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Rear window crazing

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Pat Stewart

Well Known Member
Ok guys need some advice. I used a release on the fuel filler neck that came in contact with my rear window and the result was bad. Today I plan to order a new window. What are my options, I am sure others have replaced the standard kit window with something better.

Pat
 
I learned the hard way on my SLSA. After a couple of spills from clumsy handling by me but also because you have to be really careful when fueling because too much flow will cause gendering and it'll gush out.
To me it's somewhat of a design error because of the potential for crazing.
I've had the plane a year and I'm contemplating replacing it and how difficult it would be for my mechanic.
 
I've had my SLSA for about a year and a half and its had progressive crazing for about one year now. I have a new window in a box to be installed with the next annual this fall. I'm hoping that the split bulkhead mod will be approved by then so I can incorporate that with the window change.

What I'd really like is a window that is resistant to this, my crazing is not totally due to fuel as it is occurring on both sides and as long as I've had the airplane (since hour 5) there hasn't been any fuel spilled on the pilot side and only once on the pax side.
 
rv9builder said:
Would something like this help solve the problem?

http://www.chaddpadd.com/aviation.html
Click to expand...

It 'might' but?in my case the spillage was from geysering out of the fuel fill port. The pump is just pumping too fast (partly my fault) for the capacity of the tube.
So as well as gushing out onto the nearby perspex it also runs down the fuselage side which, in my case, destroyed the adhesive for the trim across the wing root?the bit just below the fuel filler.

The mat might stop some of the spillage I dunno for sure.

What would have been good is if Vans had warned me in advance but such is Life.
Now I'm alerted to it and it doesn't happen, but now the perspex is already crazed right at the area where the spill occurs. It has immediate effect so some additive in the fuel reacts immediately so I guess a different type of perspex on the rear canopy might be the answer?
 
RV-12 Fuel Tank Vent





Basically copied factory design, except I used 1/2" I.D. tubing for better venting. I also made large funnel that fits tightly into fill neck. Eliminates splashback problems. I bought two funnels and cut top off one and riveted into other to help eliminate splashback.
 
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I've been fueling by hand using regular gas cans and I tried a Mr Funnel.

Now forewarned and forearmed I don't splash. This doesn't fix the crazing that's already happened though.

I'm contemplating buying a Goat-throat siphon pump to make fueling from 5 gallon cans a bit easier. Can't do much else in the way of mods on an SLSA.
 
I replaced my rear window and it was relatively painless. I used a sharp knife to cut through the Proseal around the edge and the old window came out easily. New one fit right in its place.
 
Suppose Vans had an alternative ...

Suppose Vans offered an alternative to the Lexan window. What would people be willing to pay?

Personally, I would be willing to pay around $400 for a Plexiglas window.

I saw one plane where the owner had replaced the Lexan with aluminum. (Actually, he may have just covered the Lexan). I thought it looked great and the rear window doesn't really add useful visibility. I would think that an aluminum skin to the replace the window would be fairly inexpensive.
 
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Good Idea?

I don't have an RV-12 handy to look at right now so maybe this idea isn't valid - but - from looking at the picture in post # six here, I am wondering if it would be possible to reposition the hole in the tank outboard more towards the side of the fuselage and then lower the outside fuel inlet a foot or so? This would make the fuel inlet lower on the side of the fuselage and thus farther from the window. I suppose that those at Van's have already thought of this and discarded it for reason. Just sayin-----
 
My reasoning - -

Splashback happens because a large vent is needed. That is why I used 1/2" I.D. tubing for vent. By having a large funnel that fits tightly in fill neck, I can pour from a fast flow can and can dump 5 gallons in less than a minute. It works very well. The funnel ( with extra lip ), can contain a splashback very well.
 
I have used a Flo Master pump setup since I started flying my 12. The carrier holds (2) 5 gal plastic containers. The pump requires about 1 min to put 5 gal in the tank and you don't have to heft it up to the fill pipe as the pump tubing delivers it into the tank. In 5 years and almost 300 hours of flying the only time I ever had an overflow was at an airport filling station. Now that the vent is installed even that doesn't seem likely to happen again. I also still have the original rear window material. Am I satisfied with this setup? You bet!
dick seiders 120093
 
Rick_A said:
Suppose Vans offered an alternative to the Lexan window. What would people be willing to pay?

Personally, I would be willing to pay around $400 for a Plexiglas window.

I saw one plane where the owner had replaced the Lexan with aluminum. (Actually, he may have just covered the Lexan). I thought it looked great and the rear window doesn't really add useful visibility. I would think that an aluminum skin to the replace the window would be fairly inexpensive.
Click to expand...

Is this it?

http://cdn-www.airliners.net/aviation-photos/photos/5/3/8/2268835.jpg

I like it!
 
There was a LONG thread this

three or so years ago. One guy even produced a number of formed replacement Plex windows but with the advice that the window is structural I gave up on that idea. The solution at the time was to coat the cut edges with sealant (several choices) and also the holes we drilled so carefully for the attaching bolts. I have a Flo-Fast setup with 15 gallon tank on the cart and carry fuel to the airport in 3 5 gallon cars. Flow rate doesn't cause a problem (19 turns per gallon) and I haven't had a spill in 5 years of flying. Having said that, tomorrow.....

Wayne120241 N143WM
 
Preventing fuel crazing of rear window

I've been following this issue (have yet to add fuel to my tank); why not carry a roll of painters tape and strip of plastic (not much weight), and tape plastic to protect window @ each fill up. Seems simple enough to me.....
 
Enquiring minds...

Mich48041 said:
The rear window is structural. Plexiglas (acrylic) is not as strong as Lexan (polycarbonate).
Click to expand...

Just can't help but wonder how one determines by what percentage that structural integrity is diminished from the Polycarbonate being crazed. Anyone poised to whup out a slide rule on that?

Every silver lining has a cloud, eh?
 
Other crazing factors

Fuel may induce crazing but it will craze in places that have never come close to fuel or other solvents.

I've seen crazing on the forward edge of the Lexan, well away from any possible fuel. Also, not at the screw holes but mid-way between the holes.

I just guessing, but I think it has a lot to do with stresses in the material that result from taking a flat piece of Lexan and bending it.
 
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