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Thread: Firewall Forward Ground / Engine Ground

  1. #1
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    Default Firewall Forward Ground / Engine Ground

    Hi, the manual says for the fuselage side to remove only the powder coat on top left engine mount attachment point (just the small ring area on cockpit side). According to my understanding, the powder coat stays on in all other areas, incl. the front discs where the firewall touches the fuselage.
    However, after installing the firewall and moving on to the engine mount, I recognized in figure FF11 (bottom right), that I have to remove the powder coat of the engine mount at all 4 attachment points on both sides.
    Basically the firewall will be grounded from the 4 points of the engine mount but is insulated towards the fuselage since the poweder coat needs not to be removed there.
    Makes that sense? I am not sure if I am doing it right.
    7B51B336-25AD-4FC4-9197-34E50FBFCC78.png

  2. #2
    Junior Member Bill Tew's Avatar
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    Default Re: Firewall Forward Ground / Engine Ground

    Quote Originally Posted by Tobi View Post
    Hi, the manual says for the fuselage side to remove only the powder coat on top left engine mount attachment point (just the small ring area on cockpit side). According to my understanding, the powder coat stays on in all other areas, incl. the front discs where the firewall touches the fuselage.
    However, after installing the firewall and moving on to the engine mount, I recognized in figure FF11 (bottom right), that I have to remove the powder coat of the engine mount at all 4 attachment points on both sides.
    Basically the firewall will be grounded from the 4 points of the engine mount but is insulated towards the fuselage since the poweder coat needs not to be removed there.
    Makes that sense? I am not sure if I am doing it right.
    7B51B336-25AD-4FC4-9197-34E50FBFCC78.png
    You will certainly have a good ground!!

  3. #3
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    Default Re: Firewall Forward Ground / Engine Ground

    Quote Originally Posted by Tobi View Post
    Hi, the manual says for the fuselage side to remove only the powder coat on top left engine mount attachment point (just the small ring area on cockpit side). According to my understanding, the powder coat stays on in all other areas, incl. the front discs where the firewall touches the fuselage.
    However, after installing the firewall and moving on to the engine mount, I recognized in figure FF11 (bottom right), that I have to remove the powder coat of the engine mount at all 4 attachment points on both sides.
    Basically the firewall will be grounded from the 4 points of the engine mount but is insulated towards the fuselage since the poweder coat needs not to be removed there.
    Makes that sense? I am not sure if I am doing it right.
    7B51B336-25AD-4FC4-9197-34E50FBFCC78.png
    Yes the manual and figures are a little conflicted. The FUSE manual says to take the powder coat off the "TOP LEFT" one as does the FWF manual but then the figures point to the TOP RIGHT one. The sides they say are "Pilot right or left", so they are conflicted.

    It doesn't really matter as long as you have at least 1 of the points grounded. The grounding strap in on the "pilot" right, top side and is connected to the engine and to the tab on the engine mount. Be sure both these attach areas are free from powder coat. I use a Dremel tool with sanding drum.

    It will then ground as long as one of the mount legs is free from powder coat where it contacts the firewall and on the opposite side (of the same attach point) the fuse flange is also bare. You don't have to have all 4 attach points free (but it won't hurt).
    Dave Embry
    "You only live once.....
    ..but if you do it right.....
    ....once is enough."..

  4. #4
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    Default Re: Firewall Forward Ground / Engine Ground

    Careful having too many grounds. It could cause ground loops (the electrical, not airplane kind). A good ground is key. The ultimate would be 1 ground for everything. But that is impractical. The next best is one long path to the battery/power ground. Having one ground at the back of the fuselage frame, one in the middle, and one up front is pretty close to that.

    Having said that, it really won't be an issue other than maybe some noisy electronics. Hopefully...

  5. #5
    Senior Member Dan L's Avatar
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    Default Re: Firewall Forward Ground / Engine Ground

    Quote Originally Posted by flyingskibiker View Post
    Careful having too many grounds. It could cause ground loops (the electrical, not airplane kind). A good ground is key. The ultimate would be 1 ground for everything. But that is impractical. The next best is one long path to the battery/power ground. Having one ground at the back of the fuselage frame, one in the middle, and one up front is pretty close to that.

    Having said that, it really won't be an issue other than maybe some noisy electronics. Hopefully...
    What about AC43.13 recommending no more than 4 grounded wires per stud?
    Flying Carbon Cub EX #11 since 2011

  6. #6
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    Default Re: Firewall Forward Ground / Engine Ground

    Quote Originally Posted by Dan L View Post
    What about AC43.13 recommending no more than 4 grounded wires per stud?
    Honestly, the whole thing about ground loops kind of goes out the window with a tube frame. All the tubes are their own path. Metal bodies are essentially one large ground plane. So, it's harder to get loops. I guess if it ain't broke, don't fix it...

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