The Cessna 120-140 Association Forum

I recently purchased a 140 and I've been flying fairly regularly to get more familiar and comfortable in the airplane. Yesterday was a calm day, which was perfect for practicing maneuvers that I'm not too familiar with in this airframe.

To cut to the chase, I was in the practice area getting a feel for how the airplane behaves in a descending slip. After performing more and more aggressive slips (flaps up) to both sides, I headed back to the home field for some pattern work. Returning, the airplane that previously flew straight required constant right rudder pressure. Rudder neutral results in about half-ball deflection.

Post-flight inspection revealed no obvious defects. Supposing that maybe the slipstream may have deflected the rudder trim tab, I tried to move the tab a bit, but subsequent turns in the pattern showed no improvement.

Question one (the obvious one): how do I fix this?
Question two: is this merely an inconvenience, or a major issue?
Question three: thoughts as to what might have caused it?

Any sudden change in the way the plane flies is reason for concern. If I understand correctly, the plane was first out of rig immediately after you finished the exercises, so something changed during that portion of the flight.

When you say "Neutral rudder" do you mean feet off, or feet even?

The first thing that comes to my mind is a deformed rudder control horn. If this is not the case, go through the entire control system until you figure out what happened.

Rudder return springs broken ? Guess on my part.

I would guess a rudder return spring has broken. Sounds like a similar situation with my 140.

A broken spring would make the pedals uneven and rudder not "neutral" with feet off, and so not "neutral," but the plane would fly straight and coordinated if you hold the pedals even with your feet.

This is a reach...probably not your issue...but just sharing results of a TW steering spring that "caught" on a TW bracket & stretched almost open. As a result, the TW steering on one side was slightly altered and it caused the TW to be more of a rudder & was obvious in flight. (...short explanation...the springs were installed "mid chain" and not IAW Scott or OEM drawings so that the spring was adjacent to the bracket & just happened to catch & "hang" during a pretty abrupt slip maneuver) Again, it may or may not help, but just throwing into the mix. Mac

Another vote for the rudder return spring. Happened to me on the first day of a 3 day trip from Illinois to Oregon (ugh). If you need right rudder pressure to fly straight, it is the right rudder return spring that is broken which is located on the left side (pilot side).

You can check this on the ground very easily. The rudder should be roughly aligned with the tailwheel. If not, barring any other control cable issues, it is the return spring. Replacing the spring is easy once you get the tunnel cover out. I forget if you have to take the floor pan cover out too.

They are available from Univar. The right rudder spring is staggeringly expensive....three times the price of the left spring. Go figure.

Mike

I previously posted this. Got it from Cessna Engr Dept. It is in a Word Doc, so hopefully will be easy to see.
Larry Lowenkron