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Canopy crack, dang it!

PandaCub

Active Member
So I'm enroute to AOPA's Buckeye, AZ Fly-in in my RV-8 when at 12,500 and -7º F over the Rockies I hear a muffled "pop" that was loud enough to break intercom squelch.

Boyle's Law potato chip bag burst, maybe? Nothing so simple, unfortunately.

I looked things over on the ground and to my great disappointment found a crack nearly halfway across the aft portion of my beautiful Todd's tinted canopy. This RV-8 only has about 120 hours and everything's been great; I can only imagine that the canopy was already stressed and extreme temperatures may have pushed something over its limit. I now join the crestfallen cadre of cracked canopy connoisseurs and am wondering how best to repair it.

Some fellow fly-in campers in an RV-10 helped me stop-drill the crack (thanks Don and Gerry!) and I've applied Gorilla tape to the inner and outer surface (also covered by aluminum tape offset .25" forward to taper the duct tape's leading edge). There's at least a .015" gap at the crack's origin, tapering down to nothing as it propagates about 14 inches to the stop hole. The good news is the crack is very linear and doesn't block either pilot or passenger view, so after repair I could cover it with a colored vinyl stripe that would almost look like part of the plane.

I know there are a few threads on plexiglass, but each case seems different and I'd appreciate any tips on new materials, techniques, and other advice to help save this treasured Todd's Canopy. Any trusted plexiglass repairmen in the Palm Springs, CA area? I'm headed there next for a few days.
 

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Lots of suppliers for this

Here is one such company that will help you:

https://www.polyvance.com/pfxcanopy.php-1

You won't ever get an invisible repair, but you can get fixed. Talk to their pros about relieving that stress.

If it were mine to repair I would run the bead all the way across the canopy and hide it in plain sight.
 
It looks so straight and square you could cut it all the way across and bond an aluminum strip on top and it would look like a 2 piece canopy. Give it that warbird canopy look.
 
That sucks. I’ve been there, and feel your pain. Couple options;

1. Repair: Skylor Piper has done one of the absolute best looking canopy repairs I’ve seen. He’s a SoCal guy, and I’m sure you could show you photos and describe the process. You can barely see the repair, and especially in your case being further aft this would be a great solution.

2. Replace: While Todd’s canopy is no longer made, there’s another vendor that makes the same curvature canopy. I think it’s more repeatable than the Vans Shape, which may help replacement, but that’s a big job. Doable, but realize that the chances the skirt just fits again are slim, so mentally prepare for some fiberglass work. The replacement took me about 2 months of work including fiberglass, paint, fitting etc. I had no experience, but was blessed with a great EAA chapter that held my hand through the process.

3. Separate the halves into a front and rear, and put a support strip across similar to many warbird canopies etc…could be done nicely, but in your case I think a less dramatic repair like Skylor’s could be the answer.

I’m happy to discuss the replacement process I went through, and the snags I ran into along the way.

Just curious, was your canopy attached with SikaFlex or Fasteners?
 
Just curious, was your canopy attached with SikaFlex or Fasteners?

Having read every RV8 canopy crack thread and talked to an owner - it seems neither attach method is immune. Sure seems like result of the canopy frame design. (Not knocking Vans)

Paul Dye posted somewhere here that using some surgical tubing around the screws had some measure of improvement allowing additional differential movement.

"You can still use the rubber grommet trick!

Get some surgical rubber tubing that is 1/4" OD, and approximately 1/8" ID (try a hobby shop). Cut the tubing into "washers" as thick as the plexiglas. Now enlarge all holes in the plex to 1/4" - yes, make them bigger! (That will also get rid of your chips). Insert a soft rubber washer in every hole, and insert the pop rivest throught the skirt, then through the washer, then pull it on the frame. Now the canopy has some "float" for thermal expansion. This has worked well for a number of folks, including myself."

Here is the thread, Danny King has more detail on this technique.

If I had the ability to do an FEA on the thing that could confirm the problem . . . and evaluate a solution.
 
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Crack

Here'e one repaired by Lou Gallagher in Greenville, SC. Looks to be near the same location but this crack was only about 7 inches long. Just to give you an idea of what a really good plexi guy can do.
 

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There's at least a .015" gap at the crack's origin, tapering down to nothing as it propagates about 14 inches to the stop hole. The good news is the crack is very linear and doesn't block either pilot or passenger view, so after repair I could cover it with a colored vinyl stripe that would almost look like part of the plane.
.

If there is still a gap after everything warmed up, that's a pretty good sign that the mounting arrangement was adding stress to the canopy and the contraction took it beyond it's limit. Several ways to address it, but a pro might be the best. Very fortunate that the location and orientation will allow adding some type of racing stripe.

I would be a little concerned that there could be other areas of built in stress. It may be worth considering bill's advice to upsize the holes. I did that, as well as insuring that no individual fastener was moving the acrylic while tightening or adding stress to the assembly. I did not use tubing. I think that I just went up a 1/16 on each hole size. That said, a 6 canopy is a good bit different than an 8.
Larry
 
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It looks so straight and square you could cut it all the way across and bond an aluminum strip on top and it would look like a 2 piece canopy. Give it that warbird canopy look.

Exactly what I was thinking and what I would do if it were my RV.

My $2...
 
Here's a more off-the-wall option I have used on some smaller cracks in the canopy and landing light lenses: Various companies make clear, UV-cure glues that are very easy to use and can fill reasonable crack sizes, and the stop-drill hole. An example is the SuperWeld product from JB Weld, which comes in a small (5 g) container with a UV light built in.
I am totally guessing that pro repair shops use something similar, but I have never tried to polished out my repairs. You could buy a small piece of Plexi from Home Depot and try it before using it on the Todd's plastic. FWIW,
Andy
 
Crack

Here'e one repaired by Lou Gallagher in Greenville, SC. Looks to be near the same location but this crack was only about 7 inches long. Just to give you an idea of what a really good plexi guy can do.
Any way you could share a way to contact Lou for some canopy help? Just walked out to find my 8 canopy cracked. Ughh. Thanks for any help
Sean
 
This cold snap sadly has me added to the cracked canopy group. Contact information for Lou Gallagher also appreciated.
 
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