Need Rudder Arm/Horn

[KewFlyer]

After landing on a hard surface [ I guess it was a pretty hard landing ], the left arm of the Rudder Arm/Horn broke... yes, on landing, so no steering other than by shinn brakes.... and yes...it was an experience.

Im told that the 3/4" shaft on the aluminum Rudder Arm sold by Wag can be lathe down to 5/8" to fit into the rudder post [ found a shop that will do it]. No problem here. Now, the shaft is "only" 1 5/8" in length (tall), which does not extent enough into the rudder tube to have the three bolts to go thru it. Maybe one !!. Thinking of maybe drilling two new holes at 180 degrees to each other at 1/2" distance from the bottom, top and of each other. I would hate to drill more holes into the rudder tube at that point and possibly weaken it at the stress point when steering the tail wheel.

Have anyone solved this situation?. any ideas / suggestions are appreciated.

and... no, I will not use "JB Weld" to get it back together.... but I have been thinking about it, though.

Thanks

Ralph

[Pearson]

Re: Need Rudder Arm/Horn

Ralph,

Putting two bolts through the tube on the rudder that close together and that near the end, would in my opinion place a lot of stress into a small area. I suspect it would work for awhile, but not long.

Have you sought the advice of a highly experienced professional welder? Someone with the correct talents and an industrial quality TIG welder should be able to repair your old part. The arms of the horn on my plane appear to be cast. A professional welder should be able to weld cast. It may be possible to clean up the ends where it broke off by making a nice perpendicular cut. Then drill and tap a hole in each piece and thread a stud between the pieces for added strength before welding. I used to use this technique to modify the pitman arm when I put a small block chevy into the early 50's pickup trucks.

The only other alternative would be to go the owner produced part route. But then you would be facing the challenge of either casting the arms, or proving the suitability of some other material. I am sure it could be done, but probably more expensive with engineering and all.

[KewFlyer]

Re: Need Rudder Arm/Horn

Thanks Richard.

That's one of the options. I may have a lead on a NOS. Will see if that pans out. Otherwise, I will take it to a recommended Metal Shop next week. They do our special welding. The owner is X-navy shipyard welder and metal shop master. They should be able to fix it.

Regards,

Ralph
My uncle in Vancouver, reported winter is setting in, so Portland is next. He forecasts a snowy cold winter. Will see.

[Pearson]

Re: Need Rudder Arm/Horn

I agree with your uncle on the winter. Leaves on the trees started turning color a few weeks early this year, and I haven't even cut firewood yet.

If you repair your rudder horn, give some thought to my suggestion of putting a stud in between the two pieces before you weld. You want a stud with opposite threads on each end. Done correctly it creates a very strong connection. If you then weld the crack where the two pieces meet, it would be stronger than original.

[KewFlyer]

Re: Need Rudder Arm/Horn

Richard:

Delivered the rudder arm to the welder/machinist.
He will place a threaded stud in both sides of the break [ just like you suggested] and "over" weld. The he will reduce the over weld to match the arm. He will possibly add a bar on the bottom side of each arm to reinforce them, as well as to take a look at the welding of the arms to the shaft and correct if required.

We took a look at the holes at the end of the arms and decided to re-weld them and drill new holes, due to their elongation due to wear and not using the correct chain attachment for past xxx years.

When finished, it will be better than new. Thanks for the advise.

Will post pictures when done.

Regards,

Ralph

[Pearson]

Re: Need Rudder Arm/Horn

Ralph,

The arms on in your pictures look thinner than on my plane. I don't see how you will be able to screw a stud into such thin material. But if you can that is great. Sounds like you found a welder/machinist. I look forward to seeing the "after" pictures.

[KewFlyer]

Re: Need Rudder Arm/Horn

Richard:
Interesting that you mentioned the thickness of the arms. One of the guys at the airport commented, that the arm look like it was from a Stinson. I'm not familiar with Stinsons, so I can not opinion. Maybe someone here may chime in on this.

The welder is to drill a small hole on each side and place a dowel with epoxy (?) into the holes. Not sure what kind of metal epoxy he will be using and if the epoxy will also be place where the two pieces come together and then weld them. He does FAA work, so I trust that his work will be acceptable and approved by my A&P IA, who recommended him.

[Pearson]

Re: Need Rudder Arm/Horn

Seems to me that the heat of welding would weaken the epoxy. Any chance on the NOS part. After seeing those pictures of how thin those arms are, I have doubts about the feasibility of repairing that one. Too bad you can't just make a new one out of 4130 steel, paint it up like the old one and call it good. Maybe there is a used one somewhere.

[Hank Jarrett]

Re: Need Rudder Arm/Horn

You probably could make one as an owner made part, and mild steel would be better (and easier to work with) than the aluminum casting some of them use. I would make sure it could be signed off before doing all the work. Most of the ones I have seen seemed to be mild steel, every aluminum one I saw was broken.
I have one that has one arm bent all the way under the shaft and didn't break the arm off. Interesting conversation piece, but I wouldn't use it if straightened.
Hank

[astjp2]

Re: Need Rudder Arm/Horn

Its the same as my prewar, and mine was cast/forged steel and is shaped like an airfoil. Tim

[Hank Jarrett]

Re: Need Rudder Arm/Horn

I would think that with a drawing you could file the arms from a piece of mild steel bend it to shape and weld it to a steel tube which would be form and fit equal to the cast one with much more strength. If it is forged originally (kind of an expensive process for Taylorcraft in limited numbers back then, but it could have been common to other planes) you would need a higher strength steel.
Hank

Get the Feds to sign off on making one BEFORE you make it!

[Pearson]

Re: Need Rudder Arm/Horn

Without engineering substantiation, I think you will have a hard time getting an owner produced part approved using material different from the original, even if it is stronger and/or better. It would probably be easier to find a used part. There was an advisory circular awhile back (a year or two ago) that basically said if you could use a part from another old plane, the FAA would try to approve it. Maybe you could use that AC as basis for approval of using a part for a Stinson, Luscombe, or some other aircraft.

[mike lutz]

Re: Need Rudder Arm/Horn

Guys,40-45 years ago a fellow had a cub based here,and had a welded(repair)rudder horn on it.Well,it broke one day as he was rolling out,got into the fence along the runway,and got the wing and both struts.
I my opinion,I wouldn't fool with it,and spend the 60-70 dollars and get one from wag-aero for a cub or what ever,and if you have to,have it turned down to fit inside the rudder tube,then you have the peace of mind of knowing you have a good part.I,ve had a cast alum. one on my t-craft for 40 years,and alittle over 2000 hours with no problems.It would be a small price to pay compaired to what Byron and his cub went thru with his repaired one years ago here.

[Pearson]

Re: Need Rudder Arm/Horn

......I wouldn't fool with it,and spend the 60-70 dollars and get one from wag-aero for a cub or what ever,and if you have to,have it turned down to fit inside the rudder tube,then you.........

Mike,

That is exactly what he was going to do, but the shaft is only 1&5/8" long. That puts a lot of torque into a very small section of the tube on the rudder. Do you know of anyone that offers one with a longer shaft?

[mike lutz]

Re: Need Rudder Arm/Horn

aAs I remember,thats about how long mine is.(rudder horn shaft that is)-Its been 11 years since I rebuilt the airplane and do remember doing a dye pen. check on it before reinstalling it.There are two AN-3 bolts about 3/4 inch apart attaching it.It never comes loose and has not caused any problems so far after all these years.