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Repairing Sliding Canopy Crack

DavidHarris

Well Known Member
I got a pit in my stomach yesterday discovering a crack near the canopy latch in my RV-7A slider canopy. The aircraft has about 140 hours on it. The canopy was attached with SikaFlex and the leading edge was sanded to reduce stress concentrations. The crack extends from the front edge of the slider about 10 inches back. I do not know the root cause of the crack. The airplane is normally hangared, but for the past week it has been tied down outside at Big Bear Lake in the cold and sun and wind. The only good thing is that the crack is outside my field of view during normal flight.

I plan to stop drill the crack as described in AC43-13 Figure 3-21. I then need to patch the crack.

AC43-13 3-24a seems to call for a surface patch, apparently made of plexiglass at least 1.5" wide shaped in hot oil to match the contour and attached with a plastic solvent adhesive. This sounds like a challenge for my level of skill and equipment.

I've searched the VAF forums and am having trouble finding how others have done such repairs. Can anyone advise?

Thank you,

David Harris
 
You can search here for "plexi crack", lots of posts there, you may find some strategies to deal with this problem.
Another suggestion is visit local shops that fabricates signs & (the extremely popular) Covid 19 acrylic dividers for stores & restaurants. They use gluing systems that might work for you.
 
Ugh, I just bonded my canopy to the frame and that is the fear when cutting/drilling the canopy and in the future... I hope the Sika process would reduce potential for cracking as it is more evenly supported. The latch hole in general was a concern and then that to the front edge also. Good luck on the fix, let us know what you decide.
 
Thanks for the pointers. Here's what I'm finding on VAF.

Here's a direct link to Scott's Unhappy Cracky Club thread. Very good but very involved.
https://vansairforce.net/community/showthread.php?t=179925

Scott McDaniels from Vans on this thread recommended Weldon #3, applied with a syringe with a thin needle. Boyd Birchler recommends drilling with a 1/16" plexiglass bit starting 1.5 x the bit diameter beyond the visible end of the crack.
https://vansairforce.net/community/showthread.php?t=179925

Vans recommends Weldon#3 or PlastiFix
https://www.vansaircraft.com/wp-content/uploads/2019/01/Acrylic_Canopy_and_Lexan_Window_Hints.pdf

Tim Crouch warns not to use Weldon #3 or #4 and recommends a mysterious friend's approach. I've contacted to see if he will share more.
https://vansairforce.net/community/showthread.php?t=156647&highlight=plexi+crack

Some people have used Weldon #16 to fill the stop-drill hole, while others have reported the Weldo #16 causes further cracking.
https://vansairforce.net/community/showthread.php?t=175738&highlight=plexi+crack

Lew Gallagher of Greenville SC, is recommended as skilled at crack repair.
https://vansairforce.net/community/showthread.php?t=157610&highlight=plexi+crack
 
Just a note, Lew IS repairing canopies. He just finished a RV-8 canopy for a friend. As usual, beautiful work.
 
Does anyone have Scott’s repair write up saved anywhere. When I try to go to the unhappy cracky thread, Scott’s stuff has been edited to a quote and doesn’t actually have any useful info.
 
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