elevator pushrod problem

WingsOnWheels said:

I did another quick check with my CAD model. If I move the F633 down just a little bit, it solves all my interference problems. So that is my plan. I'm going to double-check a few measurements first just to be sure. If that all checks out, I'll spend the $70 for new parts and be done with it.

Thanks everyone for your help. Having the pictures from other builders definitely helped clear things up. I'll report back once I get the new parts installed.

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Hi Colin,

I have exact the same issue on my 6. Did you replace the two F633 in the end ? Moving them down a little bit ... Did you by any change measure the back and forth movement of the pushrod ? I do not have the space in my workshop to put the tail on - But as it is now I am able to get 2 1/4 total movement on the pushrod - I am wondering if that will give me enough elevator travel. I have the stick set up with 5deg forward tilt - and the rear belcrank dead vertical

RV-6 elevator pushrod interference problem

Hi Jan & Colin,
I've had the same issue with my kit. At the moment it remains unresolved.
I have a couple of suggestions that might help:
1) move (vertically) the aluminum angles that hold the bearings the stick weldment mounts to.
2) make a center tunnel cover with a 'bump' to provide clearance for the elevator pushrod.
3) make another bell rank with proportionately longer arms - keep the ratio the same and you won't have any significant effect on control throw/feel etc
4) move supplied bell crank lower, taking care to add some 'structure' to the new pivot point since you will now not be able to 'hit' the 062 angle on the horizontal rib... Maybe an 062 doubler of trapezoidal shape or square or rectangular with edges turned up on two opposite sides that run in the vertical direction to stiffen it up, bulk of part is in a vertical plane

Things have been very busy at work and home lately, so I haven't had much RV time. However, I have been putting some thought into this issue. This weekend I'm going to pull out my old (early 90's) set of plans and compare the control system dimensions to the parts delivered by Vans and the current plans. There have been a lot of RV-6s built yet this issue seems limited to newer kits. I think there is a problem with the weldment. Either it was built out of spec, or the design changed. I haven't found anything in the build I may have messed up to cause this issue

If all else fails I may just re-make the weldment and make the yoke that connects to the pushrod 3/8" longer. Or replace the F-633s and shift them down 1/8" (All the margin available) and make the yoke 1/4" longer.

Wanted to follow-up on this issue:

I made a new down elevator stop limiting travel to 21 degrees (20 is minimum). I now have 20 dn, 27.5 up. I also filed a tiny bit more from the yoke of the control weldment. With those changes I can now get to where the pushrod comes up to about even with the floor. I can shift the F-633 control brackets down about 1/8" and that should buy me just enough clearance.

I am considering just making my own F-633 assemblies. The aluminum angle is about $6. The bearing is the most expensive part, but if I can reuse the existing bearing then the cost savings is around $60. Plus I can keep the 1/2" edge distance called out in the plans rather than reducing to 3/8 while shifting the position 1/8" down.

ChiefPilot said:

I had the same problem on my -6A. Van's suggestion was to trim until there was no binding. I didn't need to remove much - perhaps 1/16th of an inch - and filed out the tooling marks.

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same here. I may have had to take closer to an 1/8", but don't recall. There seemed to be plenty of meat there to work with. I remember researching and learning that many others did this as well.

Larry

Some more follow-up.

So as mentioned before, I changed the down elevator stop to a little over 20 degrees. I made new F-633s with the pivot shifted down 1/8". I now have acceptable clearance throughout the full range of the elevator. I do belive I am good to go for those controls now.