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  #341  
Old 01-13-2012, 07:36 PM
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Default

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?
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  #342  
Old 05-14-2012, 01:33 AM
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Steve Melton Steve Melton is offline
 
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Default 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.
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Last edited by Steve Melton : 05-14-2012 at 09:55 AM.
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  #343  
Old 05-15-2012, 01:44 AM
scsmith scsmith is offline
 
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Default 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.
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  #344  
Old 05-30-2012, 01:19 AM
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Default 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).
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  #345  
Old 06-25-2012, 01:20 PM
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Default

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
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  #346  
Old 09-27-2012, 12:47 PM
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Space Cadet Space Cadet is offline
 
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Default 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
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  #347  
Old 11-06-2012, 01:21 AM
Erik.37m Erik.37m is offline
 
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Location: Rancho Palos Verdes,CA
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Default 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
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  #348  
Old 11-06-2012, 08:09 AM
Erik.37m Erik.37m is offline
 
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Default

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
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  #349  
Old 11-06-2012, 09:51 AM
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Quote:
Originally Posted by Erik.37m View Post
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.
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  #350  
Old 11-06-2012, 11:38 AM
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Default 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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