Another broken rudder pedal spring

[Tsquared]

Had my third rudder pedal return spring break on me all within less than a year. This time it was the original spring on the left pedal. First two were right pedal. 170TT FX3. Broke while doing a forward slip on final.

I know there are a number of threads on this and I did see a post from 5 years ago with a home made solution. I’ll call CC Monday to get a few more springs but has anyone heard of a solution from CC?

269397B2-531C-4EAA-B116-83B5D64CAEA2.jpg

[aeroaddict]

Yup, I'm on at least two now, right pedal though. 188 hrs on the hobbs.

I generally take the spring to the local hardware store and match one up.

So far I have not seen an workable solution.

[Andy]

I generally take the spring to the local hardware store and match one up.

Perhaps a naïve question but why would you want to replicate a spring that fails? Either the spring specification was wrong or the spring did not meet specification.

I have less spring tension than standard on my FX-3 as I extended the rudder cables to maximum length to give myself more front seat leg room. The springs don't really do anything while the pilot's feet are on the pedals.

https://www.supercub.org/forum/showt...spring-tension

[Tsquared]

Perhaps a naïve question but why would you want to replicate a spring that fails? Either the spring specification was wrong or the spring did not meet specification.

I have less spring tension than standard on my FX-3 as I extended the rudder cables to maximum length to give myself more front seat leg room. The springs don't really do anything while the pilot's feet are on the pedals.

https://www.supercub.org/forum/showt...spring-tension

Andy,
I can’t speak for others, but in my case each replacement spring came from CC. At this point I’m thinking it’s a design issue with the way the spring mounts to the frame mount point.

as you observed the spring doesn’t do much, but it is rather unnerving to hear it “snap” on final while in a forward slip...

[Schwbo]

Same happened to me on CC SS and yo a friend on his FX-2. Must be a design issue.


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[Top Cub]

Any new updates here? I am also looking for a solution.

[Tsquared]

After discussing this with CC support back in April, they sent me two different connection options. First was a screw with a hole drilled thru the thread and second was a screw with an elongated head that also had a hole. See attached pics.

I used the one with the hole at the end of the thread. I’m 215 hr TT on the FX3 now, 45 since installed with a lot of forward slips on it and I haven’t had any issues with it since. Note - the one pic was taken before the spring was threaded thru the screw.

C47C54D1-FF9F-415A-9E63-EA28FC6BFD44.jpeg
7E5B0133-97E1-47CB-893A-7E09775F9E14.jpeg683ACB02-76F2-4A69-B2B2-805A0099C811.jpeg

[Top Cub]

After discussing this with CC support back in April, they sent me two different connection options. First was a screw with a hole drilled thru the thread and second was a screw with an elongated head that also had a hole. See attached pics.

I used the one with the hole at the end of the thread. I’m 215 hr TT on the FX3 now, 45 since installed with a lot of forward slips on it and I haven’t had any issues with it since. Note - the one pic was taken before the spring was threaded thru the screw.

C47C54D1-FF9F-415A-9E63-EA28FC6BFD44.jpeg
7E5B0133-97E1-47CB-893A-7E09775F9E14.jpeg683ACB02-76F2-4A69-B2B2-805A0099C811.jpeg

It appears that by running through the hole it allows the spring to move slightly and therefore not fatigue the very small concentrated spot on the spring? It does make sense. I will try that. Thanks for sharing.

[aflyer]

I am just getting to installing the boot cowl, so I took a look at this issue while I still had easy access.

It turned out that if I loosened the bolt that goes through the clamp a couple of turns (the nut is an all-metal lock nut), the spring is free to rotate there as the pedal is moved. My theory is that by clamping the end of the spring hard, there is no movement allowed, and that concentrates the stress in one spot on the spring. Leaving it a bit loose lets the spring move like it should, and like it would with different hardware as above.

The friction tape on the tube is thick enough that the clamp is still very well clamped even with a small (1/16") gap there.

Just a small subtlety left out of the instructions. It would explain why not everyone has this problem.

John

[ceslaw]

John: Good tip!