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Manual Trim Tab Cable Attachment

David Paule

Well Known Member
For me, one of the reasons I started this RV-3B was to have the challenge of figuring out how to build it.

Well, I'm getting ready to start the left elevator with its trim tab, and spent about three or four hours wondering how the manual trim tab cable fit in. I knew that it went on after the elevator was built, but couldn't understand how to do that. I wanted to get the assembly sequence clear before starting.

I looked in the RV-4 preview plans and the RV-8 preview plans for guidance. Often this is helpful, especially the RV-4 ones.

Finally, I realized that the trim cable retaining fitting, Wd-415, is attached EXTERNALLY to the elevator and then it all made sense. Thread the cable through from the front, screw it to this fitting and then rivet the fitting to the elevator. And yes, the elastomeric seals that apparently need to come off? They come off easily and go back on again, too.

Guess I don't need the actual cable itself right now. It'll go back to the hangar for a few more years.

Dave
 
Hole edge distance

Did you attach the WD-415 bracket to the elevator yet? There is a potential edge distance problem if following the dimensions on the drawings; the original RV-6 also mounts WD-415 on the outside of the skin (newer kits have it on the inside of a removable cover plate.

The attaching base plate is 1 inch square and the 4 rivets are 5/8" apart, i.e. 3/16" in from the edges. The nut that is welded on is about 1/8" thick and it goes up inside the elevator through the slot in the skin. It forces an offset of the base plate edge from the edge of the skin by the thickness of the nut 1/8" approx, so the edge distance on the skin will be reduced accordingly. The ideal remedy would be for the WD-415 base plate to be longer by 1/2". Alternatively the two rivets on the side of the nut could be located further away from the nut to better achieve the required edge distance on the elevator skin.
 
Fitting WD 415-1

For me, one of the reasons I started this RV-3B was to have the challenge of figuring out how to build it.

Seemed like my time was divided in to thirds: one third staring at the plans and trying to figure out WHAT they were trying to say; one third looking for things be it tools, parts, hardware, whatever; oh, yeah: and one third building!:D

The trim cable retaining fitting, Wd-415, is attached EXTERNALLY to the elevator and then it all made sense. Thread the cable through from the front, screw it to this fitting and then rivet the fitting to the elevator. And yes, the elastomeric seals that apparently need to come off? They come off easily and go back on again, too.

Make sure you have WD 415-1. That is a fitting with welding on BOTH sides of the nut, not just on the one edge. I just replaced mine (HUGE PITA) and the old one was cracked at the weld about half way across and, after I drilled out the rivets and was moving the fitting, the nut snapped off of the plate. :eek::eek: That's why they came up with the 415-1 replacement.

It is in a service bulletin and, as much of a pain as it is, should be replaced if you have the original WD 415. Look up the service bulletin on Van's web site and see if it applies to your airplane.
 
Thank you, friends.

Yes, I do have the WD-415-1, verified that, and have checked assembly when I rigged the tail.

Over the years I've gotten better and figuring the RV-3B out, thankfully.

Thanks again,
Dave
 
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