plug back in, I pressurized the tank and waited about 30-45 seconds. Keep in mind I'm using 120 psi. I'll bet that got your attention. No, I'm using about 1 or 2 psi. Then I went looking for leaks.
Guess what. On the very bottom of the spar, at the edge of the wing skin, where the sealant was applied, a very tiny wet spot. I got a paper towel and put it on it. It was that hard to see. There it was; the little bugger. Under pressure, at the rate it was leaking, it would take forever to drain the tank. If I had to estimate the hole size, I'd say about 100 microns.
Is it worth trying to seal from the outside?
|
I'd say yes ..... the resulting stain would be aggravating. Get some green Loctite, clean the hole: draw a vacuum on the tank and feed some MEK through the hole ...... make take a lot of patience. Keeping the vacuum on the tank, feed the hole some of the green Loctite. Remove the vacuum once you feel the Loctite has gone through whole passage. Should now stop the leak.
With the hole that small, getting fluid through the hole may be problematic ..... the hole may seal under vacuum ..... use the MEK to clean the external area real good and apply some proseal over the exterior where the hole is.
Linn
PS .... the green Loctite trick came from the RV group.
|
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teamgrumman(at)YAHOO.COM
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| Posted: Wed Jun 23, 2010 12:09 pm Post subject: Fuel leak |
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I tried Linn's suggestion with the Green Loctite. I couldn't see it being pulled into the hole with an inch or so of vacuum on it. I think if the wing were upside down, it would be easier. Anyway, resealed with Pro-Seal. We'll see now.
[quote][b]
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