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ScooterF15

Joined: 19 Jun 2006
Posts: 136

Posted: Sun Jun 10, 2007 3:13 am Post subject: Fuel Leak

I know we just had this discussion about a leaky rivet on a fuel tank. I  didn't comment because I thought I was the lucky recipient of leak-free  quickbuild tanks. You'll notice from the attached photo that I was not. Seeing  that did not make me happy.

  

 Last August I pressure tested my tanks using a pressure gauge from a blood  pressure cuff before installing them. I pumped them up to 35 mmHG (~ 0.67 psi)  and left them for 2-3 days. The pressure did not change so I figured they were  good. After filling them I checked for leaks and didn't see any. I've had fuel  in the tanks for 10 months and flown 85 hours. As I was washing the bugs off my  wing yesterday I found this leak. I'm glad I found it before painting.

  

 I plan on emptying the fuel from the wing and trying the Locktite 290  approach, unless someone has a better suggestion.

  

 -Jim

 40134

  

 Jim "Scooter"  McGrew

http://www.mit.edu/~jsmcgrew  



See what's free at AOL.com.

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flysrv10(at)gmail.com
Guest

Posted: Sun Jun 10, 2007 3:31 am Post subject: Fuel Leak

You are lucky that it is only leaking from the rivet.  Mine QB leaked in several places resulting in much debates, head scratching and a big hole on the rear of the tank to do repairs.

The 290 WILL work.  My rivet leak has held up for a year now.  I would put the same amount of neg. pressure on the tank while applying the 290 and let them sit overnight.



Do not archive.



On Jun 10, 2007, at 7:12 AM, JSMcGrew(at)aol.com (JSMcGrew(at)aol.com) wrote:

[quote] I know we just had this discussion about a leaky rivet on a fuel tank. I didn't comment because I thought I was the lucky recipient of leak-free quickbuild tanks. You'll notice from the attached photo that I was not. Seeing that did not make me happy.

  

 Last August I pressure tested my tanks using a pressure gauge from a blood pressure cuff before installing them. I pumped them up to 35 mmHG (~ 0.67 psi) and left them for 2-3 days. The pressure did not change so I figured they were good. After filling them I checked for leaks and didn't see any. I've had fuel in the tanks for 10 months and flown 85 hours. As I was washing the bugs off my wing yesterday I found this leak. I'm glad I found it before painting.

  

 I plan on emptying the fuel from the wing and trying the Locktite 290 approach, unless someone has a better suggestion.

  

 -Jim

 40134

  

 Jim "Scooter" McGrew

http://www.mit.edu/~jsmcgrew 



See what's free at AOL.com. <IMG_4540_1.JPG>



[b]

VHMUM(at)bigpond.com
Guest

Posted: Sun Jun 10, 2007 2:24 pm Post subject: Fuel Leak

I dont know why you guys in the states just dont  send your tanks back at vans expence? Several leaks on a QB tank is BS ...I  mean Vans sent me a new gear leg free of charge as it was faulty.

  

 Chris

  

 [quote]   ---

rvbuilder(at)sausen.net
Guest

Posted: Sun Jun 10, 2007 7:37 pm Post subject: Fuel Leak

What if one of you smart MIT types *cough*  figure out about how much PSI a full tank of avgas exerts while compensating for the difference in viscosity between air and avgas.  Should give you a better number to use to approx the PSI of air for testing the tanks.  Hopefully it will lead to more accurate leak tests.  

   

Just a thought.    

   

Michael  

Do not archive  

       

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of JSMcGrew(at)aol.com

 Sent: Sunday, June 10, 2007 6:12 AM

 To: rv10-list(at)matronics.com

 Subject: Fuel Leak  

  

  

     

I know we just had this discussion about a leaky rivet on a fuel tank. I didn't comment because I thought I was the lucky recipient of leak-free quickbuild tanks. You'll notice from the attached photo that I was not. Seeing that did not make me happy.  

    

   

    

Last August I pressure tested my tanks using a pressure gauge from a blood pressure cuff before installing them. I pumped them up to 35 mmHG (~ 0.67 psi) and left them for 2-3 days. The pressure did not change so I figured they were good. After filling them I checked for leaks and didn't see any. I've had fuel in the tanks for 10 months and flown 85 hours. As I was washing the bugs off my wing yesterday I found this leak. I'm glad I found it before painting.  

    

   

    

I plan on emptying the fuel from the wing and trying the Locktite 290 approach, unless someone has a better suggestion.  

    

   

    

-Jim  

    

40134  

    

   

    

Jim "Scooter" McGrew

 http://www.mit.edu/~jsmcgrew   

  



 

         

  

See what's free at AOL.com.   

  

      [quote][b]

DAVELEIKAM(at)wi.rr.com
Guest

Posted: Sun Jun 10, 2007 8:34 pm Post subject: Fuel Leak

OK, I am a short way from testing my QB  tanks.  If I do an air pressure test, and the test fails, how will I find  any leaks?  Soap?

  

 Dave Leikam

 40496

 QB Wings

 [quote]   ---

Tim Olson

Joined: 25 Jan 2007
Posts: 2879

Posted: Sun Jun 10, 2007 9:46 pm Post subject: Fuel Leak

Dave,



I'm no expert, but I actually did sleep in a Holiday Inn Express last

night, so I'll throw in my .02.



I don't consider the soapy water check a secondary check to be done

if the air pressure leakdown fails...it's more of a primary test.

I did both, at the same time.  First, pressurize the tank with the

balloon attached, and then spray it with a diluted concentration

of dish soap and water with a spray bottle.  Any bubbles coming

out will grow and should be easy to spot.  Check EVERYWHERE.

Then, leave the balloon full and see how it is the next day. If

it is still full, you're done.  If it isn't, then you probably

need to do the bubble test again, and you'll most likely find any

problem if there is one.  Other than a loose rivet, the air should

leak way easier than the fuel would.  If you really want to get

a the bubble test down to a fine level, use helium and that will

easily find its way out any tiny spot, but that's way overkill.



It's interesting to see how the tanks are becoming the downfall

of the QB wings.  Personally, I was much much happier to build

the tanks and KNOW how they were built than I would have been

to just buy them pre-built. It would be different if you were

buying from an aftermarket tank builder who would guarantee

them, because they'd take extra pride in their work. IMHO, people

make a little too big a deal out of how awful the tank building

job is...it just isn't that bad.



Tim Olson - RV-10 N104CD - Flying



Dave Leikam wrote:

 	  Quote: 	
		   OK, I am a short way from testing my QB tanks.  If I do an air pressure 

 test, and the test fails, how will I find any leaks?  Soap?

  

 Dave Leikam

 40496

 QB Wings

dmaib@me.com

Joined: 25 Apr 2006
Posts: 455
Location: New Smyrna Beach, Florida

Posted: Sun Jun 10, 2007 10:44 pm Post subject: Fuel Leak

You know Chris, that is a very good point. I am getting close to pressure tests and will keep this in mind.

David Maib

40559

QB Wings



On Jun 10, 2007, at 5:23 PM, The McGough Family wrote:

[quote]I dont know why you guys in the states just dont send your tanks back at vans expence? Several leaks on a QB tank is BS ....I mean Vans sent me a new gear leg free of charge as it was faulty.

 

Chris

 

[quote]---

_________________
David Maib
RV-10 #40559
New Smyrna Beach, FL

ScooterF15

Joined: 19 Jun 2006
Posts: 136

Posted: Mon Jun 11, 2007 2:52 am Post subject: Fuel Leak

Wouldn't it be nice if we had someone smart enough to do that?

  

 It doesn't take a rocket scientist to look up the vapor pressure of AVGAS  (the ASTM D 910 spec lists a maximum of about 7 psi). That is a lot of  pressure and that is why we have a vent line! I don't believe our tanks ever  have to or could endure that amount of pressure. So, I don't think the  amount of pressure makes too much difference; if there is a hole, air is going  to go through it. That's why I used about 0.5 psi.  In my opinion, Tim  has got it right when he suggests using soapy water along with pressure  from a ballon as a primary test.

  

 Jim

 40134

  

  Jim "Scooter"  McGrew

http://www.mit.edu/~jsmcgrew  

  



 In a message dated 6/10/2007 11:39:47 P.M. Eastern Daylight Time,  rvbuilder(at)sausen.net writes:

  	  Quote: 	
		     

What    if one of you smart MIT types *cough*  figure out about how much    PSI a full tank of avgas exerts while compensating for the difference in    viscosity between air and avgas.  Should give you a better number to use    to approx the PSI of air for testing the tanks.  Hopefully it will lead    to more accurate leak tests.   

    

Just    a thought.     

    

Michael   

Do    not archive 	


 



  

  



See what's free at AOL.com. 

  [quote][b]

flysrv10(at)gmail.com
Guest

Posted: Mon Jun 11, 2007 3:36 am Post subject: Fuel Leak

Chris, Van offered to repair my tank at no charge and will supply you with whatever you need to repair them.  They do however think that a replacement tank may not fit your wing.

At the end, I think that it is quicker and less costly to repair minor leaks at home.



do not archive



On Jun 10, 2007, at 6:23 PM, The McGough Family wrote:

[quote]I dont know why you guys in the states just dont send your tanks back at vans expence? Several leaks on a QB tank is BS ....I mean Vans sent me a new gear leg free of charge as it was faulty.

 

Chris

 

[quote]---

flysrv10(at)gmail.com
Guest

Posted: Mon Jun 11, 2007 3:37 am Post subject: Fuel Leak

Soap.

do not archive.



On Jun 11, 2007, at 1:34 AM, Dave Leikam wrote:

[quote]OK, I am a short way from testing my QB tanks.  If I do an air pressure test, and the test fails, how will I find any leaks?  Soap?

 

Dave Leikam

40496

QB Wings

[quote]---

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Jun 11, 2007 4:12 am Post subject: Fuel Leak

Tim Olson wrote:



 	  Quote: 	
		   



 Dave, 


	


SNIP



 	  Quote: 	
		   Then, leave the balloon full and see how it is the next day. If

 it is still full, you're done.  If it isn't, then you probably

 need to do the bubble test again, and you'll most likely find any

 problem if there is one.  


	


SNIP



Keep in mind that normal changes in pressure altitude will change the 

size of the balloon.  Keep an eye on the local altimeter.  You really 

wouldn't want to spend a lot of time checking for leaks caused by a high 

moving in!!! 

Linn

do not archive

ScooterF15

Joined: 19 Jun 2006
Posts: 136

Posted: Mon Jun 11, 2007 4:54 am Post subject: Fuel Leak

Not to mention the temperature of the tank itself. The temp inside my  hangar fluctuated from 55F at night to 120F during the afternoon, that naturally  changed the pressure drastically and makes it very hard determine if there is a  leak. Another reason I should have used the soapy water method over the entire  tank.

  

 -Jim

  

 In a message dated 6/11/2007 8:13:24 A.M. Eastern Daylight Time,  pitts_pilot(at)bellsouth.net writes:

  	  Quote: 	
		  -->    RV10-List message posted by: linn Walters    <pitts_pilot(at)bellsouth.net>



Tim Olson wrote:



 	  Quote: 	
		   -->    RV10-List message posted by: Tim Olson <Tim(at)MyRV10.com>



    Dave, 


	


SNIP



 	  Quote: 	
		   Then, leave the balloon full and see how it is    the next day. If

 it is still full, you're done.  If it isn't,    then you probably

 need to do the bubble test again, and you'll most    likely find any

 problem if there is one.     


	


SNIP



Keep in mind that normal changes in pressure altitude will    change the 

size of the balloon.  Keep an eye on the local    altimeter.  You really 

wouldn't want to spend a lot of time checking    for leaks caused by a high 

moving in!!! 

Linn

do not    archive

	


 

  



See what's free at AOL.com. 

  [quote][b]

Tim Olson

Joined: 25 Jan 2007
Posts: 2879

Posted: Mon Jun 11, 2007 5:12 am Post subject: Fuel Leak

Yeah, I should have mentioned the atmospheric changes, sorry I

missed that.  I did my leak test in our basement with a stable

temp.  As for weather, you can only hope to see everything

stable.  In truth, testing the tanks is kind of a big deal

that you get it right, so I would either let it stay inflated

for at least a couple days, or test them 2 or 3 days in a row.

And if you get a balloon drop, don't panic the first day unless

it drops in an hour or two....you can do the soap bubble

and balloon test many times to verify it isn't lying to you.



Tim



JSMcGrew(at)aol.com wrote:

 	  Quote: 	
		   Not to mention the temperature of the tank itself. The temp inside my 

 hangar fluctuated from 55F at night to 120F during the afternoon, that 

 naturally changed the pressure drastically and makes it very hard 

 determine if there is a leak. Another reason I should have used the 

 soapy water method over the entire tank.

  

 -Jim

  

 In a message dated 6/11/2007 8:13:24 A.M. Eastern Daylight Time, 

 pitts_pilot(at)bellsouth.net writes:

 

     

     <pitts_pilot(at)bellsouth.net>

 

     Tim Olson wrote:

 

      > 

      >

      > Dave,

 

     SNIP

 

      > Then, leave the balloon full and see how it is the next day. If

      > it is still full, you're done.  If it isn't, then you probably

      > need to do the bubble test again, and you'll most likely find any

      > problem if there is one. 

 

     SNIP

 

     Keep in mind that normal changes in pressure altitude will change the

     size of the balloon.  Keep an eye on the local altimeter.  You really

     wouldn't want to spend a lot of time checking for leaks caused by a

     high

     moving in!!! 

     Linn

     do not archive

 

  

 

 

 

 ------------------------------------------------------------------------

 See what's free at AOL.com <http://www.aol.com?ncid=AOLAOF00020000000503>.

 

 *

 

 

 *

rene(at)felker.com
Guest

Posted: Mon Jun 11, 2007 5:37 am Post subject: Fuel Leak

Ok, I will chime in.  I have not filled my tanks with gas yet, so....



I used a manometer to do the testing.  I did it in my garage with wide

temperature variations and changes in atmospheric conditions.  On the first

tank, I set it up, marked the water level, soap tested, and then marked the

water level each morning and night for three days.  Did not see any real

drop.  



On the second tank, I set up the same way, but was never really able to get

a perfect seal around the filler cap  Tried several methods, none worked, so

I just used the Soap.  I had no problem telling where I had not sealed

around the filler.  



Rene' Felker

N423CF

40322

801-721-6080

--

rvbuilder(at)sausen.net
Guest

Posted: Mon Jun 11, 2007 7:00 am Post subject: Fuel Leak

See, you smart guys jump straight to the technical aspects.  I was actually thinking the physical weight of the avgas and the PSI that that amount of head pressure that would exert.  It’s probably safe to assume that all bets are off with a plugged vent line.  

   

  Probably a wacky idea anyway as I slept at a Hampton Inn.  J  

   

Michael  

       

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of JSMcGrew(at)aol.com

 Sent: Monday, June 11, 2007 5:49 AM

 To: rv10-list(at)matronics.com

 Subject: Re: Fuel Leak  

  

  

         

Wouldn't it be nice if we had someone smart enough to do that?  

    

   

    

It doesn't take a rocket scientist to look up the vapor pressure of AVGAS (the ASTM D 910 spec lists a maximum of about 7 psi). That is a lot of pressure and that is why we have a vent line! I don't believe our tanks ever have to or could endure that amount of pressure. So, I don't think the amount of pressure makes too much difference; if there is a hole, air is going to go through it. That's why I used about 0.5 psi.  In my opinion, Tim has got it right when he suggests using soapy water along with pressure from a ballon as a primary test.  

    

   

    

Jim  

    

40134  

    

   

      

Jim "Scooter" McGrew

 http://www.mit.edu/~jsmcgrew   

    

   

  

    

In a message dated 6/10/2007 11:39:47 P.M. Eastern Daylight Time, rvbuilder(at)sausen.net writes:  

   	  Quote: 	
		    

What if one of you smart MIT types *cough*  figure out about how much PSI a full tank of avgas exerts while compensating for the difference in viscosity between air and avgas.  Should give you a better number to use to approx the PSI of air for testing the tanks.  Hopefully it will lead to more accurate leak tests.  

   

Just a thought.    

   

Michael  

Do not archive  	
  

  

    

   

    

   

  



 

         

  

See what's free at AOL.com.   

   	  Quote: 	
		    http://www.matronics.com/Navigator?RV10-List 	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
4

      [quote][b]

rnewman(at)lutron.com
Guest

Posted: Mon Jun 11, 2007 1:04 pm Post subject: Fuel Leak

So here's my take on this test.   We are building a slow build version

of the RV-10 so we took this as an opportunity to test the fuel tanks as

a two part process.  This gave us a chance to resolve issues in a more

forgiving maner.



Step 1:   As per instructions build  a tank up to the point where you

install the back baffle that closes out the tank,  but don't put the

back baffle in yet.    

              Set the tank aside and let the pro-seal dry for a week.  

 (build the other tank during the down time).     



               After the pro-seal is curred, place the tank in a set of

jigs with the leading edge pointing down and the rear baffle area facing

up.    Support tank at the rib locations (we used three plywood forms

cut to the shape of the tank profile)   

          

              Fill the tank with water just below the rivet line for

the rear baffle.  



             Let it set and check all the rivets in the ribs.   If you

have a leak a little bead of water will form around a rivet head.   Now

you can easily fix any leaks as you have full access to all the rivets

in the rib sections.  (NOTE, DO NOT TRY TO DUMP OUT THE WATER, you can

bend the tank.   siphon it out)



Step 2:   Once satisfied that the front portion of the tank is leak

free install the rear baffle as per instructions.   



               Let set a week and then perform the following test:    

add a few gallons of water to the tank and then set it on a set of saw

horses with the baffle side down (leading edge up).    The water will

cover the entire joint assembled during the close out.   

                 Once satisfied your done.



We did this process to both of our tanks.   Then as a belts and

suspenders test.   we jiged up the tanks on three saw horse and filled

them full of water up to the filler neck and let them sit for over a

week.   Periodic checks of all rivets showed two leak free tanks as the

above two step process predicted.



  

-Bob Newman

speckter(at)comcast.net
Guest

Posted: Mon Jun 11, 2007 3:28 pm Post subject: Fuel Leak

Two things to add.



Water is a bigger molecule than avgas and while it may not leak avgas can.

Don't ask me how I know.

2nd.   Drying out the tank can be difficult.  Hooking a Vacuum cleaner to

the filler and taping it off, then let it run for a few days should get most

of it.



Gary

40274



--

dc71(at)netspace.net.au
Guest

Posted: Tue Jun 12, 2007 5:50 am Post subject: Fuel Leak

Sorry to correct this misunderstanding,



Water molecule = H2O (small)

Avgas= mixture of multiple different hydrocarbon molecules, all  

larger than C4H10 (medium to large)



I'm no physicist, but my guess at the reason that Avgas leaks is  

something to do with different surface tension of the two liquids. Or  

possible the differing adherence to fuel tank surfaces.



Indran



 	  Quote: 	
		  

 Water is a bigger molecule than avgas and while it may not leak  

 avgas can.

indigoonlatigo(at)msn.com
Guest

Posted: Tue Jun 12, 2007 6:33 am Post subject: Fuel Leak

CHEMISTRY AND ORGANIC CHEMISTRY TO BE MORE EXACT.



Do NoT ARCHIVE

 	  Quote: 	
		  From: Indran Chelvanayagam <dc71(at)netspace.net.au>

Reply-To: rv10-list(at)matronics.com

To: rv10-list(at)matronics.com

Subject: Re: Fuel Leak

Date: Tue, 12 Jun 2007 21:47:30 +0800




<dc71(at)netspace.net.au>



Sorry to correct this misunderstanding,



Water molecule = H2O (small)

Avgas= mixture of multiple different hydrocarbon molecules, all  larger 

than C4H10 (medium to large)



I'm no physicist, but my guess at the reason that Avgas leaks is  something 

to do with different surface tension of the two liquids. Or  possible the 

differing adherence to fuel tank surfaces.



Indran



>

>Water is a bigger molecule than avgas and while it may not leak  avgas 

>can.

n1345p(at)suddenlink.net
Guest

Posted: Tue Jun 12, 2007 7:17 am Post subject: Fuel Leak

While water is a smaller molecule, hydrogen bonding between molecules forms clumps of water, making water "wet", instead of dry like fuel.



http://en.wikipedia.org/wiki/Hydrogen_bond#Hydrogen_bonds_in_water



mitch



---- Indran Chelvanayagam <dc71(at)netspace.net.au> wrote: 



=============




Sorry to correct this misunderstanding,



Water molecule = H2O (small)

Avgas= mixture of multiple different hydrocarbon molecules, all  

larger than C4H10 (medium to large)



I'm no physicist, but my guess at the reason that Avgas leaks is  

something to do with different surface tension of the two liquids. Or  

possible the differing adherence to fuel tank surfaces.



Indran



 	  Quote: 	
		  

 Water is a bigger molecule than avgas and while it may not leak  

 avgas can.


	




--

Learn2fly www.chickashawings.com

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