Advice: Almost 14 Retrofit Install

I am looking for advice to retrofit the almost 14 seat mod for a built RV7-A which I am not the builder. I am struggling to remove the last few rivets that are hard to get access to. (See pictures below) The first ones (yellow) are right up against the sidewall so I can't get a drill bit on it, any ideas? Additionally, I have my static line and magnometer bundle passing through on each side. Do I need to cut these and add connectors or does someone have a good idea how to remove the rivets without disturbing the lines?

The last two (red) on the top are attached to the angle iron at the top of the skin and are under the canopy track. Do I need to remove the canopy track to get access to these? If so, do you guys have a good way to do that since I'm struggling to get a hold of the nut hidden in the U-channel for the track.

Thanks in advanced.
Josh

Josh, find a long flat head screwdriver, sharpen, use as chisel and wack the heads off, may gouge things up some under there, no harm. This was my technique in a old 6A. Worked well. You’ll love the mod !

Oh, and no cutting lines, though I only had static there, magnetometer was in floor tunnel

90 degree pneumatic angle drill

This is what you need. These aviation style 90 degree angle drills are designed to work in tight spaces. I love mine! See

https://www.siouxtools.com/industrial/drills/miniature-angle-drills/

The Yard offers some used drills at

https://www.yardstore.com/pneumatic-and-cordless-tools/pneumatic-and-cordless-drills/pneumatic-angle-drills/surplus

These are always available at AirVenture & Sun N' Fun used.

Check with your local RV builders or EAA Chapter. You might be able to borrow this tool. It will make that job easy, plus you won't chance scarring up the surrounding aluminum. FYI, these drills use special short threaded bits.

https://www.aircraftspruce.com/search/search.php

https://www.amazon.com/Threaded-Pneumatic-0-3HP-Industrial-Maintenance/dp/B0BVVFXRTW/ref=sr_1_8?keywords=angle+air+drill&qid=1685961126&sr=8-8#customerReviews

I just finished installing this mod on my RV6 and I understand the difficulty you can have removing the old seatback support. The good news is, when you get the old one out, you’re almost done. I had to knock off the tails on most of my rivets that I couldn’t drill because I couldn’t access the manufactured head on the top. I used my close tolerance angle drill on a couple of them. There were several hidden under the side rail piece. If you use a sharpened cold chisel, you might have better luck. It took some very aggressive pounding with a hammer to bust off the rivet tail - or head. I really had to mangle the old seatback support to wedge it off the rivet shank, and then had to grind the bottom of the rivet shank flush to make the new SS seatback support fit nice. I also had to shave off a little on the outboard ends of the new support to get a good fit.

Bottom line is, it’s definitely more comfortable for me. I don’t tilt all the way back, because if I do, I can’t see anything at all when I’m taxiing, and my headset is touching the canopy. I thought I would have more headroom, but I don’t. The canopy slopes down going aft, so headroom on mine stays the same no matter how much tilt I have on my seatback. I modified my flapper piece on the back of the left seatback to allow more aft tilt than I had before, but just enough to allow me to see a little on the left side of my cowl ahead.

Josh,
Check your private messages in regards to Kitplanes article on drilling in tight places.

CG question for the mod

Don’t want to hijack this thread but:

I’ve thought several times about installing the “almost 14 mod” to give a little more cockpit room but I have a concern about cg. The arm for the pilot/passenger/copilot for the RV7A is 97.48. Doesn’t moving the seat frame top slightly back, like the mod does, and shifting more of the crew weight towards the aft change the arm any? What’s the impact of more crew weight towards the aft?

My aircraft recently underwent a prop change from a Hartzell aluminum two blade to the MT9 composite three blade. This took approximately 15lbs off the nose. While 15lbs isn’t a lot I was surprised to see the impact it had on my cg. It was almost a full inch. Does Allan at Antisplat discuss this issue?

interesting

It would be interesting if someone weighed their plane with a pilot in the seat before and after the mod.

Maybe someone can weigh the plane with the mod with a pilot inside, and then adjust the seat to the old position and re measure.

This will give some idea of the new station for the pilot and passenger.

I would be interested in that weighing too. I had the same concerns when I installed my almost 14 mod. Then, when I thought about it, my weight is concentrated when my bu.t sits, thanks to gravity. Isn’t the G-load where you sit? I’m just asking, because I don’t know. It just seems logical to me. I think when you pull a couple G’s, there is more force on the newly located seatback support than before because of the changed angle, but how much? I don’t think it’s a linear calculation. Where is your 18 pound head? Tilted forward, or back? Makes a difference for the sharp mathematicians among us - maybe.

I would be interested in that weighing too. I had the same concerns when I installed my almost 14 mod. Then, when I thought about it, my weight is concentrated when my bu.t sits, thanks to gravity. Isn’t the G-load where you sit? I’m just asking, because I don’t know. It just seems logical to me. I think when you pull a couple G’s, there is more force on the newly located seatback support than before because of the changed angle, but how much? I don’t think it’s a linear calculation. Where is your 11 pound (human average) head? Tilted forward, or back? Makes a difference for the sharp mathematicians among us - maybe.