The Murphy Builders Site

Posted: **Sat Feb 18, 2012 2:29 pm**

Hi,

Been reading the archives on repairing leaks (haven't pressure testing yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks along a stringer. My question is, did you have to cut an access hole or is there some other way to fix this area?

My other question concern the tank bulkheads. While assembling the wing I realized that if the bulkheads were installed with the flanges facing aft you would move about 140 rivets (and potential leaks) outside the tank. But, alas, if you turn them around they are too short because of the curve of the top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is a good filet all we need to seal the tank or are the faying surfaces important too?

Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Of course you have to cut an access hole. I do them OUTSIDE the tank.

The important thing when building a tank is clean surfaces & nice x hatched
scotchbrite pattern. Since you rarely have completely full tanks the bottom
of the tank, no different than a bath tub, is the most important to seal.
Fillet all the bottom seams, corners, rivets in tooling holes and the coat
all the rivet shop heads. Every top corner should be built up to form a
solid bridge from rib flange to rear bulkhead flange...front spar to rib
flange etc before placing the top skin. This way you are not worried about
the PRC/Proseal/Sealpack sagging away in these areas when you are riveting
the top skin on. All you have to do is lay down a bead around the tank
perimeter, place the top skin and rivet her down......dipping/rolling each
rivet in PRC as you go. Many suggestions of flipping the wing over right
after you are done...but I've never bothered and never had a leaking tank in
well over a dozen wings...well other than my very first wing with on minute
stringer leak..pin hole that had sagged away up inside the "J" of the
stringer.

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:19 PM
Subject: Tank leak fix

Hi,

Been reading the archives on repairing leaks (haven't pressure testing

yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks along
a stringer. My question is, did you have to cut an access hole or is there
some other way to fix this area?

My other question concern the tank bulkheads. While assembling the wing I

realized that if the bulkheads were installed with the flanges facing aft
you would move about 140 rivets (and potential leaks) outside the tank. But,
alas, if you turn them around they are too short because of the curve of the
top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is a
good filet all we need to seal the tank or are the faying surfaces important
too?

Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Hi Allen
I reversed the bulkheads but I used a half inch by 0.1" thick spacer
across the top of each bulkhead. I seem to recall issues with fit doing
it according to the manual regardless of which way they went in. I can't
imagine why you'd assemble the tank without prosealing the faying
surfaces. You need something in there for corrosion purposes even if you
think you can do a perfect filet and then there are all those rivets...
The last thing you want is fuel leaking in through a rivet and running
between the metal surfaces and coming out somewhere else making it
impossible to find the leak. On 119R I also used slightly larger tank
skins than supplied in the upgrade kit to get adequate edge distance and
rivet spacing along the tank skin to wing skin joint. If my memory is
correct you can pressure test the tanks before you rivet the wing skins
on so that you have access to the exterior of the tank. Exterior access
won't help of course unless you do the faying surfaces.
Ken.

apoulsen wrote:

Hi,

Been reading the archives on repairing leaks (haven't pressure testing yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks along a stringer. My question is, did you have to cut an access hole or is there some other way to fix this area?

My other question concern the tank bulkheads. While assembling the wing I realized that if the bulkheads were installed with the flanges facing aft you would move about 140 rivets (and potential leaks) outside the tank. But, alas, if you turn them around they are too short because of the curve of the top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is a good filet all we need to seal the tank or are the faying surfaces important too?

Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Wayne,

I assumed that the only way to gain access was to cut a hole in the skin but
I was hoping you possessed some divine secret that would avoid this fate.
From the old e-mail I thought you were talking about leaks along the
stringer as opposed the where the stringer exits the tank. If you were
talking about along the stringer I don't know what you mean by OUTSIDE the
tank. If we are talking about where the stringer exits I understand.

Thanks again.

Allen
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:31 PM
Subject: Re: Tank leak fix

Of course you have to cut an access hole. I do them OUTSIDE the tank.

The important thing when building a tank is clean surfaces & nice x
hatched
scotchbrite pattern. Since you rarely have completely full tanks the
bottom
of the tank, no different than a bath tub, is the most important to seal.
Fillet all the bottom seams, corners, rivets in tooling holes and the coat
all the rivet shop heads. Every top corner should be built up to form a
solid bridge from rib flange to rear bulkhead flange...front spar to rib
flange etc before placing the top skin. This way you are not worried about
the PRC/Proseal/Sealpack sagging away in these areas when you are riveting
the top skin on. All you have to do is lay down a bead around the tank
perimeter, place the top skin and rivet her down......dipping/rolling each
rivet in PRC as you go. Many suggestions of flipping the wing over right
after you are done...but I've never bothered and never had a leaking tank
in
well over a dozen wings...well other than my very first wing with on
minute
stringer leak..pin hole that had sagged away up inside the "J" of the
stringer.

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:19 PM
Subject: Tank leak fix

Hi,

Been reading the archives on repairing leaks (haven't pressure testing
yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks
along
a stringer. My question is, did you have to cut an access hole or is there
some other way to fix this area?
My other question concern the tank bulkheads. While assembling the wing I
realized that if the bulkheads were installed with the flanges facing aft
you would move about 140 rivets (and potential leaks) outside the tank.
But,
alas, if you turn them around they are too short because of the curve of
the
top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is a
good filet all we need to seal the tank or are the faying surfaces
important
too?
Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Ken,

I didn't mean to imply that the faying surfaces don't need to be sealed.
Just wondered if there was any reason not to move the rivets out of the tank
if you could. Sounds like you did what I was thinking of doing on the left
wing.

Did you feel it was worth the effort to put in the spacer and get the rivets
out of the tank? Did it/has it caused any problems?

Thanks,
Allen
----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 9:41 PM
Subject: Re: Tank leak fix

Hi Allen
I reversed the bulkheads but I used a half inch by 0.1" thick spacer
across the top of each bulkhead. I seem to recall issues with fit doing
it according to the manual regardless of which way they went in. I can't
imagine why you'd assemble the tank without prosealing the faying
surfaces. You need something in there for corrosion purposes even if you
think you can do a perfect filet and then there are all those rivets...
The last thing you want is fuel leaking in through a rivet and running
between the metal surfaces and coming out somewhere else making it
impossible to find the leak. On 119R I also used slightly larger tank
skins than supplied in the upgrade kit to get adequate edge distance and
rivet spacing along the tank skin to wing skin joint. If my memory is
correct you can pressure test the tanks before you rivet the wing skins
on so that you have access to the exterior of the tank. Exterior access
won't help of course unless you do the faying surfaces.
Ken.

apoulsen wrote:

Hi,

Been reading the archives on repairing leaks (haven't pressure testing
yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks
along a stringer. My question is, did you have to cut an access hole or is
there some other way to fix this area?

My other question concern the tank bulkheads. While assembling the wing I
realized that if the bulkheads were installed with the flanges facing aft
you would move about 140 rivets (and potential leaks) outside the tank.
But, alas, if you turn them around they are too short because of the curve
of the top skin. Has anyone tried to do this? Maybe I'm not thinking
right. Is a good filet all we need to seal the tank or are the faying
surfaces important too?

Thanks,
Allen Poulsen
786R

-----------------------------------------------------------------
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Posted: **Sat Feb 18, 2012 2:29 pm**

Talking about fuel leaking at the stringer where it goes thru the tip most
tank rib. I fillet both inside and outside the tank as well as the joining
surfaces. This gives you three shots at a complete seal. Therefore makes
more sense to fix a leak outside the tank..... by blending new PRC into the
old fillet by cleaning alum beyond the original PRC fillet.....than inside
the tank where you will comprimise what is already sealed and adding
numerous rivets that are potention leak spots in the bottom of the
tank.....since you can't go in and coat them over like you could when the
top lid was off. I have fixed numerous tank leaks on the outside. Takes a
LOT of work with tanks that weren't filleted on the outside, and especially
those that decided to go nuts with Epoxy Chromate on the outside, to get to
bare metal thru access holes..but doable!

If anyone is looking for fresh PRC/Sealpac by the way...I have 5 qts on the
way Fedex from MAM with my amphib backorder. I won't be using any of them
for the floats that I'm building and would only like to retain one can for
the fridge..... to update my numerous cans of old stock. Not sure what
current pricing is...but we can work something out if you're interested.

Wayne

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 10:13 PM
Subject: Re: Tank leak fix

Wayne,

I assumed that the only way to gain access was to cut a hole in the skin

but

I was hoping you possessed some divine secret that would avoid this fate.
From the old e-mail I thought you were talking about leaks along the
stringer as opposed the where the stringer exits the tank. If you were
talking about along the stringer I don't know what you mean by OUTSIDE the
tank. If we are talking about where the stringer exits I understand.

Thanks again.

Allen
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:31 PM
Subject: Re: Tank leak fix

Of course you have to cut an access hole. I do them OUTSIDE the tank.

The important thing when building a tank is clean surfaces & nice x
hatched
scotchbrite pattern. Since you rarely have completely full tanks the
bottom
of the tank, no different than a bath tub, is the most important to

seal.

Fillet all the bottom seams, corners, rivets in tooling holes and the

coat

all the rivet shop heads. Every top corner should be built up to form a
solid bridge from rib flange to rear bulkhead flange...front spar to rib
flange etc before placing the top skin. This way you are not worried

about

the PRC/Proseal/Sealpack sagging away in these areas when you are

riveting

the top skin on. All you have to do is lay down a bead around the tank
perimeter, place the top skin and rivet her down......dipping/rolling

each

rivet in PRC as you go. Many suggestions of flipping the wing over right
after you are done...but I've never bothered and never had a leaking

tank

in
well over a dozen wings...well other than my very first wing with on
minute
stringer leak..pin hole that had sagged away up inside the "J" of the
stringer.

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:19 PM
Subject: Tank leak fix

Hi,

Been reading the archives on repairing leaks (haven't pressure testing
yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks
along
a stringer. My question is, did you have to cut an access hole or is

there

some other way to fix this area?
My other question concern the tank bulkheads. While assembling the wing

I

realized that if the bulkheads were installed with the flanges facing

aft

you would move about 140 rivets (and potential leaks) outside the tank.
But,
alas, if you turn them around they are too short because of the curve of
the
top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is

a

good filet all we need to seal the tank or are the faying surfaces
important
too?
Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Allen, I had a leak and cut a hole behind the tank in the wing bottom and PRC it like Wayne described. I but a vacume hose in the filler neck to create a negative pressure inside the tank. It worked well and I didn't have to compromise the tank itself.

Bruce

-----Original Message-----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
Sent: Nov 30, 2005 10:23 PM
To: rebel-builders@dcsol.com
Subject: Re: Tank leak fix

Talking about fuel leaking at the stringer where it goes thru the tip most
tank rib. I fillet both inside and outside the tank as well as the joining
surfaces. This gives you three shots at a complete seal. Therefore makes
more sense to fix a leak outside the tank..... by blending new PRC into the
old fillet by cleaning alum beyond the original PRC fillet.....than inside
the tank where you will comprimise what is already sealed and adding
numerous rivets that are potention leak spots in the bottom of the
tank.....since you can't go in and coat them over like you could when the
top lid was off. I have fixed numerous tank leaks on the outside. Takes a
LOT of work with tanks that weren't filleted on the outside, and especially
those that decided to go nuts with Epoxy Chromate on the outside, to get to
bare metal thru access holes..but doable!

If anyone is looking for fresh PRC/Sealpac by the way...I have 5 qts on the
way Fedex from MAM with my amphib backorder. I won't be using any of them
for the floats that I'm building and would only like to retain one can for
the fridge..... to update my numerous cans of old stock. Not sure what
current pricing is...but we can work something out if you're interested.

Wayne

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 10:13 PM
Subject: Re: Tank leak fix

Wayne,

I assumed that the only way to gain access was to cut a hole in the skin

but

I was hoping you possessed some divine secret that would avoid this fate.
From the old e-mail I thought you were talking about leaks along the
stringer as opposed the where the stringer exits the tank. If you were
talking about along the stringer I don't know what you mean by OUTSIDE the
tank. If we are talking about where the stringer exits I understand.

Thanks again.

Allen
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:31 PM
Subject: Re: Tank leak fix

Of course you have to cut an access hole. I do them OUTSIDE the tank.

The important thing when building a tank is clean surfaces & nice x
hatched
scotchbrite pattern. Since you rarely have completely full tanks the
bottom
of the tank, no different than a bath tub, is the most important to

seal.

Fillet all the bottom seams, corners, rivets in tooling holes and the

coat

all the rivet shop heads. Every top corner should be built up to form a
solid bridge from rib flange to rear bulkhead flange...front spar to rib
flange etc before placing the top skin. This way you are not worried

about

the PRC/Proseal/Sealpack sagging away in these areas when you are

riveting

the top skin on. All you have to do is lay down a bead around the tank
perimeter, place the top skin and rivet her down......dipping/rolling

each

rivet in PRC as you go. Many suggestions of flipping the wing over right
after you are done...but I've never bothered and never had a leaking

tank

in
well over a dozen wings...well other than my very first wing with on
minute
stringer leak..pin hole that had sagged away up inside the "J" of the
stringer.

----- Original Message -----
From: "apoulsen" <apoulsen@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, November 30, 2005 7:19 PM
Subject: Tank leak fix

Hi,

Been reading the archives on repairing leaks (haven't pressure testing
yet, keep fingers crossed) and saw an old e-mail from Wayne re: leaks
along
a stringer. My question is, did you have to cut an access hole or is

there

some other way to fix this area?
My other question concern the tank bulkheads. While assembling the wing

I

realized that if the bulkheads were installed with the flanges facing

aft

you would move about 140 rivets (and potential leaks) outside the tank.
But,
alas, if you turn them around they are too short because of the curve of
the
top skin. Has anyone tried to do this? Maybe I'm not thinking right. Is

a

good filet all we need to seal the tank or are the faying surfaces
important
too?
Thanks,
Allen Poulsen
786R

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Posted: **Sat Feb 18, 2012 2:29 pm**

Allen

By reversing the bulkheads I got everything to fit well with that
spacer. I was not happy with the fit that I was getting doing it MAM's
way so yes I'd do it again. However I was influenced by thinking the
rivets were better off outside the tank. That has not been an area that
guys have had much trouble with regarding leaks so I'd go with what ever
seems easiest. Just make sure you have sufficient tank skin overlap to
rivet the main skin to the tank skin. I wanted a generous filet on the
outside of the tank (as well as inside) without the wing skin being in
the way of the filet.

I was wondering if the soft 3003-0 series aluminum versa tube that
Spruce sells would be flexible enough to make it easier to run your fuel
lines?? The 1/4" size is easilly bent a bit by hand to snake it through
bulkheads but I don't know about 3/8.

I assume you meant that you were putting access covers in the INTERIOR
corner wraps. We know the exterior corner wraps are sensitive to damage.
I wonder if the rules actually require access to AN fittings. Perhaps a
small inspection hole might be satisfactory.

Ken

apoulsen wrote:

Ken,

I didn't mean to imply that the faying surfaces don't need to be sealed.
Just wondered if there was any reason not to move the rivets out of

the tank

if you could. Sounds like you did what I was thinking of doing on the

left

wing.

Did you feel it was worth the effort to put in the spacer and get the

rivets

out of the tank? Did it/has it caused any problems?

Thanks,
Allen

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