Over the last two weeks I’ve been match-drilling the firewall components and fabricating a couple of additional brackets that bridge the firewall and fuselage floor stiffeners. There isn’t a lot of margin for error on these, and it’s easy to wind up with insufficient edge distance when match-drilling them to the existing stiffeners and gussets you see in the picture. I wasn’t happy with the first attempt, so I fabricated and re-drilled another pair of brackets – they turned out much better.

One other bit of fun is fitting this small doubler that reinforces brake line penetrations through the firewall.

Match-drilling the plate isn’t the problem, but drilling through stainless steel is. Follow Van’s guidance in the plans book and you’ll be fine, j ust remember to use slow drill speeds, and use boelube or some other cutting fluid when you drill. Also, use a Unibit for any hole larger than #30 – works like a champ and is less likely to leave burrs on the stainless. I also made sure to use the doubler as a backing plate, drilling through the stainless first and then the doubler – that also helped avoid burrs.

I’m making slow progress on getting the lower wing skins riveted on; I’ve chosen to do that work with a partner, even though it slows me down. So while I’ve had no riveting help, I decided to get started on the fuselage – specifically, on the firewall.

It’s a relatively easy place to start, all that’s necessary is a bit of plans study and some time to identify all the stiffeners, brackets and gussets that are required. The fit on some of these parts leaves a little to be desired, however.

Here’s one example where diagonal stiffeners nest into gusset at the upper firewall corners, all of which rest under steel brackets. Unfortunately, that little cutout in the gusset isn’t deep enough to allow that stiffener to fit correctly with prepunched holes in the firewall – so some adjustment is required. Vans’ plans say to tweak the end of the stiffener to fit but that would be too easy, wouldn’t it? To preserve edge distance on that part, I pulled out my trust Dremel tool and routed out the cutouts in the gusset. Problem solved, and I’ve kept an extra 0.0001 percent margin in the structure. I feel much better.

There are also a couple of 0.025″ shims that ride on top of those stiffeners. They took a few extra minutes to fabricate, no big deal. There’s also an extra stiffener that must be fabricated from 6061 angle. The stiffener itself is easy…finding the stock you’re supposed to cut it from is the challenge. There are three pieces of angle stock that could be used, just don’t choose the one that’s already cut to length for another part!

After getting the minutia squared away, I clecoed the firewall together – a nice bit of visual progress!

Finished inventorying the hardware bag…only one bag ‘o hardware missing, a replacement is on the way from Van’s.

The wing kit arrived two days ago, and it’s taken me that long to unpack everything and get parts squirreled away in my limited shop space. I lined up some unloading help from my friend and colleague Sam Seagle, but the ABF driver was a whiz with his hydraulic hand lift and was able to get the crate into our garage with no help. Like a lot of delivery folks who stop by the house when the garage door is open, he couldn’t believe that someone would actually build an airplane in their house. Here’s the crate, fortunately no damage on arrival.

Everything is so neatly packed, it’s a shame that it has to be taken out…
…but I did anyway, and managed to store everything but the skins. Got everything checked off the inventory list except the hardware bag.
Now the fun part…inventorying the hardware bag. Ugh.

I ordered the fuselage today! Expected delivery date is the week of 17 March.

One more task to accomplish before declaring success on the wing bulkheads…drilling two holes out to 0.25″ to accommodate bolts and spacers that hold the bulkhead halves exactly 1.438″ apart. Why does it have to be exactly 1.438″? I don’t know…ask Vans. Here’s one bolt and spacer in place.

Here are the bulkhead halves fitted in place around the previously-mentioned spacers and four aluminum blocks that simulate the wing spar root attach points. These were precision machined by friend and fellow RV builder Rich, who just happens to own his own machining company. That’s a handy business to have when you’re building an airplane!

Some of those close-tolerance bolts took some persuading and liberal application of Boelube, but in the end they went in. This is an extremely beefy assembly…which you would hope it would be, since it keeps the wings attached to the airplane!