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Broken piece on corner of tilt canopy
Hello all,
I am a brand new owner of an RV-7. Upon putting it in the hangar for the first time, the struts failed to hold the tilt canopy open and it slammed shut, chipping a piece off of the right rear corner and causing a 4" crack. I've done a search and read about all of the other cracked canopies out there. As I am new to this, I'd just like a sanity check on how to fix it. From what I've read: 1. Drill a pilot hole at the end of the crack. What size? 1/16" or 3/16"? 2. Use Weld-on #3 in the crack. 3. Use Weld-on #16 to glue the chipped piece back on. Do you all think this will do the trick? The airplane hasn't been painted yet, so should I replace the canopy first and then get it painted, or is this so common that I should just live with it? Any recommendations for stronger struts? It doesn't take much for the weight of the canopy to overcome the ones on the plane now. Thanks, Chuck ![]() |
I would replace the canopy before painting and add canopy guides to greatly reduce the chances of a re-occurrence -
http://www.vansairforce.com/communit...8&postcount=10 |
OTOH, I would repair the canopy by stop drilling and gluing or "Plastic Welding". The repairs will never be in your line of sight when you are in flight.
And think how many times you can tell the story!!! :p |
Take A Deep Breath
I'd consider fixing it as follows:
1. Stop drill the crack. Make certain you're at the end of or even beyond the visible crack. DO NOT USE STANDARD DRILLS. They can cause even more damage. 2. Glue the broken piece back in place. Use Sika or some other agent compatible with plexi (acrylic). 3. Add a targa strip wide enough to to cover the damage. It will help with rain protection, look good, and can be painted to match when you're ready to do the whole aircraft. 4. Replace the gas struts. You can order from Vans. Also available at auto parts stores, but you'll need the proper stroke length and pressure, or you'll still have problems. I find I need to replace these every 2-3 years as they lose pressure- don't want the top banging down because of a little breeze. Terry, CFI RV9A N323TP |
ouch! install a couple of those big ugly white canopy guides. they will protect against this in the future.
I see they now have black too. http://www.bullerent.com/CanopyGuide.htm ![]() |
Thanks for the advise gents. I ordered some canopy guides. I am going to try to repair it now, and re-evaluate replacing the canopy later, before we paint. I'm not sure I'm ready to tackle replacing the canopy just yet.
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Thanks, Chuck |
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Greg |
The above suggestions are all right on the money. I had this happen on my RV-9A and it still makes me sick to think about it. In my case the broken-off triangle was slightly smaller and didn't reach any of the screws, so I was able to fill the gap with foam and fiberglass and hide it under a strategically-sized targa strip.
For me the ultimate fix to this problem was to build a new airplane with a slider canopy, but you probably didn't want to hear that. ;) |
Not wanting to sound belittling.....
Can I ask a question? You say 'Upon putting it in the hangar for the first time....' Did you have the canopy open when you were moving it? I'm paranoid about leaving my canopy up outside even when there is no wind. I never leave it up when moving it-the gas springs on mine are basically as strong as they were when they were new, but they aren't hydraulic. :)
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Second the targa solution. I did the very same thing before flying!
1) Glue the broken piece in place. 2) Lay up a targa strip (especially since it hasn't been painted) and that will do a couple things; one, covers the cracked part, and two, provides a pretty decent seal for airflow and water. It's a lot easier than replacing the canopy and you'll never know it was a problem. |
And fabricate some strut locks to prevent a failing cylinder from allowing this to happen again.
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I found some of these type thingies on Amazon and use em:
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I like the idea of making a targa strip to reinforce the overhang and cover most of the damage, but what exactly do you guys use? I am not that familiar with what material would work best. Do I need to be concerned about the targa strip and the acrylic expanding and contracting at different rates with temperature change?
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Thanks again for the info. |
Targa Strip
Chuck:
While a few have made Targa strips using aluminum, the more common approach is using fiberglass and resin to create a buildup. Personally, I don't think aluminum would be a good choice in your case. I believe there are instructions for this in the plans - contact Vans if you don't have them. Construction involves masking off the canopy fore and aft, using a non-binding material on the area to be bridged, and scuffing the plexi on the forward bubble so that the glass will adhere. Builders have used different thickness and layer numbers for buildup, but in this case, more may be better. The good news with fiberglass is that after the layup is done, you can fill and fair to the level of perfection that you're looking for. As you've not yet painted, the targa will match perfectly with the rest of your aircraft. Look at some of the RV slider models - you'll see fiberglass fairings all around the canopy. Fairly easy to do and get great looking results. In your case, it can cover the cracked plexi completely. You'll be fine. Remember to breath in and out. You'll learn some new skills and afterwards will be able to offer first hand advice for others that encounter similar problems. Just like the rest of us. Good luck. Terry, CFI RV9A N323TP |
Weld-on
As a suggestion, don't let the crack repair on your canopy be your first attempt at using Weld-on. Watch some youtube videos and practice on scrap first. It's possibly to make an almost invisible repair but it takes practice. The targa strip solution with Sitka bond for the broken piece are great solutions.
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wild plane
Chuck
after cut my canopy under 48?C sunny day heating and breathing parts of it, that bad ugly inconvenient is my nightmare any time I open/close my tip-up :eek: ....but.... if I were in your shoes (hoping never) , like my friend Pete say, I would try to repair it, the cracks aren't in your view so no problem scanning around and, I would never a targa strip because that would cover the great scar that seem so bad and wild plane ;) tell us about your fix ciao Lucio |
Ordered two similar to this today from Amazon. They are called "Lift Support Clamps".
Thank you all for the detailed responses. I am much more relaxed now and looking forward to fixing this thing. ![]() |
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Or...you could just take a 6" length of 3/8" fuel hose, slit it length-wise, and slip it over the strut push rod for a nifty safety that will keep the canopy open. I carry a couple of them in the flight kit. I would be concerned about that clamp-thingie marring the strut pushrod and ruining the seal. |
The clamp thingies I bought have brass screws. No damage after many many many clamps.
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All of the talk about clamps, stronger struts, etc. are all sidestepping the root cause of the problem, that the canopy was left open while moving the aircraft. A cracked canopy is a painful (and expensive) way to learn that lesson.
When I bought my tip-up -6, one of the other RV owners on the field told me to never trust the pistons, and never leave the canopy open (a) unattended or (b) while moving the aircraft. |
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I use the clamps for extra protection. I don't move it with the canopy open and I don't leave it open unattended. I use the clamps so I don't have to constantly be in fear of it slamming shut. This can happen at almost any time and I have gotten away with it at least once and once was enough for me to realize the clamps are not a bad idea to use.
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Yep, had it slam shut once and scared the bejebers out of me, so I came up with that solution. However, I like the looks of the clamps. Might have to get some and check them out. |
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I know i've seen the piston part numbers posted here on VAF in the past, and people have posted the next size up in piston as well, which has a little more force. Personally I don't think you need more force over the stock piston, the stock one works great when it's working the way it should. |
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