Brake Lines, Center Spar Bolts and Extra Holes: 5.0 hrs

September 13, 2020

Had to order the right Loctite for the brake lines, but now that it came in, its time to cut the plastic lines and get them sorted. I debated upgrading to steel lines everywhere and I just couldn’t justify it. The plastic line is rated to 500 psi, and being a tail dragger we’ll end up flipped over long before you get anywhere near that level of brake application. A lot of people have used this plastic setup with no issues, so I’m not super concerned about it. I will be running steel flex line and aluminum tubing from the firewall to the caliper and I’ll highlight that in a later post when I get around to the firewall forward bit.

After those went in, Kacy noticed the empty holes in the center spar. I was assuming I would get to these later, but since we were both working in the area already, we went ahead and tackled it now. There’s 6 empty holes on each side of the center spar from the quickbuild phase. If you’re running tricycle gear, this is where it would mount. Since we’re running conventional gear, these holes have to get filled with something. We could fill them with rivets but that has two issues:
1) Squeezing this size rivet after the spar has been put together is dam near impossible. You can do this earlier if you do a standard build and are set on a tail-dragger.
2) Filling with rivets makes it impossible to later swap the gear to tricycle if you ever need/want to.

So we decided to just go with what the plans called for, and filled the holes in with some bolts. I also downloaded the “Official guidance for drilling holes in wing spar center section 7s and 9s”. The document I found was hosted on someone’s personal google drive, so I won’t link it directly, but if you search for the phrase above, you’ll find the forum posting on Vansairforce and can easily find the document. The passenger side extra hole is dedicated to the smoke system install and is the smallest hole. The middle two and pilot side extra hole will be used for anything that might need them. I labeled the spar to make sure I didn’t upsize any of the holes past the maximum recommendation based on position.

-Paul
(Total Build Time: 641.6)

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