2nd Step Bearing Drilled – 1.5 hrs

Wednesday Aug 10, 2011

Tonight I successfully drilled the right step bearing block to the baggage rib using the same technique I described last night so I am not posting more pictures of the same. But I followed that by countersinking two more floor stiffeners and deburring and scrubbing those and two F-722 stiffeners for priming. Just trying to nibble away at it.

Drilled Left Step Bearing – 1 hr

Tuesday Aug 9, 2011

So I found myself in a dilemma over how to drill the step bearings to the luggage ribs. I bought a 90 degree drill adapter but I found that the cross hole that goes through the plastic bearing and the tube is too close to the rib for my Tight Fit drill adapter. The hole is .375 from the rib and the drill will get no closer than .450. So I came up with a sneaky way to drill it outside of the fuselage. I started by putting all the parts in place; clecoing the step to the side skin with the bearing pre-drilled on one side and clamped in place where I would normally match drill it through the tube and the second wall of the bearing. Then I put four dabs of torque seal between the tube and the bearing around the diameter as you can see below.  I set this up last night and let the torque seal cure for 24 hours.

The nice thing about torque seal is it is like weak cement and it cracks when it breaks. So tonight I carefully unclecoed the step and removed the bearing from the tube. When I got the parts on the bench I was able to put the bearing right back where it was on the tube by matching up the broken torque seal at all four locations. Then I clamped that to the work bench with the pilot hole up so I could drill through the tube. I did that very carefully so as not to knock things out of position.

Then I put the parts back into the fuselage but this time I put the long bolt through the tube to lock the position of the bearing. The alignment looked very good with the bearing flush against the rib as I had hoped. Then I used my new angle drill to drill through the two holes in the bearing that go through the rib. You can see those bolt heads in the picture also.

While this worked out successfully it is not without risks. There are lots of opportunities for things to get out of alignment but if you are careful you can pull it off and not have to buy one of those $300+ low profile angle drills that can get up really close to a wall. I’m not done because I still have one more step to drill the same way.

2nd Step Hole and Conical Bend – 2 hrs

Wednesday Jul 13, 2011

Tonight I started by working on the fit of the left wing step by tweaking the hole to make it fit around the weld bead better. It is now essentially flush on the forward side.

The aft side still has a little gap but this might be about as good as it gets. I may fill the gap later with ProSeal after everything is riveted up tight. So then I moved on to the other side of the fuselage.

I cut the hole for the right step (remember the fuselage is upside down) and did the first fit check with the right step. I had to grind about .12 inch off the tube on this side also. OK so this is good for now.

Then I removed the right forward side skin and set it up for the conical bend. I deburred the inside edges of the tight corner as before and attached the aluminum angle for bending.

It only took a few minutes to make the bend this time since I knew what to expect. Then I put the skin back on the fuselage and checked the fit there. Again, it looks good. I don’t even need to tweak it. I am really amazed that the predrilled holes line up so well and the aft edge of the conical surface fits so nice to the aft skin. Well done Vans.  It is a big relief to have both of these conical bends done without mishap.

First Conical Bend Completed – 1.5 hrs

Tuesday July 12, 2011

This was a big night as I got mentally psyched up to do the first conical bend. This is an area where serious problems can befall me, like a crack in the side skin. I started by removing the left side skin from the fuselage and gently deburring the edges of the skin at the relief radius where the tightest bend occurs using fine sand paper and scotchbrite. I just don’t want any sharp edges that might initiate a crack. Then I clamped my back rivet plate to the skin and the work bench along the bend line. I offset the aft end a little as you can see in the picture just because they show it that way in the illustration provided in the plans.  I cut a short piece of aluminum angle and match drilled it to the skin holes along the free edge. With clecos holding that in place I attached a vice grip to the angle to gain some mechanical advantage for the bending. I took this picture when I was set to start bending.

Less than 10 minutes later I had it bent into a gentle roll. Next time I’ll attach the angle to the other side of the skin because the cleco nearest the sharp corner wanted to pop out as the bending progressed. I made a small doubler out of .025 thick sheet to reinforce the hole in the skin and cut a few corners off the angle along the way to give more clearance for bending but I got it done. Here it is after bending.

Then I put the side skin back on the fuselage and low and behold it fit nicely; better than I expected. I thought a few iterations might be required but this looks good to go. One down and one to go.

I couldn’t resist putting the step back in to see how it fit after bending. The hole was tighter around the tube but it fit.

I opened the hole up just a little more and the plate now almost sits flush to the skin. Just a little more tweaking is needed to get this side flush. The inboard end of the tube is currently about .032 away from the baggage rib so that looks just about perfect. When I open the hole a little more it should just touch.

The other side is a bit further away from the skin because the conical bend overlaps the plate. The plans say to put a generous radius on this corner to eliminate the overhang. But that will have to wait until next time.

Making Hole for Left Step – 1 hr

Monday Jul 11, 2011

Tonight after work I reviewed the build instructions and it is almost time to start the dreaded conical bends on the side skins. But first, the instructions say to drill the holes for the external step kits (optional). I ordered steps for both sides since the tri-gear model is a very big step up to the wing walk without them. Fortunately there is a pilot hole for locating the 1.5+ inch diameter hole in the skin. I say 1.5+ because the step tube is 1.5 OD and there is a weld bead at the flange that needs to be cleared to get the flange flush to the skin. So first I marked the hole diameter at 1.5 ID  for cutting. Then I opened the pilot hole to 3/4 with the unibit which was not necessary in retrospect. Then I drilled a ring of #30 holes just inside the cut line and finished the hole with a sanding drum on my rotary tool. Kind of brute force, but it works. Here is the finished hole.

Then I inserted the step and surprise, it fit pretty well except for stopping about 1/8 short of flush. I then trimmed a little bit off the inside end of the tube because it was bottoming against the rib inside but then the weld bead was the limiting factor.

However, instead of opening up this hole more at this time I think I will complete the conical bend of the skin first then see how much more clearance I need to get the step flush.