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  #31  
Old 08-17-2006, 05:14 PM
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rvator51 rvator51 is offline
 
Join Date: Jan 2005
Location: Peoria, AZ
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Quote:
Originally Posted by Kahuna
To ad some data.

This one is a stumper and a good thread. I thought I was the only plane on the planet with this problem. Misery loves company,
Best,
MY 1987 RV-4 had the same problem with blisters forming in the paint on the fuel tanks top and bottom. I ended up pulling the tanks off, cutting access panels in each bay, and re-prosealing each rib and rivet.
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  #32  
Old 08-17-2006, 06:44 PM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Quote:
Originally Posted by JohnR
Mike, I think you might be on to something here. I know some people have used proseal to fill around rivets before painting on other areas of the airplane. Has anyone that has done that had a problem with paint lifting on areas other than the tanks? If so maybe it ca nbe attributed ot the proseal/rivet combo and not just the tanks.

It would be interesting to know if there was a common prep used also.
John, that common prep could be MEK. Perhapts there is a pro seal out gassing reaction with MEK. I know my machine was cleaned with it.

dd
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  #33  
Old 08-17-2006, 09:25 PM
redbeardmark redbeardmark is offline
 
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Location: EDVK
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Default Agent 86 reporting for duty...

"Sorry about that, chief."
Corrosion is certainly a possibility.
Also, someone mentioned prep chemicals. I used acetone to wipe the surface before painting... but I did that on all surfaces and only got bubbles on the tank rivets.
Uh, there's one more thing, I did use Marvel Mystery Oil in my fuel a couple of times. Is this a possible commonality?

Quote:
Originally Posted by rzbill
Sheesh,
Always throwin' a wrench in the works, Redbeard!

Seriously though, I think this hints at the corrosion mentioned above. I would have thought paint prep issues would have "popped up" quicker.
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  #34  
Old 08-17-2006, 10:49 PM
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wyoflyer wyoflyer is offline
 
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Default wyoflyer

just noticed the exact same problem today on my rv-6. Tank vents are the straight tube cut at an angle. Pro-sealed ribs on top. Dupont DB-48 epoxy primer & base-coat, clear-coat paint. Thought maybe I would try a thin hypo needle and some CA glue????

Dave Mader
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  #35  
Old 08-17-2006, 11:12 PM
jim jim is offline
 
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Posts: 141
Default semi smoking rivets?

Just wondering if it may be a possibility that because of the proseal and rivets in the tanks, maybe there is some motion secondary to expansion/contraction of the tanks or due to vibration. The proseal still could be preventing leaks, but because the proseal is there, acting like a rubber motor mount, may be some motion of the rivets is loosening the paint?
Just a thought.
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  #36  
Old 08-17-2006, 11:34 PM
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cytoxin cytoxin is offline
 
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Location: south carolina
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Default self etch

mike did you self etch..or etch, i know on the cars i have painted if you self etch over filler you get a very similar reaction..the seal may absorb the acid temporarirly then give it up later
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Last edited by cytoxin : 08-18-2006 at 08:41 AM.
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  #37  
Old 08-18-2006, 03:17 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Matrix the Data?

This is an interesting problem with a lot of interesting data from different sources. It would seem to be iof general interest to get to the bottom of it. When I went out to the airport today I looked at my tank rivet locations and I saw no lifted paint on them. In my old job I would have thought "process" (including the materials) or "contamimation" and called in M&P Engineering and Contamination Control Engineering specialists to investigate in support of the project but we are on our own here (ain't it great?). The development of a matrix in Excel managed by a central controller with inputs provided by builders/owners would be nice but this is what I see so far:

Kahuna - RV-8, red paint on tanks, three color scheme, 15 rivets per side so far affected, linear progression from 10 to 200 hours on both tanks, only on top of tanks, only at rivet locations, no fuel in bubbles, no mention of flight before paint, the bubbles start at the rivet edge and extend outward over the skin, never is a full rivet head involved, built own tanks, did not ad proseal to the top, self painted, tanks sat for a year before prime and paint with caps off, rarely run full tanks since carries 60gal, tops of my tanks generally have air in them, pressure tests for 24hrs on 3psi with no leaks prior to flying, Georgia

Helicopter - RV-7A, Color unknown, number of colors in scheme unknown, 20 rivets after 25 hours on one tank only, now has 175+ flight hours and the problem is not reported to be progressive, no mention of isolation to top of affected tank, the bubble height is described as slight, no mention of surface other than rivet heads affected, Texas

Redbeardmark - RV-8A, Color unknown, number of colors in scheme unknown, only at rivet locations on top, "tank" is used in the description so may be isolated to one side, did the entire preparation and paint process (degreaser, 3M scuffing pad, acetone, etch prime, sealer primer, basecoat, clearcoat), described as minor annoyance, no mention of surface other than rivet heads affected, I flew my RV for 15 months before painting, it had roughly 400 hrs on the Hobbs with several trips to the desert SW to bake in the sun. Blisters didn't begin to appear until several months after painting, wiped down with acetone prior to paint, South Dakota

David-aviator - RV-7A, Color unknown, number of colors in scheme unknown, Quickbuilt tanks, Van's claims ignorance, started 2 years ago, painted by a professional, same vent design as Kahuna, bubbles on bottom as well as top of tanks, plane wiped down with MEK prior to paint, Mississippi

rvator51 - 1987 RV-4 "had the same problem with blisters forming in the paint on the fuel tanks top and bottom. I ended up pulling the tanks off, cutting access panels in each bay, and re-prosealing each rib and rivet", Color unknown, number of colors in scheme unknown, tank builder not mentioned, painter unknown, problem on top and bottom, described as blisters instead of bubbles (may be the same thing - or not), no mention if the fix was effective, Arizona

wyoflyer - RV-6, reported discovering the same problem (assumed bubles in paint isolated to rivets on tanks, no mention that the problem is isolated to the top surface, color unknown, number of colors in scheme unknown, tank builder not mentioned, painter unknown, tank vents are the straight tube cut at an angle, pro-sealed ribs on top, Dupont DB-48 epoxy primer & base-coat, clear-coat paint, Wyoming

Bob Axsom
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  #38  
Old 08-18-2006, 07:20 AM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Bob,
Thanks for summerizing the reports.
I have taken the liberty of sending a copy of the summation to Van's support. The dialogue with the factory has been reopened.
At this point, I have done nothing about repainting because it may happen again. We need to know what is causing it.
David Domeier
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  #39  
Old 08-18-2006, 09:07 AM
szicree szicree is offline
 
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Location: SoCal
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My first vote was for some type of solvent outgassing from the proseal around the rivet or something that soaked into it, but after reading more accounts I'm not that sure. However, I would like to know from the people who make proseal whether exposure to heat causes the stuff to give off gasses long after curing.

I do have a second theory, although it's gonna sound pretty far-fetched. Is it possible that the proseal is insulating the rivet from the surrounding structure and causing the rivet to retain heat? Then the temp differential is stressing the paint bond right at the edge of the rivet head. I said it was a long shot, but maybe?
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  #40  
Old 08-18-2006, 09:29 AM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Quote:
Originally Posted by szicree
My first vote was for some type of solvent outgassing from the proseal around the rivet or something that soaked into it, but after reading more accounts I'm not that sure. However, I would like to know from the people who make proseal whether exposure to heat causes the stuff to give off gasses long after curing.

I do have a second theory, although it's gonna sound pretty far-fetched. Is it possible that the proseal is insulating the rivet from the surrounding structure and causing the rivet to retain heat? Then the temp differential is stressing the paint bond right at the edge of the rivet head. I said it was a long shot, but maybe?
Steve,

Rick Galati knows as much about pro seal as anyone on the forum. He has worked with the stuff for years with a major airplane manufacturer. I will try to get him on this thread for his thoughts on whether or not pro seal is a factor. He is aware of my problem and does not think a poorly mixed batch of pro seal will cause out gasssing. But I have not heard his view on MEK or acetone and pro seal, and a possible conflict of chemicals. Whatever he uses to clean pro seal works, so we may be able to illiminate that prep item.

I will contact Rick.

dd
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