There are a couple more tasks I needed to finish before I start riveting the forward fuselage assembly together including
- Dimpling the firewall
- Installing tunnel access panels to make future inspections inside the tunnel easier
 |
| Firewall recess flange holes dimpled. Here you can see that I had already started thinking about control cable pass-thrus and had made some markings in the recess. I'll talk to this in an upcoming post |
 |
| Dimpling the firewall with the DRDT-2. Stainless steel dimples very easily and the dimples appear crisp |
 |
| Holes near the flanges of the firewall were dimpled with the squeezer |
 |
| For a few holes right next to the flanges, I used the rivet dimpling technique |
 |
| Firewall dimpled as seen from the forward side... |
 |
| ...and the aft side |
 |
| I test fit all the angles and brackets to make sure everything aligned |
I also decided to redimple the scat tube support as I wasn't fully happy with the attempts earlier. To get a crisper dimple I pulled the flange out about 20 degrees using a hand seamer, and was then able to use standard dimple dies to redimple the nutplate screw holes without deforming the flange bend. After redimpling, I used the hand seamer to return the flange to its 90 degree position relative to the web.
 |
| Scat tube support flange pulled out to allow redimpling using the squeezer |
Next I decided to work on the tunnel access panels. I will be installing one access panel on each side of the tunnel (as many other builders have done) and now is a good time to get everything cut to size prior to any assembly. I am using the prefabricated tunnel access panels available from
Airward.
 |
| The first step involved match drilling from the floor panel holes in the tunnel into the access panel doubler. After first upsizing the center hole in the doubler, I clecoed the doubler in position below the tunnel side skin (positioning 4 holes back to avoid interference from the fuel valve bracket) and carefully aligned the predrilled holes in the doubler to the tunnel side panel. |
 |
| Doubler match drilled to the tunnel along its perimeter |
 |
| Next I used a #19 bit to upsize the nutplate screw holes in the 4 corners of the doubler through the tunnel |
 |
| I then match drilled and clecoed the access panel cover corner holes to those same 4 holes in the doubler/tunnel panel. With the cover clecoed in place, I traced its outline onto the tunnel to mark where the access panel hole would be cut |
 |
| Next I removed the access panel cover and doubler, clecoed them together and match drilled the remaining nutplate screw holes |
 |
| All screw holes match drilled |
 |
| I then used a #8 nutplate jig to drill the nutplate attach holes |
 |
| Nutplate attach holes all drilled into the access panel doubler |
 |
| With the doubler and cover clecoed together again, I countersunk all the nutplate screw holes for the head of a #8 screw |
 |
| and repeated all the steps on the second access panel |
 |
| I also countersunk all the nutplate attach holes and now both access panel doublers were ready for priming |
 |
| To cut the access panel holes in the tunnel webs, I first used a step drill to enlarge the #19 holes I had previously drilled, making sure I didn't drill beyond the marked cover outline |
 |
| Four corners drilled up to the cover outline |
 |
| I then used a jigsaw to carefully cut out the tunnel material between the drilled holes. This worked really well, and I was able to cut very close to the markings leaving little further trimming required |
 |
| Next I clamped the tunnel side panel into the vise, and used a combination of a vixen file, a needle file and a deburring wheel in the die grinder to trim the access panel hole to the required final size |
 |
| With some finish sanding in a few places, the access panel cover fit perfectly in place over the doubler on the inside of the tunnel. Again, this was repeated on the opposite side of the tunnel with identical results. |
At this time, I also decided to follow another tip on rv10.org to trim the ends of the flanges of the F-1001D and F-1001M side angles. Later in the build I'll need to be able to match drill into the upper and lower firewall brackets right next to the side angles, and if left untrimmed the flanges will be in the way. I drilled away just enough flange so that my angle drill could fit.
 |
| Firewall side angles with flange ends drilled away |
 |
| My angle drill, with a stubby #40 bit, needs only about 1.5 inches of space to fit |
Time Taken: 11.0 hours
Dates: March 20 2025 - April 19 2025
Firewall Total Time: 24.2 hours
RV-10 Build Total Time: 1011.1 hours
Priming Total Time: 126.0 hours (not included in build time totals)
