Replacing windows - glue or rivets?

[Auster]

I'm about to replace the perspex window, pilot's side, on my Mk V. After about 12 years and 500 hours it has cracked around some of the rivets, especially at the rear where it experiences stress from hitting the fuel drain when the door is opened in flight.

My question is - has anyone glued their windows in place instead of riveting?

My feeling is that stresses and cracks will always occur around the rivets even if installed according to the build manual. I've found some posts about gluing the small rear windows in using 3M tape but what are the thoughts on gluing the main door windows in, either with 3M tape or a perspex or glass silicon glue?

[airlina]

20 years ago when building my Series 5, I didn't like the idea of riveting the windows in place for a couple reasons. Didn't like that with the rivets the sqeueeze pressure of each fastener couldn't be controlled and cracking could occur , and I wanted the ease of removal for replacement if necessary. The screws are just snugged up enough to keep the windows in place and so far , I have not had to replace any of my windows , so they stood the test of time. Bruce N199CL

[Av8r3400]

I used riv-nuts and screws on my door glass. A tiny drop of low strength loc-tite keeps the screws in place without tightening them. I brought the screws down just to where they touched with a small washer.

If you choose to use an adhesive, keep in mind plastic off-gasses through its lifetime. If you use a urethane type glass adhesive it will fail. Use a specific plastic adhesive.

[Auster]

20 years ago when building my Series 5, I didn't like the idea of riveting the windows in place for a couple reasons. Didn't like that with the rivets the sqeueeze pressure of each fastener couldn't be controlled and cracking could occur , and I wanted the ease of removal for replacement if necessary. The screws are just snugged up enough to keep the windows in place and so far , I have not had to replace any of my windows , so they stood the test of time. Bruce N199CL

These are exactly my thoughts about rivets. I'm currently replacing most of the perspex in my Auster and it's all held with screws, either into rivnuts or timber, there are no rivets. Also, Av8R's suggestion is helpful so I'm going to use a combination of screws and glue. One of the techniques I will use with the screws is to place a small piece of silicon tubing around the screw (in the hole in the perspex) so that it seals and at the same time allows for expansion and contraction. Thanks for the guidance.

[jiott]

In the model 7 build manual the install procedure calls for 3M tape (so you are essentially gluing it in place), then screws in oversize holes with plastic washers, and don't overtighten the screws. Also, be VERY careful about what glue you may choose to use either on the glass or the screws; some products, especially some Loctite products offgas fumes during the curing process that will permanently fog and even crack the plexiglass! I just used the standard screws and chrome acorn nuts that come in the kit and installed them just over hand tight, but I used a drop of Elmer's white glue (no bad fumes) in the acorn nuts to keep them from vibrating out. It is now 10.5 years and 1300 hours later and not one single screw has come out or even loosened.

[desertdave]

Personally I think gluing will look horrible unless you completely cover the steel frame with adhesive. When I redid my doors I went with slightly oversized holes in the Lexan and pulled rivets in the old, existing holes.

[jiott]

How you install Lexan (polycarbonate) doors vs. plexiglass (acrylic) bubble doors are two totally different animals. The Lexan will tolerate most anything without cracking- rivets, screws, tighter torques, bending, etc., but is softer and more easily scratched and fuel stained. The plexiglass bubble doors , and windshield, are where all the extreme care must be taken, but you get a harder, more durable, clearer, and stain resistant result.

[Auster]

In the model 7 build manual the install procedure calls for 3M tape (so you are essentially gluing it in place), then screws in oversize holes with plastic washers, and don't overtighten the screws. Also, be VERY careful about what glue you may choose to use either on the glass or the screws; some products, especially some Loctite products offgas fumes during the curing process that will permanently fog and even crack the plexiglass! I just used the standard screws and chrome acorn nuts that come in the kit and installed them just over hand tight, but I used a drop of Elmer's white glue (no bad fumes) in the acorn nuts to keep them from vibrating out. It is now 10.5 years and 1300 hours later and not one single screw has come out or even loosened.

Jim thanks for this info. It appeals to me as a good way to tackle this. I have a question re the model 7 instructions. After gluing the glass in place with the 3M tape, how many screws are used or what is the approximate distance between the screws? I'm guessing they are there as a fail-safe measure should the 3M tape not do its job.

Also, I won't be using Lexan, rather Plexiglas, or the name I have always used, perspex. It's essential that it is petrol resistant and not too susceptible to scratching.

Thanks.

[Auster]

Personally I think gluing will look horrible unless you completely cover the steel frame with adhesive. When I redid my doors I went with slightly oversized holes in the Lexan and pulled rivets in the old, existing holes.

Dave yes it would look awful but I've always had the window painted around the edge where the steel frame is - so it just looks like a frame on the Plexiglas. Looks good and completely hides the frame.

[jiott]

Auster, I can't remember how many screws are called out in the model 7 build manual, but there are not a lot of them; seems like 6" or more between screws, and yes they are more of a safety backup to the tape. You can read the exact installation process by downloading the build manual from the Kitfox website for free.