Archive for the ‘Center Section’ Category

Finished Tank to Selector Fuel Lines – 6 hrs

January 14, 2012 Leave a comment

Saturday Jan 14, 2012

To finish the fuel line on the left side today I needed to put the wing back on the fuselage and measure as closely as I can the dimensions from the fuel tank attach bracket to the AN fitting on the tank so I could get the final bend and flare formed right to fit the tank. There is not much give in this rigid aluminum tube so it is critical to get it right or the whole tube may have to be scrapped.

But before I put the wing on I needed to drill some holes in the side of the fuselage for the pitot and AOA plastic tube routing from the wing into the fuselage. I have been grappling with this issue in my head for some time because it is not in the plans and I haven’t found any examples on the forums or on the web that fit my needs. I do not plan to have any steam gauges up front on the panel that require pitot or static pressure lines. Only the Skyview ADAHRS module in the tail cone will need it. But I want to keep the door open in the future in case I decide to add a backup instrument like a Dynon D6 later. So my challenge now is to get the pitot and AOA lines from the wing root near the main spar to the aft cone of the fuselage, avoiding any possible interference with the flight controls which are nearby, provide an easy way to connect those lines when the wings are mated for the last time, and identifying a good location where I can T-off the pitot line in the future to route it to the panel.

So I finally have a plan that I think will do all of those things which I am going to document here over the next few posts but it starts with drilling two new holes in the side of the fuselage  at the wing root to get the pitot and AOA lines into the cabin under the pilots seat. So before remating the wing I drilled those hole this morning as you see in the photo below. The are the two new holes on the right of the big aileron pushrod tube hole with rubber grommets installed. Those grommets are sized for the plastic pitot and AOA lines. The new holes are on the aft side of the pushrod hole to allow the plastic lines to route around the aileron pushrod in the gap between the inboard rib and the fuselage skin because there appears to be no good place to pass through the skin in front of the pushrod and that area is very crowded anyway.

Part 2 of the pitot and AOA routing is to install 90 degree quick disconnect fittings on the pitot and AOa lines between the wing inboard rib and the fuselage skin. These fittings come with mounting hardware so I plan to make small brackets to secure the orientation of the fittings to point around the aileron pushrod one going above and one going below as you can see in the photo below. Now with that small detour task completed I can go back to finishing the fuel line routing.

So then I put the wing back on the fuselage and made measurements for the final bending and flaring of the fuel line. The distance from the tank attach bracket forward to the centeline of the fitting tells me where to locate the last 90 degree bend and the distance from the tank attach bracket hole outboard to the tank AN fitting tells me where to cut the tube and flare it. I was very cautious about this because I did not want to screw up on the last steps and scrap the whole fuel line. I even made a test piece for the last bend which I marked out and bent to make sure I had the reference marks right to make the tube line up with the fitting.

Then I took the wing back off, removed the tank attach bracket from the fuselage again and gently bent the tube out away from the fuselage to get just enough room to use my Imperial 470 tube bender. That is the only way I can get a nice tight 1-inch bend radius without kinking the tube. After I made the bend in the actual fuel line I gently bent it back parallel with the fuselage and installed the tank attach bracket again. Yes, a few iterations were required to recenter the tube with the hole in the bracket. Then I marked the tube end based on the distance I measured from the center of the hole in the attach bracket to the end of the tank AN fitting. I slipped an AN818 nut and AN819 sleeve onto the tube and flared it with the Parker Rolo-flare tool. The photo below shows the result.

Next came the big test – the wing was remated and the fuel line was mated to the tank. Actually it went right on without fuss. As you can see in the photo below, the fuel line is almost dead center in the hole of the attach bracket which is what I was shooting for. Yipee, one down and one to go!

The right side fuel line was less stressing and went quicker having learned what I did on the first line. I created a mirror image set of bends on the tube for the area under the fuel valve and routed the rest of the tube as before. Here is how the interior of the cabin looks with both lines in place.

This is the outside of the fuselage on the right side all done and mated. I actually got a little sloppy on the marking of the final bend and the AN fitting came out about 1/8 inch too far forward for the tank fitting but I was able to reshape the tube slightly between the fuselage exit hole and the fitting to bring it into alignment. Lesson to self – don’t get too comfortable or you’ll make mistakes.

Here is another view of the interior showing the s-bend where the tube exits the side skin.

Finished Installing Soundproofing – 1 hr

October 5, 2011 1 comment

Wednesday Oct 5, 2011

Tonight I finished installing soundproofing foam under the center section and baggage floors. I may decide to put more in at a later date but this is it for this phase.

Riveted Steps – 1 hr

September 16, 2011 Leave a comment

Friday Sep 16, 2011

It occurred to me that it will be easier to rivet the steps to the side skins before rolling the canoe so Denise helped me take care of that tonight. I got underneath to buck and she shot the rivets from outside.

The rule of thumb is to put the factory heads of rivets on the side of the thinner material. But in this case that would put the uglier shop heads on the outside where they would be eternally visible. Since Vans lets you put pop rivets in these holes from the outside for retrofit purposes it makes sense that putting the factory heads of solid rivets would be OK too. Everybody else does that also. And they do look nice and clean on the outside as you can see below.

Categories: Center Section, Fuselage

Drilled Left Step to the Fuselage – 1.5 hrs

August 4, 2011 Leave a comment

Thursday Aug 4, 2011

In this episode I started by drilling the left upper longeron to the F-724 vertical rib tab. I just marked a spot near the center of the tab on the F-724, measured that location relative to the edges of the longeron and the tab, transferred that spot to the longeron side and drilled it through.

Like other builders I found that there is a gap of about 1/16 inch between the upper tab and the F-623 rib. Rather than bend the tab down to the surface as the instructions suggest I made a .062 shim to fill the gap. I cut a small piece of aluminum a little oversize and slid it in, then match drilled from the skin side through the shim and tab. Afterward I trimmed the shim down to final size making sure I had good edge distances.

Next I inserted the external step into the hole I made weeks ago and did some final tweaking of the flange to get it as flush as possible to the skin. I also double checked to make sure the fit of the tube inside was good also. Then I set about drilling the step to the fuselage. The tricky part is getting one column of rivets aligned with the F-724 rib flange in the inside. The skin and F-724 are already drilled with three holes along that flange so I was thinking that I was supposed to use those three holes as part of the pattern. Not so, it turns out. The step kit instructions show five holes along that line and four of them definitely don’t match the locations of the pre-drilled holes. One hole is a very close match. So plowing ahead I started by aligning the edge of the step flange parallel with the centerline of the holes in the F-724 flange and taped it down with duct tape. Then I drilled the step flange through the three F-724 holes. That was a mistake. When I realized that two of those holes were well off the pattern shown on the step kit instructions I started to bum out a bit. But fortunately those two holes are more than 3 diameters away from the intended hole locations and I had used a small (#40) pilot drill through the step flange. So the strength of the step is not compromised by going ahead and drilling the holes in the correct locations. So that is what I did. You can see the final pattern in the picture below. The final hole sizes are #30 and some of those have clecos. You can see the two extra #40 holes if you click on the picture to blow it up. I will probably just go ahead and install .093 diameter rivets there also. The other option is to fill them with epoxy just to hide them cosmetically.

I will have to repeat all these steps (without the screw up) on the right side next. I determined I will definitely need a 90 degree angle drill attachment to drill the bearing holes inside the fuselage so I ordered one from Isham PlaneTools yesterday. I should have that next week sometime.

Categories: Center Section, Fuselage

Baggage Ribs and Side Walls – 1 hr

August 1, 2011 Leave a comment

Monday Aug 1, 2011

Tonight I started by riveting the firewall recess together. That is just a loose end I have been putting off.

Then I fit the F-724 vertical baggage ribs, followed by the F-722 horizontal baggage ribs which needed a bit of fluting to straighten. Then I drilled all the holes to the skins.

Then I clecoed the F-750 aft baggage side covers to the F-222 and F-724 ribs. That’s all I had time for tonight.

Categories: Center Section, Fuselage

Joining the Center and Aft Sections – 7 hrs

July 9, 2011 Leave a comment

Saturday July 9, 2011

Last night I got some some help from Denise to rivet four more seat ribs to the bottom skin. We would have done more but her back was hurting at the outset so we kept it short. Not to worry, Scott is coming over today.

I cleco’d in the F715 outboard ribs and the seat pans and match drilled the upper flange of the ribs through the seat pan holes. The edges of the ribs are aligned 1/32 inch outboard of the edge of the seat pans. I think this is to provide clearance for removing the forward sections later with the side skins installed. In this photo you can see the clecos installed after drilling. While I was at it I drilled all the matching holes between the seat pans and baggage floors to the ribs.

Then I took the pans off and installed nut plates for the forward section seat pans. I just put a #8 screw through the flange into a nut plate and drilled the rivet holes using the nutplate as a guide.

Then I dimpled the flange rivet holes and the nutplates and installed the rivets using my pneumatic squeezer.

Scott arrived around 12:30 and our first order of business was to finish riveting the bottom skin onto the center section skeleton including the F-715 outboard ribs but not the F-625 corner ribs (per the plans). We knocked that out in about an hour and a half but I forgot to get a picture at that stage.

Then the big move started to mate the center section to the aft section after we rearranged the aft section to make room for the mating. With the aft section upside down on two sawhorses, we set the F-704 bulkhead of the center section on the third sawhorse and mated the two sections along the F-706 bulkhead. We found that the F-625 corner ribs needed more trimming to avoid hitting the aft section skin so we took those off temporarily. Without those it still took some futzing to get the hole lined up and cleco’s in place but we made it. Here you can see Scott posing for the picture and trying to look candid. Notice the longerons are not installed. More on that in a minute.

I am perplexed about the aft most row of holes on the overlap of the bottom skins. I did not realize that there would be two rows on rivets at this joint. This aft row does not mate to the bulkhead, only the skin. How am I going to dimple those holes? I can’t do it with the pnuematic squeezer because the F-706 bulkhead is in the way. I’ll have to do some research on this.

It looks pretty cool to have these structures together. This view shows the F-704 bulkhead all the way to the tail. It’s here just because it looks neat.

Then I realized I really should have notched and installed the longerons before flipping this monster upside down. I was hesitating because I was hoping to check the fit before cutting the notches near the aft end but a fit check is not really possible so I might as well do it according to the drawing dimensions and hope for the best. I started with the left longeron and cut the notches as you can see here.

Afterward I inserted the longeron into the notches in the bulkheads along the left side of the fuselage and found that the forward notch is a little too narrow. But that will have to wait for tomorrow because I am out of time today.

Categories: Center Section, Fuselage

Started Riveting Center Section Bottom Skin – 1 Hr

July 7, 2011 Leave a comment

Thursday July 7, 2011

In case you noticed that I had no posts on progress on the airplane for almost the last two weeks it is because we have been on vacation cruising the inside passage of Alaska. I won’t bore you with the details but of course things were in disarray at work when I got back. After the last three days of work I was finally able to get back to the airplane for at least a short while tonight. I had help from Denise starting to rivet the bottom skin onto the center section skeleton. It not a lot; we got four of the seat ribs riveted starting in the center and working outward; but it is progress again finally. We’ll need another couple of hours at this to finish.

Categories: Center Section, Fuselage

Riveting the Center Section, Part 3 – 3 hrs

June 25, 2011 Leave a comment

Saturday Jun 25, 2011

This morning I went out to Corona to fly a little in a Cessna 172N. I can’t wait to start flying my own RV-7A. I stopped by Aircraft Spruce for a few supplies while I was nearby. I bought a gallon of MEK because you can no longer buy it in Orange County I am told.

After getting back I attached the F-705 bulkhead and baggage ribs to the seat ribs and began riveting. It took longer than I expected but I finished riveting the skeleton minus the F-715 and F-623 ribs.

I torqued all the lock nuts including those for the seat belt brackets and torque striped them. Then I flipped it over and cleco’d on the bottom skin. So this is ready to start riveting again.

Here is a shot of the center section next to the aft fuselage. These two will be joined together in the not too distant future.

Categories: Center Section, Fuselage

Riveting Center Section , Part 2 – 2 hrs

June 24, 2011 Leave a comment

Friday Jun 24, 2011

Tonight I finally got back to riveting the center section. In this session I riveted the F-714 ribs to the F-704 rear bulkhead and installed the AN3 bolts, washers, and lock nuts. You can’t use the squeezer here, you have to shoot them with a double offset cup set and bucking bar.

Categories: Center Section, Fuselage

Mounting Aileron Trim Servo Motor – 1 hr

June 22, 2011 Leave a comment

Wednesday Jun 22, 2011

I’ve been working extra long days this week so it’s been hard to get out to the shop. I did receive the missing aileron trim servo parts in the mail today from Vans. Thanks Ken! So with a time available I installed the link between the servo motor and the weldment arm. Then I aligned the weldment arm to the neutral position by measuring the distance between rib webs, dividing by two and placing the center of the end of the arm at the mid position. Then I removed the right rib so I could get access to drill the mounting holes using the servo motor holes as a guide. In this picture it is set up ready to drill.

In this picture I have drilled the holes to 9/64 for clearance for #6 screws and have the screws inserted to confirm alignment. With that done I can now get back to assembling the ribs to the spar and I won’t need a 90 degree angle drill later to install the motor.

Categories: Center Section, Fuselage