Thu Jan 5 2017

Fabricating lower flap actuator channel bracket

I'm continuing to work on the bracket to replace the two little brackets which tie the lower end of the forward flap actuator housing channel to the floor. It's time to match drill the holes to the floor, so I removed the floor pans from the fuselage and set this rig up on the workbench. I'm going to have to drill thru from below.

However, this arrangement is pretty darn floppy and the position of the floor pans to the bracket could vary quite a bit depending on how non-parallel the inside edges of the floor pans were to each other. So, I decided to fabricate a couple clamping blocks the same width as the flap actuator channel, 2.39 inches wide. These will be clamped between the two flap actuator side covers to hold them parallel.

I also had to find the little brass nesting tubes I use for match drilling. The holes in the floor are drilled .164 for a #8 screw, so using these little tubes will allow me to drill #40, then #30 before drilling to final size.

Here's the arrangement all clamped up with wood blocks setting the spacing. It's also hanging precariously over the edge so that I can drill from below.

Here's a view from below. You can see the wood blocks clamped between the blue side covers if you look closely.

When setting up to drill, I found that I didn't have a brass tube that was sized to fit into a #19 hole. So I chucked up the one which fits into a #12 hole (for #10 screws) and sanded and filed the diameter down to .164.

Here are the two holes drilled to #40. It looks a bit like the holes are off center, but they're not...that's just the parallax of the camera.

...after drilling up to #19.

I then reinstalled the parts back in the fuselage.

The hole on the right side is a near perfect match.

The hole on the left side came out pretty well, too, but may need to be opened up a little bit in the outboard direction.

Next thing to do is to trim all the extra material away from this bracket. I started by marking the edge distance around the holes. Looks like my edge distance is slightly under on the right side.

The rest of the profile is marked out.