Something may have changed. I very carefully made a rubber mat shield for when fueling, to avoid spillage touching the window. Then the VERY FIRST TIME I fueled the plane - from the flo-fast system using one hand with the crank - the hose popped out and made a big spill behind the mat and on the window!! darn!! But I quickly wiped it off with a rag as thoroughly as I could and there was no effect at all on the window. Now I jam in a no-lint rag with the plastic tube in the fueling port.
hey guys, I'm not a -12'er, but am pretty familiar with the materials.
If you want to keep the lexan window for whatever reason, you can apply ( or have a sign shop do it) laminate to the outside of the lexan.
The polyester series of laminates are quite solvent resistant, and will have minimal effect on the clarity, although some waviness is apparent.
The edge of the lexan is still a weak point, and repeated fuel exposure will contribute to crazing. I suggest trying to seal it with an acrylic sealer.
I can suggest a couple; 3M 7248 - 2mil, 8912 - 3mil, and 8991 - 4mil, all should conform easily to the single curve of the -12 rear glass.
the stuff ranges from about $1 to $2 per square foot.
I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll. I do use a rubbery mat (home depot) when fueling to cover the Lexan and fuse just aft of filler neck. I cut a hole in the mat for the filler ring. The mat is large enough that it covers about 30% of the rs rear Lexan. Hopefully that will provide the necessary protection.
Dick Seiders
I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll. I do use a rubbery mat (home depot) when fueling to cover the Lexan and fuse just aft of filler neck. I cut a hole in the mat for the filler ring. The mat is large enough that it covers about 30% of the rs rear Lexan. Hopefully that will provide the necessary protection.
Dick Seiders
So, with all the crazing and cracking, maybe it is not such a great structural necessity after all?
Side comment -
What I did say was that when completing all of the test scenarios as specified in the ASTM's for testing the structure, that the rear window proved to be a structural component in transferring the tail loads into the fwd fuselage.
That's an interesting comment. The fact that the window was found to transfer loads during testing and was therefore `structural' is not surprising, but from previous discussions I got the impression that the window was designed from the start to be a structural component. It seems that may not be the case. Neverthless changing to a different material or design would place you in the `untested' zone.
I like to worry as it keeps me from doing dumber things than I usually do.
So Scott am I to understand that if 100ll splashes on my rear window it's not a problem? If so I didn't know that. I thought Lexan was affected by all fuels. I have always used the mat I described as spilling fuel (mogas 91) tends to soften fuse paint around the neck.
Regarding letting the ramp guys fuel my plane that NEVER happens. Fifteen yrs ago when I landed for fuel at Lynchberg, VA in my 172 I happened to look out the window as I was filing IFR for next leg. I almost broke the door getting it open to yell to the ramp guy to stop moving my airplane by pulling it by the very tip of the prop. I do all the necessary work thank you.
Dick Seiders
I think maybe my words are getting twisted around somewhat.
It was expected that the window would transfer load. The testing to verify compliance with the ASTM proved that it does.
The rear window material wasn't primarily chosen for it strength. It was chosen because it can be CNC punched to make it quick/simple to install.
I recently put two gallons of car gas in my 12, according to PAP checklist, to check for fuel leaks, when disaster struck!
As I poured in the gas, a few drops struck the lexan and immediately numerous fine cracks (crazing) appeared. Since I had not seen the thread on lexan and gasoline here, I was surprised, to say the least.
Van's says a "Caution Note" is in section 5 of the manual (concerning lexan & gasoline), but why isn't it in section 25 where the instructions for installing the aft window are located? Or, better yet, why not in the PAP fueling checklist ? This isn't the sense of responsibility I've come to expect over the three Van's projects I've completed in the last 14 years.
So, now I'm faced with living with a very ugly rear window or replacing it with (you guessed it) another lexan unit. By the way, does anyone have an extra aft window, either lexan or plexiglass, laying around? Don, are you willing to part with one of yours?
Walt Shipley
RV-12 (DAR coming Friday)
RV-8 (sold, now resides in Australia)
RV-8A (sold)