Light Aircraft Association

I now have to replace my Jodel front screen after have just done it 4 months ago.
The first screen was polycarbonate and a fuel spill made it disintegrate in front of me it just crazed and split in only a few seconds right across where the petrol splashed on it.
I replaced it with perspex and that seemed a lot better, until I was taxying with a full tank and some spurted out of the breather/fuel gauge hole and little hit the screen directly behind the filler and crack, it split about 5 inche in a straight line. I know the screen is a flt piece of perspex bent cold around the fuselage so it is under a bit of stress but it is a total and expensive nuisance to keep having to replace them. Why did they put the filler there? right in front on the transparency where the fumes and splashes are guaranteed to hit the plastic. Any ideas as to material change might help, polycarbonate was a total disaster as it completely fell apart, the perspex just cracked along a stress line.

From another place, a recommendation by our CEO:-

"I had a similar problem and discovered PETG sheet. It is as flexible as Lexan, extremely easy to drill and cut and completely fuel proof. The plain stuff isn't very UV stable so make sure that you get the UV stable version."

I have not tried it yet but if it doesn't craze, it will be very worthwhile.

Hi Graham,

I did start researching the various material options for my Jodel glazing but have not reached any conclusion yet. Clearly polycarbonate is a problem for a Jodel windscreen given the location of the fuel filler for the front tank.

UV resistant PETG seems to be an option if it can be found in cast form with good optical properties.

Not all Acrylic is equal I think. There are also co-polymer material like Spektar that might be worth a look.

I found this video of the effects of ethanol on acrylic which shows a good way of testing samples for chemical resistance under stress,

Regards,

Colin

http://www.eastman.com/Markets/VMTC/Ext ... tance.aspx

I had loads of grief with windscreens on my MW6 and tried Petg. It's not as strong as Macrolan as I found out when the screen failed on take off! OK it was unsupported at the top but the macrolan was as well. So take care folks, not all plastics are equal.

I have remade the screen with PETG but I did try a sample with fuel and when it is under tension ie bent it does craze like the others. But hey ho worth a try. Silly place for a tank filler though, even the fumes get it on the screen. I will do away with the gauge rod and do it by calculation for fuel filling and put a forward pointing vent on it. The float has just sunk anyway, leaking solder.

Every time i fill up i throw over a cover over screen for this same reason..sounds blinking psinful

Recommend talking to Gilbert Curry Industrial Plastics at Coventry. They have a website with data sheets and material working instructions for a range of Lexan products. I have used Lexan EXELL D supplied by them, which is the same material used by aircraft kit suppliers.

Made another set of transparencies from PETG as this is more resistant than polycarbonate and stronger than perspex. Kept the master from the original screen so getting used to cutting them on a bandsaw.