Various tasks completed today.
I ended the last session with some frustration that I could not set the F-724 baggage bulkhead rivets that connect bulkhead to the F-623 corner rib and center bottom skin.
I tried two times and had to drill them out again. The reason for this is that the spacing between the corner rib and bulkhead was just to big. On the other side, there was also a small spacing and I was able to rivet them and the rivet pulled in the tab towards the corner rib. On this side, the gap was just to big.
So yesterday, I finished by making a small shim, dimpled and primed it with a brush.
It's a shitty job to do this now so do yourself a favour and make the shim while all can go appart. In my case the bulkhead was already rivetted and getting the shim in and out was kind of a difficult operation.
Installed the shim and now at least, the spacing is filled. I'll rivet it later on but now I get some help from Cindy and I want to work on the bottom skin.
First installed the center bottom skin stiffeners and squeezed them to the firewall and the F783B cover support ribs.
Only the last cover support rib attach point can not be squeezed and had to be shot with an offset rivet set.
shop heads.
More shop heads on the cover support rib side. Some small denting but nothing to worry about.
Before the bottom skin goes on, you also need to set the connection of the F-902 bulkhead with the F-717 lower longeron.
It's almost impossible to do this when the bottom skin is on so don't forget it. The other side that connects the F-902 to the F-718 upper longeron does not have to be rivetted now. There is a note on DWG23 saying to wait with the top flange until the sup panel structure is drilled.
Before the bottom skin goes on, we need to do one more thing which is sealing the firewall in place with fuel tank sealant.
Yes, black death is back !
The feul tank sealant is put in between side and bottom skin and the firewall itself. The reason for this is to keep the toxic fumes and co out of the cockpit area.
The tank sealant is also used to glue the static ports in place. These can be rivetted on the side wall or glued.
The glueing option looks nicer so decided to go that way. Unfortunatly I didn't think of this earlier so I had to scuff away the primer from the tailcone side skin in order for the sealant to attach to the bare aluminum.
Then after scuffin and cleaning, I prepared a 30gram batch of sealant mixed at 10:1 and applied a layer of sealant on both sides and top of firewall.
It doesn't have to be a thick layer as lots of it would be squeezed out when you put the clecoes in.
Dirty clecoes, shitty mess... my fuel tank building experience is suddenly very vivid again.
Eh voila, all sealed... ready to dry.
I didn't touch the inside but it looked good as it got squeezed out. The spacing is very narrow between those firewall angles and side skin and you would only make a mess if your try to clean that.
Then glued in the static ports.
Back view. Play safe and put some tape over the static port opening. Would be hard to get the sealant out there.
It's all ready to dry and rivetting the bottom skin on will be next point on the list.