>The point here is that ALL of the metal in the airplane should be at the
>same potential. This includes wings, tail surfaces, ailerons, flaps, just
>whatever is made out of metal.
>
>There is a current AD note on the Beech King Air series to install ground
>straps on the rudder of the airplane. The reason for this is that static
>electricity would build up charges on the rudder and then discharge to the
>fuselage. In the process of doing this the hinges would become eroded.
>
>Now our little GStars are not in the same speed range, and will not be
>flying through the same kinds of weather, but the point here is that you do
>not want different parts of the airplane to be at different potentials.
>
>What Bob suggested earlier is a fine way to go about doing that, but I
>suspect it is a bit of overkill. In our case we have a bonding strap that
>runs from the engine to the cage to the wings to the vertical tail and to
>the horizontal tail. To accomplish this a #2 copper wire runs from one of
>the starter mounting bolts to the lower left side engine to cage mounting
>bolt. The negative pole of the battery is grounded to the cage using a #2
>copper wire to the bolt that secures the cage to the shell underneath the
>baggage compartment floor. Short pieces of braided strap ground the wings
>to the cage and one long strap runs from the bolt under the baggage
>compartment floor to the tail section of the airplane.
Were talking about two different issues here. The "bond-everything-
to-everything-else mania swept through the Ez crowd about 10 years
ago. These efforts are to elminate and/or reduce noises in radios
due to static build up on surface of aircraft that causes tiny
currents to flow in not-so-well connnected joints like control
surface hinges. I've yet to see any confirmed case where this
was useful on a homebuilt and I doubt that it's going to show up
on anything less than a Lancair or Glasair in the 200 kts range.
The DC POWER DISTRIBUTION ground system is another thing all together.
Here, we're trying to (1) reduce the resistance in the starter
cranking pathways to the lowest practical value, (2) avoid running
battery currents through structure . . . especially welded steel
where unwanted magnetization can take place, and (3) avoid the
fabrication of ground loops where alternator and/or battery
currents flowing in airframe can induce noises in other systems
not well thought out with respect to installation and grounding.
Bob . . .
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