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  #41  
Old 08-22-2015, 10:05 PM
Slane Slane is offline
 
Join Date: May 2008
Location: Hillsboro, OR
Posts: 153
Default Failed Canopy Strut

Hello everyone,

I have an embarrassing story to share and do so with the hope I can save someone from making the same mistake.

It all started with an ignition check that indicated the B-module was offline. My ignition checks were showing too large of an RPM difference on the B module. The problem turned out to be a loose spark plug wire that had been dislodged when I was re-installing the lower cowling. Such a simple fix!

That's the good news.

The bad news is that while testing in 92 degree heat, I had the canopy closed, not latched but propped open for air ventilation. I ran the ignition check and all was good with the world until I turned to head back to the hangar. At that point, the cross wind caught the canopy and blew it open. The lift struts both broke at the end attached to the canopy and the canopy had the momentum needed to tip forward into the prop. This all happened so quickly it would have been impossible to intercede.

I'm in the process to replace/rebuild the canopy. Sensenich repaired the prop and Perry Robertson did a gearbox check for me.

I'm very lucky not to have been struck by any of the flying, very sharp shards! This has been reported to Vans and I was told they are looking into this aspect of the design with no hint of a timeline nor outcome.

Henceforth, I'm always going to have my canopy latched when the motor is running. I'm also thinking of modifications to use so that on very hot days the canopy can rest on the handle/latch but not fly open. The metal rod ends are also of interest to me.

I hope this information is of use and helps others avoid duplicating my mistake.

Slane
RV120043
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  #42  
Old 08-22-2015, 10:15 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,183
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Sorry to hear of your misfortune. Every time I open the canopy with wind I am paranoid about what could happen.
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  #43  
Old 08-22-2015, 10:16 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
Posts: 2,183
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I should have added that wind slammed mine down once with the tow bar lying across the canopy rail. It bent my canopy trim.
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  #44  
Old 08-23-2015, 06:03 AM
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tomkk tomkk is online now
 
Join Date: Apr 2014
Location: Port Orange, Fl
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Quote:
Originally Posted by Slane View Post
... propped open for air ventilation ...
Sorry to hear about your incident Slane but thanks for posting it.

How did you have the canopy propped up? I usually prop mine open by closing the latch with the canopy open then resting the protruding latch on the top of the canopy bow. That doesn't let in a huge amount of air but has been sufficient for me in our Florida heat. Did you have it propped more open than that?

As a separate question, I picked up the habit of propping mine open on the latch like that from other -12 owners I've talked to. I've often wondered about the twisting stress that puts on the canopy. Does anyone have an opinion about that?
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Port Orange, Fl
RV-12 N121TK ELSA #120845
First flight 06/10/2015

Last edited by tomkk : 08-23-2015 at 06:05 AM.
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  #45  
Old 08-23-2015, 07:53 AM
Slane Slane is offline
 
Join Date: May 2008
Location: Hillsboro, OR
Posts: 153
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Quote:
Originally Posted by tomkk View Post
How did you have the canopy propped up? I usually prop mine open by closing the latch with the canopy open then resting the protruding latch on the top of the canopy bow. That doesn't let in a huge amount of air but has been sufficient for me in our Florida heat. Did you have it propped more open than that?

As a separate question, I picked up the habit of propping mine open on the latch like that from other -12 owners I've talked to.
This is exactly how I had mine propped open. Just about every RV12 pilot I know props their canopy open in this fashion.

Slane
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  #46  
Old 08-23-2015, 08:39 AM
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DonFromTX DonFromTX is offline
 
Join Date: Oct 2010
Location: La Feria Texas
Posts: 3,719
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I had an interesting moment just yesterday - INSIDE MY GARAGE! I hook the canopy open by a hook around the canopy latch to the garage door opener track. While pushing down on the tail to place a board under the nose wheel (so the tail would not punch a hole in the sheetrock) the hook came unlatched allowing the canopy to bang down on the roll bar. Bent the latch mechanism pretty badly! I was able to straighten it back, no expensive harm done.
It got me to thinking, that the struts SHOULD be the slow motion type that would not permit any of what has been discussed here.
Another point came up in discussions with others, one must NOT tighten the upper end bolt, since that puts a bending motion on the upper eye. The plans are a bit vague, but does allow for that with loose bolts on the upper end.
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  #47  
Old 08-23-2015, 08:47 AM
Ex Bonanza Bucko Ex Bonanza Bucko is offline
 
Join Date: Jul 2013
Location: San Diego, California
Posts: 291
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I think any engineer would want both metal rod ends and a through bolt at the top end. The current design is simply going to fail at some point due to the plastic rod ends breaking out at the top end when the canopy is allowed to open without restraint or in a wind/prop blast that is going to happen sometime in the life of the bird. Even with a metal rod end at the top there will someday be a failure of the screw through the carbon fiber on only one side up there. Van's airplanes are such masterly designed airplanes it's hard to understand how the canopy strut design was allowed in the plan.
EBB
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  #48  
Old 08-23-2015, 09:03 AM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Quote:
one must NOT tighten the upper end bolt, since that puts a bending motion on the upper eye
Doesn't the bolt tighten against bushing C-1204 and not put pressure on the strut eye?
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RV-12 Flying
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  #49  
Old 08-23-2015, 09:04 AM
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tomkk tomkk is online now
 
Join Date: Apr 2014
Location: Port Orange, Fl
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Quote:
Originally Posted by Slane View Post
This is exactly how I had mine propped open. Just about every RV12 pilot I know props their canopy open in this fashion.

Slane
Thanks. That leaves such a small gap, I'm flabbergasted the wind was able to get under it enough to flip the canopy open. I'll have to pay more attention when I have it outside with it propped open.
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Port Orange, Fl
RV-12 N121TK ELSA #120845
First flight 06/10/2015

Last edited by tomkk : 08-23-2015 at 11:54 AM.
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  #50  
Old 08-23-2015, 09:49 AM
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DonFromTX DonFromTX is offline
 
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Location: La Feria Texas
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No Joe, that is part of the apparently sloppy way to get the angle to to align with the bottom attachment. I checked the plans this morning. It is my belief that the UPPER end fails because it bends the top eye about 5 degrees every time the canopy is opened if the bolt is tightened, which several builders have told me they did..
Quote:
Originally Posted by Mich48041 View Post
Doesn't the bolt tighten against bushing C-1204 and not put pressure on the strut eye?
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