Back from vacation and time for more airplane work. I had one remaining day off before work, and got the replacement F-729 parts drilled and then clecoed the whole F-706 assembly together.

We’re back from our trip to France…during which we didn’t actually go to France! My daughter’s figure-skating team was supposed to participate in competition in Toulouse, but due to the eruption of Iceland’s Mount Hafnafjordsigginastimoosebite…or whatever it’s called (Eyjafjallajökull, I think), we got refunds for our France tickets (thanks, Air France!) and bought tickets to St Thomas.

Needless to say, it was a little warmer in the Virgin Islands. We also had to put up with views like this every evening…

Moved on to the F-706 bulkhead today, including a rib and a channel that will eventually hold the elevator bellcrank. The rib annd channel are match-drilled to pieces of 6061-T6 angle that are fabricated from stock. Here’s the F-729 bellcrank rib match-drlled to its corresponding angle…

For some unknown reason, I didn’t take any pictures of the F-728 – but it looks pretty much the same. One minor screwup…both of these assemblies have a 1/4″ hole for the bellcrank attach bolt. When match-drilling that hole in the F-729 angle and channel, I managed to let the drill bit drift a little and wound up egging out the hole – not something you really want to happen when dealing with a primary flight control system. Fortunately, I have a lot of spare angle stock, and Vans delivered a nice new F-729A to my door. Problem solved!

I have three weeks of work travel and then a family trip to France, so no more updates for a month or so…

Got all the fabrication done on the rear spar carrythrough parts for rear spar carrythrough bulkhead, including the F-705B spar strap, F-605C doublers, and seatbelt anchors. The new bar stock still had some milling marks, so I buffed them out with scotchbrite. Only had to take off 0.002″ or so – around 1 percent – of the material to get the marks out. Vans says that you can go up to 10 percent without issues, so I’m good with the replacement parts.

A little bit of frustration over the last couple of days. When I started cleaning and prepping the F-705 parts fabricated from 2024-T4 bar stock, I noticed a lot of “mill marks” – gouges and scratches – that appear to be left over from the rolling process at the foundry. The stock was somewhat oxidized and dirty, and the marks weren’t apparent when I was fabricating bulkhead parts from it.

One example of the “mill marks” – longitudinal gouges on an F-605C spar carrythrough doubler –

…and a gouge on the edge of the spar carrythrough strap itself –

I had some phone and email conversations with Vans, who said that milling marks are normal. Nevertheless, I’m not really happy with using them for what I think would be a pretty structurally important part – maybe it’s just an attack of OCD on my part. I talked again with Scott Risan at Vans, and he offered to hand-pick good bar stock from their inventory and send me new material for free. Very cool!

One minor challenge on the F-705 is cutting that big mambo hole (that’s a technical term) in the middle of the angle. That required a lot of filing, sanding and finishing. I think it has something to do with the tip-up canopy latch…

With the angles done, it’s time to prep and prime all those F-705 and firewall parts.

Not much work going on the last couple of weeks, partially due to work travel and family time. The new 2024-T4 material arrived from Vans, so I started fabricating all those parts that you see in the pictures below. I didn’t take any new pictures, so use your imagination!

Fortunately everything came out well when match-drilling the angles…good edge distance all around. Bonus!

Looks good here, too…

One last bit of fabrication…these heavy angles nest into the intersection of the F-705 bulkhead side and top channels. For RV-7s/9s with tip-up canopies, these angles also provide an attach point for the cockpit rollover structure.

It’s not difficult to fabricate the angles themselves, but getting them properly clamped in place is important to ensure proper edge distance for all the rivets.

With all the subcomponent fabrication complete, today I clecoed the entire bulkhead assembly together and started match-drilling.

In addition to everything else it does, the rear spar carrythrough bulkhead supports the flap actuator arm. This is a weldment that transfers the motion of the flap motor (or hand-actuated bar) to the flaps. The arm rides in two delrin blocks that are drilled to accomodate the arm ends.

Not too much work is required to mount these blocks, just a little effort to lay out one hole and drill it on the drill press. The block is then bolted in place through that hole, aligned to the bulkhead, and the other hole is match-drilled in assembly.

Done and done!