Joshua's RV-9A Project

Fabricated the lower firewall-to-longeron gussets, which are made from a pre-cut piece, but have a series of holes which must be drilled, a relief cut, and two bends made.  Clamped and drilled these in position, then drilled the lower longerons to the gusset, firewall weldment, and side skin.  Need to read ahead and see whether the #40 holes at the aft end of the longeron (in the gear tower area) are drilled for their final fasteners now, or if they’re just drilled to #40 for the time being.

While I did that, Allison took on an art project and traced two copies of the gear leg cutout template.

Continued work on the forward fuselage today, fabricating the angle clips which attach the side skin stiffeners to the firewall, drilling said stiffeners, then fabricating and drilling the lower longerons.  These require a section of one leg of the angle to be cut away, then twisted to match the fuselage.  Several rounds of clamps, measuring, and test-and-try-again have things fitting well.  Once fit, the four bolt holes attaching the longeron to the lower firewall weldment are drilled.

Now that the center fuselage is attached to the tailcone, and the side skins fitted, the forward fuselage must be added to the assembly.  This is made up mostly of various chunks of angle that take the thrust produced by the engine and transfer it to the rest of the airframe.  First up, I tweaked the bends of the forward portion of the main longerons to match up to the skin, then clamped and drilled them in place.  Once drilled, I marked the longerons for the required 3/4″ cut line, removed a few clecos, and trimmed the longerons, then filed the ends smooth.  That done, the small straps that connect the top of the 904 bulkhead to the main longerons are cut to length, clamped in place, and drilled.

Next, we add the firewall by clamping it to the main longerons.  The bottom skin is added, then couple holes are drilled to the firewall assembly to fix it in the proper place.  More clamping, measuring and drilling, and the skins are drilled to the firewall.  Next we clamp the upper firewall weldments to the main longerons and–after making sure everything still fits well–drill through the weldments. Some 1/8″ rivets are used to hold the skin and longeron in alignment during fitting of the firewall.

At this point, the firewall location is set, and the bottom skin is removed to allow the structural parts to be added.  First up, the auxiliary longerons, which must be twisted, using the same padded-vice-and-big-wrench method used for the main longerons.  This is a bit of a trial-and-error process: set the angle in place, eyeball it, go twist, come back, look again, perhaps make a sharpie mark or two, bend again, until it’s fitting nicely in place.  Then, clamp it in there and drill.  After both left and right auxiliary longerons were in place, I called it a night.

No, it doesn’t sound like over four hours of work, but there are many holes to be drilled, and the thin stainless steel firewall, especially, requires extra care to drill.

Much drilling today.  Began by drilling the armrests and removing them, and trimming the 623 bottom skin corner ribs to clear the step tubes.  Next, pulled the side skins to do the conical bends where they meet with the center bottom skin and tailcone, and reinstalled on the fuselage.  The bending was pretty easy, and in fact, I will have to un-bend the left side just a bit later, as it’s a bit concave just above the bend.  The right side turned out perfectly.

The next step is drilling the main longerons, and that is indeed a lot of holes.  I worked from aft to fore with clamps and drill, doing every fifth hole on both side, then filling in with the third hole, then going back and drilling all the even-numbered holes.  Now, the longerons are drilled up to the 904 bulkhead.

After the longerons were drilled, I drilled the bottom and side skins to the skeleton, and to each other.

Started out the weekend by drilling the baggage & seat floors to the skeleton and making sure everything was clecoed solidly in place.  Also, filed the slots in the tailcone bulkheads wider, so that the longeron angle would fit — the slots are too narrow as they come from the factory.  Fortunately, this issue is well-documented on other builders’ sites, so it’s easy to be prepared.

Next step is to prep the longerons for the big join: trimming the excess length from the aft ends, cutting the necessary relief into the aft end, and slotting them for the HS attach bars.  Once prepared, they get placed in the tailcone and clamped in place at the appropriate location.

Then, it’s time to set the center fuselage in front of the tailcone, and let the two become one.  The actual join can be a bit tricky, as the tabs of the baggage ribs like to get hung up on the 706 bulkhead.  This is easily resolved by partially un-clecoing the baggage floors (in my case, I had only to open up the left side) enough to reach in and apply some coaxing to the tabs.  Once the tabs were aligned, it slid right into place, and a row of clecoes across the bottom secured it.

Adding the forward side skins is next, but first, the step hole must be drilled…this is where trouble strikes.  Grabbing the hole saw marked for 1 1/2″, I drilled a hole.  Hmm, looks a little big, I thought–turns out I had grabbed the 2″ saw, which was also marked “for 1 1/2′ pipe clearance.”  Oops.  Try the step–of course there’s a big gaping hole underneath…The skin is nearly $100 to replace, plus s/h, so I will inquire as to whether a suitable doubler could be employed here, since the larger hole (it’s only 1/4″ bigger all the way around) is mostly hidden by the step’s mounting flange, anyway.  Any spot on the bottom where the oversize hole & doubler might be visible coule probably be filled with something later, before paint.  Moving on, I drilled the other skin with the proper size saw, filed some extra off to allow the mount plate to site flat (the weld on the step increases it’s diameter), and attached both sides to the now-lengthy fuselage.

Finally, fluted the armrests and clecoed them in place.

Completed riveting the bottom skin to the center fuselage with Allison’s help; easy as pie.  Proceeded to flip the assembly right-side-up and attach the forward half of the 904 bulkhead, then cleco in the baggage and seat skins.  The baggage skins gave me some pause, as they didn’t want to fully align with the 905 bulkhead…starting from the center and working out solved the issue; there is a curve formed at the aft edge of the center fuselage, to match the forward bulkhead in the tailcone.  The bottom skin wants to pull the curve flat until the baggage skins are in place.

We should see the first iteration of the center-to-tailcone join this weekend.

Picked up a hole saw set today, so I was able to cut the holes for the step tube, and smooth them out with a small scotchbrite wheel and some primer on a Q-tip.

Riveted together the little cutout pieces from the center seat ribs.  Squeezed the nutplates on the seat pan ribs, then riveted and bolted the ribs, once at a time, onto the aft part of the 904 bulkhead.  Once that was complete, added the 905 and riveted the ribs to that, adding the baggage floor ribs as appropriate.  One rivet in an awkward place (905, in the center tunnel, with both a seat rib and a baggage rib) needed to be drilled out a couple times, and I ended up having to drill it up and put in an AN3 bolt.  Oh well, life goes on, and it is in a place that is accessible for inspections.

Once the skeleton was riveted together, the assembly was flipped inverted and the bottom skin added.  Clecoed in every other hole, then riveted began.  Completed the outermost ribs of the seat and baggage areas…I’ll have to see how far I can go before my arms grow too short and help must be called in to drive rivets.

Finished dimpling the center section parts–Allison deburred & dimpled the bottom skin while I dimpled the ribs and sorted all the hardware bags into a couple new organizers I picked up awhile back.  I think I’ll get two more, to cover all the various length bolts, too…it’s so handy to have everything separated out.

Once everything was ready, it was on to etching & priming all the components.  The downdraft priming table continues to work well, and the quartz heater helps things move quickly, so it didn’t take as long as I expected to prime everything (though etching still kills my back).  Should be able to get a start on final assembly tomorrow afternoon.

Deburred all the center fuselage parts, except for the bottom skin.  Still need a hole saw to make the step holes…otherwise, ready for dimpling.

Completed the center section fix today by etching & priming the new right side pieces, then riveting to the center section bottoms.  Put the center section bulkhead back into the assembly and drilled the side plates, this time double- and triple-checking for correct orientation.  The primer didn’t seem to go on as well as it did on the last batch of parts (perhaps it’s time to completely pull the gun apart and solvent-clean it?), but hopefully it’ll dry harder over time.

Countersunk the forward row of holes on the bottom of the center section, then pulled the whole thing apart to begin the deburr/dimple/etch/prime process.  Deburred the center section bulkhead and started on the seat ribs, before it was time for dinner.

To do list:

• countersink inside of center section bulkhead flange at outermost 5 rivets
• buy 1.5″ hole saw for step tubes
• drill to final size all holes for nutplates & screws
• determine what parts need to be painted with interior color (center section sides?)