Mid-fuselage ribs riveting done, skins started

We finished riveting fuselage bulkhead and baggage ribs:

All mid-fuselage ribs and bulkhead riveted in place

I clecoed the bottom skins on and final-drilled all the holes:

Mid-fuselage section with skins on
The floor stiffeners required some fluting to line up properly, then they were final-drilled as well:

Floor stiffeners, fluted and final-drilled in place

Mid-fuselage section with skins and floor stiffeners only (it barely clears the ceiling!)
I found that the holes from the skin to the outboard seat ribs don't align :( so I'll need to flute that part, which will be especially tricky with it already riveted in place:

Since I only have a vise-grip-style fluting plier, which would be even harder to use in this space, I've ordered a regular plier from Spruce and will give that a try when it gets here - I have plenty of other holes and edges to deburr in the meantime.

Time lapse:

Total mid-fuselage ribs and bottom skins rivets: 412
Total mid-fuselage ribs and bottom skins time: 67.5h

Mid-fuselage ribs riveting, part 2

With the parts all primed, I started by riveting various small parts to the ribs:

Step mounting brackets and seat rib subassemblies riveted together
Of course, while doing this, I realized that two little parts had been forgotten when doing primer :( so one more primer session had to be done:

Two seat belt attach lugs I forgot to prime :(
I got lazy this time and decided to do it with rattle-can primer. The color difference doesn't really matter since any apparent parts of the interior will be painted anyway:

Rattle-can-primed seat belt attach lugs, riveted to the rib
I also inserted the heat tee, which allows me to continue riveting the ribs:

Rear tunnel with heat tee installed
I riveted some of those ribs so far:

Most rear seat ribs have been riveted in place

Time lapse:

Total mid-fuselage ribs and bottom skins rivets: 326
Total mid-fuselage ribs and bottom skins time: 55.2h

Firewall riveting

I dimpled then started riveting the firewall parts by the forward seat ribs (aka tunnel), adding all the nutplates, the inspection panel backing plate, the fuel valve attack bracket flanges, and the scat tube support:

Inspection panel backing plate/cover, fuel valve flanges and scat tube support with nutplates riveted

Forward fuselage ribs with nutplates, inspection panel backing plate, nose gear tension fittings and fuel valve bracket flanges riveted on

Forward fuselage rib riveted to nose gear tension fitting

I then dimpled the recess box and the firewall bulkhead to accept the rivets:

Dimpled firewall bulkhead
and finally started riveting it all together:

Firewall bulkhead with most parts riveted to it

Forward side of the firewall bulkhead, with most parts riveted to it

In the process, I also realized that the rivet gauges I have don't match Van's spec - Van's allows smaller shop heads overall, and with some of the rivet lengths they specified, it's impossible to get to the gauge's "official" spec. This applies to most firewall bulkhead rivets, so I had to measure those with a caliper - specifically, the gauge has a hole that's about .19", and the spec calls for .163". The height was almost right on the gauge - the gauge has .06", and the spec is .05".

"Standard" rivet gauges don't really match the MIL-spec that Van's recommends

There's still quite a bit of riveting left to do, but this is a good start.

Time lapse:

Total firewall rivets: 512
Total firewall time: 49.9h

Started fuselage side skins

I got started on the dreaded section 29 - Fuselage Side Skins.

Longerons and roll construction angles ready for cutting

The first part of this is bending of the longerons, which is a lot of brute force with a mallet to get them to match the template:

Longeron matching template after bending

Time lapse:

Total fuselage side skins time: 6.4h

Mid-fuselage ribs and firewall primer

We finally did another batch of primer, after periods of heavy smoke, then business travel, then too-cold weather. This included parts from the mid-fuselage bulkheads/ribs and the firewall:

Some parts drying after washing with PreKote

All parts after PreKote

Ribs, firewall and inspection panel parts after primer

Ribs and firewall parts after primer

Ribs, firewall, ventilation ducts and inspection panel parts after primer

Ribs and firewall parts after primer

A less-than-amused primer applicator at the end of the day
With this, we can finally resume riveting for both sections!

Time lapse:

Total mid-fuselage ribs time: 48h
Total firewall time: 24.4h

Forward fuselage countersinking and inspection panel

I finished machine-countersinking forward-fuselage parts:

Machine-countersunk center section side plates

Machine-countersunk fuel valve flange brackets

I then continued to installing the tunnel inspection panel - this starts by drilling the rivet holes onto the tunnel rib:

Tunnel inspection panel rivet holes match-drilled

then marking and cutting the rib for the panel:

Tunnel rib with corners of panel opening drilled out

Cutting edges of the tunnel rib panel opening

Tunnel rib panel opening
After that I trimmed the hole slightly to make sure the cover plate fit nicely over the doubler:

Tunnel rib with backing plate clecoed on

Tunnel rib panel with cover plate on

I also got some work done on some parts that are officially done as part of section 28, but not used/installed until later for some reason:

Seat floor assemblies drilled, deburred and machine-countersunk.

Mid seat rail supports drilled, deburred and machine-countersunk
With this, most of these parts are ready for primer.

Time lapse:

Total forward fuselage bulkheads and ribs time: 34.5h

Firewall deburring and countersinking

I finished deburring and countersinking the firewall parts:

with this, most firewall parts are ready for primer:

Time lapse:

Total firewall time: 21.4h

Mid-fuselage ribs deburring

I spent quite a bit of time deburring parts for primer. No pictures, only the video below.

Time lapse:

Total mid-fuselage ribs rivets: 196
Total mid-fuselage ribs time: 44.6h

Forward fuselage ribs and bulkheads progress, Andair fuel valve bracket

I made some more progress in this section. I started by trimming the control column mounts, which my new band saw blade made a trivial task:

Trimmed control column mounts
I then clecoed and match-drilled the forward bottom skin ribs, which go underneath the pilot/copilot floor:

Forward bottom skin and ribs
I attached the firewall parts to it and final-drilled their holes:

Firewall and tunnel attached to forward bottom skin and ribs
then finally added the floor panels:

Floor panels mounted to bottom skin/ribs/firewall

Floor planels mounted to bottom skin/ribs/firewall
I got a kit for a tunnel side access opening - its holes didn't line up with the pre-punched ones, so per their recommendation I shifted the whole thing forward and drilled new ones. This also required trimming off the corner of the doubler:

Tunnel access panel doubler match-drilled into place
A few days later, I received my Andair fuel valve:

Andair duplex fuel valve (extender not shown)
The small challenge with those is that they don't fit into the Van's-provided bracket, so I had to fabricate a new one - slightly annoying since the flanges are at an angle (the tunnel does not have parallel walls). I'll leave somewhat more detailed steps here, in case it's ever useful to anyone.

I started by laying out the existing one onto a new sheet, and then mirrored it to make room for all the holes:

Fuel valve bracket sketched on aluminum sheet, based on original part
I also realized the holes are not symmetrical, so it'd be tricky to transfer them onto the sheet, but luckily the face plate has the exact same alignment, so I used that:

Fuel valve face plate holes align with the valve holes exactly

Transferred holes from fuel valve face plate to sheet layout
I drilled the holes, including the center one with a unibit to 1-1/4", and adjusted slightly to make sure the valve fit:

Valve temporarily attached to new bracket web
This would make the web for a new bracket, and I also cut two 2" x 2.5" rectangles for the flanges. I bent them using a wood block and rubber mallet, then transferred the holes from the original bracket onto them, making them exactly .064" lower (so that the web, coming atop the flanges, would be at the same height):

Transferring holes from original bracket to new bracket flanges

Side view of hole alignment between old and new bracket parts
I picked two points at reasonable edge distances on the "webs" of both flanges, and drilled holes for nutplates there:

Nutplate holes on new fuel valve bracket flange parts
With those loose parts, I clecoed the flanges to the tunnel, laid the web on top, and then clecoed the original part just above them, to get the same spacing:

Fuel valve and web part laying onto flange parts, with original bracket above it
I started by visually aligning the center shaft with the original bracket's hole, and clamped the web to the flanges:

Alignment of Andair fuel valve center shaft with center hole of the original bracket
I verified by putting the tunnel cover on and checking that the center was aligned (minus parallax) with the original hole meant for the valve:

Tunnel cover on top of tunnel, for valve alignment

Valve shaft alignment through the cover hole
With that, I went on to match-drill the nutplate screw holes onto the web:

Match-drilled web and flanges for the new valve bracket, seen from the top

Match-drilled web and flanges for the new valve bracket, seen from the bottom
I checked that it overall matches the original part in size and flange angles:

New valve bracket, with original bracket on top to check for matching angles and distances
Then finally, I countersunk the nutplate holes, deburred and clecoed the whole part back in the tunnel:

Final-drilled, deburred and countersunk parts for new valve bracket

New valve bracket mounted into place
Finally, I attached the forward center section bulkhead to the forward ribs and match-drilled them:

Center section bulkhead clecoed to forward ribs and skin
Next I'll start disassembling and deburring all these parts, then priming and riveting them.

Time lapse:

Total forward-fuselage ribs and bulkheads rivets: 0
Total forward-fuselage ribs and bulkheads time: 23.6h

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