Wayne DelRossi's canopy latch removal & replacement


1. Yes, you can do this work yourself, but if you follow the letter of the law, you can only do it under the direct supervision of a licensed mechanic. Replacing canopy latches is not one of the items that an owner is allowed to do under "preventative maintenance".

2. Once you have your mechanic closely looking over your shoulder and supervising you - keep in mind that he or she has never seen an Alon canopy latch before - you can follow these steps to remove and replace the latch (if your mechanic approves):

a. Take a close look at how the phenolic block inside the canopy roller track is oriented. Also look at where any washers might be used. You should have two upholstery type finishing washers under the screw heads on the inside of the airplane, and no washers under the nuts on the outside of the airplane.

b. Get inside the airplane with a Phillips screwdriver, and slide the canopy almost all the way closed, leaving it open about 3 inches. Have a helper on the outside of the airplane grab the bottom edge of the canopy frame and gently lift it up just enough to get a thin wall, deep well socket on the nuts. If you can't get a deep socket on the nuts, you can grab them with a pair of pliers. The canopy track will keep the pliers from turning, so this is easier than it sounds. Make sure your helper doesn't drop the canopy frame onto the socket or pliers.

c. Remove the nuts from the screws, catch the nuts, slide the screws out with the washers on them. Then slide the whole latch assembly straight up to remove it. You can either leave the phenolic block there, or remove it to inspect it.

d. If your interior is original, the screw heads and washer are probably tightened down on the black Royalite plastic arm rest piece. Be ready for this stuff to disintegrate when you touch it. It will probably be very brittle.

Reassembly is the opposite of disassembly. If you happen to install new screws, make sure that they are the correct length. Also make sure that the phenolic block goes back in place properly. One block on either side of the canopy is all that keeps the canopy from sliding too far back when the canopy is not latched. Also, when you tighten it all back up, check for how tight the latch feels when you snap it closed. If it's too tight, loosen the nuts and try repositioning the latch slightly fore and aft. A slight amount of movement makes a big difference in how hard the canopy is to latch.

After you remove and install these latches about 10 times, the thought may occur to you to install a couple of miniature nut plates on the phenolic blocks instead of using the elastic lock nuts. Then you would be able to remove and install the latches (and the canopy) without any help at all.



Page last modified on May 07, 2008, at 12:33 AM