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RV-12 Fuel Tank Site Window

Geico266

Well Known Member
Looks like there is a service notice on the clear site window in the fuel tank. Don't install it if you have not done so already.


I wondered about having this plastic submerged in fuel. It is suppose to have a coating on the surface, but the edges are not recoated. I guess that's why it's called experimental.
 
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I have fixed the last fuel tank problem and reinstalled it. Now this. I sure wish they would have just use a sight tube with a couple fittings .

Just finish the fiberglass project on the canopy today. Nothing left but to wait for the engine/Avionics.


Brad Stiefvater
 
Hey Brad

I agree with your plastic hose and fittings. That has worked well for years. NO - I don't have any other quick fix to offer either, so I guess we wait and see. Hope we have enough 'gooooooo' left to take the top off likely. Hard to reach back thru the end plate it would seem. Nothing good here at all.

John Bender
 
To replace the window the top of the tank would have to come off. In addition the front of the tank would have to come off to reach the clips that are holding the fuel return line to the top of the tank. IMHO, a major pain.

This material compatibility issue is a simple but major engineering error, realizing the tank is inside the fuselage.

There can't be many of us that have the tank complete as of today. The tank should be acceptable for the near term, but, for those of us that have it completed, the factory should supply us with a complete set of new tank components at no cost, within the next 6 months.
 
Service notice?

Looks like there is a service notice on the clear site window in the fuel tank. Don't install it if you have not done so already.


I wondered about having this plastic submerged in fuel. It is suppose to have a coating on the surface, but the edges are not recoated. I guess that's why it's called experimental.

I went to Van's site and can't find a service notice about the fuel tank window. Where is it?
 
Jim,

It is GREAT to hear from you. The notice came via e-mail from Van's and I forwarded my copy to you via e-mail at your olypen.com address.
 
I went to Van's site and can't find a service notice about the fuel tank window. Where is it?

Good to hear from you Jim, we need a Jim Cone update.

The notice came in an e-mail as a PDF, and for some reason is not yet posted to the Vans web site. I have contacted Vans to ask them why.

I don't know how to post a PDF.
 
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To replace the window the top of the tank would have to come off. In addition the front of the tank would have to come off to reach the clips that are holding the fuel return line to the top of the tank. IMHO, a major pain.

This material compatibility issue is a simple but major engineering error, realizing the tank is inside the fuselage.

There can't be many of us that have the tank complete as of today. The tank should be acceptable for the near term, but, for those of us that have it completed, the factory should supply us with a complete set of new tank components at no cost, within the next 6 months.

Now that's the best idea I've heard yet! Go Marty.
 
To replace the window the top of the tank would have to come off. In addition the front of the tank would have to come off to reach the clips that are holding the fuel return line to the top of the tank. IMHO, a major pain.

This material compatibility issue is a simple but major engineering error, realizing the tank is inside the fuselage.

There can't be many of us that have the tank complete as of today. The tank should be acceptable for the near term, but, for those of us that have it completed, the factory should supply us with a complete set of new tank components at no cost, within the next 6 months.

I agree with Marty. I spent three days putting it together. I can't even imagine how much time it will take to disassemble. I hope Van's makes this right.
 
Another fuel tank compatibility question

I think this relates to the thread; has anyone asked Van's about E10 autofuel issues with the sight window and also the fuel tank sealant?

Tony
 
RV-12 Fuel Tank

I also have finished my fuel tank and I agree Vans should make it right. It would be easier to build a new tank. I am really getting tired of all these redos. I have built two RVs and have not had the problem with them that I have had with the Twelve.
Gerry
RV-12, N6GC, waiting on engine install kit
 
Another question

Maybe someone who has been inside the Red RV-12 can answer this. Can you actually see ( and read ) the site window while in the seat flying ? If not, then I wished they had put a mechanical gauge/cap like the garden tractor folks have done in the past. Just look at the cap and see how much fuel you have. It could have been a cap that could be removed, but still non-vented. If installed near the front, you possibly could turn around and actually read it to verify the dash gauge.

I feel the many holes in the skin of the current design increase the possibility of a leak. Easy to criticize, but my feelings.

John Bender
 
RV-12 Fuel tank

The fuel tank is not the best design work to come from Van's, now would be a great time to redesign the tank and make it right with properly formed ends so that we are not counting on a 1/4 inch of goop to hold the fuel in the tank in the corners. It should be a solid welded tank with all the fittings welded in and an inspection hole that can be sealed like the ones on an RV-8 wing tank. The current tank is going to have lots of leaks as there are just to many holes that fuel will run out of if the Proseal fails, and it is like hard drives on our computers, it is not if a hard drive will fail but when.

I hope we will all express our disappointment with the fuel tank to Van's and sincerely hope they will provide a much better tank.

Best regards,
Vern
 
Maybe someone who has been inside the Red RV-12 can answer this. Can you actually see ( and read ) the site window while in the seat flying ? If not, then I wished they had put a mechanical gauge/cap like the garden tractor folks have done in the past. Just look at the cap and see how much fuel you have. It could have been a cap that could be removed, but still non-vented. If installed near the front, you possibly could turn around and actually read it to verify the dash gauge.

I feel the many holes in the skin of the current design increase the possibility of a leak. Easy to criticize, but my feelings.

John Bender

I'm not sure why we even need a gage on the tank, you can't see it when you are filling the tank. The Dynon has fuel flow and fuel level on it, so why do we need the site gage? While I like having a site gage cause it is simple, I'm not happy about a leak in the cabin.
 
Jim Cone update

Good to hear from you Jim, we need a Jim Cone update.

The notice came in an e-mail as a PDF, and for some reason is not yet posted to the Vans web site. I have contacted Vans to ask them why.

I don't know how to post a PDF.

I went to Italy for a little over two weeks for a hat sighting and you guys all passed me on your projects. So now I am reading your posts to find the "gotchas". I have been busy catching up on work and have not done much on the 12. It is on the gear and I have finished the fuel tank except for the flange for the fuel pickup. Now I have to wait to see what the fix will be for the sight guage window. Keep posting those hints and tips. They are invaluable.
 
I'm not sure why we even need a gage on the tank, you can't see it when you are filling the tank. The Dynon has fuel flow and fuel level on it, so why do we need the site gage? While I like having a site gage cause it is simple, I'm not happy about a leak in the cabin.

Is it no longer a standard preflight practice to visually check the fuel level in the tank(s) and then cross check that to the indicated fuel level on the panel mounted gage or EFIS ?

I my 32 years of flying I have never know it to be good practice to entirely trust a panel mounted fuel gage and fuel computer. I don't think it would be a good idea for anyone to start doing it now. Even an EFIS based fuel gage and computer can be wrong.
 
Is it no longer a standard preflight practice to visually check the fuel level in the tank(s) and then cross check that to the indicated fuel level on the panel mounted gage or EFIS ?

I my 32 years of flying I have never know it to be good practice to entirely trust a panel mounted fuel gage and fuel computer. I don't think it would be a good idea for anyone to start doing it now. Even an EFIS based fuel gage and computer can be wrong.

I know of no other RV with a site glass on the tank, do you?

If you want to visually confirm the fuel in an RV-12 you can use a calibrated dip stick.
 
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Another thought

I mentioned above a gauge/cap like garden tractors and such have used. The marine industry has made portable tanks with simple float, sweep gauges that have worked well for years. You could also see them while you are fueling the plane. You could also see it from the seat even while flying. They are far less likely to ever leak. I would still like to see them go to such a secondary gauge system.

John Bender
 
I mentioned above a gauge/cap like garden tractors and such have used. The marine industry has made portable tanks with simple float, sweep gauges that have worked well for years. You could also see them while you are fueling the plane. You could also see it from the seat even while flying. They are far less likely to ever leak. I would still like to see them go to such a secondary gauge system.

John Bender

I have one on my Harley that would work great!
 
Forget what you see....the only way that really works is to know what you put in, how much you burn an hour and how long you have been flying. Unless you have a leak, nothing works better. I would never trust a gauge of any kind.
 
Hey Pete

If the electronic gauge indicated 1/4 tank, and you could turn around as see a simple float type gauge, and it also indicated 1/4, - AND - you know how many hours you have been flying, I'd feel pretty good about the gauges. The problem is, I don't think you can actually see the site window as it is now, if you are flying, and you sure can't if you are putting in fuel. If a leak, chances are you will smell it.

John Bender
 
I know of no other RV with a site glass on the tank, do you?
Nope, and I have flown them all including the RV-12. One big difference though...you can remove the cap (like pilots have been doing for years) and look at the fuel level. You can't do that with the RV-12

If you want to visually confirm the fuel in an RV-12 you can use a calibrated dip stick.
That's going to be kind of tough to do with any accuracy with a curved riser tube from the filler opening to the bottom of the tank., but hey, give it a try

Forget what you see....the only way that really works is to know what you put in, how much you burn an hour and how long you have been flying. Unless you have a leak, nothing works better. I would never trust a gauge of any kind.

Not entirely trustworthy in my opinion. Many airplanes have been wrecked because someone else flew the airplane and then a pilot failed to determine how much fuel was in the tank(s). Please don't use the counter argument that "it will be my airplane and no one else will fly it". The RV-12 wasn't designed for how a specific person would use it, it was designed for all of the different ways in which it might get used.
 
Thanks, pioneers!

Threads like this make me REALLY appreciate the work you leading edge guys are doing, and the fact that you are sharing your experiences on VAF. Keep up the good work!
 
Why not use a rotomolded tank like what we have in the Tornados, CGS hawk, Quicksilver, My dirt bike, etc... You can have all the penetrations out the top of the tank except the sump drain. The tanks are "clear" so you can see the fuel and in an accident they will not rupture. When I first saw the current tank design I figured I would weld up a tank. I can cut the material and weld one faster than building the factory tank, unless I build a mold and have one rotomolded (not likely though).
 
Hoping for a better solution

For one, I'm hoping they come up with a nice little pre-molded tank that you can pop in place before I get to that step. The fabrication of a metal tank seems very messy and time consuming, and in the end not even a good solution, from what I have been reading. I hope Van's engineers take note!
 
Premolded tank

Wouldn't it be nice if Van's supplied a see through plastic tank. All we would have to do is set it in place and hook up the connections. It might look something like this:http://www.overtons.com/modperl/product/details.cgi?r=view&i=39532
39532_M1.jpg
 
Wouldn't it be nice if Van's supplied a see through plastic tank. All we would have to do is set it in place and hook up the connections. It might look something like this:http://www.overtons.com/modperl/product/details.cgi?r=view&i=39532
39532_M1.jpg

That tank looks very nice!!! Looks like it might also work nicely as a fuel transfer container. Could mount it in a pickup tuck tool chest with an electric fuel transfer pump.

Maybe Van's engineering can look at this solution.
 
Polyethelene weight

A polyethylene tank could weigh 15 or 20 pounds. The aluminum tank probably weighs a lot less. Some of the weight of a plastic tank could be offset if it served a dual purpose, i.e. passenger seat back. The tank could be molded to form not only a seat back, but also to fit into the wasted space above the center channel, thus freeing up cargo space. See page 2 of this pdf: http://www.moellermarine.com/sites/moellermarine/files/MM177_Custom_Tank_Sheet.pdf
This company can make any shape tank and even have the filler neck align with the fill tube of the RV-12. A custom made tank might cost more than some of us would be willing to spend. And the supplier might not want the liability of their products installed in airplanes.
Joe
 
Request for suggestions to VANS

I really love the RV-12's engineering. I have designed some fine products too (nothing that good) but it seems like at the end I'm just tired and I dont want to fight with one more elegant solution, I just want to get it out the door.

I really wish we could get our final inspections on the RV-12's with the gas tanks in place, as well as annuals.

I finished my tank a month ago, I covered the edges of the window with proseal, and it doesn't leak, so I am going to fly it that way if Vans lets us.

If they want to redesign the tank window, I would rather build a new tank.

For new builders, I wish a redesign would also cut a 3" or so 45 degree chamfer of the inboard aft and inboard bottom sides of the tank so the inspection panels could be removed with no gas smell in the cabin. I just thought I would put this out, maybe someone has a better idea.

The aluminum tank is amazingly light, and I like it. When you build it, do your best, and remember each piece only costs $20. I wish canopies were like that.
 
The sonex guys use the rotationally molded tanks like the ones mentioned above. It is customized to fit the aircraft and maximize use of space. The cost for the initial mold is something like $10,000+, so it may be cost prohibative for a single builder to have one made. However A company like Van's could afford to have it made and spread the cost amongst all of the customers.

There are also details in the plans on how to make the tank out of aluminum (IIRC, the prototype had an aluminum tank), however I don't know of a single builder (even the plans builders) who went that route. There may be one or two floating around there, but I don't know of them. For us plans builders, it cost about $325 to buy the tank separately. I would be willing to bet that if Van offered the option enough builders would take him up on it to make up the cost of having the mold made.
 
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