CUSTOM CENTER CABIN COVER
After I designed the Custom Tunnel Cover, I thought it might be nice to carry the idea forward to the Center Cabin cover. I made some parts up quickly (photo below left), too quickly as it turned out. More on that later. I wanted to have a compartment level with the spar that ran all the way to the firewall. I would use as much of the original Center Cabin Cover as I could. I decided to attach it to the F-704 by modifying the F-983A fuel valve plate. I changed my mind and decided to replace the plate with a new one of slightly different design. The original part is .063 thick. Not knowing why it is so thick, I made a new one from .040 2024 T3. I joggled it to attach to the forward side of F-704 (photo below right). The cover that I had in mind to attach to it is .040 thick so for all practical purposes my fuel valve attach is a little beefier than the original design.
The right forward seat floor plate P/N F-739 overlaps the left forward seat floor P/N F-740. In order for my modified cabin cover to look right, I needed to add shims so that this overlap would not be noticeable. The right arrow in the photo below left is pointing to a shim that is .040 thick. The other shim spans the three screws that the left arrow is pointing towards. A view from the rear is shown in the right photo below.
My first attempt at making the side plates was a failure. I had the angles wrong on the front and rear. I got some construction paper and made a template, shown in the photo below left. I made new side plates and they fit perfectly (below right).
The fuel pump bracket that comes with the high pressure fuel pump is .063 thick. The plans have you cut off about 40% of the cabin cover. I decided that I would beef up the existing cover. I made two doublers that overlap at the center (below right). They are made from .025 2024 T3. The original cover is .020. My stack up is .070 in the middle and .045 along the sides. This should be plenty strong enough o hold the pump and the filter..
Below left is a photo of the top cover in place. I made it to go inside between the two side covers. I am having second thoughts about that decision but I haven't changed it yet. The photo below right shows the side covers clamped in place.
These two photos show the Tunnel cover and the Center Cabin cover cleco'd together.
I took all of these parts with me on one of my Tennessee trips. I drilled the holes to size as required. I dimpled as required. I drilled the nutplate holes as required. I then etched, alodined and primed all of the parts. I returned to Florida shortly thereafter.
The next step was to assemble the detailed parts (photos below). Notice in the right photo that I am back riveting using the fixture that I made for the aft fuselage.
Below left is a picture of the assembly from the bottom with the doublers riveted in. Notice that I have also added two angle stiffeners. The right photo shows the complete assembly cleco'd together. I riveted 3 angles on the forward end, 1 each for the top and the two sides (not shown).
In the view below left you can see the heat shroud for the heat box. There are two options for heat valves and I haven't decided which one I will use yet. The right photo below shows the (Custom) Center Cabin Cover and the (Custom) Tunnel Cover in place. They are even with the F-704 bulkhead/spar carry-through. I have ideas on things to add to these assemblies. Stay tuned. We will see if they work.
As you can see from the above photos, the center cabin cover was essentially finished by the end of December 2004, however I was not completely pleased with it. I decided to remake it but I did not get to it immediately.
The first thing to get remanufactured was the floor of the cover. I made a new one from .050 2024 T3. At left above the floor is installed temporarily. The photo above right shows the rest of the parts that I made for this modification to the modification.
I made two angles the length of the floor At left above they are drilled and cleco'd to the floor. I made two new side covers, above right. They will be attached to the angles with countersunk screws.
I made a different type of attach bracket for the fuel pump. The photos above show two views of the bracket. The rubber strips are not glued on yet.
I did a quick check with the pump installed to make sure that there would be clearance with the side panels. I then made an identical bracket for the filter. Actually I made them both at the same time. In the photo above right I am in the process of locating the bracket for the filter.
In the photo above left I have put both the pump and the filter in place for trial fit. At right I have the floor reinstalled in the fuselage.
Above left I am fitting the upper cover. At this point I also cut the forward vertical portion of the original cover off of the original cover to be attached to this cover (arrow). At right I am adding one of the side covers. Note the clecos along the top of the upper cover. The point of this modification was to make the side cover flush with the top cover.
At left above I am in the process of priming the parts. At right all of the center cabin cover parts as well as a few fuel system parts are primed.
Here is a view of the upper cover above left. You can see that I have riveted the attach plates for the nutplates in place and that the side covers will be flush with the upper cover. Above right is one of the fuel pump or filter brackets just prior to attachment. The two spacers allow the clamp to pass between the bracket and the floor of the center cabin cover.
Above are two photos of the clamps in position to add the fuel pump and the filter.