Today I started fitting the fuel tanks in the right wing. The plans call for the fuel tank to be 1/16" from the skin stiffeners. Two AN 970 washers are exactly 1/16" so I taped 4 pairs of the washers to the upper skin stiffeners to act as temporary shims. One procedure that has been bothering me was the cutting of the hole in the upper skin for the fuel filler. There isn't much room in the fuel tank bay for the tank to move around so the hole has to be placed absolutely perfectly. The builders tips suggests that you put something in the tank filler neck that has a sharp point then put the tank in the tank bay and press down on the tank. The sharp point is supposed to dimple the upper wing skin and that's where you drill. Sounds simple. Until you try to find something that will fit perfectly in the fuel filler that has a sharp point exactly in the center. Well a 1 3/4" hole saw is a perfect fit. The hole saw is tapered so it slides almost all the way in but won't go all the way in and drop into the tank. Either way I put some duct tape on it just in case. I dropped the tank in, positioned it where I wanted it then pushed down on the tank making a nice dimple in the top skin. Then I used a 2 1/4" knockout and there you have it, a perfect hole. I made two top straps to secure the tank. I still have three bottom straps to make but that's all I had time for today.
