Sat Aug 15 2009

Drilling tunnel cover to floor stiffeners

Well, work has seriously been kicking my butt this week, so I didn't get anything done on the plane through the week. Today, however, we went to the pancake breakfast at DLZ, took a nice nap, then got to work on fitting the center tunnel and fuel pump covers. I knew that I wanted to have all the screws uniformly positioned which attach the stiffeners to the tunnel cover, so I started by making a little drilling jig out of some square corner angle scrap I had laying around. This isn't something that came in the kit. It's a leftover piece from the scrap bin at work.

After some work with various saws, sanders, and files, I had this little gem. Measuring along the inside faces, this angle is 11/16 x 1/16 inch. The hole is 9/32 down from the short flange.

Here's an action shot. You can see that it does a good job of locating each hole 9/32 down from the edge of the floor stiffener angle.

After drilling all the pilot holes to 3/32 inch, I opened them up to #19, then match drilled through the stiffeners into the flanges of the center tunnel cover and the fuel pump mouting plate. Becuase I was bent way over the side of the fuselage and had no good visibility towards where I was drilling, it was quite difficult to keep the covers from sliding up or down. I ended up using a little mirror propped up on some blocks at an angle so I could see how the line drawn on the side flanges of the tunnel covers aligned with the top edge of the stiffener angle flanges. Wow, that's not very clear at all. If you're doing this yourself, I hope you can figure a better way than me, because it was a serious pain in the rear.

I also measured and drilled an extra hole in the flanges of the F-7115 fuel pump cover side panels. It is 3/4 inch aft of the forward edge of the fuel pump mounting plate.

Note that even though the plans call for #6 screws, I'm using #8 screws everywhere. I'm not a big fan of #6 screws...they're just too dinky.

I also modified the fuel valve cover by first marking the cutout, then drilling 1/4 inch holes in the corners for 1/8 corner radii.

The bandsaw was really snagging this thin sheetmetal, so I only used it for roughing the cutout. To get right up to the line, I used a 3 inch sanding disc in my new right angle die grinder, then did final cleanup with some files.

As a side note, the right angle die grinder is the shiznit. I think if I had it to do over again, I wouldn't even bother with the straight one. The right angle one is soooo much easier to control.

Last item for today was to start fitting the Andair fuel switch to the mounting plate. I didn't have a unibit large enough (needed a 1" hole), so Kerin and I drove over to my friend Tom's place and he was nice enough to let me use his large unibit to pop this hole in. Tomorrow I hope to get the fuel switch mounted up.