Monthly Archives: December 2016

Sections 28 and 29 of the RV-10 build manual are quite long and involved. There’s a lot of bending and manipulation involved to assemble the fuselage to the point where it resembles a large bathtub. I’ve decided to forge ahead and assemble / match drill everything through to include the side skins, tear it all apart for one large priming session, followed by a large amount of riveting to take me through to the end of section 29. I’m doing this rather than the piecemeal steps in the build manual order because I’m using a spray gun and 2 part epoxy primer – it takes me a while to get set up to spray but once setup I can paint a very large number of parts fairly quickly and this is the way I prefer to work.

To bend the longerons, the instructions say to clamp them in a vice and hit them with a hammer. I’ve done this in the past for the empennage longerons – successfully – but some time ago I bought a longeron bending die set to use for the fuselage longerons. It’s just as easy to mess up the bends with the die set compared with a hammer, the trick is to take it slowly and never over-do a curve so that you don’t get into a situation where you are un-bending, i.e. going backwards. All four longerons turned out well and slotted into the fuselage just fine.

I also fitted the gear brackets, and match drilled the forward legs into the forward fuselage assembly. The plans call out for a 0.063″ spacer, WD-1021P, to be fitted and match drilled between the side of the brackets and the side rib. Many builders have run into trouble in this area, it is just not possible for Van’s suppliers to bend the steel brackets accurately enough. Van’s have in the past told people to just go without the spacers, but I didn’t want to do this. The gap in my case was tapered, the right side worse than the left, so I filed the WD-1021P spacers into a wedge shape in order to fit them to their respective slots. This worked out OK, and I’m not worried about punching through the Aluminium layer of the Alclad because I’m priming them.

Next step is to bed the skins, and I can’t do this until I build a fuselage stand, to get my work benches back.

I’ve been thinking a lot about the firewall insulation. Best practise in the RV community seems to be the use of Fibrefrax on the outside of the firewall, held in place with stainless steel foil. To that end, after a US trip last year I brought back some 1/8″ Fibrefrax and a roll of 0.002″ stainless steel foil. A secondary but no less important issue is what to do about the floor in the area immediately behind the firewall. In the event of an engine fire, temperatures could reach 2000 degrees F in the engine bay, and cowling airflow will direct hot gases / flames out the bottom and under the front seat floor. While I’m trying to get the aircraft on the ground, the floor could literally melt out from under my feet, since the melting temperature of Alclad is 500F. It is interesting to note that the Cessna 172’s and 206’s I’ve trained in have basically nothing in terms of insulation/protection on the firewall forward floor area.

Commonly used ‘flameproof’ floor insulation materials such as Soundex are a non starter as far as I’m concerned, since they will in fact catch fire and expel all sorts of noxious fumes in the event of an engine fire. Again, best practise in the RV community seems to be external ceramic insulation. In the case of the RV-10 with a Showplanes cowl, the cooling air outlet spans the entire width of the lower forward fuselage skin (see picture). I obtained a roll of 18″ wide, 0.005″ thick Titanium and some 1/16″ Fiberfrax ceramic insulation to do this external insulation. The Titanium is secured in place with a combination of Monel pulled rivets, which will not melt at fire temperatures, and regular AN426 rivets on the outside edges, which will melt at fire temperatures. The rivets on the sides and rear will not be exposed to these extreme temperatures, so only the rivets along the firewall bottom flange would be an issue. The monel rivets will hold the Titanium in place, and I’m applying a layer of 3M fire barrier 2000 sealant to this forward edge as well, the combination of these should be adequate to keep the front edge of the insulation in place long enough to effect a forced landing. Or at least give me a fighting chance.

I sandwiched the Titanium foil between the F-1072 bottom skin and a piece of MDF, and drilled through the assembly for Monel rivet lines, match drilled AN426AD3 rivet holes, and platenut positions for the Showplanes cowl mount points. After that, I was able to de-burr and dimple the skin and the Titanium foil, which I put aside for later assembly. I primed the skin and then reverted back to the regular plan assembly steps. This is a long section of the build, and I’m currently at the point where I have mated the mid fuselage and forward fuselage assemblies. Now I have to prepare spacers to go between the two main spars and a set of bolts to hold the spars together. The skin overlaps and a few other parts are then match drilled, I pull the assemblies apart to de-burr and dimple, and will then mate them together for the final time.

The combination of the forward and mid fuselage assembly is quite long, to which gets added the empennage. I’m going to have to build a roll-around stand for the assembly so that I can get my workbenches back.

After quite a few riveting sessions, the mid fuselage assembly is finally complete. There are more rivets than normally the case due to various doubler plates for the A/C condenser mounting points and two COM antennas. I’ve also riveted the forward fuselage ribs to the firewall, and installed platenuts on various forward fuselage parts and sub-assemblies.

I’m held up now waiting for the nose gear mount pieces of the showplanes cowl. I want to install platenuts on the forward fuselage skin to mount the aft moulding and that is best done before assembly.