Flap Positioning System
The design of Van’s electric flap positioning system leaves
much to be desired (IMO). As the flap actuator rod goes up and down,
it twists left and right as much as 30 degrees causing the flap positioning sensor
rod to bind in its narrow switching track.
Vans issued SERVICE BULLETIN 7-4-12 designed to stop the jackscrew from
disconnecting from the flap actuator rod, but this does little or nothing to
stop the flap positioning sensor rod from binding/bending in its narrow track.
We believe we came up with a solution to stop the twisting motion. Using a steel
washer we machined to have a convex shaped hole, the inner, tapered
circumference of the washer bears against the concave bearing limiting its
rotation (left and right) without limiting its rotation around the flap actuator
weldment shaft.
The following picture of a washer is NOT what we used but serves as an example of a convex washer.
Here is another example of a convex washer (not what we used).
The next photo is similar to the bearing in the flap positioning system. Note the concave inner bearing surface. It will rotate as much as 30 degrees.
A properly machined washer would bear against the inner bearing surface allowing it to rotate on the bolt, but would constrain its ability to rotate in its socket.
In other words, the bearing operates normally but does not swing around causing the flap positioning sensor rod to bind in its narrow track.
Chet, my engineer build partner, created two drawings. The image on the left represents the problem, the image on the right is the goal. Chet believes this washer can be made of delrin or steel. I chose steel.
Chet and I welcome comments on this suggestion. I suspect some folks have not had a problem as designed (yet) and others simply tolerate the matter altogether. What I need to do is to make sure I log this mod and convey this arrangement to any subsequent owner of my RV9A. If service is required, it's important that it's reassembled properly because only one side of the washer is convex.
This is the kind of product Stein would be great at (hint, hint).
Please feel free to email me your comments at barry@arizonaairparks.com