Source: 2022 Q1 Beartracks, Bruce Case
Installing the hinges on the ailerons and flaps requires a methodical approach to turn out well. Here is the method that worked out for me. I first made two jigs to aid in drilling the aileron and flap hinges. The first jig shown here allows me to precisely locate both the bolted mounting holes and the hole which the ailerons and flaps pivot about. I used hardened drill bushings in my jig but you could simply do this with a large piece of angle iron. Just be careful that your drill is perfectly perpendicular to the hinges when drilling. What is most important is that you create the hinge pivot hole in all hinges at exactly the same distance from the mounting face of the hinge. The jig will guarantee this. If these holes are not precisely placed the hinge pins will not all be perfectly horizontal and binding of the aileron or flap can result. The locations of all the holes are called out in the plans.


Above is a picture of the jig in action. I use clamps and a vise grip to securely hold the hinges while pilot drilling the mounting holes with a #30 drill. I then pilot drill the hinge pivot holes with a #16 drill and then open up the pivot hole to the final dimension using a .188” ream which is the perfect hole size for a good fit on an AN3 bolt.

The photo above is my second jig in action. This jig precisely locates the location of the rod end bearing hole in both the long arm aileron and flap hinges. These holes are pilot drilled with a #16 drill and then reamed to .188” for an AN3 bolt.

Above is the hinge after drilling the rod end bearing hole. All necessary holes have now been placed in the hinges.
The hinge mounting procedure is the same for both the flaps and ailerons so I will only illustrate the aileron here. Note that the hinges will be offset in their pockets. This allows easy insertion of the hinge bolt. The plans call out an 1-3/8” centerline location for the hinges. Make a .628” wide aluminum spacer. Taping this to one edge of the pocket will give the necessary 1-3/8” centerline dimension when the hinge is butted up against it. Refer to the plans for the correct location of the 1-3/8” dimension as you don’t want to tape the .628” spacer to the wrong edge. You will only use the .628” for the first pocket as the location of the second set of hinges is governed by the 2nd steel pivot bracket attached to the spar:

The aileron is located flush to both the top and bottom sides of the wing using two contoured wood templates. I made this template using the wing Mylar airfoil plot furnished with the plans. Note you will want to create a little additional space at the rear of this wood pattern to allow the aileron some latitude in front to back positioning. It is important to clamp the wood pattern firmly to the wing so there is no gap. You will have to start out with this wood template slightly loose to allow for moving the aileron around to the
correct position:

Select the correct hinge bracket and place it against the spar and the .628” aluminum spacer previously taped down. Insert the longest AN3 bolt that you can install in the hinge. I found that an AN3-11 was perfect.
Now apply pressure so that the hinge is firmly pinched against the .628” aluminum spacer and then move the two wood wing templates into position so that they are tight against the wing and the aileron. This takes some time but can easily be done by one person. The goal is to have the hinge tight against the .628” spacer and tight against the spar. The wood template will force the aileron into the correct location. Now with everything held firmly move the hinge up and down so that the AN3 bolt is perfectly horizontal when sighting from the rear of the aileron. The hinge is now in the correct position for drilling the first hole. I secured it firmly in position using a ¾” piece of wood and a small C-clamp at the bottom of the hinge before drilling (photo below).

Using a right angle attachment drill a #30 hole in the top hole location only (photo below).

Now remove the aileron from the wood wing templates and carefully open up the #30 hole you just drilled to the correct size for a #6 screw. Mount the hinge using a short #6 screw and nut. Remove the C-clamp holding the bottom of the hinge and firmly holding the hinge in location against the .628” spacer drill the bottom hole to a #30. Enlarge the hole just drilled to a #6 screw and attach using a second #6 screw and nut. This first hinge is now securely located.

Make a wood spacer block that is .288” thick. This is the required gap to just clear the hinge bearing. Insert the AN3-11 bolt into the hinge hole as a visual reference. Insert the 2nd half of the hinge bearing into position. Now move this hinge up and down to get the AN3 bolt as horizontal as possible. You can do this visually by sighting along the rear of the aileron. With the 2nd hinge in the correct location use a clamp to firmly hold it in position. You can also add a vise grip as I have shown in the picture to the left for more clamping power. Now pilot drill both holes with a #30 drill. Enlarge all the holes for #6 machine screws and then attach the second hinge half with #6 hardware.


At this point you can use the same procedure to drill and mount the second set of hinges at the other end of the aileron. Again use the two wood wing templates for positioning the aileron vertically. This time you will not use the .628” aluminum spacer but rather you will locate the first half of the hinge visually so it is perfectly vertical and parallel to one side of the aileron pocket and snug up against the 2nd hinge bearing. Again use the two wood wing templates to firmly push the aileron into the correct position. This second operation takes more time than mounting the first hinge in the first pocket as you don’t have the convenience of the .628” spacer. When everything is located draw a reference line using a small Sharpie along one edge of the hinge. Drill the first #30 hole as on the first hinge set with a right angle drill. Remove the aileron from the wing. Mount the hinge using the hole just drilled with #6 hardware and then using the Sharpie reference line, locate and drill the second #30 hole in the hinge. Enlarge that hole and mount the hinge with a second set of #6 hardware. Now using the .288” wood spacer locate the mating hinge and again use the AN3-11 bolt to visually get the correct vertical location of this 2nd hinge half. Drill and mount the 2nd hinge half using the same procedure as outlined in the first pocket. Reinstall the aileron on the wing and check for correct location and freedom of movement. At this point you will remove all the hinges and enlarge the mounting holes to .188” first with a drill and then final reaming to .188”. All the #6 hardware holes in the spars will also get enlarged to .188” in preparation for riveting on nut plates.
Below you can see the finished 2nd set of hinges mounted with AN3 hardware and also showing the required joggle to create clearance for the Aurora rod end bearing.