PR-148, PS-890-A-2 and preparation

Wray Thompson · Post by **Wray Thompson** » Fri Feb 17, 2012 8:39 pm

Check here for another tip on sealing the stringers
http://wrayt.tripod.com/hints.html#Prosealing Stringers

Roger and Alice Hoffman wrote:

Scott,

I'm not that far along with the wing construction yet, but I'm curious how
you will be able to reach into each bay to apply the brushable Pro-Seal?
Don't the main ribs within the tank have baffles which will prevent your
access? Or does each bay have an access panel?

R Hoffman #687R
Eugene, OR USA

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Wray Thompson ...Rebel 306 ...home page http://wrayt.tripod.com/
My ICQ number is 29764664

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Drew and Jan · Post by **Drew and Jan** » Fri Feb 17, 2012 8:39 pm

If I recall properly RV's don't have stringers, all the seams are turned to
the outside and the tank is built separately from the wing then screwed on
a la piper. All the same if you ask an RVator what he thinks of pro-seal
you'll just get a scowl.
One hint I haven't seen repeated for a while is to use tons of clecoes and
pull the rivets by hand to make sure the pro-seal has time to flow out
properly. I used brushable pro-seal on the bottom and side seams only
before I attached the top.
Drew

At 10:05 PM 1/22/01 EST, you wrote:

Bob,

Do RV builders have stringers going thru their tanks?

Bruce 357R

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Rebflyer · Post by **Rebflyer** » Fri Feb 17, 2012 8:39 pm

I Guess I'll add my .02 on this subject.
It's pretty obvious that the bottom of the tank is easy to install. You can see all and you can build mountains of proseal to stop any chance of a leak. But sooner or later you have to put the top on. When this part of the process begins, you suddenly lose the ability to see what the sealant is doing. From all I've read, and my own experience, the leaks usually occur when the installer has to move the part slightly to align the rivet holes correctly, and wipes off the sealant. The best way that this list has suggested to prevent that is use blank drill rods as alignment tools to slide the top over and into place. The second most common reason, and I really believe far behind the first, is the eaisest to prevent. Proper cleaning and then be sure to use gloves to prevent the oils from your hands contaminating the surface.(Helps protect your hands from the goop also). Well that's my .02
Keep at it it's worth it! Curt N97MR
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Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 8:39 pm

Thanks David !

Good tip about the oil in air from compressors - I guess
many have in-line filters for oil and water ....

......bobp

-------------------------------orig.-----------------------------------
At 08:22 AM 1/23/01 -0500, you wrote:

On 22 Jan 2001, at 21:18, Bob Patterson wrote:

homebuilts - including all the Van's RV series. It is the lightest,
easiest way to get durable, reliable fuel tanks. ( Funny - you never
hear grumbles from RV builders, although they use the same materials
Don't complain too much. The Velocity is _much_ harder to seal.
The fuel is in the strakes (The thick delta part of the wing near the
fusalage.) and the strakes are made from two large, unwieldy
fiberglass and foam skins. There are ribs and bulkheads that run
every which way that have to be made and then trimmed to fit
between the skins, then sealed with strips of fiberglass and epoxy.
You may have fuel appearing in one place and the real leak is three
feet away.

wipe with Metal-Sol, scuff with ScotchBrite, BLOW clean (NO more
One caution I've heard is about blowing clean. Since parts are held
together by fiberglass and epoxy tapes instead of rivits, surface
contamination is a serious problem. Air from an air compressor
may have oil mist in it. Don't know how serious that would be with
Proseal.

---
David Parrish

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Don Boardman · Post by **Don Boardman** » Fri Feb 17, 2012 8:40 pm

wipe with Metal-Sol, scuff with ScotchBrite, BLOW clean (NO more
One caution I've heard is about blowing clean. Since parts are held
together by fiberglass and epoxy tapes instead of rivits, surface
contamination is a serious problem. Air from an air compressor
may have oil mist in it. Don't know how serious that would be with
Proseal.

An additional consideration if considering blowing a solvent washed
surface dry. The solvent's job is to dissolve the contaminant. It is my
understanding that letting the solvent evaporate from the surface will just
redeposit the contaminant (unless the contaminant is equally as volatile as
the solvent or has strong molecular attraction to the solvent molecules).
The function of the clean cloth in drying the surface is to remove the
solvent while the contaminants are suspended in the solvent. This achieves a
dry surface with minimal evaporation. Blowing with compressed air may not
only introduce oil vapor from the compressor (if not filtered very well) but
will also promote evaporation of the solvent. This potentially leaves
contaminants behind, as opposed to a clean cloth's absorbency removing both
solvent and contaminant from the surface.

Don Boardman
SR130

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tjpackard · Post by **tjpackard** » Fri Feb 17, 2012 8:40 pm

I'd like to introduce myself (Tom Packard) to the group and comment on the
tank sealing issues that have been discussed recently. I'm a first time
builder, Super Rebel 043 and have put about 1800 hours into it over the
last three years and I'm halfway thru the fuselage construction. So far so
good, and like others, the wet tanks were the worst part of the project so
far. When I pressure tested my tanks (@ 2 psi), they held pressure for 7
days with only minor pressure fluctuations up and down with temp. changes.
When I built them, I did a few things differently as a result of my
experience at work. I work for 3M Company's Aerospace Lab/Adhesives
Division and from my experience with adhesion to aluminum after ScotchBrite
scrubbing, blowing the surface off after the ScotchBrite prep is not
sufficient to obtain good adhesion. A layer of ScotchBrite and Aluminum
particles will remain on the surface and reduce adhesion at the
ProSeal/Alum interface. It is true that many towels/rags may have starches
or other contaminants that could be a problem. We use unsized/lint free
cheesecloth and 91% Isopropyl Alcohol or other solvents to wipe the surface
clean before applying adhesive material to aluminum. Other solvents are
more effective, but are more toxic than IPA. eg. MEK, Toluene, etc.
Another thing I did to make sure I got a good seal was to rivet a length of
stringer across and near the top of each of the two center tank ribs so
that the top flange was straight and would line up with the holes in the
top skin when I brought the two together. This prevented having to move
the rib flange around (and the ProSeal) for hole alignment. I believe this
helped to keep enough sealant between the flange and skin to get a good
seal. I also made different corner brackets and stringer seals on both
sides of the outboard tank rib. I'm keeping my fingers crossed but I'm
optimistic about the results.

Tom P

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Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 8:40 pm

Don,

The solvent should have been absorbed by the cloth when wiping,
BEFORE scuffing with ScotchBrite. The important point is NOT to touch
the clean, freshly exposed metal with ANYTHING after scuffing !!

The blowing was merely to clear away any leftover ScotchBrite
particles, or aluminum shreds.

Even "clean" cloths can leave deposits - someone has already
mentioned silicone from fabric softeners, and many other things ...

.....bobp

-------------------------------orig.--------------------------------------
At 10:00 PM 1/23/01 +0000, you wrote:

wipe with Metal-Sol, scuff with ScotchBrite, BLOW clean (NO more
One caution I've heard is about blowing clean. Since parts are held
together by fiberglass and epoxy tapes instead of rivits, surface
contamination is a serious problem. Air from an air compressor
may have oil mist in it. Don't know how serious that would be with
Proseal.
An additional consideration if considering blowing a solvent washed
surface dry. The solvent's job is to dissolve the contaminant. It is my
understanding that letting the solvent evaporate from the surface will just
redeposit the contaminant (unless the contaminant is equally as volatile as
the solvent or has strong molecular attraction to the solvent molecules).
The function of the clean cloth in drying the surface is to remove the
solvent while the contaminants are suspended in the solvent. This achieves a
dry surface with minimal evaporation. Blowing with compressed air may not
only introduce oil vapor from the compressor (if not filtered very well) but
will also promote evaporation of the solvent. This potentially leaves
contaminants behind, as opposed to a clean cloth's absorbency removing both
solvent and contaminant from the surface.

Don Boardman
SR130

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Don Boardman · Post by **Don Boardman** » Fri Feb 17, 2012 8:40 pm

Bob,

Yes, Bob I see, you are just removing the "dust"
I missed that you did not use solvent after the ScotchBrite.
My procedure is to clean with solvent, ScotchBrite, and clean again with
solvent to insure a clean mechanically etched surface.
I have used this procedure when doing Al to Al bonding with Hysol Adhesives
for a motorglider project with excellent consistent results.

I have not worked with pro-seal.

Don

The solvent should have been absorbed by the cloth when wiping,
BEFORE scuffing with ScotchBrite. The important point is NOT to touch
the clean, freshly exposed metal with ANYTHING after scuffing !!

The blowing was merely to clear away any leftover ScotchBrite
particles, or aluminum shreds.

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rebelair · Post by **rebelair** » Fri Feb 17, 2012 8:40 pm

Hi Louis

I helped a friend install the plastic fuel tanks. We riveted the wings
shut. After the problems developed, he extricated the plastic tanks & went
to wet wings. Not a good thing at all!

Proseal is not that bad. Just be careful the first time & you will have the
lightest possible construction.

Brian #328R

-----Original Message-----
From: Drew and Jan [mailto:drewjan@execulink.com]
Sent: Monday, January 22, 2001 3:19 PM
To: Murphy Rebel Builders List
Subject: RE: PR-148, PS-890-A-2 and preparation

Louis the early rebels had 3 plastic tanks in each wing with an aluminum
fitting at the back and a large interconnect hose. Almost everyone of them
leaked at the joint between the plastic and the aluminum. The wet wing is a
good solution and even though it's tough on the rebel wing with ribs and
stringers in the tank to get a seal it can be done.
Drew

At 09:41 PM 1/21/01 -0600, you wrote:

Guys, (remember I am a student in this stuff...and not a builder yet...)
It seems that there is a WHOLE lot of mail on sealing up these tanks....It
sounds like it is a real bear, so why is there not a better solution ??

How about a blown plastic tank a'la Rans and Rotorway ? Or a rubber
bladder like C-210's and late Piper's...There must be a reason other than a
pound or two of additional polymers per side...?

Once again, I like fuel to stay where intended....and away from my tender
pink skin..Just wondering....(for months!)

Louis Young
www.justplanevideos.com

-----Original Message-----
From: Bob Patterson [mailto:bob.patterson@canrem.com]
Sent: Sunday, January 21, 2001 9:24 PM
To: Murphy Rebel Builders List
Subject: Re: PR-148, PS-890-A-2 and preparation

Right on, Scott !!! You should have success with that approach !!

If there's any doubt about oil or other contamination from the
towels or rags, you could just use an air blast - several builders
have found that worked well.

.....bobp

----------------------------orig.---------------------------------------
At 04:54 PM 1/21/01 -0800, you wrote:
Bruce, the rebel manual says to MEK or Acetone, then abraid and then
wipe with a clean dry towel. Murphy also suggested to me that I might
soften the ProSeal up a little with light MEK, but I think that I will
rely on the abrasion and adhesion promoter to do that.
--
Best Regards,

Scott Hibbs
hibbs@pacifier.com
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Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 8:40 pm

Re - sent because list was down

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

Subject: Re: PR-148, PS-890-A-2 and preparation
Message-Id: <E14MInh-0007Wj-00@smtp1.interramp.com>
Date: Fri, 26 Jan 2001 19:01:06 -0500

Hi Don !

I can see how the 'second wipe' method might work for you and
Tom, because you are VERY careful about your choice of rags & solvents,
but I've heard SO many horror stories locally about contamination from
rags, or oxidation, or solvents .... It seems that several have had
good results with just blowing - I guess a few grains of ScotchBrite
mixed in over totally clean metal are better than coated or
oxidized metal ....

For all you newbies: as always, gather all the comments, and...
- 'you get to choose - it's your airplane !!' These are only suggestions.

FWIW, one of our inspectors has suggested that acetone might
be the best choice of solvent, because it will remove moisture, is
clean, should completely evaporate, and is less toxic than MEK
(still nasty stuff, though !!) ....

.....bobp

---------------------------orig.-------------------------------------------
At 09:23 PM 1/24/01 +0000, you wrote:
Bob,

Yes, Bob I see, you are just removing the "dust"
I missed that you did not use solvent after the ScotchBrite.
My procedure is to clean with solvent, ScotchBrite, and clean again with
solvent to insure a clean mechanically etched surface.
I have used this procedure when doing Al to Al bonding with Hysol Adhesives
for a motorglider project with excellent consistent results.

I have not worked with pro-seal.

Don

The solvent should have been absorbed by the cloth when wiping,
BEFORE scuffing with ScotchBrite. The important point is NOT to touch
the clean, freshly exposed metal with ANYTHING after scuffing !!

The blowing was merely to clear away any leftover ScotchBrite
particles, or aluminum shreds.
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Legeorgen · Post by **Legeorgen** » Fri Feb 17, 2012 8:40 pm

Bob,

Skystar Aircraft (Kitfox) recommended denatured alcohol. They said it was a
saver solvent and did the job for them for prepping metal for painting. I
don't see way it won't work for Proseal.

Bruce 357R

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Bob Patterson · Post by **Bob Patterson** » Fri Feb 17, 2012 8:40 pm

Hi Bruce !

The reason our inspector recommended acetone was that it DIDN'T
attract water, like alcohol does, and that would reduce the risk of
oxidation.... and it was only for use for that 'final wipe', if
you must do it. (not general use)

Just a suggestion .....

.....bobp

-----------------------------------orig.----------------------------------
At 12:03 AM 2/2/01 EST, you wrote:

Bob,

Skystar Aircraft (Kitfox) recommended denatured alcohol. They said it was a
saver solvent and did the job for them for prepping metal for painting. I
don't see way it won't work for Proseal.

Bruce 357R

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