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I'm reposting this for those of you that don't have a canopy safety lock. There are other options, don't choose, none of the above.
We had this discussion a year or so ago, I installed a temporary solution until I was able to come up with a simple solution. The potential problem had been the canopy opening in flight, not a good thing. Like many of you, I wanted to add a Lock/latch/pin that was engaged after closing the canopy and engaging the latch.
Another consideration was Emergency access, needed something that could be disengaged from the outside, and was close to the existing canopy handle. The pin will protrude and can be pushed in to disengage. Need to add some labels, "Emergency" and "Push to Release".
Here is my solution using a quick release pin and two pieces of .063 aluminum. Why is the pin on the outside? If I inserted on the inside, where it belongs, it would be difficult to get a picture. I think you get the point.
Jergens Stainless Steel 17-4 PH Kwik-Lok L-Handle Quick-Release Pin...There is a 3/4" available, but it costs $19, the 1" is $12.34
Jergen Specs Rate the Double Shear Resistance Minimum (lbs)* at 5,150 pounds. That's enough for me since the pin cannot be inserted unless the canopy is latched.
20mm x 30mm .063 aluminum doubler. I had planned to install this inside, but my canopy isn't flush on the left side. It is important to mount the doubler lower than the upper longeron, figure 30mm minimum from the top. Attached using flush rivets, unless you mount inside.
30mm x 70mm .063 latch strap. This needs to be riveted through the canopy 3/4" square tube frame.
Installation. Close and latch canopy, this is best done after you've added any weatherstripping or shims. Drilled 3/32" pin pilot hole through doubler and strap. Locate a position behind the front gear upright and below the top longeron, this prevents any clearance issues. Drill two 3/32" rivet pilot holes in the doubler. Place on the fuselage and use as guide to drill through fuselage. If your canopy is flush, the doubler will be installed inside. Drill pin pilot hole in fuselage.
Cleco the doubler and latch strap using the pin pilot hole to the fuselage. I was able to locate between two existing rivets on the canopy frame. Using the canopy frame rivet line, mark for two rivet holes. Remove, drill pilot holes, reinstall, drill through canopy frame. Keep clecoed to pin hole in fuselage before drilling to maintain proper alignment.
I used A4 rivets, not sure if A5's are necessary since the main canopy latch would have to fail before any of this assembly would be stressed. Drill out the pin hole to 3/16". Install a keeper wire on the Pin ring to dangle near the hole.
Total cost, less than $15.
Live long and prosper!