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New Section 37 - Fuel Tank

Looks good to me, glad the issue is behind us. The -12 is a great flying machine just made safer, courtesy of the Vans engineering and the anonymous crash test pilot.

Marty, you are right, they do not call out AN hardware. Hmmmmmm. Nylon? Brass? Hollow breakaway?
 
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Yes it is nice that Van's has addressed the problem for people who have yet to build the tank. I did not see any indication that a kit and service bulletin are available to tell us what to do. At this point we have to try to find all the parts in the drawing and purchase them from Van's when they become available along with another can of tank sealer so it will cost about $ 100 or more and several days of fun to fix the tank and see that it still is not leaking.

So far not my best Christmas present.

Best regards,
Vern
 
The number called for is a washer for a 10-32 bolt. I presume the bolt would be closer tolerance and higher strength if it is NAS. Of course maybe the bolt is something else, but I don't see that indicated on the dwg. That dosen't really tell me anything. I don't believe we will be getting a fix like this for existing in- service tanks. If we are it's practically a rebuild of the tank. Given all the opportunities (hurdles) the tank offers to a builder I would hope Van comes up with a retro fix kit for us poor slobs already flying that doesn't require a rebuild.
Dick Seiders
 
It certainly will be interesting to see if Vans offers all builders, from Kit 120001 onwards, the parts to make this vital safety improvement. Their redesign is an admission that the original had a hidden flaw. It will be a good test of their customer support to see how they treat existing owners.
Rod
 
This has to be some sort of breakaway bolt. The extra brackets surely would not prevent tank rupture in the event of the failure mode that started this thread. This also doesn't seem like a retrofit solution.
Maybe the brackets are simply adding extra thickness to the bolt hole so there is more of an unthreaded bolt portion holding up the tank? If so, a simple doubler piece could accomplish that, which would not have to be riveted to the tank wall, but only that front bracket end. Aren't there bonding glues that are as strong as a riveted connection of a small piece like this? I guess the answers will come out soon!
 
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Yup, it is a retrofit

From the service bulletin destructions, referenced above by Dheal, it is a retrofit--albeit not a fun one to do...have to deal with the dreaded devil's snot tank sealant once again.
 
Great stuff Vans, a simple fix for what most of us "over thought". Still a little concerned that once the bolts have broken away if the aircraft continues to tumble the tank could totally break away and will be flailing around in the cabin with me. This is a common problem for all aircraft that have fuel in the fuselage. Maybe further secure the tank to the floor structure at a later date. Hopefully I never hit anything with enough force to dislodge the main gear/center section. I hope this will become available as a retrofit kit for us guys with completed tanks.:)
 
I'm happy

After reading the service bulletin, Vans strategy to fix the tank appeals to me. Simple and elegant, a small bunch of inexpensive parts, no new skills to learn, do it in a day or so. Good work, Vans engineering.
Rod
 
Rod - agree mostly - -

I will do the mod, but I think I will keep my strap design, and maybe make it to be permanet. Can't see where it will hurt anything. Keeping the tank in general position still appeals to me. As always, do what you feel is best.

John Bender
 
I feel lucky

The fuel tank is task coming soon in my finishing kit. Just need to check how to order the parts needed for the mod.
 
Talk about great timing, I was about to put the tank sender plate on in the morning and start pressure testing the tank! Now I can install he "fix" with no aggravation at all, don't even have to drain or remove the tank. I must be living right.
 
fuel tank

I am in the process of pressure testing my tank now. I guess I'll wait until my parts arrive before disassembling the tank?
Van is sending the parts..................aren't they?
 
Don't you wish! I want to order the kit now, but they don't even give a part number for a kit yet.

I am in the process of pressure testing my tank now. I guess I'll wait until my parts arrive before disassembling the tank?
Van is sending the parts..................aren't they?
 
Pre-built tank

Well, at least I will have had at least some experience at tank building. It was kind of cheating to buy it already built anyway.

Note: this is false sanguinity. But what are ya gonna do?
 
Chasing the Chips

At first glance, I was relieved that the modification appeared to be possible without opening up the tank. But then I realized that we're going to have to chase the chips inside after drilling holes through the tank walls for the new reinforcement clips. This will require removal of the T-1209 Sender Plate Assembly. Oh well, I guess it coulda been alot worse.
 
Ordering Info

For those wanting the repair kit, order P/N "SB 11-12-14" from Van's Aircraft Parts desk. Price is $25 includes all parts including Tank Sealant.
 
fuel tank fix

The parts are $6 (without the sealant) + shipping. Gus says Van's can't make you do it, but recommends the fix.:mad:
 
Well, at least I will have had at least some experience at tank building. It was kind of cheating to buy it already built anyway.

Odd how one person freaks on the tank and the other on the canopy fairing. I found the tank exciting to build and comforting when finished with zero leak points, also I wanted to cover the sight glass. Now, I am freaking just thinking about the fiberglass fairing.
 
Odd how one person freaks on the tank and the other on the canopy fairing. I found the tank exciting to build and comforting when finished with zero leak points, also I wanted to cover the sight glass. Now, I am freaking just thinking about the fiberglass fairing.
Well, if I'm perfectly honest, I would have probably bought a pre-faired canopy too! :)
 
I also found the tank and canopy straight forward. Vans instructions are very good. The two tasks are also a change from riveting. I have learned a new skill and have promised my wife I will repair a curved window flashing on our house which is causing problems, using my fiberglass skills.

I have followed the site glass discussions. If you have a site glass you can see straight away what amount of fuel you have in your tank. Simple and reliable. If you install a fuel guage you will be back to having to dip your tank to check the amount of fuel.

Julian 120316
 
Stand pipe

Had an A&P IA look at the overall tank design. His concern was that there is no "stand pipe" in the tank. Are we missing something ... There is a mesh screen for debris ... But the standpipe will rise the intake above possible water that accumalates in the tank. We will put a sump below the tank as others have done after Elsa cert.
 
That would work if you never accelerate, decelerate, brake, or bank in a turn.

Had an A&P IA look at the overall tank design. His concern was that there is no "stand pipe" in the tank. Are we missing something ... There is a mesh screen for debris ... But the standpipe will rise the intake above possible water that accumalates in the tank. We will put a sump below the tank as others have done after Elsa cert.
 
That would work if you never accelerate, decelerate, brake, or bank in a turn.

since most tanks are in the wings ... there is a stand-pipe that keeps the intake above water .. the dihedral in the wings keeps the water at the lowest point under the standpipe and then can be sumped out. I'm guessing our -12 tank has a low point elsewhere than near the pickup?
 
In the RV-12 the water (if any) must be moved from the tank to the gascolator on the lower firewall to get it out as there is no other exit point to drain it from, so it makes sense that there would be no stand pipe with no way to get it out.

Best regards,
Vern




since most tanks are in the wings ... there is a stand-pipe that keeps the intake above water .. the dihedral in the wings keeps the water at the lowest point under the standpipe and then can be sumped out. I'm guessing our -12 tank has a low point elsewhere than near the pickup?
 
gonna wait till ...

My annual inspection will be in June of next year, so I'm gonna wait till then to have the mods done to my gas tank. Since I've decided my building days are "behind" me, I'll allow Lockwood Aviation at Sebring to do my annual and modify my gas tank. In for a dime ... in for a dollar.

I hope to complete the "ELSA Repairman's Course" before then, but I'll still let the pros do my annual ... a suggestion made by the FAA examiner when
I got my airworthy certificate.

While building my gas tank (not a pleasant experience), I covered all the peep holes and now "stick my gas tank" like I've "stuck" every other plane I've ever flown.

I wonder if it would be worth it to install the "prebuilt" gas tank at the annual ... or just keep the one I have.

As far as the Rotax problem ... my heart goes out to anyone with the faulty crankshaft. I've yet to check my serial number ... just going by the delivery date so far ...
 
Low Point Drain

We have modified our 3/8" fuel supply below the tank with a "T" for a real low point drain, to allow sumping directly below the tank.
The gascolator is still on the firewall.
 
Run boost pump before checking gascolator for water

This thread got me thinking - I have been sumping the fuel at the gascolator drain after fueling, as I have always done with all the previous airplanes I have ever flown. Now that I think about it, that procedure does one no good with the RV-12 design. From now on I will run the electric pump 30 seconds or so, long enough to move any water in the tank to the gascolator bowl, before sampling the fuel. I think this should be a standard procedure in the "12. Don't know why I didn't think of it before.
 
to move any water in the tank to the gascolator bowl

Hi John,

Won't this procedure just wizz the water past the gascolator, around the fuel system, and back into the tank via the return line?

Cheers...Keith
 
Wow - Jerry Parr

Your simple and elegant solution to what I perceived to be a missing part in the fuel system of the RV-12 looks great. Van's should consider inclusion your solution in the kit in my opinion. Your solution is now on my list of 'changes' that I will make after certification. Good going, Jerry!!!

Thanks you sir:cool:
 
I am using the Jerry Parr design. To me this is the first place water or contaminants will show. Thanks Jerry!
http://www.vansairforce.com/community/showpost.php?p=548933&postcount=76

Your simple and elegant solution to what I perceived to be a missing part in the fuel system of the RV-12 looks great. Van's should consider inclusion your solution in the kit in my opinion. Your solution is now on my list of 'changes' that I will make after certification.

I have no evidence to suggest that this modification will cause a problem, but my experience tells me that if I had an RV-12 with this modification, I would very carefully monitor the condition of the fuel lines directly below the fuel tank.

Making an extension with soft aluminum tubing, adding the mass of the additional fittings coupled with airframe vibration, and mixing in the slight bending stress introduced each time the drain is activated with a sample tube, and you have a potential for a cracked fuel line.
 
I tend to agree with Scott. At first blush it looks like it would work, but there is a fair amount of load on that first leg of alum. tubing from vibration. Not to mention that each time you checked the sump for water you would be bending the assembly somewhat as the upward force on the drain would be very difficult to insure it is 100% vertical. All the bending motion would be absorbed by the tubing.
I see no reason why the gascolater sump check is not sufficient if done on a regular basis. If there was enough water in the gascolator that it was forced back thru the return line I suspect you wouln't be able to start the engine in the first place. Just my two cents.
Dick Seiders
 
....If you have a site glass you can see straight away what amount of fuel you have in your tank. Simple and reliable.....

Except that it doesn't seem to show up. This was pointed out to me when Colin gave me an RV-12 demo. The fuel, 100LL, was not visible at all in the sight gauge. It didn't matter whether I was in the left seat or on the ground.

Now I'm not going to let myself be draw in in to the discussion of which fuel would be visible and which wouldn't. If one fuel, a common one, isn't visible then I want something that actually works.

This seems to be one of those cases where theory and practice meet. You know the difference between theory and practice, right? In theory there is no difference, but in practice there is.

Dave
 
Except that it doesn't seem to show up. This was pointed out to me when Colin gave me an RV-12 demo. The fuel, 100LL, was not visible at all in the sight gauge. It didn't matter whether I was in the left seat or on the ground.

I have no trouble seeing the fuel level (100LL or Mogas) with my 50+ year old eyes, if I do what I guess I have assumed is obvious to everyone else (but maybe not).... I shake the airplane slightly. I can then easily see the fuel level bob around.
 
Drain point

FWIW, I think Jerry's drain modification is very neat and was going to install it, but eventually decided to keep it simple and go with the original design. Fewer connections, therefore fewer potential leaks.
As there should only be 100-150ml of fuel in the line between the tank and gascolator, I can live with drawing off a little more than usual when testing.
 
A little kink - -

Since the line goes up hill into the shut-off valve, a small amount of water may not find its way into the gascolator right away. First time you get the nose down for landing as example, it would transfer then. Just saying !

John Bender
 
Point well taken -

Thanks, Scott for your well thought out comments on adding a fuel/water drain under the RV-12 fuel tank. I have long wondered why Van's chose not to put a drain directly under the tank.

Brings to mind - do we know what happened to the plumbing under the fuel tank in the incident wherein the fuel tank broke loose from the floor during a crash? Did the tubing bend or was it ruptured by the force of the fuel tank coming loose? So, if I was to 'firm up' the drain in effort to reduce the effects of operational vibration, would it be less safe in the advent of a 'crash' than the current set up? Very interesting!!! I am interested in any and all thoughts on this. Thank you all.
 
I can answer that - -

I saw it and took many pictures. The lines did NOT rupture or even badly kink. They distorted some, but seemed to stay connected.

OPINION - not sure if a drain like Jerry's would have made any difference in that exact case. It might have caught on the hole in the inspection plate, but just a guess.

John Bender
 
Since the line goes up hill into the shut-off valve, a small amount of water may not find its way into the gascolator right away. First time you get the nose down for landing as example, it would transfer then. Just saying !

John Bender

..Umm yes, good point, John! :confused:

Just amended my pre-takeoff checkist: "Deflate front tyre and over-inflate mains before sampling fuel" ;)
 
ain't gonna happen ...

It's hard for me to believe, that all the owners of all one hundred and fifty-one flying RV-12's and perhaps another hundred, perhaps two hundred or more RV-12's still being built ... all with their non-leaking gas tanks installed and not yet flying will all remove their gas tanks, tear them apart, drill another twelve holes in a fuel tank with hundreds of predrilled holes manufactured in them already, clean the old sealant, add clips, nutplates, drill out and re-rivet and etc, etc. etc. ... ain't gonna happen.

Seems to me, the only way that it would happen would be in the form of an AD (Airworthy Directive). I know I'm not the sharpest tool in the shed and I will if I must but ...
 
It's hard for me to believe, that all the owners of all one hundred and fifty-one flying RV-12's and perhaps another hundred, perhaps two hundred or more RV-12's still being built ... all with their non-leaking gas tanks installed and not yet flying will all remove their gas tanks, tear them apart, drill another twelve holes in a fuel tank with hundreds of predrilled holes manufactured in them already, clean the old sealant, add clips, nutplates, drill out and re-rivet and etc, etc. etc. ... ain't gonna happen.

Seems to me, the only way that it would happen would be in the form of an AD (Airworthy Directive). I know I'm not the sharpest tool in the shed and I will if I must but ...

Experimentals don't have AD's.....just SB's. Van's can only advise us of a problem.

I plan on leaving my tank with headless bolts and a strap to secure the front of the tank. Oh! and no 500 fpm landings. ;)
 
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