Cut the hole in the LH bottom skin for the pitot/AOA tube mast. After marking the outline of the opening using the template that was supplied with the mast I drilled a few large holes in the inside of the cutout area using a step drill. I then used a dremel cutoff wheel to rough cut the mast opening to shape and then I used a dremel sanding wheel to open the hole to the final shape while periodically checking the fit of the mast in the hole.
After the mast hole was cut to shape I clecoed the skin to the wing, installed the mast in the hole and match drilled the forward edge of its flange using the three holes that attach it to the spar/skin. I then used the supplied template to mark the location of the two holes that attach the aft end of the mast flange to the bottom skin. I then removed the mast and skin, deburred all of the holes, countersunk the two aft holes in the mast flange and dimpled the two corresponding holes in the skin.
I then celcoed everything back in place. It all looks good and I'm happy with the fit of the mast in the opening. I did slightly mislocate one of the aft holes when I let the drill wander a little, even though I center punched its location. I need to be more careful when laying out hole locations. The hole location is acceptable from a structural standpoint but it isn't symmetrical with the other one if you look closely. Good thing it's on the bottom of the wing.
