Failed Canopy Gas Struts

[todehnal]

Originally Posted by gossend

Tom, when and where can I find you at OSH? I'd like to see your 'necklace' 😊

I'll be at the Monday evening RV social, and wearing the blue RV-12 T shirt.

Tom

[Alex Edwards]

Originally Posted by rvbuilder2002

Considering the small number of occurrences with the number of years in service of 400+ airplanes it appears that there is something situationally specific that causes it.
Even so, it has been more than just a couple of airplanes so different design ideas are being evaluated and tested.

To have the plastic eye of the strut fail it would have to be loaded in tension. In normal circumstance this shouldn't happen unless due to wind when the canopy is up. Could there be an alignment issue in some installations where the strut on one side reaches the end of its travel before the other. The further movement of the canopy would then load the slightly shorter strut in tension causing the failure.

The repeated failures on particular aircraft would be explained by this cause.

[Mich48041]

Good point about the canopy struts failing only in tension. The canopy is flexible enough so that it is unlikely that one strut could be applying tension to the other strut. The most likely cause of failure is that the pilot lets go of the canopy before it is fully open. The inertia of the moving canopy applies a large tension load on the struts when they become fully extended.
If the hole in the plastic eye has been enlarged by drilling, then it is much weaker and is more vulnerable to tension loads.

[Bill_H]

Some say there is a bending moment on that piece of the strut. Haven't verified yet...

[rvbuilder2002]

Originally Posted by Alex Edwards

The repeated failures on particular aircraft would be explained by this cause.

I would agree it was a possibility if it was always the same side that had failed repeatedly, but I don't think that is the case.

[todehnal]

Update: It has been brought to my attention that the upper rod end has a different thread size than the bottom. I had actually only measured, and tested the bottom end, which is the trouble spot. So, only order 2 of the posted rod ends. If someone gets to it before I do, please measure and post the thread measurement for the upper end, and we will come up with a replacement for it as well. Sorry for the inconvenience......Tom

For those who I missed seeing at Oshkosh, if you are interested in replacing your canopy strut ends, here is the supplier, and procedure that may work for you. Note that you will end up with the larger diameter bushing on both the top, and the bottom of the strut ..............Tom



July, 2015

Canopy Mod: Heavy Duty Lift Strut Eyelets
Parts needed:
2 Heavy Duty Metal Eyelets M6 X 1.0 thread
Source: LiftSupportDepot.com SKU H00005W $1.90 each
1 set Canopy Bushings N/S C-00002 ( these are only necessary if you have and early kit and the old style bushing.
Source: Van’s Aircraft.

Procedure:

1. Drill/ream hole to 3/8” and clean away any burs on the 2 eyelets.

2. Install new rod ends on bottom end of both lift struts, and install per plans page 43-02
Questions or comments to: Tom Odehnal tomscub@gmail.com

[DonFromTX]

Thanks, I have 6 on order (in case I manage to screw up the process)

[mturnerb]

Originally Posted by todehnal

For those who I missed seeing at Oshkosh, if you are interested in replacing your canopy strut ends, here is the supplier, and procedure that may work for you. Note that you will end up with the larger diameter bushing on both the top, and the bottom of the strut ..............Tom

July, 2015
Canopy Mod: Heavy Duty Lift Strut Eyelets
Parts needed:
4 Heavy Duty Metal Eyelets M6 X 1.0 thread
Source: LiftSupportDepot.com SKU H00005W $1.90 each
1 set Canopy Bushings N/S C-00002
Source: Van?s Aircraft
note: If you have the old style lower bushings, and have not made
the mod, order 2 sets.
Procedure:
1. Drill/ream hole to 3/8? and clean away any burs on all 4 eyelets.
2. Remove stock from the shoulder of 2 of Van?s bushing to match the overall length dimension of the old upper bushings.
3. Install new rod ends on both lift struts, and install per plans page 43-02
Questions or comments to: Tom Odehnal tomscub@gmail.com

I'm assuming this would not be acceptable for S-LSA....

Fingers crossed and knocking on wood, no problems with mine so far....

TB

[DonFromTX]

Just paint em black and don't tell anyone

[RFSchaller]

SHAME on you, Don! --- but good advice!😈