Finishing Tiedown Brackets – 2.5 hrs

Wednesday Aug 18, 2010

Tonight I finished tapping the 3/8-16 threaded holes for the tiedown rings in the tiedown brackets. To gauge the depth of the tapped holes I just counted sixteen turns of the tap handle to get a 1-inch depth.

I mentioned yesterday that I drilled 3/4 inch holes in the spacers instead of 1 inch because I don’t have a 1-inch metal bit. So tonight I drilled four 15/64 holes in each spacer around the 3/4 inch hole to take a little more weight out of the parts. Now the parts are within 0.4 ounce (total for all spacers) of the weight if I had drilled 1 inch holes. You can see the additional holes in the photo below.

I scrubbed the parts with scotchbrite and Simple Green, dried them and then shot a coat of Dupli-Color self etching primer. Here are the primed parts.

Next I riveted the parts together with the nut plates.

And intalled the left tiedown bracket onto the left spar. I torqued the bolts to 25 inch-lbs and applied torque seal.

Here is the aft side of the spar showing the brackets for the aileron bell crank. Notice that I forgot to apply torque seal to the four nuts. After I saw the photo I went back and applied it. That’s one good thing about keeping a photo journal. You get a second look at everything.