Eye Bolts & Tailwheel Steering Chains

[Bcone1381]

I suspect that the tailwheel steering chains may cause the hole on the rudder attach and the tailwheel attach hole to elongate over time. I've seen the wear on other aircraft. I wonder what our fleet experience has seen.

Some other craft use eye bolts to attach the chains. Here is a photo of a Super Cub...AN42B eye bolt with the steering arm sandwhiched under two AN970 fender washers. Am I creating a solution to a problem that does not exists?
Screenshot 2024-02-09 at 4.35.45 PM.png Screenshot 2024-02-09 at 4.55.19 PM.png

[jaredyates]

303AP has what you show in the bottom photo. I'm not sure where in the 1350 hours the eye bolts came in, maybe they have been there the whole time. 805TB had the springs directly into the holes, and at 500 hours were still looking fine.

[Battson]

I suspect that the tailwheel steering chains may cause the hole on the rudder attach and the tailwheel attach hole to elongate over time. I've seen the wear on other aircraft. I wonder what our fleet experience has seen.

Simpler is better.
I can tell you there is minimal wear if there's a little slack in the chains. The springs don't wear much either. There's about 6 years and 600 hours of use on our rudder.
If the chains were kept tight, maybe wear would be more of an issue.

It could become a problem after 20 or 30 years, but you can always:
- oversize the hole and put a bush in the hole
- weld over the hole in-situ and re-drill a new one
- install an eye bolt at that time

Simpler is better. Suggest taking no action yet.

[alaskabearhawk]

Older photo, but I put eyebolts in mine as well.

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[Bcone1381]

I'm seeing rigging of the chains mentioned by Battson. so, Some data I've since gathered on tailwheel rigging.

Here is a video of an authority showing proper rigging of these chains on a Scott 3200.

https://www.youtube.com/watch?v=QtokU8mIDQk&list=PL60284BB23539461F

The video below shows him rigging the chain slop/length. At 1:40 he shows a degree of of "Chain loosness". At 4:02 he shows a common erroneous rigging issue that leads to high stress on these chains. Its not a Bob tailwheel, but I hope I'm within reason to apply the principle to our tailwheel.

Lastly, he rigs the chains with no weight on the tail wheel. If its rigged with weight, then the chains will tighten whenever no weight is on the tailwheel. I wonder if to of tight chains would torque an eye bolt so it twists and deforms our steering horn. Things I, a builder a with no experience, wonder about.

[rodsmith]

Thanks for the video link Brooks. Now I realize I have my chains too tight.

[Nev]

Here's a visual showing a little slack on both sides. I videoed it inflight and both chains dance around a little while the wheel stays centred without stretching the springs. I'm thinking that a small amount of slack also ensures that if a chain comes off inflight, then the consequences on landing will be limited. I did put this to the test one day - a chain detached itself while flying - and it wasn't noticeable at all on the landing. I then removed both chains and flew several hours with the tailwheel free castoring. It was great and in many ways I preferred it. The one exception was taxying in a cross-wind which became difficult.

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[Bcone1381]

A significant data point....The smallesst mis spec eye bolt is 3/16" shoulder & threads. The holes in both the rudders horn and the Bearhawk tail wheel are smaller than 3/16 (they fit a size 8 machine screw) and the edge margins on these steering horns are not generous....downright frugal. I enlarged my holes and installed the eye bolts, but I am really on the fence whether this was prudent. I think the best practice is not to install them. Maybe If they wear and elongate over time, then consider installing them.