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Broken Bond Rear Window

Drippy

Well Known Member
I could use some technical advice.

Yesterday I leaned on my co-pilot side rear window and heard a "pop". Upon examination it appears I broke a section of the bond along the top edge about 6" long.

The windows were originally installed with Lord Adhesive about 5 years ago - but I hadn't gotten to installing a layer of cloth over the window edge and canopy.

Anyone else seen this? If so did you pull the window and sand of the old adhesive and start over?

Ideally I would like to get away with just installing a layer of cloth, as described in other posts, to capture the edge of the window.

Thanks for the feedback.
 
Mike,

A gentleman on the forum posted last year or the year before last about losing a passenger side window. The good news is that, apart from a bit of noise, the aircraft was not negatively affected. He was able to make a safe landing. I'm not sure a conclusion was ever reached on what material he used to bond the window.

But, if it were my airplane, I wouldn't trust a window to an already weakened bond, hoping that a layer of fiberglass would secure it sufficiently. I'm sure others will chime in as well.

It is possible to remove the window and try again. Heck, Vic Syracuse replaced his entire windscreen on his RV-10. The rear passenger window should be quite a bit more straightforward than that.

Good luck with your repair. If you do choose to remove and replace the window, I'd really appreciate it if you'd post how difficult it was to break that Lord adhesive bond.
 
Lord Adhesive, Weld On and Sika does not have any UV protection. They require a UV blocker (something on the outside of the window to prevent exposure to UV). The glassing provided this protection. It’s possible this is what cause the failure.

If you are going to remove it, you should get a wire tool for removing car windows. Push the wire through, attach the handles and pull it around the window to remove.
 
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Silpruf

What specific adhesive are you recommending SCS2000?

What is your experience with it?
 
Silpruf is good. Yes SCE 2000 black or grey. It is silicon base and UV resistant. It has more elasticity than the others. I did the Glassair 2+2 window install method so no glassing in the windows. But you must be very careful avoiding getting Silpruf on unpainted surfaces. Sika is a good product and Cirrus uses this to install their windows. Cirrus windows install on the inside of the flange
(the -10s install on the outside of the flange) so Sika is protected from UV.
 
Lord Adhesive, Weld On and Sika does not have any UV protection. They require a UV blocker (something on the outside of the window to prevent exposure to UV). The glassing provided this protection. It’s possible this is what cause the failure.

If you are going to remove it, you should get a wire tool for removing car windows. Push the wire through, attach the handles and pull it around the window to remove.

Sika IS UV resistant. The product name even has a UV suffix. It is designed for boats windows with 24/7 sun exposure.
 
Carl:

Add Silpruf to your list.

Then get rid of the other items ;) :D

I used the Lord Adhesive to install windows, wish I hadn't. After plane was painted, wish I had used Silpruf like the Glassairs do.

Here's how my painter explained it to me: The plexi expands and contracts differently than the fiberglass it's adhered to. So, over time, paint will crack around the window at that joint when the paint covers both window and cabin top. With Silpruf, you don't paint "over" the joint, you paint up "to" the joint. The Silpruf becomes you finished edge. So, now the paint won't crack over time because it's not overlapping both cabin top and windows (cabin top only). My paint looks gorgeous, but I know I will end up with a crack someday.

Google Glassair window installation on YouTube and follow their method.
 
Sika IS UV resistant. The product name even has a UV suffix. It is designed for boats windows with 24/7 sun exposure.

Yup. I used Sika for this reason (and others). However, even with the UV resistance, I plan to paint over the area where the actual adhesion is taking place also, to provide additional protection. The paint will break at the tiny "bead" between where the window pane meets the fiberglass joggle, to prevent paint cracking.
 
So now I’m thinking of how to use Silpruf but still avoid having to look at the adhesive through the glass (it reminds me of the RV-10s I’ve seen with “window frames” where they just filled in the gap with mico and painted - the paint will alway crack if you don’t use glass). The silicon aspect of the Silpruf is the rub for painting the glass to eliminate the frame.

I have some questions for the crowd:
1. Would using a Urethane adhesive like this avoid the silicone problem for paint?: https://www.amazon.com/3M-08693-Ure...ocphy=9025207&hvtargid=pla-524154367895&psc=1
2. Looking at the very nice YouTube video on using Silpruf to put in windows on a GlassAir, I’m wondering if I skip the step to fill in the grove around the window would leave option to do a traditional fiberglass finish? Specifically I’m thinking:
- After the Silpruf has cured, fill in the grove with micro, sand flush after cure. The objective is not to have a bond between the micro and whatever Silpruf is in the grove, just make a flat surface to glass over.
- Now use a couple of bids of fiberglass over the window, extending to the end of the bond area and an inch or so over the cabin top (or doors). This would make for a secondary mechanical means to hold the glass in, and provide for a good base for paint.

Carl
 
Carl, I don't like the idea of a micro slurry filler hard up against the edge of the plexi all the way around - because of differential expansion concerns.

That... and I don't think the gray Silpruf showing through the tinted plexi is a bad look at all, since it is very smooth, bubble-free and consistent width all the way around.

May be over-thinking this, but thought I'd mention the concern in case it did something bad when things warmed up or cooled down a lot.
 
Carl, I don't like the idea of a micro slurry filler hard up against the edge of the plexi all the way around - because of differential expansion concerns.

That is the exact reason for why I glassed over the joint on my first RV-10 - in addition to adding a second retention for the glass. Never had any cracks.

I’m looking for adhesive options other than Weld-on or Hysol - so my interest in using Silfpruf or something similar.

Carl
 
Yup. I used Sika for this reason (and others). However, even with the UV resistance, I plan to paint over the area where the actual adhesion is taking place also, to provide additional protection. The paint will break at the tiny "bead" between where the window pane meets the fiberglass joggle, to prevent paint cracking.

The sika is designed for significant flex to support the significantly different expansion rate of acrylic. My Sika bead goes from convex to concave, based upon the temps. This is great from a bonding perspective, but is too extreme even for paint designed to flex. The paint WILL crack in the areas of highest expansion / contraction rate, which is usually the corners. My paint dealt with it very well until the first night we dropped below 0, Then the cracks appeared.

Recommend not painting it.. I chose to paint over it due to not wanting to clean up the horrible job done on the top. The rounded edging at the rear window area was horrific on my green top; It looked like a third grader cut the mold (lines were NOT straight) and the radii were riddled with air pockets. In hindsight, I wished I had done it. Now plan to use vynal wrapping in that area to get rid of the cracks.

Windshield however is more rigid and larger, therefore have no cracking in the paint there.


Larry
 
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All you using Silpruf, it seems to me that installing the windows after final paint makes the most sense. Do I have this right?

Carl
 
All you using Silpruf, it seems to me that installing the windows after final paint makes the most sense. Do I have this right?

Carl

You can do either.
If you do paint after windows, you leave the gap void between the window and the cabin top. Then come back after paint mask both sides and fill the gap with Silpruf and radius it.

sort of depends on you plans to paint relative to first flight.
 
All you using Silpruf, it seems to me that installing the windows after final paint makes the most sense. Do I have this right?

Carl

If I had it to do all over again, that is what I would do. Just be sure to clean up the areas where the silpruf will end so that you have a pleasing transition.

Jan from down under did this and posted pics here. Looked very nice.
 
Did you check the section to see if the Lord Adhesive was hard? Reason I ask is I had a section that didn't mix right and never cured. Fortunately I was still building and found it a year after the window was installed. I dug it out and inserted some new in, but was curious if this might be the cause, if not was it a clean split where it came off the top or window like maybe that area wasn't scuffed enough?

I could use some technical advice.

Yesterday I leaned on my co-pilot side rear window and heard a "pop". Upon examination it appears I broke a section of the bond along the top edge about 6" long.

The windows were originally installed with Lord Adhesive about 5 years ago - but I hadn't gotten to installing a layer of cloth over the window edge and canopy.

Anyone else seen this? If so did you pull the window and sand of the old adhesive and start over?

Ideally I would like to get away with just installing a layer of cloth, as described in other posts, to capture the edge of the window.

Thanks for the feedback.
 
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