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Paint Blisters/Fuel Tank Rivets

Kicking back is what I will do. The product I would use is Muggy formulation #1. This uses a flux that is non corrosive and allows the product to flow. There are other products that may work as well. But there are many questions before this can really be considered. What are the consequences of heating 2024 locally to 350 degrees? Will this procedure truly seal the rivet? How will it work over time with temperature changes, vibration, etc? Is the filler and flux truly non corrosive over time? A test tank built to test this idea would be easy enough. And if it did work it may be a very good way to do tanks in the future.
 
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Boil and bubble, toil and trouble...

...What are the consequences of heating 2024 locally to 350 degrees? ...

According to AC43.13-1B, Paragraph 4-54(b):

Reheating at Temperatures Above Boiling Water. Reheating of 2017 and 2024 alloys above 212 ?F tend to impair the original heat treatment. Therefore, reheating above 212 ?F, including the baking of primers, is not acceptable without subsequent complete and correct heat treatment.

Of course, we as experimental aircraft builders are not obligated to adhere completely to AC43.13. But it is usually a good idea to do so.

Thanks, Bob K.
http://www.hpaircraft.com/hp-24
 
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solder and 2024?

I would be stunned to learn that there is a solder that works on 2024. There are some products out there that will solder (braze) 3000 and 5000 series aluminum, I think. I have tried a couple on 6061 with no luck.
 
Test it on a Briggs&Stratton

A test tank built to test this idea would be easy enough. And if it did work it may be a very good way to do tanks in the future.

You could at least test the vibration resistance by building and running a test tank on your mower.;)
 
if you want to have a welded tank, make a welded tank...
I don't think the skin (both the structural design and the material) are meant to be welded or soldered.
 
Paint Blisters

I have read through this thread (and others about the same problem) but I see that the last response was in 2009 and I do not see a solution. My RV has been flying for one year now and I also noticed the paint blisters over the rivets on my QB wings and also only in the fuel tank area. No fuel in these blisters or any coloring.

Has anyone found a cause / solution to this yet?
 
Patience please.

There is work being done on this by one of the members here, he is trying to keep a low profile till he has solid proof of what is going on, then will make a report.

At this time, further speculation is not going to be much more than a waste of time.
 
OK I'll chime in

Has anyone found a cause / solution to this yet?

My QB wings developed major blisters and started about a month after fuel went in them. It progressively got worse for about a year until I had to do something about it. It was a major PITA! I had to take a perfectly good aircraft out of service to repair it. I was involved with the experiment mentioned along with several others. Some have not repaired yet, others have. I pulled both tanks off, made a mess with the paint, I had to strip and repaint them (4 different colors). The fix is to open the rear baffle between the tank ribs to gain access. I will not elaborate on what I found but resealing them properly has fixed my problem. Repainted them and over a year later, no sign of a blister. You will hear they were painted improperly, not cleaned properly and many other things. If you open them up and seal them correctly they will not leak anymore. You won't find fuel in the blisters and the tanks will easily pass the balloon and soap test, yet they will blister if not sealed properly. I have sold my 8 and about to build another, guess who will build my next tanks. I will never order another QB tank. That's my story. YMMV
 
SAD news here as well!

Aslo a QB.
The tanks have passed the ballon test.
The wings have been painted a few months before the first fuel went in.
Saw ONE BLISTER a few days :mad: ago on the RH tank top and who knows if any other will develop.
 
Blister event he shop heads are encapsulated.

Pat, of course you can get general coating problems, including trapped solvents, if the preparation and paint job on a plane are not done properly.

HOWEVER, what we are talking about here is specifically blistering on rivets AT THE FUEL TANK ONLY and where they do not appear anywhere else on the entire plane. This has proven to be a very common phenomenon.

The ONLY logical conclusion one can draw from this particular phenomenon is that the blistering is caused by fuel or fuel vapour weeping through rivet holes.

To date, no-one has reported a case of this occurring on fuel tanks when their shop heads (inside the tank) have been fully encapsulated.

I again request anyone who has experienced blistering on tanks with fully encapsulated shop-head rivets to step forward. If no-one comes forward I think we can conclude what the problem is.


I have a slow build and it happens only on the upper side. My shop heads are all encapsulated. My suggestion is, that I used to much sealer. As I removed the paint, I could see, that some of this rivets out of center. Maybe, as I squeezed the rivet, the redundant sealer could not went out fast enough and now is enough space for vapor to escape and lift the paint.
I also run a paint shop for more then 20 years and think, that I have a lot of experience. But why happens this??
 
.....My suggestion is, that I used to much sealer.......
I really doubt the amount of sealer you used has anything to do with your problem. It is the proper application of that sealer that is far more important. Besides, rivet shop head encapsulation is not the only thing that will prevent blistering, a good fay and filet seal is also very important. Some, if not most builders did not encapsulate the rivet shop heads, yet most builders have not experienced paint blistering. How is this possible? See posts #187 and #207 to understand how a fuel tank can still develop paint blisters regardless of how good the rivet shop head encapsulation is.
 
Doubt over Vans quality control.

I will quote directly from the fuel tank construction section of Van's RV7 Builder's Manual:

"Dab a bit of sealant over every rivet head".

And yet Vans has repeatedly failed to ensure that their QB tank subcontractor follows this specific guideline.

Attached is a photo I took recently inside an RV7 QB tank. Note that there is NO proseal on the rivet heads. It doesn't say much for Van's quality control procedures.

It is now apparent from feedback on VansAirforce that some QB tanks have had the rivet heads sealed but many have not. In other words the QB tank subcontractor deviates in the construction sequence at will.

I have several friends with blistering paint over QB tank rivets. It's a widespread and common problem and Vans needs to address the situation immediately (if they have not already done so). To date they seem to have simply left the QB subcontractor to his own devices.

The real tragedy of the weeping rivets is that normal pressure testing methods will not reveal the problem. You only find out after the tanks have been painted and are in service. That's a very sad situation for those who have beautiful paint jobs ruined.

I'm not saying that lack of rivet head sealant is the only cause of fuel weeping....but it's one of the causes. Rick Galati has clearly outlined on this thread (and other threads) the numerous reasons why unsatisfactory sealant application can lead to leaks in many areas.

Initially the rivet weeping problem caused widespread confusion and many theories were put forward as to the cause. Time and feedback have however confirmed the initial theory of Rick Galati in that poor sealant application is solely to blame.


 
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I rotated Bob's picture 90? so the casual viewer has a normal perspective of the quickbuild fuel tank stiffener illustrated in his post. In addition, I inserted a page pulled from the RV builder's manual because that information is available to everybody who builds an RV and describes the cause of the condition of the circled rivet shop head as "bucking bar slipped."

In the real world, that rivet *could* endure just fine EXCEPT that in this case the stakes have been raised dramatically because that defective rivet is set in a dimpled hole through a sealed fuel tank and is obviously not encapsulated. In the real world, all it would take is the slightest microscopic pin hole though the existing sealer barrier to open up a (potential) pathway to the paint coating on the surface. You could put a balloon test to the tank for a solid week or more and not perceive the (potential) problem. If I were going to apply a labor intensive, multi thousand dollar paint job, I most certainly would not view nor accept that circled rivet as "good enough" and then like so many others, succumb to the siren call of "BUILD ON!" In fairness and to be completely objective about it, that rivet may never weep...apparently the quickbuild production facility is betting it won't...but are you willing to take that chance with your custom paint job and then risk having the blistering problem reported by so many others raise its ugly head in your direction weeks or even months later?

15eva4h.jpg
 
Rick,

You have stated more than a few times that correct application of the sealant is most important and that the fay technique used by your employer is best. Obviously it is, big corporations do not waste money on production techniques that do not work.

WHY is this method better than Van's recommended method of immediate riveting as the parts are assembled with the sealant?

I have thought the matter through and come up with this scenario.

Two parts clecoed together with sealant between them and allowed to cure partially will leave more sealant between the 2 parts than if they were riveted immediately. There is more compression on a joint with bucked rivets and the sealant will be forced out from between the 2 parts and could leave some areas of the joined surfaces rather devoid of sealant.

Is this reasoning in the ball park?
 
....This I also know. When you shoot or squeeze rivets into very wet sealer, in reality only a thin film of sealer remains between the parts because the majority of the sealer is squeezed from between the parts in the riveting process. If the builder fay sealed in a manner that allowed ANY voids to exist in that remaining thin film of sealer...it is all the more reason to suspect that fuel or fuel fumes could eventually find its way into a void or voids hidden within that fay sealed surface.....
Dave,

To help answer your question, I quoted myself drawn from post #97.

"Fay" sealing is not just a big corporation issue with its eye focused on the bottom line, it is a sheet metal best practices issue. Fay sealing, filet sealing, butt sealing, encapsulation are all accepted practices outlined in a variety of places that production facilities use because they know the accepted standards work. Saying that, the specific technique I personally use (clecoing wet parts together and then allowing the sealer to partially cure) is my own self developed technique borne out of decades working with sealer. I've always had an interest in keeping the mess to an absolute minimum. I can assure you with an army of Quality Control inspectors, Navy auditors, Air Force auditors, and engineers from a variety of disciplines CONSTANTLY looking over your shoulder, not one time was my technique ever challenged as violating industry standards that McDonnell-Douglas codified into a 6 foot long row of books formally referred to as the "Process Specification."

...WHY is this method better than Van's recommended method of immediate riveting as the parts are assembled with the sealant?

Van's method has to be driven in large part by pure economics. People work by the hour and a cost conscious employer will not buy into the idle workers' excuse "I'm waiting for the sealer to dry." The quickbuild option has to be an affordable alternative or builders would not buy into them. It is very hard to go into this further without getting political. But the reality is that to build those affordable fuel tanks for the mass market, the labor is currently done elsewhere. By and large that labor does a fair job and safety is never compromised. Since blistering has been characterized as a "cosmetic" issue, there is little incentive to increase costs to Van's and the consumer by asking that foreign labor to spend any more additional man hours than they really have to in order to get the product out the door. That may seem a simplistic notion to some, but that's how I see it.
 
Dry set rivets.....may be the answer

As reported in another thread, I am building new tanks and have been reviewing the many suggestions and tips here and else where to get these tanks built right.

In the process of that review, one suggested cause of the blisters is rivets not being wet installed or with inadequate sealant leaving part of the rivet dry. Having set a few rivets getting started on the project, I can understand how this could happen.

I just returned from the hangar after inspecting some of the blisters with a bright light and magnifying glass. I can not see any proseal in the edge between the skin and the exposed rivets, none. Proseal may be around the rivet shank but it is not visible on the surface where the rivet head meets the skin.

One new blister this year (7 years after build) has a blister over part of the rivet. The part of rivet exposed due to the bliser is very shiny between the rivet edge and the skin, there is no proseal in evidence on the surface.

Could it be the problem is as simple as inadequate proseal between the rivet head and skin? Perhaps that's just part of the problem. Inadequate proseal application in the interior with exposed shop heads and voids could be the other half of the equation.
 
Paint blisters on one tank but not the other

For another data point, we have slow build tanks we did ourselves. Fully encapsulated shop heads inside. Quick wipe with MEK on the outside. One tank has a few blisters, the other doesn't (since 2006). I believe the blisters developed after about two years. Paint is Imron over etched, alodined, variprimed surfaces. About six months ago I cut out the blisters and painted Imron (no other prep) on the spots with a brush to touch up. They have not re-blistered (yet).

LeRoy Johnston
RV-6A N176LD "Esperanza" 440hrs
 
Still no fix...

Yrs have passed and 317 postings on this thread and still no fix. I purchased QB wings/tanks just 3 yrs ago on the theory that my tanks would be perfect since would be done by someone who knew what they doing. Well... NOT!!

After 6 mo of fuel in them, both tanks developed scores of blisters top and bottom. OK I'm P.Od!! The multiple color paint job is as good as ruined. This IS a problem Vans is responsible for because they didn't, and one can only assume still have not, ensured adequate QC.

My painter had me pin prick the blisters as they occurred to at least limit the extent of the delamination. Even on the really large blisters, there is no evidence of liquid. This is clearly a vapor barrier breach from within the tank.

Has anyone found a successful sealing repair from the outside?
I'm wondering about flush filling the rivets heads with some kind of epoxy
filler.
What about "superglue" around the rivet heads, it seems to have a pretty good wicking action.
Frustrated as h---!
 
Hopefull data point

I have what appears to be a success story. Can't really draw any conclusions, but it is information.

I have RV-8 Quick-Build wings with tanks built in April-May 2007.
Wings were painted before ever having fuel in them, except for a quick leak test.

Before painting, on the slight hope that it would make a difference, I put a drop or two of green Locktite sealant on each tank rivet head. This was allowed to penetrate for two days. I had no mechanism to pull a gentle vacuum on the tank at the time, or I would have. After two days, the excess green Locktite was washed off with a quick wipe of acetone.

Wings were painted with JetGlo system. First washed with a phosphoric acid wash, then soap and water, then dried several days. Then the self-etching primer that is used with JetGlo, then White JetGlo.

Wings were then stored for 6 months before assembling airplane and filling tanks with fuel. First fueled in August, 2009. So, it has been TWO YEARS, 150 hrs hobbs. Airplane has always been hangared except for a few long trips where it sat out for a few days in the summer sun.

NO BLISTERS! NONE!

I can say that I do NOT have particularly good paint adhesion on my wings. When trimming the inboard edge of the flaps when assembled to the fuselage, the aluminum curled up when cut with the shears, and the primer and paint peeled off the aluminum.

I can not say much about the particular level of sealant inside my tanks. I never looked that close. I think I recall significant fillets around shop tails, but not fully encapsulated. I think I recall generous fillets and evidence of fay sealant.

I don't know if perhaps the fact that they where made in April or May in the Philippines helped - maybe there was less need to contaminate the sealant by thinning with MEK if the weather was milder? (Is it even milder there in our spring?)

I don't know if my Locktite sealant application helped? Maybe?
 
Has anyone built their tanks with Proseal 890 only instead of the flamemaster sealer from vans? Has there been any blistering on the proseal tanks? I used the flamemaster and have some on one tank. I also had a leak on the rear baffle and the sealer along the lower seam softened from the leaking fuel. I have used proseal at an OEM facility for years and have never seen any blistering or softening. Just wondering if the flamemaster is the culprit here. I know it is supposed to meet the mil specs for 8802, but I am not happy with the results. I wish I had used the proseal 890.
 
Has anyone found a successful sealing repair from the outside?
I'm wondering about flush filling the rivets heads with some kind of epoxy
filler.

Hi!
I sanded down the paint to the rivet and covered with one layer of very thin glass with epoxy (West System).
I have again one blister after 3 month.

Detlef
 
Paint blislters

I am getting ready to paint my QB tanks and will look inside next week to check the quality of the seal. I might also try the green Loctite as an added effort that may help prevent blisters, can't hurt!

Other than that, I am open to suggestions.
 
Hi!
I sanded down the paint to the rivet and covered with one layer of very thin glass with epoxy (West System).
I have again one blister after 3 month.

Detlef

Can you tell if the blister raised the glass and epoxy, or has the vapor, creating the blister, seeped through the fiberglass.
 
My attempted fix

I noticed the blisters only after 6 months but it may have appeared earlier. I removed both tanks, stripped the paint and primer and painted it again. This time however I ensured that I paint over the primer within 12 hours as Van?s think it may be the bonding between the paint and the primer. In a way I tend to agree with this as the primer did not blister, only the paint. It has now been 6 months after repainting and no blisters.
 
Van's can point their finger at painting all they want. But the reality is it takes a force to lift the paint off the surface and that clearly comes from within the tank. So the root cause is not a paint issue, but a leaking rivet issue. There is no way to fix a poorly assembled QB tank except from the outside. To me, all QB tanks should be approached with great suspecion. There needs to be a reliable way to remedy this externally. Using something like Green Locktite sounds like it might be reasonable place to start. I sure as heck don't intend to build new tanks...
 
I am currently adressing the blister situation with my left tank. The right one is blister free. Both were built by me and not at the same time. I am convinced that I was not careful enough with sealant regarding shop head encapsulation and wet installing rivets.
So....since I am fixing up other issues with the plane, I decided to sand down the paint over the tank rivets and smear some proseal over each head ensuring that it gets between the rivet and the side of the dimples. Some of my rivet heads had gaps between the edge and dimple. :( I know that sealant repairs should be done from the inside, but I am taking the simplest route first.
I will prime over them soon and report the results.
 
Loctite 290 Wicking formulation

I would think proseal on the outside would leave a visual telltale of "goop" even after painted.

I stumbled on a local RV builder who used Loctite 290 Wicking formulation (it's red rather than green) to seal a leaking rivet. Rather than drawing a vacuum on the tank, he used a shop-vac to pressurize the rivet head. Didn't leak afterwards.

Also found this interesting article: http://www.seqair.com/skunkworks/Maintenance/TankLeak/TankLeak.html

I detect a big winter project coming up...
 
2006 TO 2012 and no answer yet? I did the 290 Loctite method on my QB wings last night just for extra insurance. I am getting ready to paint the wings this week end. So what is the success rate of the Loctite procedure as of now?
 
Loctite

All my fixes done with Loctite have held up to 220 hrs. so far

Have developed a few more leaks on other rivets on my QB wings since paint.

Total leaks to date 8.
 
Sitting here thinking about this problem and one thing comes into mind when I worked in the payphone division of the local phone company. The steel screws used in aluminum phone booths on the Oregon coast were affected by electrolysis between the unlike metals. It was the aluminum that turned to white powder next to the steel screws. Another thing to consider is electricity is also used in the booths which may accelerate the electrolysis process. Now consider the plating process on the rivets and was the coating removed prior to painting and just maybe the alloys in the metal of the rivet might have migrated to the aluminum causing a release of gases (ever so small quantity ) to form the bubble. I might be inclined to use a straight pin to pierce the bubble at first sign. Maybe static wicks?

Just my two cents worth but a penny or two for your thoughts. Vi'sa Versa or whatever!@#$%^&*
Ron in Oregon.
QB9A
 
No blisters w/ loctite 290 (green)

2006 TO 2012 and no answer yet? I did the 290 Loctite method on my QB wings last night just for extra insurance. I am getting ready to paint the wings this week end. So what is the success rate of the Loctite procedure as of now?

I put a dab of loctite on each tank rivet of my QB wings prior to paint. That was 3 yrs ago, and 2.5 yrs since first fuel in tanks. No blisters.

A few posts back, someone suggested using a shop vac to locally pressurize the outside of each rivet to force the loctite into the rivet. Thats a great idea, I wish I had thought of that -- although it would be pretty time consuming.

Wicking without a pressure differential appears to have been sufficient.
 
Willmar aircraft

Has anyone asked the guys at Willmar Aircraft in Willmar Minnesota about this problem? They are the Mooney leaky fuel tank experts, great guys. They worked out a special process to remove tank sealant from the inside of Mooney fuel tanks and re-sealing them. I bet they would know all about tank rivet blisters etc.
 
I am still convinced, in my case anyway, that I did not use enough sealant along with improper sealing technique when I built my left tank. Specifically: inadequate shop head encapsulation, inadequate fillet seals, and not filling gaps between the manufactured heads and the dimple. I was apparently more careful on the right tank because it has had no blisters. The left tank blistered in numerous location at the heads.
This past summer I stripped the paint at the offending rivets and could actually see a gap on some between the edge of the head and the dimple where there was no sealant. I pressed some fresh sealant over the heads, let it cure, then sanded and brushed on some epoxy. After some light sanding and repaint, the repair is barely noticeable. Unconventional yes, but it's working very well with no blisters yet.
 
I put a dab of loctite on each tank rivet of my QB wings prior to paint. That was 3 yrs ago, and 2.5 yrs since first fuel in tanks. No blisters.

A few posts back, someone suggested using a shop vac to locally pressurize the outside of each rivet to force the loctite into the rivet. Thats a great idea, I wish I had thought of that -- although it would be pretty time consuming.

Wicking without a pressure differential appears to have been sufficient.

A lot of good hints!
Much easier as I did with covering with Epoxy. After six months, I had another leaking rivet. Will try Loctite 290 now.

Detlef
 
When I did the 290 with the shop vac the other night, I did not rig up the water column and what not, I held the hose over the tank fill about 3/4 covered and watched the tank skin, It would take a lot of the vacuum force before even starting to bring the skin in, I would imagine I was way over the 15 or so inches of water vac that others have suggested, my thinking was that it needed a lot more force to wick in the loctite. Also one tank handles about 750 Lbs of force if you use the 6 G load formula...right? so I was not worried about any damage to the tank.
Anyway, I prepped and sprayed epoxy primer today so we shall see......
 
...Also one tank handles about 750 Lbs of force if you use the 6 G load formula...right?...

Yes, that is so.

However, when you look at the projected area of the tank, it's not much pressure. Eyeballing the tank at 50" span x 15" chord, that's 750 in^2 of area upon which the fuel rests. So at 6g, the fuel applies on average 1 lb/in^2 to the skin. Still, that's 144 lbs/ft^2, not inconsequential.

Thanks, Bob K.
 
Just had a thought, some one else posted a possible cause of the primer or paint not curring and trapping in the reducer-solvents.
The epoxy primer I am using says cured and able to sand in 8 Hrs, that is for a flat surface, the rivets hold a deeper layer of primer, I can see where if you top coated too soon you can trap this uncured primer. After , 24 Hrs I wet sanded the primer and could smell fumes, So my thinking is that if you have a marginally sealed rivet, the uncured primer-paint layer could yield fuel vapors and bubble the finish?
 
5 RVs at out field 3 of them have bubbles on tank rivets. 2 of that 3 are QB

Mine is QB and i have 4 or 5 very small bubbles, but all on the top of the tanks I used Upoxy 2 pack etch primer and Automotive base coat with clear laquer


Dave
 
Just trolling around the threads I cam across some one on the 8 sight that has noticed an oil type film around the skins at joints and rivets, apparently they coated the QBs with something for the ocean voyage. I never notice this before, but last week I epoxy primer-ed, wet blocked and left to cure. yesterday I go out to the garage and at the tank seam there was a 1/4" wet line along the seam, look like some type of oil, none of the rivets had this and maybe because I did the Loctite 290 thing. But any way I wiped with grease and wax remover and it did not come back. Painting tomorrow and hope it comes out well. Paint Blisters,Fuel vapors, uncured primer paint thinners, OIL?
 
skin trap

perhaps the wing skin opens enough to allow a small amount of fuel around a rivet or flange when it flexes in flight and then traps it after unloading (skin flexes back to ground condition position). most probable area for skin flexing would be the top skin towards the spar. when baked in the sun the fuel vapor finds the easiest way out... around a rivet. the only way to fix this type of problem is from the inside of the tank. I have QB wings in a stand and plan to take a look at the inside with a borescope. thinking about paint, would an acceptable solution be to paint everywhere except the tank or maybe paint everywhere except the tank rivets? that would look cheesy, swiss cheesy.:D
 
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just a reminder

I have almost 3 years of flying now, 200 hrs, and my QB wings have no blisters. maybe the green Locktite 290 treatment really helped?


Or maybe my wings were made on during a cool spell, so they mixed the proseal right, no MEK, and did a good job getting the rivets coated.

Anyway, I recommend doing the Locktite treatment, can't hurt, costs almost nothing, no reason not to do it.
 
No Paint - Rivets Weep

My QB RV-10 tanks are weeping, profusely, around many rivets. I see weeping only when the tanks are full & in the hangar for several days. All weeping rivets (~3 on each tank) have been circled with blue marker. After last fill-up (two weeks ago) noticed another rivet weeping.

In my case the plane is not painted, has had no paint preparation, and just over 1 year flying. While the weather is much warmer, now, the weeping started in February soon after relocating the plane to it's current hangar.

I spoke with Paul @ Weep No More & he's had no experience with sealing tanks for an RV-10, but thought the process would be no different than other seals (except that the tanks are relatively new). I sent him pix today & expect to chat with him tomorrow. Shipping of the tanks could be an issue due to size; more later.

I subscribe to the idea of pressure differential, but not to the notion that painting has anything to do with the weeping.

Clearly, this condition requires resolution before painting (planned for early Winter 12).
 
I got the rivet blisters about a month after I first filled the tanks with fuel. It was already painted over six months earlier. I have never seen so much as a drop of fuel in the blisters, they are all dry. They are only on the RV-10 fuel tanks - nowhere else. My tanks were Quick Builds.
After one year of flying, I now have one rivet that actually leaks fuel, but it never had a blister and it's the innermost row of rivets on the starboard side. It's on top, and could be explained by passenger feet on it. I plan on fixing it with the green loctite method.

John
 
New blisters to add to database

Just to add to the database- my 10 just started showing about a dozen paint blisters, top and bottom of fuel tank, all on rivets. Mostly on one side, but a couple tiny ones starting on the other.

Facts: QB wings, bought from another builder but think they are originally from around 2003-5 or so vintage (I'll go double check). Painted myself, SW JetGlo Express with SW epoxy chromate primer, thoroughly cleaned with soap/water, MEK, and a pre-paint cleaner (ammonia-based I believe). Only 60 hrs total flying, hangared, fuel in tanks since early spring. Vents confirmed to function (with empty tanks, think I will double check it again). Only significant outside exposure was my week at Osh this summer, which was also the last time it flew before I noticed them. Only one or two had anything inside them (that light brown oily fluid previously discussed, and those were on the top), rest were dry. No fuel seepage that I can tell, yet. I did not do any real inspection of the fuel tank interior rivets prior to flying, so don't know how well they were covered with sealant.

Dwight
 
WOW, what a thread/Story!

I've read this thread for about 3 hours and man.... what effort has gone into this problem is incredible! I've notice people here now that were reporting on this back at the start! I'm very much impressed with everybody! Some quite funny! I'm way past bedtime and still at work reading this thread.

I'm planning on a RV-14 QB purchase and sure don't want any issues. I'm in manufacturing and I know how hard it is to get good workers so you have to rely on the leadman to keep Q/C intact. I hope they have rules they must follow and they don't skirt them when given a chance.

My take is it is a sealing issue. I'm a welder/ machinist/ fabricator and I know all too well about little tiny cracks, voids, etc. Try sealing for 150 psi pressure in a fatigued-thermally cycled chunk of steel and you can chase leaks all day long.

All joints have to be sealed, mating surfaces, rivets, anywhere there is a joint.

I'm not up to speed with aircraft but "Slosh sealing" is done all the time. Maybe the weight is the issue. I have seen bladder tanks and they are heavy.

Vans should emphasise this to the vendor in the Philippines in the up most. This phase of building should definitely rank a stamp of conformance by their inspector.

I feel very sorry for the poor guy way back when when his pride and joy show plane was pulled from "Best of Show" contention at SNF and Oshkosh.

Erik
 
I gave this more thought last night. I thought of a inspection technique that could be used after assembly. I worked at a company called hi shear in Torrance , Ca.. They make aerospace fasteners for the likes of Boeing. For heat treating Titanium parts they have vacuum furnaces. When they weren't able to pull down a vacuum to purge the retort of air they would call in an outside vendor to do a "Helium leak test". Those tiny molecules can pretty much find any opening.

I don't know really how big of a problem this is in the real scheme of thing but it is a fast inspection technique and cheap. If the Q/B team had this for an inspection process it would ease the buyers mind I'm sure.
Erik
 
I'm not up to speed with aircraft but "Slosh sealing" is done all the time. Erik

Slosh used to be pretty standard for fuel tank sealing, but over time it has been a problem------eventually comes off and plugs up the fuel lines.

I do not know if the issue is the ever changing formula of our avgas, or if the slosh compound has a limited service life or somethinf, but many folks have had to remove the stuff from their tanks.
 
QB Tank leaks external sealant

I definitely recommend that any builder using QB fuel tanks, that they also seal all tank rivets externally with Lok-Tite wicking formula or filling over the rivets with micro and a strip of fiberglass tape. You really don't know for sure what you're getting with QB tanks.

My tanks are a mess, top and bottom. Plan to work them over this winter/spring.
 
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