>I am planning to install Aeroflash nav/strobes, Duckworth landing lights,
>and a Gretz heated pitot tube in the wings. Is there an accepted method
>for attaching to the frame for the ground return. In other words, should I
>do something like drilling and tapping a #4 or#6 screw to the spar and
>attach the ground wires to that?
Would suggest #8 is smallest and #10 is better. Use PIDG terminal
with appropriate hole for the wire you're going to ground.
Buff area of contact between terminal and airframe with VERY
fine sandpaper. Fasten to the airframe and tighten a #8 screw
to 15 in-lb. The reason you want #8 or bigger is that the smaller
screws don't have enough "meat" in their cores to force a
gas tight joint between the airframe and the mating surface
of the terminal.
Ground failures are almost always traceable to inadequate
mate up force when the joint was fabricated. Moisture
gets into space between terminal and airframe . . . they
ARE dissimilar metals after all. Add the ravages of time
and electron flow and eventually the joint fails. Get
it tight enough the first time and it will still be good
the day your airplane gets scrapped.
Bob . . .
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( The only time you don't fail is the last )
( time you try something, and it works. )
( One fails forward toward success. )
( C.F. Kettering )
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http://www.aeroelectric.com
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