My RV-8 Gear Tower Mod

Here is my detailed account of the gear tower mod for the RV-8.

This is not my design, but a common approach already completed by many RV-8 builders.  This is just a photo log of my gear tower mod project.

There are many people who have done this many ways.  Special thanks to Axel Alvarez for his template which he kindly mailed to me.  Thanks Alex! If you want to see any photos bigger for detail, just click on the image and it will enlarge significantly (800 x 500 pixels+/-)

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Essentially this revolves around one of the gear tower pieces, F-802C (in my pre-1 plans) being modified so that you can get inside the gear tower structure to (buck rivets, tighten nuts, fittings) without losing your religion.

First off, why do it? Well my hands and forearms are just too darn big to do much through those tiny holes, much less, hold a bucking bar or turn a wrench.

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So what’s a guy to do?  Cut out this web of .040 aluminum (the area between the Sharpie lines)

But the question is always, “Won’t that weaken this crucial area?”

Well, I’m just an A&P and not an engineer.  I understand what is going on (stress factors) but have relied on others (an aeronautical engineer/RV-8 builder for example) to run the numbers and show that the mod, may if anything make this area stronger!

Here is what the removed piece amounts to.  Not much!

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Here is the completed F-802C top plate with cut-out done.(left side only here)

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Next you need another piece of .040 2024 to make the cover plate.  Thanks to local RV builder, Mike “Fossil” Ballard, who had two 8 x 12 spare pieces in his shop, I was able to get it done quickly.

Several guys have good info on the Van Airforce site also on this (Mike Stewart, Dan Horton and Alex Alvarez)  They all ran the numbers and I was convinced it was a safe mod.  Mike’s is a little more straightforward, but he hasn’t had any problems with his version.

Alex went so far as to make his template available.  I made my own based on his description and was happy to see his template matched mine.  Nice thing about his was he already had the holes marked, which saved me a few more precious minutes.

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Nuff said.  Don’t wonder or ask what the vise grip is on there for.  I forget.

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I positioned the cover plate over the hole in the F-802 piece with the side angles cleco’d on to make sure spacing didn’t get off (look at the back side of the F-802C). I then drilled the top (of radius) holes on each end, cleco’d those then drilled the rest all with #40 drill for pilot holes.

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Next I removed the top plate after match drilling, and marked and drilled for the K-1100 nut plates.

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I went ahead and drilled all the holes for screws the correct sizes (#19 for the screws and others already done with #40 for nutplate rivets)

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I guess you could mechanically countersink these, but being where it is, I (personal preference) didn’t want to removed any more material.  So I dimpled these.

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In the end, there are several ways to skin this cat.  Of course, many people have built their 8’s without this mod and that’s fine.

But as for me and my hands….I’m pleased with the result.