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RV-12 Canopy Incident

This gives me pause...

"Testing has shown that the aircraft structure will begin to yield before the new strut design fails."

Does "yield" mean a slight bend and a return to normal once the pressure is off? Or does it mean permanent distortion? Am I trading one problem for a more expensive one?

Depending on the long-term consequences of the "yield," I'm not sure that I wouldn't be better off buying replacement plastic-tipped struts now and then.

In almost 200 hours I've had exactly one break, and I suspect that was my own fault.

Will the original style still be available? Or is the transfer of forces to the airframe itself benign?
 
Given the apparent strength of the canopy frame that the strut is bolted to, if it "deforms" from a gust of wind in future that would have to be one heck of a stress on the canopy. I haven't had any issues at 240 hours with the current struts but will be upgrading for sure after watching that disturbing video.
 
The reality is the Canopy is some what frail when not locked down for takeoff. There is only so much Vans can do to improve the system under normal conditions. There is a limit for everything.:p With a lot of wind, say more than 15kts the canopy can act like a sail. As seen in the video large dynamic forces will be imposed when the wind lifts it up. Even though the gas struts are improved and may not break the bolts may rip out of their threads or skin may wrinkle where the struts are attached. Maybe one last improvement would be a lanyard to hold it in the non locked vented position so it doesn't lift up at all during summer months. ;) Another alternative is a canopy unlocked limitation in the POH. Example, "Canopy must be locked for Takeoff after start when the Wind velocity exceeds 15kts".:rolleyes:
 
I was having thoughts along those same lines JetGuy. I have put steel eyes on the bottom end, that seems to be the weakest point because of the larger holes, and am making an "open canopy latch for taxi". I feel that with some self imposed discipline when it is open and unlatched, I might be better off with this setup than with one that does some nasty things to the airframe if it pops open..
 
"Testing has shown that the aircraft structure will begin to yield before the new strut design fails."

To assure a worthwhile benefit of changing to a new style gas strut, static load pull tests were done comparing the old strut to the new strut.
The test results showed that with the new strut, the structure it is attached too would begin to yield (deform) before the strut failed, but this load value is well above what would break the plastic ended strut (which was still quite high if installed properly).

The intent of the statement was meant to mean that there should now be a surplus safety margin in situations similar to those that a few people have had canopy incidents, but that it should still not be considered indestructible (the reason for the 737 engine blast comment).

The addition/design of a restraint for the canopy open position is also being looked at, but no estimate on if/when that might be available.
 
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The intent of the statement was meant to mean that there should now be a surplus safety margin in situations similar to those that a few people have had canopy incidents, but that it should still not be considered indestructible (the reason for the 737 engine blast comment).
Thanks for the clarification. It's helpful to know where caution is required when it isn't always an obvious case.
 
Having had the canopy flop up during run up and only by luck having the plastic rod ends hold, I am definitely getting the new air springs.

When it happens the canopy floats up a couple of inches until the air springs have sufficient mechanical advantage to flip open the canopy to the air spring stops. It's quick. I did not have a chance to grab the canopy handle.
 
Having had the canopy flop up during run up and only by luck having the plastic rod ends hold, I am definitely getting the new air springs.

When it happens the canopy floats up a couple of inches until the air springs have sufficient mechanical advantage to flip open the canopy to the air spring stops. It's quick. I did not have a chance to grab the canopy handle.

Yes, there is definitely aerodynamic lift on the canopy from prop wash when the engine is run up. Wind is not the only factor. When I did a carb pnematic sync a couple weeks ago I had the vacuum hoses over the canopy rail and into the cockpit so I could not lock the canopy. I noticed the canopy try to lift when the rpm's were increased. I used a 1" baggage strap over the horizontal seat bar and through the handle to keep 'er down. Some sort of mechanical restraint at the handle end is needed, the improved gas struts are perhaps an improvement but not the complete solution.
 
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I believe once the canopy rises to a certain level, nothing is going to stop it, including the new steel struts. I suppose most of us are guilty of leaving the canopy latch sitting on top of the fuselage frame to improve ventilation during taxi and run up, a situation set up for disaster. I have installed a secondary safety catch as shown in the photo. It is not foolproof, but should help.
 
Hallo.
Don't want to highjack the post. Could you please tell me how long is the gas strut in the closed and in the opened positions? I cannot find dimensions in the new 34 dwg. I would like to install the gas strut on my -4 to hold canopy safely opened. I read that a 7'' closed and a 15' opened brace would be ok.
Thanks.
Camillo
 
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I believe once the canopy rises to a certain level, nothing is going to stop it, including the new steel struts. I suppose most of us are guilty of leaving the canopy latch sitting on top of the fuselage frame to improve ventilation during taxi and run up, a situation set up for disaster. I have installed a secondary safety catch as shown in the photo. It is not foolproof, but should help.

Like your idea...simple, but provides "anti-lift" protection... Love this forum😎
 
I'm not sure if it's been suggested yet, but I'm thinking of installing some safety cables to help keep the canopy from over-opening when open, if a wind gust or anything of the like happened.

The stock struts have weak plastic ends, and I know there's a metal upgrade, but safety cables would really REALLY keep that canopy from folding forward and causing a prop strike.

To me, in my mind, they'd be easy to install, and would offer MUCH greater protection than just the struts, plastic or metal.

Race car wheels are all tethered so in crashes the wheels don't separate from the cars, and I think properly installed cables (simple bicycle cables would suffice if installed properly and in the correct manner), and those struts on our RV12's have really bad geometry, and I suspect a good gust could rip the metal ended ones from their mounts.

Safety cables would solve this issue permanently IMO.
 
I thought of doing the same thing but it's pretty tight at the canopy end of the strut. I wasn't sure how to attach the cable at that end without risking it binding up. I'll be interested to see how it works out for you.
 
I would be afraid of cables just damaging the attachment points as they rip out in the event of a truly evil wing gust (or jetwash). Leverage can be a b**** and that canopy is an awfully big sail. Better to keep it from getting away from you, than to try to arrest it once it does. I like Scott's idea a lot because it is simple, dead easy to use, involves no cutting and no modification to the canopy latch itself.
 
To me, we're talking about two things here. One is keeping the canopy from blowing open when it's shimmed up by the latch, maybe while taxiing or stationary, and then there's the other thing which is keeping the canopy from blowing forward when fully open.

I plan to buy the metal ended struts soon.

I talked with someone at Van's and they said they were working on a cheap and easy to install latch safety doo-hickey so you can taxi with the canopy shimmed up (oven door cracked open mode).

In my head, I'm thinking that a pair of cables, attached at points with better geometry (the stock strut setup gives the canopy a LOT of leverage over the struts), if installed properly, could save the canopy if it were to be blown open. I would think the cable loops could simply drop down inside and hang down near the little utility pouch.

I'm going to explore this as soon as I get my plane back from it's annual.
 
It would be extremely unlikely for an RV-12 canopy to fail the struts from a wind load if the canopy was already in the fully opened position.
It is the shock loading when the canopy slams from closed to fully open that is the problem.

A prototype safety bracket was on the RV-12 Demonstrator for the trip to OSH. It or something similar will likely be available in the future.
 
It seems like if we could get some struts with better internal damping, that would extend the time to fully open the canopy, could solve most of the problems.
Don't know if the struts come with different specifications in damping?
 
..........
A prototype safety bracket was on the RV-12 Demonstrator for the trip to OSH. It or something similar will likely be available in the future.

Scott, I predict substantial early demand for such a bracket from those with flying 12's.
Hopefully there will be a good inventory of the new safety brackets available at the time they are released.
 
The demonstrator had the same design I posted on page 4 of this thread except instead of the three top rivets it had the two top and the one below to form a triangle to anchor it and it was made of aluminum. I finished my first concept by using larger rivets, rounding the sheep hook, painting to match and adding a piece of heat shrink tubing for cushioning at the handle contact point.
 
Scott, I really liked seeing yours at Oshkosh. I forgot to ask -- what thickness stock did you use, and how did you form the bend?
 
Put me on the list for one of the first of the first

batch of Van's simple, approved mod. Always taxi with the canopy popped here in Ohio summer's especially with a first-time Young Eagle aboard.

Wayne 120241/143WM
 
I will order one when it is available.
Maybe if we indicate here those that intend to order we can help Van's to know how many to make in first batch.
 
When someone gets one done, would they post a photo please - struggling to 'see' the application.

We're in build and will incorporate when we get there.
 
I am curious as to why Van's configured the F-1231G Canopy Catch so that when in use the Canopy Handle is not positioned 90 degrees to the canopy frame/rollover frame -- the handle locking tab appears to rest on the rollover frame about 10 degrees out of skew. This results in less surface area between the handle locking tab and the rollover frame. Is this skewed orientation on purpose to visually alert the pilot as to the handle's incorrect positioning?? :confused:
 
I am curious as to why Van's configured the F-1231G Canopy Catch so that when in use the Canopy Handle is not positioned 90 degrees to the canopy frame/rollover frame -- the handle locking tab appears to rest on the rollover frame about 10 degrees out of skew. This results in less surface area between the handle locking tab and the rollover frame. Is this skewed orientation on purpose to visually alert the pilot as to the handle's incorrect positioning?? :confused:

It was a compromise between making it a very easy retrofit to all existing airplanes (utilization of the existing rivet holes in the rollover structure), and the allowable bend radius for the material used to make the part.
It works just fine... even with the slight offset.
 
I installed the Vans canopy catch today, and I think it's great for ground ops, but I still worry about the canopy being up during loading and unloading on windy days (even though I switched to metal rod end air springs), so I drilled out the manufacturing hole in the crash arch on the passenger side just under the catch and installed an AN4 eyebolt with a keyring through the eye. Next I made a 3/32" cable lanyard with a caribiner at each end. One caribiner snaps on to the canopy lock handle and the other snaps on to the key ring to hold the canopy about 1' short of full open travel so any wind load that occurs while open is taken by the lanyard and not the air spring rod ends. Next I intend to install the aluminum sleeves over the air springs suggested by one post to eliminate slamming shut in a wind. I was unlucky enough to have mine slam shut during unloading and damaged my lower edge canopy trim.

I
 
I tried to install a sleeve on my pilot side air spring, but I found that it keeps my canopy from fully closing even when over the cylinder. It's probably due the wall thickness of the aluminum sleeve (.0625"). Has anybody that was successful using the sleeve to prevent the canopy slamming down in a wind got any advice about what type sleeve to use?
 
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Finally got around to installing the canopy latch tab. Hanger neighbor offered to powder coat it - choose a contrasting red color to more easily see it. Did notice in others pictures how beat up this area gets over time with the handle scraping the cross bar area. Mine had some scratches so I used left over vinyl wing walk material to cover more of the surfaces.
 
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