Cleanup is well under way. Acetone, paint thinner, scotch bright pads, and elbow grease were my main tools this last week. Oh, yeah, and more disassembly. After the hull skins were removed from our entire Seabee, I inspected and found the water rudder post to be severely corroded. After a few nights of PB blaster, and soaking what I could, I was barely able to rotate the external steel post that connects the water rudder to the fuselage. The rudder control arm was attached to the assembely (with a significant amount of play) but there was no way any rudder pedals would move the water rudder – which subsequently is connected to the air rudder through the same control cables. Taking it apart, and finding out the cause was my only course of action.

At first blush, it appears to be a steal post inside of an aluminum post. Both of these are then inside of the aluminum collar that is riveted to the tail skins which then extends upwards to a cross member that is riveted to both sides of horizontal tail stiffeners. Drilling off the collar from the bottom skins was easy, but the 6 rivets inside the tail proved much more difficult. I only had the 2 access holes to get a drill or air hammer in which also had to fit my arms, and also allow a line of sight to see what I was doing…..just not enough room.

All of this had to be drilled out as there was no chance of pounding out the rudder posts. I couldn’t get a good line of site and drill angle to properly and safely drill the rivets so I ended up chiseling the tails of the rivets off. This released the entire assembly free. I was then able to pull the entire thing out of the vertical stabilizer hole (since the vertical stab is off).

I don’t know the best course of action to fix or replace the water rudder assembly. Until I figure something out, back to cleaning….I can only summize that the steel tube was used for strength. That post was then inserted into the aluminum to prevent dissimilar metals in contact with each other. Meaning, the inner aluminum pipe was that buffer to the aluminum collar riveted to the plane. If one was to be damaged, they were hoping that it would damage the inner aluminum. That inner aluminum would turn inside the outer aluminum collar and being the same metal, it would not introduce as much corrosion. Unfortunately, the corrosion was bad enough that it cracked the inner pipe…..clear as mud?!

 

Rudder location
The red circle indicates where the rudder is located. The red lines indicate where the rudder post goes, with the cross member that supports it.
 

Rudder post close
This is a close up shot of the rudder post still installed.
 

Rudder assembly
Rudder assembly removed from the airplane.
 

Steel/Aluminum Collar
Looking at the steel tube, inside aluminum tube, inside aluminum collar.
 

Crunched top
This is the top, where the rudder control horn goes.
 

Cross member
Cross member is removed from the assembly.
 

Split
The aluminum collar was removed, now you can see the inner aluminum post is split from the corroded steel post.
 

Chisel off
Since it was already cracked and needed to be replaced, only way was to chisel it off”
 

Success
Successful, all pieces are completely separate.
 

Rudder post collar
The aluminum collar, removed and could be reinstalled.
 

Thoughts? Anybody have any ideas or examples of building a better water rudder assembly?

 

  1. That doesn’t look like a terrible design, I assume the engineers had a service life in mind and you are likely will will beyond that. A similar designs doesn’t seem unreasonable but some some grease fittings would certainly help to keep the steel inside the sleeve lubricated, protected from the elements, and displace moisture and salt water.

    • Yeah, thanks for the comment. Excellent point about service life.

      We were briefly discussing a repair, kicked around the idea of stainless steel and grease zerks. And as you mentioned, that would help displace moisture and in general, keep it well lubricated.

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