Hangar Flying => Hangar Flying => Topic started by: bbrown on October 31, 2006, 01:02:57 PM
Title: Is the lower firewall structural?
Post by: bbrown on October 31, 2006, 01:02:57 PM
Does anybody know for sure if the lower portion of the firewall is structural? I would like to make a notch in the lower portion to accommodate the air intake like so: http://bbrown.smugmug.com/photos/106918671-S.jpg The engine I have is an IO360-C1C6, and it's intake faces the firewall, and there's not enough room for the throttle body without putting in a relief.
Title: Structural Firewall
Post by: GlennBob on November 01, 2006, 11:12:37 PM
Dear Bbob,
I've not responded because I'm not a builder, but from what I can see, the main spar crosses the firewall above the area you show. I think as long as you stay away from the main spar and the longerons (area where the motor mounts attach), I think you should be O.K. Maybe a true EZ builder will respond. Waiter would be a good one if you can get his attention.
Glennbob
Title: Is the lower firewall structural?
Post by: Waiter on November 02, 2006, 06:18:14 AM
You should be OK, Be careful, there really isn't that much room in there. This is the area inside the "hell hole"
When cutting, don't cut into the center spar or the gear leg. (this will ruin your entire day)
Good luck
Waiter
Title: Is the lower firewall structural?
Post by: Bruce Hughes on November 02, 2006, 08:24:03 AM
Many of us have a NACA duct in that area. We also have an access plate in the top of the duct so the inside of the "hell hole" can be reached (with difficulty)
Just be aware that the area you are changing is extremely useful for passage of (1) throttle, mixture, and carb heat controls (2) fuel line (3) 12 V and ground wires (4) sensor wires (5) rudder cables (6) aileron controls (7) cabin heat air or oil line and vacuum line if you have such
The area is nearly impossible to reach unless the aircraft is sitting upside down. ALL of the above (1-7) should be installed while you have it upside down. Nothing there is easy to change later
I think there is a VERY high potential for you to find that the change in the plans was NOT a good idea.
It will be VERY difficult to change back to the original configuration after you do the cutting. I have a NACA duct there but I have often wished that the air was coming in on each side ABOVE the strakes. Lots of builders use downdraft cooling.