Lift ring sealing

[Daveembry]

Yes, that’s the type foam weatherstripping that should be around the window. Usually it’s put on the window side (less visible) like you said your was (but deformed). I also put a piece across that metal part of the latch on the window. The figure shows stopping it on either side but I put a piece all the way across to seal that area

If that bottom, front corner is the problem, usually it’s the latch adjustment that can be changed to pull the window in tighter. The screw holding the window latch into the window should have some plastic washers used as spacers, You can simply add or remove some of the spacers to make it so that you have to pull that window fully shut up.

Here's what I ended up doing. First I did a flight using some normal weatherstripping to fill in the gaps at the top of the window forward of the hinge and it didn't help that much, but maybe a little.

It seemed that most of the water was coming from bottom half of the window when it was closed. So I bought some of this stuff at home depot and just ran it along the entire front window threshold. It worked great, 130 mph through some pretty constant rain and not a drop in the cabin. How will it hold up durability wise is the question. Hopefully it doesn't absorb a bunch of water and cause corrosion.

This weatherstripping is compressible foam, so it doesn't make the window hard to close yet seals out water reasonably well when the window is closed.

I also took some shorter strips and touched up the factory window weatherstripping along the bottom of the windows where it closes on the window latches. The metal of the latch housings in the top of the door on the aircraft right and top of the sidewall on aircraft left seems to be deformed the factory weatherstripping that was put onto the windows along the edges.

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[Narwhal747]

Thanks Dave! Yeah, the glass window already had the D shaped gasket from CubCrafters installed on the front edge, so this expanding foam kinda mates with it. I guess that's why I had to put the foam gasket on the frame and not the window glass.

After a few flights with the front edge double-gasketed with the expaning foam on the fuselage and rubber D-seal on the window, no leaks, but I did notice the silver latch slot in the door starting to get loose....so I probably do need to add a washer or two to that front latch to compensate. I'm surprised that it seems to just be glued to the door, I figured that would take to much stress to remain there with adhesive! There has to be a happy medium somewhere between gasket size and latch tension!

[Andy]

I'll check that window hinge gap next time I'm at the hangar.

On the right side the windshield wing root seal extends back to the front of the hinge. The D section window seal turns the corner and runs to the hinge. There is no gap.

On the left side the windshield seal stops a bit (maybe half inch) short of the hinge.

Mine leaks at the front edge of the side windows, not at the hinges. If the windows are adjusted tight enough to compress the D seal at the bottom there is a risk the latch plates will move. The latch plates are secured by 3M VHB adhesive which is strong in tension but creeps and may fail with continuous shear load.

[Daveembry]

Yes the 2 sided tape is under the latch catch on the door and window sill but that isn’t what holds it in place. When fitting the piece, a slot is cut down into the door on the right side and through the top of the left interior panel and down into the fabric spacer there. When the window latch is fully engaged (down, latched position) it should fit up against the cutout which prevents it from moving the catch. If you can pull the window in enough for it to engage the slot, it isn’t going to “fail”. The tape is not what holds the catch in place.

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On the right side the windshield wing root seal extends back to the front of the hinge. The D section window seal turns the corner and runs to the hinge. There is no gap.

On the left side the windshield seal stops a bit (maybe half inch) short of the hinge.

Mine leaks at the front edge of the side windows, not at the hinges. If the windows are adjusted tight enough to compress the D seal at the bottom there is a risk the latch plates will move. The latch plates are secured by 3M VHB adhesive which is strong in tension but creeps and may fail with continuous shear load.

[Andy]

Yes the 2 sided tape is under the latch catch on the door and window sill but that isn’t what holds it in place. When fitting the piece, a slot is cut down into the door on the right side and through the top of the left interior panel and down into the fabric spacer there. When the window latch is fully engaged (down, latched position) it should fit up against the cutout which prevents it from moving the catch. If you can pull the window in enough for it to engage the slot, it isn’t going to “fail”. The tape is not what holds the catch in place.

I understand how the window latch should be fitted but my post was based on experience with a latch plate that was not properly fitted.

When you build an EX at home you can take whatever time it takes to do it right. The FX-3 "builder" has no control over the work done on the production line at Yakima.

The front latch hole in my door is far larger than required and provides no location of the latch plate. The latch plate came off on my ferry flight home after CubCrafters had tightened the latches in an attempt to fix my rain leak. The failure mode was as I had described. The VHB adhesive crept and then failed.

The window sealing question was asked by an FX-3 owner. Perhaps he had the same person fit his windows and doors.

(BTW - VHB is not a double sided tape. It an adhesive transfer tape that has no central substrate)

[Daveembry]

The “2 sided tape” (regardless of your word games, it’s “2 sided tape” to us lowly laymen) is not used to hold the window shut as I said. The door or panel slot is. (Regardless of whether yours or his….was fitted right or not). I said the way it’s designed to work so don’t say it will “fail!…..it won’t. It’s a cosmetic “cover” for the hole. If it moves over because the window isn’t fitted properly…..it didn’t “fail” it’s purpose.

Most likely it can be moved over until the latch contacts the inside edge of the slot and then the number of washers increased if needed to move the window frame outward to fit nicely.

Your turn….🤦*♂️

I understand how the window latch should be fitted but my post was based on experience with a latch plate that was not properly fitted.

When you build an EX at home you can take whatever time it takes to do it right. The FX-3 "builder" has no control over the work done on the production line at Yakima.

The front latch hole in my door is far larger than required and provides no location of the latch plate. The latch plate came off on my ferry flight home after CubCrafters had tightened the latches in an attempt to fix my rain leak. The failure mode was as I had described. The VHB adhesive crept and then failed.

The window sealing question was asked by an FX-3 owner. Perhaps he had the same person fit his windows and doors.

(BTW - VHB is not a double sided tape. It an adhesive transfer tape that has no central substrate)

[Narwhal747]

Thanks Andy and Dave! I think what I will do is take a razor blade and cut the thickness of that expanding foam by 30-50%, then add a washer to the latch mechanism and see if that strikes a happy compromise between tight seal and too much pressure on the latches.

[Narwhal747]

Ultimately, cutting my foam weatherstrip to half thickness seemed to un-waterproof it. I think I need to experiment with partial weatherstripping instead of one long strip the entire length of the “a-pillar”. Interestingly the long strip on my left window seems to work great with no loosening of the latch catches on the left side and no more water. The right side remains problematic, probably due to the wind/door fit and maybe the sizes of the latch holes in the doors that Andy referenced.

in the meantime I need to resecure the metal window latch catches in the right side door, as they are creeping pretty badly now. Is this the correct product to use: https://www.amazon.com/Double-Length...-1-spons&psc=1 ?

[Daveembry]

No it looks like the 3M “Tape” (as 3M calls it) is this tape (clear mounting tape) except they send 1/4” but this will work just as good. https://www.amazon.com/3M-Mounting-P...ps%2C78&sr=8-3

Here is how it goes on:

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Heres a photo of how the wing root weatherstrip should wrap around the forward wing root panel and go back to the forward hinge:

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The foam seal used around the windows is 1/8” thick. You could put 1 complete line of it onto the A plillar and then put a short piece on the bottom of the window itself if you need it thicker at the bottom.

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i put the “D” weatherstripping along the front of the door on the outside of the latch holes.

Ultimately, cutting my foam weatherstrip to half thickness seemed to un-waterproof it. I think I need to experiment with partial weatherstripping instead of one long strip the entire length of the “a-pillar”. Interestingly the long strip on my left window seems to work great with no loosening of the latch catches on the left side and no more water. The right side remains problematic, probably due to the wind/door fit and maybe the sizes of the latch holes in the doors that Andy referenced.

in the meantime I need to resecure the metal window latch catches in the right side door, as they are creeping pretty badly now. Is this the correct product to use: https://www.amazon.com/Double-Length...-1-spons&psc=1 ?

[Narwhal747]

Great info, thanks Dave! Much appreciated!