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RV-12 Fuel Tank

johns4689

Well Known Member
I found a small leak in my tank this week. I did a pressure test and found two leaks coming from around the site glass holes. Anyone have any ideas
on how I can stop the leaks. I just orders a quart of the tank sealer.
 
Hey John - -

Did you have the stiffener inside of the window, which was an update to the earlier tanks ? Is the plastic showing any cracks ?

John Bender
 
No, the plastic shows no cracks but there is a little yellowing. And the stiffener was not put in. I'm hoping for a quick fix, (if there is such a thing), without taking off the access cover,
 
Sorry, but there is no quick fix that will last. Some claim you can remove the old sightglass and do a good job cleaning and resealing all through the center circular opening. I had to remove the top cover to gain access.

You may want to consider sealing the sightglass opening and adding the top mounted fuel gauge. Many photos and posts in this forum. Search on "Moeller".

I eliminated the sightglass and added the top mounted gauge. Very happy with this arrangement.
 
Marty and John have it right. Close off the sight glass and add a fuel gage on top of the tank.

You cannot see the site glass in flight.
 
Hey John - -

Marty is right - no quick fix. You will likely find it is best to take the top off also. It is really not that bad. Wash it out good to avoid a big boom !. Drill out the rivets and clean off the surface, and correct the problem or do what I came up with, close the window and install a MOELLER MARINE mechanical fuel gauge on top. Go to the search box and you should be able to find my initial post and go from there. Ask if you have questions.

John Bender
 
Johns, they are all right in their advice. You have to do it right or it will continue to leak. I took my top off twice, (1st time tried to touch up pro seal)put in the new glass and stiffner and pro sealed big time. The tank does work per Vans if you get the latest parts and use plenty of pro seal.
Dick Seiders
 
Thanks everyone. I removed the glass and sealed the holes with a new piece of aluminum and plenty of sealant. I'll wait a day or two and then pressure test again.
 
Since the sight glass seems to be such a sore spot with (what seems to be most all -12 customers), could Van's not replace the sight glass with the gage, note it in the whatever paperwork, then let that be the "per plan" thing? Just asking, I don't know what's involved in changing things on the factory level.

Marshall Alexander
 
Thanks everyone. I removed the glass and sealed the holes with a new piece of aluminum and plenty of sealant. I'll wait a day or two and then pressure test again.

Now add he fuel gage to the top. Very simple install, and you need two ways to verify fuel levels. You cannot see the fuel level now.
 
Apparently it is a lot of hassle. I could not even get them to "authorize" me to use the Moeller gage.
 
Since the sight glass seems to be such a sore spot with (what seems to be most all -12 customers), could Van's not replace the sight glass with the gage, note it in the whatever paperwork, then let that be the "per plan" thing? Just asking, I don't know what's involved in changing things on the factory level.

Marshall Alexander

Those posting about their sight glass are not necessarily "most" of the builders, only the ones who have a problem. I think most tanks assembled correctly after the initial design was fixed are trouble free.

Personally, I like the sight glass and being able to actually see the fuel in the tank at the preflight.

Also the ability to visably check the fuel level may be a requirement of the ASTM standard and not changeable at the factory level. The "per plan" thing is a good thing ;).

Tony
 
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Those posting about their sight glass are not necessarily "most" of the builder, only the ones who have a problem. I think most tanks assembled correctly after the initial design was fixed are trouble free.

Personally, I like the sight glass and being able to actually see the fuel in the tank at the preflight.


Tony

I agree with Tony's thoughts on the sight glass.
 
Fair enough statements, but - -

I think if you had a Moeller Marine mechaincal fuel gauge in your planes next time you flew, you would NEVER consider taking it out. You can see where you are during filling, and best of all, you can turn around and see the gauge during flight. Long term, plastic of any kind I feel is an unknown near fuel, especially with ethanol. I hope we are both right.

John Bender
288.4 hours
 
Fuel Tank

I didn't and do not have any fuel tank problems...the sight holes are useless as far as I can see: you cannot see the fuel level while refueling, you cannot see the fuel level while in flight, and you cannot see it even using a flash light while on the ground.

I put in a Mueller float gauge after the DAR was done and I had the AW certificate.

At some point I will simply cover the series of 'holes' with an aluminum plate and a lot of proseal and forget the whole idea.

FWIW
 
Agree with Tony

I also agree with Tony. Admittedly, my kit contained the new and improved sight glass and backing plate. I made sure that each screw was coated with Proseal (all threads filled) and that the sight glass screw slots were filled with Proseal so that when the screws were tightened, the backing plate applied pressure to the Proseal and made it ooze out of the open sides of the sight glass slots. Not much Proseal is needed between the backing plate and the sight glass except around the screws, because fuel needs to get into the backing plate center channel anyway. Although not required to prevent leaks, I put Proseal on the nuts and exposed threads to keep the nuts from coming lose and to keep the screws from rusting. My tank never leaked.
JohnF and John B make good points too.
Joe Gores
 
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My understanding is that the sight glass is a pre-flight device, allowing to cross check the consistency with the electronic fuel level display. In flight, the cross check could come from the estimated consumption vs display: is there a need to twist your neck to cross-cross check? (the case of detecting a fuel leak can be better handled via the nose :eek:. ). The issue of checking gas level while refueling is more concerning: I had like to know what the supporters of the sight glass have to say about it?
 
I have the sight gauge as stated earlier and the only time I look at it is at preflight, and refueling. During flight the Dynon information displayed and simple math will pretty much assure I'll know when I'm at 4 gal which is my personal minimum.
Dick Seiders
 
My understanding is that the sight glass is a pre-flight device, allowing to cross check the consistency with the electronic fuel level display. In flight, the cross check could come from the estimated consumption vs display: is there a need to twist your neck to cross-cross check? (the case of detecting a fuel leak can be better handled via the nose :eek:. ). The issue of checking gas level while refueling is more concerning: I had like to know what the supporters of the sight glass have to say about it?

Some of the guys who have the Moeller can confirm or not confirm this, but I think the Moeller gauge would top out before the tank is full, so you probably can't top off the tank completely full by referring to it. Before refueling I refer to the electronic Dynon reading and the sight glass. Then I know within a gallon or two how much to put in. Go slowly toward the end and you can hear the fuel come up into the filler neck. If you are careful, you should not spill any. For insurance, I made a thin synthetic rubber mat to place over the lexan window to protect it in case you do overfill the tank. The material came from the local hardware store and was inexpensive.

Tony
 
Hey Tony - -

The Moeller does top out with about 18 gals. It is easy to know you can put in about 2 more gals. After you have filled it a few times, you learn how it reads. The Dynon only goes up to 16 on the display, so you learn the systems quickly. I like the Moeller more for filling, as viewing in flight. Still nice to turn around and see it moving some. Confirms what the display is telling you. I still don't want a piece of plastic in the side of my tank. With the latest design, I hope they never fail, but I feel better without the 'window'.

John Bender
 
Tony, I seem to recall that you use a 'fuel caddy' of some kind when fueling locally...and which may have both a different kind of control on the fueling hose and flow at a different rate (or more easily controlled rate) than if someone is fueling right off a fuel truck or at a self-service pump. Do you have one of those nice, clean 'Tony Pics' of what and how you fuel when at home base? Thanks.

Jack
 
I don't mind the glass either. During the tank calibration, I placed discreet reference marks at the sight glass area at 5 gallon increments. During pre-flight I can always see the level by rocking the fuselage slightly and looking for the level in the glass. As Tony said, filling the tank and listening to the neck will allow you to top it off. Could be famous last words, but I haven't spilled more than a drop or two. Truthfully, if I ever have to do surgery on the tank, I will probably install the Moeller.
 
I overfilled mine slightly today for the first time. The rubber mat laying over the Lexan (see Tony's post) did the job of protecting it.
Dick Seiders
 
Tony has a FLO-FAST system (flo-fast.com). I just bought one. I bought:
1 PDG-15501 FLO-FAST 15 Gal Red Utility Jug $79.95
1 PDG-30303 FLO-FAST Pump system for PDG 15 gal jugs $149.99
These were the best prices I could find. Free shipping. I did not buy the cart because I already have one I can use.
These were the best prices I could find, with free shipping. Got it at
www.racerpartswholesale.com
I'll use regular 5 GAL plastic jugs for transfer and a Mr. Funnel.
 
Flo Fast

I have been using the Flo Fast system using two 7.5-gal units since they are easier to handle...over 80-years old things seem a bit heavier. I have had nothing but good luck with this system. Even used the "turn it backwards" feature to un-fuel the plane once. Works fine. A good unit at a reasonable price - I am not connected in anyway with the supplier.

FWIW
 
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