Cabin cover holes

I've been very slowly working on the remaining fuselage tasks - between shelter-in-place, losing my 15-year-old cat to cancer (I took July off to take care of and spend more time with him), and a lot going on at work, I've been far less productive on the plane than I'd have hoped.

R.I.P., friend

So, when time permitted, I started match-drilling the metal parts into the cabin cover. First, that involved using some spreaders to push it up/out flush with the skins:

Cabin cover clamped in place and pushed up against the tailcone skin

Cabin cover flush against the tailcone top skin

I match-drilled the side and tailcone top skins into the cabin cover:

Fuselage and tailcone skins match-drilled and clecoed to the cabin cover

Then the bulkhead side channels into the cabin cover door flanges:

Aft bulkhead side channel match-drilled and clecoed to the cabin cover

Wife match-drilling aft bulkhead side channel into cabin cover

And finally the bottom flange of the door opening into the mid-cabin deck and longerons:

Bottom door opening flange match-drilled and clecoed to the mid-cabin deck and longerons

To my own surprise and relief, the holes did line up nicely right at the center of the longeron flange :)

Next was the forward bulkhead side channels, including the bent top portion:

Forward bulkhead side channel match-drilled and clecoed to the cabin cover

Bent portion of the forward bulkhead side channel and gusset

The right side had almost no gap with the gusset in place, but the left side had a significant gap (meaning I sanded too much?). That doesn't matter much, since it gets filled with structural filler later:

Right bulkhead side channel, with no gap to the cabin cover

Left bulkhead side channel, with a significant gap to the cabin cover

It was then time to final-drill those holes to size (#12 on the bulkhead, #19 on the mid-cabin deck), which became significantly easier after I removed the forward top skin:

Door opening flanges final-drilled to the metal structure

And finally, I countersunk the holes for screws to sit flush (contrary to what the manual says, there is room for a countersink cage on the bottom flange):

Bottom door opening flange with countersunk holes for screws

Screw sitting flush on the bottom flange of the cabin cover door opening

Aft door flange holes after countersinking

Screws sitting flush against the aft door flange

The forward vertical flange is where the thickness difference is most apparent, and the countersink is clearly at a slant relative to the gel-coated surface, and those holes required me to at least hand-tighten the screws in order to see if they were really flush:

Screws sitting flush against the forward door flange

Screws sitting flush against the outboard side of the tapered flange

On the side that had a gap, I used a .125" piece of aluminum to make sure the countersink bit had some backing:

Aluminum backing for the countersink bit

I skipped the parts of this section involving the windshield and rear windows for now (I'll get the Cee Bailey's transparencies later), and I'm waiting for the Aerosport overhead console before I drill the center cabin brace. There's still a lot to do here - countersinking all the side and top holes, drilling holes for antennas, adding antenna ground planes, giving it a smoother finish in areas that won't be covered up, etc.

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 39.9h

Cabin cover sanding

To make the upper portion of the bulkheads nest properly against the cabin cover, I marked the contact area between them, and sanded that flat:

Bulkhead attachment surface after only partial trimming

Flattened bulkhead attachment surface

For the door inside flanges, I read several reports of people that trimmed too much off and had to rebuild it (VAF post) and recommendations to not fully trim it until I'm fitting the doors (VAF post 1, post 2), so I trimmed it but gave ample margin from the suggested 1" from the bottom, and from the side scribe lines:

Markings for cutting the inside door flanges, well below the target 1" distance from the bevel

Plenty of margin between the scribe line and my cut

Inside door flange, trimmed far from the scribe line

I looked at several photos from other builders (like these and these) and they all seem to have trimmed more than this, so I should be fine with final-trimming later with the doors. I do plan to use the McMaster-Carr seal (post).

I realize this means there'll probably be a second cut later to adjust these, but at least I can drill and countersink the holes along the flange without interference.

Towards the end of this process, I found the the Dremel rotary tool actually cuts the fiberglass much more easily than the oscillating tool, and while it makes a bigger mess, it's basically a "directed jet" of fiberglass dust, so as long as I stay away from it, I actually get less fiberglass on myself:

"Working with fiberglass is not messy at all", said no one over

Besides that, I had several more passes of trimming the various flanges to fit well.

Cabin cover fitting well on the fuselage

Now that it fits properly, I can start drilling the attachment holes.

P.S.: OMG I hate fiberglass. How do people find it fun to build entire airplanes out of this?

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 27.6h

Cabin cover started

We got started on section 43, the cabin cover, which is the largest fiberglass part of the build. It starts with making some markings for later drilling the door flange:

Cabin cover door flange hole reference markings

It quickly jumps to trimming and sanding the cover. We trimmed the edges with a Dremel oscilating tool, then sanded with a combination of an orbital sander, sanding block and Dremel rotating tool, and that has taken almost 10 hours of work so far:

Trimming the mid-side skin flange on the cabin cover

Sanding the cover flanges

And more sanding of the flanges

The corners of the door flange need some additional sanding and a notch to fit around the mid-cabin deck flange:

Notch on the corner of the door flange

After 5 attempts and many hours sanding and trimming, the cabin cover finally fit properly:

Cabin cover fitted against side skin and tailcone bulkhead

Mid-side skin flange clearing the longeron

Tailcone forward top skin fitted over the cabin cover

Victory! Cabin cover fits!

In the process, I also found that the scribe lines are pretty much useless, since they don't match at all the required dimensions:

Trim line doesn't match the dimension on the plans

There's still a lot more sanding and trimming to be done - I haven't trimmed the other window flange, the inside of the door flanges, or the windshield flange, and the tailcone top skin flange could use some slight sanding to not push against the bulkhead.

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 16.3h

Brake lines done

I got the fuel hoses from Aircraft Specialty, and installed the one that's done in this section, and torqued all the fittings:

This involved enlarging the system bracket holes a little more (to 5/8"), and splitting the AN931-6-10 grommets so I could put them around the hoses (I also took the opportunity and did the same for the fuel hose holes, to 7/16" for AN931-7-11 grommets).

Time lapse:

Total brake line rivets: 8
Total brake line time: 11.0h

Forward fuselage access panels (OP-43)

I was planning on adding access panels forward of the windshield anyway (seems to be a common mod), so I was happy that Van's released an official OP kit for this (OP-43). It works pretty much like all access panels - match-drill the doublers, cut the skin, then file it all down until it fits well:

Doublers and covers atop the forward fuselage top skin

Forward fuselage top skin match-drilled for the doublers and marked for cutting

Forward fuselage top skin after cutting, with doublers and cover on

Whenever I do the next batch of primer, I'll include these so I can start riveting them (though I won't prime for rivet the top forward skin for quite some time still).

Time lapse:

Total forward fuselage access panel rivets: 0
Total forward fuselage access panel time: 4.3h

Brake lines mostly done

We started bending the brake lines - it was at first an exercise in patience, and our first attempt was definitely not good :)

Very irregular curve on our first attempt on making the brake line (left), vs a better result on the second (right)
Kink made during our first attempt on making a brake line

We persisted, and the second and third attempts were actually quite decent:

Firewall fittings connected to rigid brake lines

Rigid brake line bends
Rigid brake lines going down the firewall
Rigid brake lines going aft through the tunnel
With that done, I dimpled and riveted the ducted flanges to the tunnel:

Ducted flange riveted to the tunnel above the brake lines

For the tunnel-to-gear tubing (as well as the pedal tubing in section 38), I'm just getting the lines made by Aircraft Specialty, plus I need to torque all these fittings, so I'll have a short follow-up, but other than that this section is complete.

Time lapse:

Total brake line rivets: 8
Total brake line time: 6.5h

Tailcone attachment complete

The next step in the tailcone attachment was, well, to detach it :) so I did:

Tailcone detached from the fuselage

I added the Panduit conduit mounts to the lightening holes:

Match-drilling Panduit conduit mounts to the bulkhead

The sequence here was to attach the tailcone, the baggage/rear seat floors, drill everything needed (e.g. door, floors, covers, etc.) while the cone was attached, then detach it, so that I could do a single larger batch of primer and need less post-primer drilling.

After that batch of primer, I riveted the bulkheads together:

Bulkheads riveted together and to the Panduit conduit mounts, after primer and paint
and attached those to the fuselage - the plans call for attaching it to the tailcone first, but I figured this would be easier since there are more rivets on the baggage rib attachment:

Bulkhead riveted to the baggage ribs
With this, we finally attached the cone for good:

Tailcone clecoed to the fuselage once again

then riveted it:

Left side skin riveted around the baggage door opening

Fuselage and tailcone longerons bolted together

Tailcone (left) and fuselage (right) bottom skins riveted together

About going out of order and it being easier this way - wellll, at the very end, when we got to the part that would normally be done without the fuselage in place, we screwed up badly on one rivet and had to upsize it. We tried setting the surrounding ones but they were starting to look really bad too, so we removed it all and switched to CherryMax (CR3213-4-2, CR3243-4-2 and a CR3243-5-2 depending on the hole):

Enlarged hole from removing a bad rivet :(
That face you make when you badly enlarged a hole while removing the rivet :)
Fixed bellcrank rib attachment, using CherryMax rivets

With this, section 32 is complete!

Time lapse:

Total tailcone attachment rivets: 236
Total tailcone attachment time: 22.8h