RV-8 Gear Tower Mod Question?

After doing my research I decided to do the "Gear Tower Mod" including the lower two holes in the F802-C R1 & L1. I noticed my access cover will partially cover a 5/32" hole adjacent to the 10th rivet up from top of the WD813-1 weldment. It's the same on both the left and right towers. My questions are:

1.) What is this for?
2.) Is it something I can move?
3.) If not, do I need to make room for it in my cover panel?

Thanks for all your help!
Tim

Aluminum tube mount screw

I think I remember this is a screw for mounting a clamp. I just made a notch for crearance.

I did not use it, but then I did not plumb the brakes or the fuel vent per the plans... You can always drill another hole to suit...

Thanks!

Thanks for the help!
Tim

This is why I donate for this site.
Started planning out my gear tower mod today and encountered this same issue. Did a quick scan of the plans and couldn't see why I couldn't cover the hole up but thought I would see if anybody else had encountered it before. You can see the hole just to the right of the top tape. Need to confirm it makes min edge distance with the planned hole right next to it or I might have to adjust some dimensions on my template to get the MED.

Be sure you check the clearance between the nut plates and the L chanels on the back side before you drill your screw holes!

Two mods or one?

It seems there are two issues w/in the gear towers: installing and inspecting the gear bolts and installing fuel lines. There seems to be a school of thought to invert the gear bolts so the nut is on the bottom, eliminating the need to get back into the tower to torque it. My question is; if you invert the gear bolt, is it still necessary or helpful to do the tower mod? How often do you need to get in there other than for the gear bolt installation or inspection?

Bolt up or down, to properly torque the bolt, you must get the gear off the ground. Once off, the bolt(s) will spin most likely. So you will need to get in there regardless. You will check the torque annually, or when you hear noises. Mine creaked on taxi as wing rocked to alert me to go torque them again. They have not creaked, nor changed torqued since installing the NAS nuts.

Questions for Kahuna

In your 2012 VAF post you described finding a loose gear leg nut. You mentioned that your gear squeaked; did you ever notice squirrelly ground tracking behavior? When you replaced the NAS679A6 nuts with the NAS1804-6 nuts were you able to use the same length bolts? I am not sure that the grip-length is the same with those two nuts. Finally, did you use the same hardened washers under the 1804-6 nuts? I have a terrible time getting a socket on the 679A6 nuts and am hoping the 1804-6 nuts are much easier to reach.

Thanks!

Dan Miller
RV-8 N3TU 1500+ hours

cdmiller said:

In your 2012 VAF post you described finding a loose gear leg nut. You mentioned that your gear squeaked; did you ever notice squirrelly ground tracking behavior? When you replaced the NAS679A6 nuts with the NAS1804-6 nuts were you able to use the same length bolts? I am not sure that the grip-length is the same with those two nuts. Finally, did you use the same hardened washers under the 1804-6 nuts? I have a terrible time getting a socket on the 679A6 nuts and am hoping the 1804-6 nuts are much easier to reach.

Thanks!

Dan Miller
RV-8 N3TU 1500+ hours

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Never noticed any ground handling changes. I could easily tell it was getting to be time to retorque by the creaking. Slight creak, got another 50 hours. Lots of creak, time to torque em.
I used the same washers. The nuts are NOT easier to reach! But they ARE easier to deal with. With the smaller 1/2" 12 point nut, a smaller socket than the 9/16, and that gives you the room you need to get onto them with a 12point 1/2" socket with no hassle at all.

BTW, my cutout goes all the way to the top of the tower. And this is useful. A lot of wires and things go up through the top and to the panel.

Why Doesn't Vans Make this Standard?

I'm a purely interested observer here and I don't mean to derail the discussion. That said, I do have a question. First, some caveats. I'm happily flying and maintaining my purchased RV-4 and I've never built an RV. I'm thinking I might want to in the future though and what I read hear concerns me. What I don't understand is why Vans wouldn't make such an apparently important mod as this gear tower mod a revision to the plans. What do the engineers at Van's have to say about this modification? It just seems odd that so many builders would be going down this road without any support from Vans.

Thank you!

Kahuna, thanks for the quick reply. So, did you use the original bolts with the new nuts? I can reach the nuts with difficulty, but can't get a 9/16 socket on some of them due to interference with all the AN3 hardware nearby. Thanks for your help.

Dan

There is more than one way to skin a cat when it comes to torquing those bolts hidden in the gear tower in a very difficult place. My friend Bruce, in Cincinnati, has designed a piece of hardware that captures the head of the bolt inside the gear weldment so that the bolt can't turn. The bolt installs from the top with the nut on the bottom. The bolt can't turn, you torque it from the bottom, very easily. The exposed bolt/nut combination protrudes further than the bolt head in the plans configuration, but I've never seen an upper intersection fairing that wouldn't cover this additional exposure completely. Bruce is hopefully making me a set and I will change them out on my RV8 next annual. The extra opening in the gear tower is nice for routing wires and running vent lines, etc during your initial build, but not as necessary, since you won't have to go in there to check torque on those sinful nuts (nasty language loudly observed) every year.

cdmiller said:

Kahuna, thanks for the quick reply. So, did you use the original bolts with the new nuts? I can reach the nuts with difficulty, but can't get a 9/16 socket on some of them due to interference with all the AN3 hardware nearby. Thanks for your help.

Dan

Click to expand...

I have the original bolts.
I also flipped all the an3 hardware around in the tower. That was a pain, but doable. Im not sure how doable that would have been without the tower mod. Probably still doable. My towers are full of stuff. Most notable a 2" scat for my rear heat. Also extra -6 lines from my smoke tank both supply and vent. My towers are busy.
To be clear, the nuts are about increased tensile strength first and foremost. As an added benefit, you can get a socket on them easier.