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Firewall Forward Watchouts

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Doug Rohrer

Well Known Member
I am starting work on the firewall of my RV-9A project. I will be using an O-320 engine, and want to do as much drilling, wiring, etc. as possible before mounting the engine. It seems like there could be some "gottchas" at this step. Any advice relative to the sequence of work or problems with the instructions or drawings? For example, can the piano hinge be installed on the fuse with the engine mount bolted on? I can see some riveting accessibility issues. Thanks.
 
Exactly - you may end up with a lot of gottchas with this approach.

I recommend:
- mount the engine
- fit the cowl
- figure out all the firewall placements being careful to look ahead for such things as oil line runs to the firewall mounted cooler.
- Do the prop, mixture and throttle runs per the Van?s plans, again noting interference with hose lines (the hose lines can move, the control cables have little leeway).
- Last are the firewall penetrations for wires.
- Now figure out if you can mount all the stuff with the engine present. If not, pull the engine and engine mount off the plane, do the work, then reinstall.

Carl
 
One thing I found out while drilling the firewall was to have someone back you up with a wood block. There is a lot of expansion with the thin stainless if too much pressure is applied.
 
Lay out and position things to make maintenance easy. Many RV's I've worked on have had a mess of wires in the way of removing the oil filter, for example. Run wiring such that there is a clear path to access mags and bits behind the engine without fighting wiring and plumbing.

One of the things I like about my Rocket is the intake scoop is attached with camlocs. Which makes changing oil easy without having to pull the whole bottom cowl, but still be able to have a good look around. Most things under the engine are accessible.
 
firewall penetrations

Hi Doug, If you have not seen these, they might help.

http://www.vansaircraft.com/public/rv14Cockpit.htm

Also, the full RV-14 plans are really helpful - even for an RV-8 so I guess they might be useful to an RV-9 builder. This was one of the best $10 I spent.

https://www.vansaircraft.com/cgi-bin/store.cgi?browse=videos&product=fd_plans

Google can help, but keep in mind these are random pictures of what other builders have done, and might not always be Van's recommended best practice.

https://www.google.com/search?q=rv-9+firewall&tbm=isch
 
The Van's recommended firewall penetrations are only for the engines that Van's sells. If you have any modifications to your engine the throttle, mixture or other penetrations may not work, but the locations are a starting point for adjustments.
 
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