Chief Rudder Rigging

Post-War Aeronca Chief airplanes
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Chief Pilot
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Chief Rudder Rigging

Post by Chief Pilot »

I discovered recently that I am not able to get full left rudder deflection with the control column full aft. The rudder pedal contacts the aileron pulley bracket on the column and limits the rudder to about 3/4 deflection. I've set the adjustment plates for the shortest length possible. I suspect the rudder cables are too long.

I received a replacement cable set from Univair and measured them. One is 3/8" longer than specified by the Aeronca drawing, the other is 9/16" longer. I haven't installed them yet, but expect they won't solve the problem due to their extra length. I haven't checked the control column yet to see if it moves too far aft, but I don't believe that is the problem - the full forward position is against the firewall. Chief owners may want to check their airplanes. This won't show up in the usual control and rigging checks unless you try various combinations of control inputs - specifically full aft elevator with full left rudder. Has anyone else experienced this?
EDGEFLY
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Re: Chief Rudder Rigging

Post by EDGEFLY »

You don't say how much less than "full deflection"you get but apparently enough to spend money on new cables. With 15 view of this message, I'm surprised that you haven't gotten some comment from the A&P/IA segment but would think that someone ought to do a full rigging check before cable replacements are made. Just MHO.

Dale
Paul Agaliotis
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Re: Chief Rudder Rigging

Post by Paul Agaliotis »

Check and see if you are over-traveling on your controls. Both elevator and rudder, there should be no contact. Check the rudder cable length to the installed cables.
Paul
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Chief Pilot
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Re: Chief Rudder Rigging

Post by Chief Pilot »

Elevator travel is within specifications of 26 degrees up, 24.5 degrees down. With the control column forward, left rudder is at the specified 28 degrees, but limited by contact between the rudder pedal and torque tube and by simultaneous contact between the tailwheel steering arm and tailwheel leaf spring :shock: . The rudder horn does not quite touch the fuselage stop. With the control column aft, left rudder travel is 25 degrees, limited by contact between the pedal and the aileron pulley bracket on the control column.

Right rudder over-travels to 33 degrees, limited by simultaneous contact between the rudder horn and the fuselage stop and contact between the tailwheel steering arm and the leaf spring.

Shorter rudder cables would fix the pedal interference issues, but obviously not the right rudder over-travel. I don't know what to do about that - maybe weld a small stop pad to the rudder horn? Incidentally, the rudder is warped to the left. Maybe the over-travel was set deliberately to compensate. For an airplane that was recently restored and has had 5 annual inspections since, this one sill seems to have its share of issues.
Paul Agaliotis
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Re: Chief Rudder Rigging

Post by Paul Agaliotis »

With the elevator travels correct, I would be suspicious of the rudder cables and rigging. The controls should not overtravel. the rudder pedals may be too far forward or not even at neutral. If they are too far forward this may be the cause of your interference.
I'm don't quite understand the warped rudder to the left. Maybe the steering fork was installed crooked. The rudder arm is pretty stout and not easily bent.
Paul
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Re: Chief Rudder Rigging

Post by Chief Pilot »

The pedals are definitely too far forward, I expect caused by rudder cables that are too long. Univair is making up a new set to the length specified in the drawing and I expect this will solve that part of the problem. The over-travel to the right is due to the stop pin on the fuselage being too short - as if someone filed it down. I don't know why someone would do that except possibly in an ill-advised attempt to compensate for the warped rudder. The rudder seems to be twisted from uneven tautening of the fabric during recovering. Contact between the steering fork and leaf spring could be due to the wrong fork being installed. The fork on my airplane bolts to the outside of the rudder. Most of the photos I've seen show a steering fork with a shaft that fits inside the rudder tube. I haven't been able to find any part numbers or drawings for the steering fork. I've posted some photos here: https://www.flickr.com/photos/125544839@N05/
Paul Agaliotis
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Re: Chief Rudder Rigging

Post by Paul Agaliotis »

I see the twist now. The tab should compensate for this, in the future you might fix that. I would do it when the rudder was removed for condition.
The tailwheel horn is a pre-war style. ACA still can supply the correct one, still used on the Citabria.
The rudder cables should solve the pedal positions. The stop can be lengthened by slipping a larger tube over the stop pin and secure it with a cotter pin. Remember to measure the travel from the top, counter balanced, area that is not twisted.
The plane looks familiar, are you at Independence?
Paul
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Re: Chief Rudder Rigging

Post by Chief Pilot »

Hi Paul, thanks for the feedback. I like the idea of installing a sleeve with a cotter pin to extend the rudder stop. Sure beats trying to weld on an airplane or rudder that's already covered. I'll leave the rudder straightening and fork replacement for another time if I can get through the annual inspection this way.

Raleigh
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