Too much play in control stick

[pilot5173]

Hi all,

I took ownership of an S7 last August and have noticed a lot of fore/aft play in the right control stick (more than the pilot’s side). Well, I finally got around to talking a closer look, and there appears to be excessive play in the control stick pivot and Im unsure of how to correct it. Per the manual, the pivot is reamed to .2500” so if there is excessive play, my suspicion is that there is wear in the control stick pivot (or the hole was reamed too large on initial assembly). Video attached for reference.

Regardless, unless there are other suggestions, the next step appears to be removing the control stick pivot. I’m struggling to see how this can be done with the bearings in place. Does the group have an guidance?

https://youtube.com/shorts/V02UWGkNpKM?feature=share

[Kitfox Pilot]

I believe that is a bearing. Check to see if the play is in the bearing or in the housing that holds the bearing. If it's the bearing it will have to come out to be replaced. If it's the housing around the bearing I would try some kind of filler like jb weld or hysol to glue it in its place and fill the gap were the play is. Good luck.

[Dave S]

The pivot needs to be taken out to determine what is going on and what needs fixing.

Your video is quite good and appears to indicate the forward bearing has fallen apart or the ball retainer has come apart so the balls might not all be positioned right or may have fallen out (it is a small ball bearing). I would not swear 100%, but sort of looks like that.

The bolt should come out to release the pivot from its cage.

Good idea to reference the builders manual and work in reverse. If you don’t have the original printed builders manual, I think that Kitfox has one online on their website.

[Eric Page]

I had similar problems on my second-hand build. I found that the bearings are marked 7R4 and they measure 0.250" ID x 0.625" OD x 0.196" wide. Double-sealed stainless steel replacements are available at Fastenal. Part number 4126716.

[pilot5173]

Hey Folks, thanks for the responses and thank you Eric Page for sharing the bushing part number.

I figured I'd need to remove the pivot, but I'm struggling to see how to do that with the bearings installed. There just doesn't seem to be enough room fore/aft to twist the pivot out of the horn, and based on the assembly manual, I believe the bearings are fixed in place with sealant. Do you have any guidance on the best way to remove the bearings without other damage?

Thanks all!

[jiott]

If you need to remove the whole stick assembly (which you probably do), you will need to access the mounting bolts from the underside. This may require cutting some of the belly fabric if you don't have some access panels there already. Just install some round rings/covers when you are done. I highly recommend doing this during the initial build for those who are at that stage in their build. You don't have to cut thru the rings until you need to.

[pilot5173]

Following up on this thread for those interested in the corrective action.


Upon further inspection, it became apparent that when the control column which is originally assembled, the bushings were not pressed in far enough. As a result, the face of the bushings did not contact the ends of the tee in the control column, which resulted in for and aft play. Because the copilot control column is infrequently used, it vibrated along the bolt during every flight, eventually wearing the inside of the tee cross tube, resulting in the play shown in the video I shared. By replacing the bearings and ensuring they were pressed firmly up against the ends of the control column tee, all the play is removed.

You might say that the correct action would be to replace the control column tee in addition to the bearings, but given that the motion is now carried by the bearings, as it should’ve been in the first place, a little out of round, and the tee is not consequential.