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Aft window cracked

jtdehaan

Member
This morning I put fuel in the tank for the first time and some fuel spilled onto the window. It immediately cracked from the edge in about a dozen places. Most of the cracks were from the screw holes, but not all. I was pouring fuel into a Mr Funnel and the wind blew some of the fuel out of the funnel. This was a $175 plus freight mistake. Has anyone else experienced this? With the window so close to the fuel filler cap, I don't see how this can be avoided. I guess I will have to invest in a fuel pump and nozzle arrangement.

Jake
 
If the 12's back window is normal plexi, there's gotta be an underlying cause. I've seen many windows literally awash in 100LL. Doesn't do anything to them.
 
It's NOT plexiglass!

If the 12's back window is normal plexi, there's gotta be an underlying cause. I've seen many windows literally awash in 100LL. Doesn't do anything to them.

I've been told by Van's that the canopy is Lexan (polycarbonate). Lexan does NOT like petroleum based products. I was also told that this "particular" Lexan is OK with fuel.
 
Sure there wasn't alcohol in the fuel?

It's hard to find auto gas today without ethanol. Maybe it's time to test the polymer used on the RV12 reaction to this solvent. Anyone got any scrap pieces?
Terry, CFI
RV-9A N323TP
 
The rear window appears to be VERY sensitive to gasoline. Here is another thread describing the same.

http://www.vansairforce.com/community/showthread.php?t=53406&highlight=cracks

Also know of at least one other fellow that spilled a bit during the fill and experienced crazing almost immediately. Maybe he and others will relate. His gas did NOT contain alcohol.

Scott mentioned in a previous post that the aft window is Lexan and has a coating on it. The crazing in all the cases I know of originates from the untreated edge or the untreated screw hole(s).

Be cautious......The rear window and ANY amount of gas do not like one another. There was also a previous thread that indicated some masking tapes placed on the aft window will induce the same to occur.

AND have a question......If the rear window is so susceptible to petroleum products, what should we be using to clean it. I think most, like PLEXUS, are petroleum based.
 
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uhhh....yeah. I did exactly the same thing and watched it craze before my very eyes. $200 later I now am extremely careful about putting fuel in my 12. For one thing, I don't let linemen do it (on the trip to Sun n Fun I had to leave one place because they wouldn't let me fuel it). Number 2 I virtually cover the entire window with a blanket. It will craze when touched by car gas or 100LL. Of course the reason they use Lexan is because it bends and works perfect in this situation. Just be real careful.
 
I'm not building a -12 (yet) but a possible solution to address the issue: how about applying some kind of film to the outside of the window? It would easily protect the window and could be replaced periodically if it gets cloudy from spilled fuel (unless the film is applied prior to installing the window). One could even use a static-attach type window TINT.... Certainly seems cheaper to keep $50 worth of static film on hand rather than have to replace a $200 piece of Lexan.... :rolleyes:
 
Mr Funnel

I was getting ready to order a Mr Funnel today, when I noticed they have to stay level while fueling, so you almost need to fabricate an upside down saddle to hold the Mr Funnel level while it sits in the fuel hole.

Maybe there could be an EPDM tarp (pond liner) of 2' diameter or so around it.

Is there a better solution?
 
I'm not building a -12 (yet) but a possible solution to address the issue: how about applying some kind of film to the outside of the window? It would easily protect the window and could be replaced periodically if it gets cloudy from spilled fuel (unless the film is applied prior to installing the window). One could even use a static-attach type window TINT.... Certainly seems cheaper to keep $50 worth of static film on hand rather than have to replace a $200 piece of Lexan.... :rolleyes:
I'm afraid that this would not prevent fuel from seeping down between the seams and attacking the "edges" of the window.
 
All I can say is: WOW!
How long before any and all of us get fuel on the rear window with the fill tube adjacent to the window?
Hope Van comes up with an alternative material promptly as I suspect most will experience the problem sooner or later.
About 2-3 weeks from first flight and now another fuel concern. Sheeeesh!
Dick Seiders
 
Seal the edges?

Would it help to seal the edges of the Lexan with something to prevent any spilled fuel from penetrating? I have sanded all the edges smooth, but not yet installed the window.
 
Lexan Damage from Fuel

This incident prompted me to do some internet searching and I see that it is well known that gasoline will destroy Lexan...and its been known for a long time. That's why I cannot understand why it was used in our RV-12's when the filler so very close to the Lexan...surely something better could have been devised. I am really dissappointed...the entire fuel idea...the "window" and now this...not good.
 
This incident prompted me to do some internet searching and I see that it is well known that gasoline will destroy Lexan...and its been known for a long time. That's why I cannot understand why it was used in our RV-12's when the filler so very close to the Lexan...surely something better could have been devised. I am really dissappointed...the entire fuel idea...the "window" and now this...not good.

Got to comment. The RV-12 design is MAGNIFICENT! I love the flying characteristics. When filling it with fuel, just be CAREFUL. DO NOT SPILL. Using 5 gallon cans is not the best idea. Put a rubber mat or blanket down and you should not have a problem. Using a hand pump from a 15 gallon container, like I have been using has worked very well. This issue, is much different than the tank window issue which appears to have been solved.
 
tank window

The T1210 tank window is some unknown plastic type.It is flexible, but it might not be UV resistant or it might be very expensive. Maybe Vans can tell us what it is made out of.

The back window is made of Makrolon, which is a chemical resistant lexan, just not gasoline resistant.

John
 
While I did spill gasoline on mine and ruined it, understand there are other things you can do to it that are just as damaging. The major one is overtightening. Another is a hole in the Lexan that binds the screw. Either of those two issues will craze it as well. You can make the whole as large as 3/8th. All you want is for the Lexan to "float" between turtle deck and the nut...or the roll bar. Lexan is famous for its strength (bulletproof windows) and its ability to bend, but it cannot handle the stress of any binding. As to the location of the filler tube, my back window had been on since I flew it in November. I didn't screw up splash gasoline on it until just before leaving for Sun n Fun. As Marty says, just be careful, its not something that happens everyday. The good news is if you do craze it, its just that...ugly, not something you can't fly with or that will get worse. Fix it when you have an extra $200. It certainly is not an issue to change the way I feel about this special plane. Just the way it flies is worth the build. There is no comparison on the market. I spilled gas on it, not the manufacturer. Just be careful. As careful as you need to be with the static electricity that is generated by plastic gas cans. That has an even worse potential problem which can be solved easily with a grounded metal tank.
 
Window Problems

I found the manufacturer's web site that listed dozens and dozens of things that the Makrolon is resistent to, and dozens of things that it is not...gasoline is one of the 'not' things.

I have ordered a Flo-Fast fuel delivery system (look it up) that allows me to hand pump it from a ground level container into the filler via a hose, which can be 'shoved' down well into the neck, so there is a greatly reduced likelyhood of fuel contact. I will also cover the area with a flexible lightweight rubber sheet while fueling to add some protection.
 
I'm afraid that this would not prevent fuel from seeping down between the seams and attacking the "edges" of the window.

Applying a film (tint) to the entire window prior to installation may not protect it from massive fuel spills but it might protect it from the type of spill reported in the original thread post, no? I'm just thinking that something is better than nothing....
 
Sounds like a few good preventive ideas in the posts. I am about to final install rear window. Think I will enlarge the screw holes slightly, as well as look into application of a fuel resistant film. Am also thinking abouit a metal tank with hand pump and hose in my pickup (grounded) for fueling the 12. Should help. Keep the ideas coming. Thanks.
Dick Seiders
 
This really is a very simple issue to solve and the current rear window material is not a part of the solution, much like the window in the fuel tank, the rear window is made from a material that is not correctly suited to the job required of it. Lets not wast a lot of money replacing rear windows with the wrong material just to get the same result each time. With great care you may keep fuel off of the rear window most of the time, but you can not keep fuel fumes off of it as the fuel vent is just inches away from it and with out a major change in the fuel system that is where it will be.

The fix is simple lets get one of the windshield companies from Trade-A-Plane who do this for a living to select the correct material for this use and if, as I suspect, it requires heat shaping over a mold to work then lets get on with it and get a rear window that works just like the one in a Cessna 150 which lasts for many years even with fuel spilled on it from time to time.

Lets light a candle instead of complaining about the darkness.

Best regards,
Vern
 
Link to Makrolon Product Datasheet

After reading the various posts, I looked at the Makrolon website to see exactly what the product data sheet said regarding resistance to various chemicals. I have provided the link below. The specific reference to fuels is on page 3 where it states "Makrolon? is not resistant to the standard
carburetor and diesel fuels. The low-molecular, aromatic hydrocarbons that are present in carburetor fuel, in particular, cause cracking in parts that
are subject to stress."


http://plastics.bayer.com/plastics/...on/product_datasheets/docId-34631/KU28057.pdf

I do tend to agree with Vern- even with great care, there will be some point where fuel finds its way to the window. Too bad because in all other ways, it seems like the Makrolon is a great material- very durable.

Jeff
 
If true that the window is not compatible with fuel then it is not a good material choice. I guarantee you will spill fuel at some time. Then What? I hope Vans is taking note...Rudi
 
Lexan woes

Until a better solution is found, I'd try sealing the edges AND holes ( which of course are raw edges) with a latex based sealer. Even silicone can cause problems with it's components.
Makrolon and other polycarbonates are better suited to glazing applications, but we just keep forcing them into use because they bend easily, and are less prone to cracking in fabrication and use. I could never stand the optics.
 
New Unit

Vern, I agree 100%...it should be possible to get a Plexiglass unit molded to pretty much be a direct replacement...I'd rather buy one rather than a Lexan one every now and then as I have an 'accident.'

JohnF
 
I know a bunch of ex-ultralighters (now Sport Pilots) who have known of this problem for years. All of them have some type of rubber mat with channels, that they put over the filler neck, that will direct any spillage directly to the ground. Without 1 drop touching the airframe. Most 'accidents' are caused by overfilling/overflowing.
 
Until a better solution is found, I'd try sealing the edges AND holes ( which of course are raw edges) with a latex based sealer. Even silicone can cause problems with it's components.

What would that "latex based sealer" be? My first thought for a sealer was silicone, but you say that isn't a good idea.
 
sealant

John,
we went thru a variety of sealants on the windshield of our previous homebuilt.....from the grey putty using to caulk window frames, to silicone ( which crazed the edge of lexan). It seemed that regular household exterior latex caulking, like DAP, mono etc, worked well, stayed flexible, and pretty much glued the window in, should a fastener work it's way loose.
Perhaps the boat-building, snowmobile, jet ski or motorcycle industries have something better, as they use polycarbonate windshields as well.
 
Vern, I agree 100%, with your proposed solution. but lets not be too hard on the complainers. After all is said and done they get a lot more accomplished bringing light to the problems usually resulting in the necessary improvement than philosophy ever will.
Dick Seiders
 
I want to let all the RV 12 builders out there know that I have found someone who can heat mold Plexiglass to fit the aft window. He's been building experimentals since the mid 80's so he knows our pain. He just finished mine and charged me $250.00. Beautiful craftmanship and it fits perfectly!!! It took several weeks to get it but its worth it. He's from the local chapter so I didn't have to pay shipping etc.

I will be installing the lexan for purposes of getting the plane air worthy but will replace it if I have problems with the lexan. Before I posted this I asked him if he would be willing to build more, and he said he would for the RV 12 and RV 7A. He now has molds for both aircrafts. If any one is interested let me know I will forward contact info etc.

I used the dark tint to help keep the gas tank cool.

Below is link

http://img199.imageshack.us/img199/4876/aftglass.jpg

Gary Eldridge
RV 12 - 99.00%
 
I want to let all the RV 12 builders out there know that I have found someone who can heat mold Plexiglass to fit the aft window. He's been building experimentals since the mid 80's so he knows our pain. He just finished mine and charged me $250.00. Beautiful craftmanship and it fits perfectly!!! It took several weeks to get it but its worth it. He's from the local chapter so I didn't have to pay shipping etc.

I will be installing the lexan for purposes of getting the plane air worthy but will replace it if I have problems with the lexan. Before I posted this I asked him if he would be willing to build more, and he said he would for the RV 12 and RV 7A. He now has molds for both aircrafts. If any one is interested let me know I will forward contact info etc.

I used the dark tint to help keep the gas tank cool.

Below is link

http://img199.imageshack.us/img199/4876/aftglass.jpg

Gary Eldridge
RV 12 - 99.00%

NOW you tell us...lol...sounds cool! Good job.
 
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