SECTION 25: MID FUSE BULKHEADS: Difference between revisions

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* If you are jumping straight from the empennage to the fuselage, note that this section, like most of the fuselage sections, has multiple priming steps.  

* When you hit a priming step, you can usually jump ahead and start working on other portions of the instructions, then perform multiple priming steps all at once, then go back and finish the steps after each circled "prime" step.

Later in the build process (Section 28, page 28-12, Figure 2) you will need to have 7x double-flush rivets on each side of the forward main spar. That requires you to machine countersink the top/inside of the bottom flange for those 14 holes. The outermost holes on each side are very hard to properly countersink after you have attached the F-01004C center section bulkheads.

[[File:2024-09-18 15.33.48.jpg|thumb|Seven double-flush rivets -- this is the top of the bottom flange of the forward bulkhead, and these are the shop ends of the rivets flush due to the countersinks.]]

The holes in the bulkheads are only big enough to have cables run directly through them using snap bushings (vs. in a conduit). Also, there are only two holes on each side and depending on your needs, you need more.<br>

You do need conduits for sure but only to tunnel underneath the baggage compartment. You can go back to snap bushings forward of the baggage compartment if you like. Some people though like to just run at least some of the conduits all the way from the tailcone to the front. Now that is where the diameter needs to increase from .75 to at least .77 for Van's Nylon conduits. It is a pain to enlarge those holes afterwards since they are tucked in underneath horizontally-running structures. Adding more holes can be done later but is also a bit easer if the bulkheads aren't in the plane yet.

If you run conduits all the way from the back to the front, it will be easy to route the static pitot tube, the pitch and yaw servo cabling, the pitch trim servo cable, the battery cables etc. Also makes cabling for later add-ons easy.<br>

Step 8 details the assembly of the bulkheads to the center section prior to deburring and priming these parts.  Now is a very good time to consider whether you will need additional pass-through holes in the bulkheads for items like conduit, pitot, static, and AoA sensor tubing, air conditioning lines, and other electrical circuits.  Many builders find that the two holes referenced here and on [[#PAGE 25-4]] are insufficient for all of the required lines and circuits for an RV-10, especially if it is going to have a full glass panel and backup/redundant electrical systems.  

See also this [https://www.facebook.com/groups/vansrv10/posts/5766330576821327 FB thread] on the subject.

* Step 6<br> Step 6 requires you to 'Rivet the Mid Seat Rail Support Subassemblies, F-1004C-L and -R Center Section Bulkheads and F-1004N Stiffener Angles to the F-1004A Center Section Bulkhead per the callouts in Figure 2.' Figure 2 in the plans (Rev 1 Date 1/7/21) omits the quantity and rivets to be used. The older plans (Rev 0 Date 7/24/14) shows the rivets and places.

* Step 7<br>Don't insert the snap bushings instead widen the two holes to a bit larger than .75 inches (.77) so they can pass through Van's conduit later. Also drill a third / forth hole with same diameter underneath the two holes for a more conduits if desired.

* Step 7: Check that F-1004J has the correct length and is not pushing the spar caps out of their proper position where the wing attach bolt holes no longer line up through all layers. See also this [https://www.facebook.com/groups/vansrv10/posts/7122547791199592 FB Post 2/2024].

*Step 4<br>Don't insert the snap bushings instead widen the two holes to a bit larger than .75 inches (.77) so they can pass through Van's conduit later. Also drill a third and forth hole with same diameter underneath the two holes for more conduits.

* Enlarge the two holes at the lower corners of F-1005A to a bit larger than .75 inches (.77) so they can pass through Van's conduit later

* Step 3: In section 29, page 29-14, step 9, you will be instructed to machine countersink the outboard #40 holes on the flanges of the F-1005C-L and F-1005C-R Bulkhead Side Channels. If your kit is newer and has final-sized holes, you will not need to final-drill these holes between now and then. Consider countersinking these #40 holes now as it is somewhat easier than doing it after it has been riveted to the fuselage. They should be flush on the outside and should accommodate an AN3 rivet with a 0.032 skin. Section 29-18 shows these five countersunk locations (on the inside of the F-1005C-L and -R parts) to be riveted double flush, just as the seven locations (per side) were done as shown above for Section 25-3.

* Step 5: If you will NOT have 5-point harnesses in the rear seats, you probably don't want to rivet the F-1005D crotch-strap lugs in this step.

I am still unable to interpret Figure 1 -- is the part shown concave or convex? I'm not sure. But F-1034D-L and F-1034D-R are definitely different. I thought I had it right, I riveted on this page, and I didn't notice I had them backwards until the end of Section 26. I found that my F-1034C-L and F-1034C-R were angled outboard and they should be more or less perpendicular to F-1034A. I don't see a downside to leaving these cleco'd and riveting in section 26.