Model 4 rudder repair

[rv9ralph]

Watch this short video on YouTube:
https://youtu.be/mABYn7UFgVA
The title is: Repairing Aircraft Structural Tubing (Piper Cub) 1945 US Office of Education; WWII

It is vintage but relevant and explains the inspection and repair issues you need to repair your type of damage.

Ralph

[David47]

From the photo it looks like there may also be some crushing at the lower end of the spar tube. Therefore I think you should also look at that lower rudder hinge bracket. Check for any cracks in the weld, distortion of the two bearing plates etc. I'd also think splicing a new tube would be better than straightening. Maybe also check if there's any other damage to the brackets supporting the forward bolt on the leaf springs, just as a precaution.

[Av8r3400]

If that is your "new" replacement tailwheel spring, don't use it. It s far too flat. This will only happen again. Either re-arch it to the proper angle or get a different unit.

[Jollyrancher]

Thanks for all the help, I'll make an inspection of hinges ect, the video was very helpful, and the new spring is already installed. The straight edge was just a piece of 304 that was handy.
Wings folded, what's the distance between the top of the wheel assembly and the rudder. Thanks

[avidflyer]

I think you could straighten the tube rater than cutting it out. My guess is that the rudder post isn't bent, just the picture may make it look like that. You can see that if it is. I will send you a private message. JImChuk

[Geowitz]

If that is your "new" replacement tailwheel spring, don't use it. It s far too flat. This will only happen again. Either re-arch it to the proper angle or get a different unit.

This!!!

It looks like there is a new steel top spring in the pic, but you said you've replaced? Just making sure... In the pic the geometry looks backwards. Not only is the unit too close to the rudder, but this is also the main cause of tail wheel shimmy. The "vertical" post that swivels and comes out of the top of the fork should actually lean with the top to the rear of the plane and bottom closer to the front. Need much more angle.

I agree about straightening as being probably sufficient rather than replacing.