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Center bearing and elevator brackets drilled

Welcome back to the empennage page. There are just a few wrap-up items to take care of before the wing kit arrives in August.

The first wrap-up item was verifying the correct spacing on each elevator rod end, then match-drilling the elevator control horns to the HS center bearing. Setting rod-end distance was easy…the control horn holes proved to be a little tricky.

The plans call for using a 1/4″ OD, 3/32″ ID drill bushing to drill a #40 pilot hole in each control horn. Taking a cue from Dan Checkoway’s website, and wanting to be more precise when drilling these holes, I ordered a drill bushing from McMaster-Carr. This is a press-fit bushing and had to be turned down slightly to fit in the bearing, but once in place it worked well. The #40 pilot holes were enlarged to just under 1/4″ with a drill, then reamed exactly to size.

One detail to look for on those elevator control horn weldments is the minimum spacing between the bolt hole and torque tube. If the hole is drilled too close to the torque tube, it will be impossible to get a washer and nut on the bolt. The plans don’t say anything about this minimum spacing, so beware…other builders had this problem and were forced to weld up the original hole and start over.

Wanting to avoid this pitfall, I checked the spacing by sticking the non-fluted end of a 1/4″ drill bit through the center bearing with one elevator mounted, then the other. I was able to use that drill bit to visualize where the bolt hole would be located. After checking, I found that the rod ends on both elevators hat to be backed out to the maximum distance in order to get these holes in the right place.

Elevator horn weld detail

Also note that Van’s has left a little gap in the torque tube weld fillet to accommodate the washer and nut – above and just to the right of the bolt hole.

With the elevator horns drilled, I tweaked the HS elevator brackets to make sure the rod end bearings fit precisely between them with no space on either side. That prevents any side-load on the bearing when hinge fasteners are torqued down, thus preventing a source of friction and binding in elevator movement.

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