Tailwheel cables slack

[N3243A]

I have been running an L19 spring for years now. The tailwheel chains are just barely slack with the tailwheel on the ground and they tighten up just a bit when in the flying position.

As for the question about running 3 or 5 coil springs, this is what I was told by several sources. The thrust plate pins engage 3 of these springs at a minimum and the other two are considered optional. These springs also help prevent the tailwheel from shimmying. The best advice I got for 170's was that if you are running light, you can probably run just the 3 of them that engage the thrust plate pins. If you fly a lot at gross weight you should probably put in all 5. I felt my previous configuration with all 5 resulted in a pretty stiff setup so I am switching to 3 of them for trial. The Supercub guys only run 3 of them typically but of course they are lighter aircraft.

There is also the question of how much to tighten the castellated nut on the "kingpin" holding the whole thing together? Alaska Bushwheel advises that one should tighten the nut to snug so there is no more play in the system (don't go overboard, crushing the bearing cone though) and then back off 1/2 turn. Too tight and you are just fighting spring tension and friction and too loose and you allow too much play in the system allowing parts to get worn and out of spec sooner.

[canav8]

I have been running an L19 spring for years now. The tailwheel chains are just barely slack with the tailwheel on the ground and they tighten up just a bit when in the flying position.

As for the question about running 3 or 5 coil springs, this is what I was told by several sources. The thrust plate pins engage 3 of these springs at a minimum and the other two are considered optional. These springs also help prevent the tailwheel from shimmying. The best advice I got for 170's was that if you are running light, you can probably run just the 3 of them that engage the thrust plate pins. If you fly a lot at gross weight you should probably put in all 5. I felt my previous configuration with all 5 resulted in a pretty stiff setup so I am switching to 3 of them for trial. The Supercub guys only run 3 of them typically but of course they are lighter aircraft.

There is also the question of how much to tighten the castellated nut on the "kingpin" holding the whole thing together? Alaska Bushwheel advises that one should tighten the nut to snug so there is no more play in the system (don't go overboard, crushing the bearing cone though) and then back off 1/2 turn. Too tight and you are just fighting spring tension and friction and too loose and you allow too much play in the system allowing parts to get worn and out of spec sooner.

Sorry, 3243A, I dont know your name but your thinking is correct. 5 springs were used with aircraft that have heavier tails. Even the 170 can get by with 5 but I have noticed more complaints from owners with them having problems with their tailwheel action. The kingpin should be tight enough to allow the break out to be distinct. To tight and again you have unreliability.
Here are a couple good video links on tail wheel maintenance and set up.
http://www.youtube.com/watch?v=S-0i2MTe-A0
http://www.youtube.com/watch?v=X1uAd0KSnCc
http://www.youtube.com/watch?v=QtokU8mIDQk

[daedaluscan]

I looked at the tailwheel today with my AME.

he feels that the left hand tailwheel cable is slipping on the rudder cable, and that he can see movement.

We are going to take off the empennage and have a good look in a couple of weeks when he has a free day.

I have decided to fly the plane meanwhile, and monitor closely. I took out two links from the left cable only to maintain the tailwheel pointing in the same direction as the rudder. I flew 10 circuits and there was no further movement. I had very direct steering on the ground which is a pleasant change for taxiing, but I never felt unsafe with less.

This is a new plane to me (and its my first plane) so I am probably a little cautious, so even though this is a fairly big project to (hopefully) make a minor fix I am happy to do it just to see what is in there in detail. And I hope to keep the plane for a long time so I am happy to do it right.

[canav8]

Charlie, If you have to keep taking links out every time you fly it, please do not fly it. There is a problem. If a cable gets bound up it may restrict rudder throw, you just don't know. Since this is a new plane to you can I also assume you have low 170 experience? I cannot advocate doing that unless your AME has other ideas. I know your chomping at the bit but does it really make good sense? Sorry I ere to the conservative side of armchair quarterbacking.

[Roesbery]

The parts book shows only one clamp on each cable. I replaced a cable on mine that was frayed and it has two clamps on each cable. If yours only has one clamp each. I would suggest you put two clamps on each cable.. Be a lot less chance of it sliding then. Kind of a mickey mouse way for Cessna to do it, but it has been working for 50+ years.

[daedaluscan]

I have two clamps each side.

I appreciate that if the clamps continue to slide too far they can restrict rudder travel, but I have a good four inches before that could happen. I think that the worst I risk at the moment is the cables become slack again and losing precise tailwheel steering. Rudder cables look in good shape and the clamps cannot restrict rudder travel yet.

I will be keeping a very close eye on this.

[daedaluscan]

Today was my annual so we pulled the empennage and looked at the tailwheel cables.

The left tailwheel cable had slid on the rudder cable. It had two clamps, one finger tight and the other really not much tighter. Quite a lot of work to get here, but this is a new plane to me (and my first plane) so I figure this is all time well spent for me to learn about the plane and see what is going on in there.

We also found that the cables were rigged incorrectly, and were chafing where they cross. When they were swapped they ran nicely.

Everything else went well, no surprises, so a good day:)

[Roesbery]

Gives you a good feeling to KNOW how things work and that you have them working as they should in that area. Right!

[GAHorn]

After I saw how small the hardware was that holds that entire tail on, I was surprised! No spinning my 60 year old airplane for sure...

I also never spin my 60 year old airplane. It was completely rebuilt15 years ago (took 17 years of restorative effort) and all new cables, hardware, pulleys, etc. etc......but why stress a flying museum piece? Go rent a real aerobatic fun machine for that kind of stuff....especially for the POWER!