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Another builder e-mailed to ask my opinion on electric elevator trim wiring:

I have delayed rolling and riveting the leading edgeof my left elevator until I come up with a good plan for routing theelectrical wires from the motor into the stab. I've seen guys route thewire bundle thru the hole directly behind the motor, but the trim screwdrive wants to occupy that same space at times, and seems like a future wearproblem to me. I will probably drill another hole close by, (any problemswith that?) with a rubber grommet, but were you able to come up with sometype of quick disconnect to allow you to take the elevator off withouthaving to cut wires? Any good ideas for a protective shroud to contain thewire bundle as it routes from the elevator to the stab?

I responded: Like you, I didn't want to run the wires through the hole where the trim tab screw moves. That looked like an invitation for trouble. I put another hole with a grommet in the elevator spar a bit further outboard. My plan (not yet achieved, it is just a plan) is to run the wires through the hole in the spar, then run them inboard inside the leading edge, bring them out the inboard end of the elevator leading edge. Then I'll go over the HS rear spar in the area of the fuselage aft deck. I'll probably use stick-on attachment points inside the elevator leading edge to attach the wire bundle to with wire ties. As far as the means to break the wire bundle, I'm still wrestling with that one. At the moment I'm considering two options:

  1. Use a D-sub connector, as described by Bob Nuckolls at:http://www.aeroelectric.com/articles/macservo/macservo.html
  2. Or, I might just crimp on male and female D-sub pins on each wire pair, and then put heat-sink over them to keep them from pulling apart. I would stagger the break point in each wire so as to avoid having all the joints in the same place, which would make the wire bundle look like a snake that had swallowed a frog. Having the joints staggered would also serve as a natural way to identify which wire went with which.

    I got idea #2 from the Aeroelectric-List:

    "I'd like to pass on a suggestion one of my friends made about wire splices,useful on small wires. Attach the pins for a d-sub connector onto each wire(obviously male on one and female on the wire to be joined.) Then, insteadof inserting the pin into a connector, simply slide a piece of heat shrinkover the pins and the splice is made. If the part needs to be changed out,just cut off the heat shrink."

    Bob Nuckolls' response was:

    "I've used d-sub pins exactly as you have described. They are an excellent, low volume alternative to butt-splices with the advantages of a knife splice. Obviously, the BIG consideration is controlling installation of the bundle to tightly control and limit TENSION on the wires. But what you propose is quite rational."

Both my solutions involve crimping on D-sub pins, but I needed the D-sub crimp tool for my avionics installs anyway. I bought the one that B&C Specialities sells - $44, but it works great.

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