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Canopy Mistake

acroboy

Member
Ok, I've messed up! I drilled the front latch hole (for C-409) through the canopy frame and into the instrument panel (F-403). The problem is I managed to align the hole exactly with the nutplate that attaches the fwd top skin (F-421). Anyone have any clever ideas how I can get myself out of this mess? I might be able to use a thin stop nut instead of the nutplate but I doubt it. In any case the screw and nut will interfere with the nylon block (C-410). I've included a few pictures to show my predicament.

651wur.jpg


2093og9.jpg


Brad, McKinney TX
 
Or.....

Swap the nut plate for one with both rivets on one side.....it looks (might be the angle) that the hole will only interfere with the bottom portion of the nut plate.
 
Leave it

I think you will be fine. On mine, I installed a phenolic block about 1/4" thick on the forward side that the pin fits snuggly into, but I believe it could just as easily be installed on the AFT side as there is quite a bit of room between the canopy frame and the panel. Any extra pin length can be trimmed off, as it doesn't need to be that long, and actually causes problems with the forward skin panel interference. I believe many others have done the same. I also put a microswitch on the forward side that is contacted by the pin when fully closed, which extinguishes a bright red LED indicating the canopy is fully locked.
 
Do away with the nut plate. Make your block out of delrin and just drill a hole so you can use the block as a substitute for the nut plate. You don't even need to thread it since it will act as a self locking nut. Just drill the hole undersize for the screw and screw it in.
That will also help hold the block in place.
You could even put number 4 screws where the rivet holes are to fill them in and hold the block even more firmly.
 
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Thanks for all the great ideas. I will probably go with Steve's idea of using the block as my nut plate. I figure I can always helicoil it if the plastic starts to wear. As far as I can tell there isn't room for any kind of nut plate. I had thought of trying a pk-7 clip nut since it might be slightly thinner. No matter which way I go, even the screw must be very short in order not to interfere with the shaft. The idea of using the block on the aft side is definitely worth considering as well as long a I penetrate the panel with enough margin.
 
On mine I just modified the nylon block to fit around the offending nut plate. Ground clearance with dremel tool, etc.

If the nut plate and installed screw don't prevent the canopy latch rod from fully engaging you have no problem. I'd do this before going the helical, tapping the nylon block route. Works fine on my airplane this way.
 
i just did away with the block and used a .125 or .250 inch aluminum doubler on the panel instead.

bob burns
rv-4 N82RB
 
Add me to the list of people that carved a cavity in the holddown block to clear the nutplate.
 
Add me to the list of people that carved a cavity in the holddown block to clear the nutplate.

Me as well,,
And in addition to modifying the block with a dremel to snug up against the nut plate,, I also cut the block in half, and have equal portions of the block on both sides of the panel.

And, I also have a "special" screw for that hole, in that it is trimmed very short, and does not protrude beyond the nut-plate. Another one of those "custom-features" for my airplane :)
 
Plans Change

My 4 is number 32 to fly circa 1986. I made very few changes to Van's plans...but one was moving the nylon to the canopy side of the panel and the aft cockpit bulkhead. The nylon was cut to cradle the canopy frame, and the pins engage the nylon right at the frame. Working 27 years so far with very positive engagement and no visible wear. MTCents John N95JF
 
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