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FOT Location?

D

Doug Rohrer

Well Known Member
I am starting to populate the firewall on my RV-9A project. I am using a carbureted O-320 engine and Garmin G3X Touch avionics. I want to do as much firewall work as possible while the fuse is on the rotisserie; that is, before mounting the engine. To those who have gone before me, where should I install the Forrest Of Tabs ground terminal block? It seems it would fit well high and centered on the forward side of the firewall, but a lower location would be more convenient on the rear of the firewall where many more ground terminations will need to be made. I want to avoid any interference with engine systems, mags, oil filter, etc. The front top skin is still off for accessibility.
 
Doug Rohrer said:
I am starting to populate the firewall on my RV-9A project. I am using a carbureted O-320 engine and Garmin G3X Touch avionics. I want to do as much firewall work as possible while the fuse is on the rotisserie; that is, before mounting the engine. To those who have gone before me, where should I install the Forrest Of Tabs ground terminal block? It seems it would fit well high and centered on the forward side of the firewall, but a lower location would be more convenient on the rear of the firewall where many more ground terminations will need to be made. I want to avoid any interference with engine systems, mags, oil filter, etc. The front top skin is still off for accessibility.
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Yes, more grounds will be from within the cabin. I located mine above the longeron level on the backside of the firewall. It is a bit too high and hard to reach to debug any ground issues. You might want to consider how you would reach any possible locations for that possibility. You could locate it just below the longeron plane, over the battery and on the cabin side. It could be grounded to a common bolt as the battery to chassis, accessible, and still out of the way. But that is just thinking out loud. Maybe, Walt (or others) would have some better insight with multiple avionics installation experience.
 
I Installed a forest of tabs high up and pretty much centered on the firewall, and I used zero tabs on the engine side....only the engine grounding strap went there. As with BillL, I used lots on the cockpit side.
 
Be careful that when you install things easily accessibility with skins off that you can still access things with the skins back on. As a quick check, cleco the skins on and see what you find.

I've bought RVs that had unmaintainable and inaccessible components...

Ed
 
I'm planning above the firewall angle that connects to the fuselage longerons. This ensures that they FOT and wires don't interfere with the rudder pedals/cross tubes.
 
I worked on a RV-9A a couple weeks ago that had the 'forest of tabs mounted on the engine side of the firewall... It had only one wire plugged into it... Everything else was grounded inside the cabin.

As for mounting anything top center of the firewall, think of later maintaining the airplane, try not to restrict easy access to things like batteries, oil filters & such.
 
FOT

I am glad I asked. I now plan to install the FOT near the battery and put both parts of the device on the aft side of the firewall, since that is where all the grounds will be. Thanks to all. Happy New Year!
 
Doug Rohrer said:
I am glad I asked. I now plan to install the FOT near the battery and put both parts of the device on the aft side of the firewall, since that is where all the grounds will be. Thanks to all. Happy New Year!
Click to expand...

Consider moving it even further back to the aft side of the sub-panel.
 
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