Tailwheel won't unlock...

[CptKelly]

We have had problems with our Champs tailwheel steering since we bought it. I've had 4 different tailwheels (three were brand new) on the Champ, and the problem still persists. I just bought a new tailweel spring, and since I haven't solved the problem, I'm going to install it soon. I've had three IA's work on it for days, still the problem isn't fixed. Any suggestions?

Mike

[skyking3286]

Maule Scott or other?

If it's a Maule, you really have to work on it to have it not unlock... like leaving the spring out or putting in a odd sized one, muck it up with grease or really screw up putting it together. Its must a little cam and a few pieces of metal. Hard to miss what would be the problem.

Compression or bedspring springs?

Take it off the plane and play with it.

[MikeB]

I have a Maule and it works fine other than I've never been able to cure a shimmy problem. Tried everything (angles, etc.) with no luck so I just live with it and unload the tail with the stick as much as possible on hard surface. Not the brightest idea in a x-wind though.

However, it seems unlocking should be a 'no brainer'. Does it get better with more weight in the back seat??

MikeB

[CptKelly]

I've had two Maule tailwheels on it, a brand new Scott 3200 clone (Bushwheels), a brand new Lang, and now it sports one of those, I forget the name- tailwheels like on the new Champs. I have had several IA's work on it, still, it won't unlock. I've added hydraulic brakes, and when you do a 180 turn, it just drags the rear end around. I've never had any shimmy with any of them, they just won't unlock.
If you put the tail up on a sawhorse, and go full rudder, it will unlock. Even though the tailwheel spring looks fine, I just bought a new one to try it out. I do not have a clue whats the problem. Any ideas?

Mike

[seaheli]

Mike B has the correct answer, "weight"! "Springs" also important in the equation!

Usually there are spacers in the stack-up assembly of the cam and spring mechanism (swiveling cam). Look at the spacer and torque values of that mechanism.

I like the Heath tailwheel.

Charles

[MikeB]

Another thought here (Charles popped my memory): how much tension do you have on the 'steering springs'? Some folks tend to let them run loose or with little tension which could cause the tailwheel to not unlock. Think of it this way: if the springs are weaker than the tailwheel unlocking mechanism, it probably won't unlock. Technically, if you stand at the rear of the plane, push the tail down and shove sideways, the tailwheel should go to the unlock position. That's why I asked in a previous post if it was better with weight in the rear.

MikeB

[CptKelly]

I am not sure if I remember if it is any better with the rear seat occupied. As far as I remember, the problem exists no matter who sits where. I cannot believe that all the tailwheels I have tried have some sort of fault, perhaps one or two may have had a fault, but not all of them, especially since several were brand new. I have two other tailwheel aircraft (L-19 and Supercub)... and both of these are absolutely normal with the tailwheel unlocking upon demand, but not the Champ. Our Champ came with the little captive springs at the tailwheel, and they are not loose. What am I overlooking? It looks like to me that the only remaining thing is the tailwheel leaf spring. I just ordered and received a brand new one, and I'm going to install it and see if the tailwheel will unlock. Comments please.

Mike

[seaheli]

Mike,

Could you post a picture of your tailwheel installation, please?

Charles

[N86250]

You seem to have looked at everything that could be wrong on the tail end. Is there something interfering with the rudder pedals themselves? Are the rudder cables rigged to give the correct throw? Do you get a full rudder deflection with a full rudder pedal deflection? Pullies and fairleads free? Are the rudder pedal return springs at the firewall correct and not binding or jamming the pedals? Put the tail on a sawhorse with the tailwheel hanging free and see how it operates with someone in the cockpit. Well, there is something on the tailend you haven't mentioned. While the tail is on the sawhorse, grab the trailing edge of the rudder and try to twist the rudder fork in the bottom of the rudder. I think you will find motion there from missing or broken bolts, corroded or elongated holes in the rudder horn or the tube, or a broken rudder horn. jrh

[CptKelly]

I've had the Champ up on a sawhorse, and the rudder operation works fine, plenty of throw, nothing binding, etc. We already did the simple things, and now I'm stumped.... Perhaps the tailwheel spring is bent? I'm going to install a new spring, and see if it fixes the problem. Anybody have any better ideas? Oh, I don't know how to post photos although getting a few is no problem.

Mike

[Champ99b]

I bet that is in the tail spring not in the tailwheel. The tailwheel has to be at the correct angle, I have seen that the tailwheel is to stright down and not streched out behind the tail.

Ron

[N86250]

[ While the tail is on the sawhorse, grab the trailing edge of the rudder and try to twist the rudder fork in the bottom of the rudder. I think you will find motion there from missing or broken bolts, corroded or elongated holes in the rudder horn or the tube, or a broken rudder horn. jrh[/quote]
Too many hot toddies. It's not the rudder horn, it's the aluminum yoke. The aluminum yoke is turning ever so slightly in the bottom of the rudder. It is tight enough from friction that you haven't noticed it with the tail off the ground. But with the tailwheel on the ground there is enough movement to miss pulling the tailwheel to the unlock position with the rudder at the stop. Anything less than perfectly tight between the yoke and the rudder can be enough to be a problem . jrh

[skyking3286]

I say sir, brilliant Holmes, brilliant deductive logic Sherlock...

And shouldn't there be two little bolts in the rudder post to keep the arm from rotating?
It would be easy to cover those over and forget...

[MikeB]

Good point and good possibility!! On the Champ I'm presently flying the bolts were missing. Apparently never put back in when it was last covered in the 60's. I discovered the missing bolts after I bought the plane and recovered the rudder. Maybe that's why the guy who previously owned the lost control. Lord knows how many annuals it went through like that.

MikeB

[CptKelly]

When I change the tailwheel spring, I can check the rudder horn for twisting inside the rudder tube. That should be easy while the tailwheel springs are disconnected. I don't think its loose, however. I've pulled on the rudder, back and forth, while all was hooked up, and I see no lost motion. Thanks for the comments. IF I find what is wrong, I'll post it. If I don't, I reckon I'll just have to stand back and throw rocks at it.

Mike