Rudder Cables

TP · Post by TP » Sun Mar 14, 2004 11:53 pm

I was out at the airport the other day doing the bumm thing and trying a j3 cub on for size, got a lot of laugh's out of that. When everyone's sides hurt to much to laugh anymore they pried me out an we went onto other thing's such as admireing a 1955 170B that was visiting from a privite strip not too far away. Proably came by to see what the laughter was about.

Anyway I was talking to the owner who I kinda know and asked him to look at another 170B that is slowly growing into the ground there and give me his thoughts about it . During our conversation he pointed out that the rudder cables on the 170b came out of the tail cone in a diffrent place than his did even though both planes where built in the same year 1955. The cables on the one plane came out low and ahead on the tail cone like the ones on the plane pictured on the cover of the latest 170 news where as his where further back and higher up on the tail cone comeing down almost parallel to the tailwheel leaf spring. Why the difference ? TP

doakes · Post by **doakes** » Mon Mar 15, 2004 12:18 am

My rudder cables are different than others also. I ask around to other 170 drivers and finally our conversation came to the question, had there been an auto pilot on the airplane. I said yes and I removed it because it was one axis and the equipment was old.
Maybe that is why the one you refer is different. Just a thought

Dave

mit · Post by **mit** » Mon Mar 15, 2004 5:06 am

It was a factory change in late 55. They cross over inside the tail like a 180.

Dr. Dave · Post by **Dr. Dave** » Tue Mar 16, 2004 4:38 pm

Wow this is timely?? I don't get much chance to get on the site lately but I am doing my annual and noticed a warning posted here about pulling the horizontal stabalizor and "really" inspecting the cables pulley/fair-lead assembly inside the tail cone...

Luckily I have an inspection port on the lower right hand side beneath the horizontal stabilizer.... I was able to feel around and see a fair bit and did discover a problem!

My rudder control cable assembly passes into the tail cone quite high up and after passing through a large pully have two shorter cables attached to them, which then pass forward through the same pulley and downwards and cross each other to opposite sides, through another set of pulleys.... then these short cables pass rearward and out through the lower sides of the tail cone and attach to the tail wheel assembly...

My problem was, that I discovered that where the two short cables cross each other they are actually rubbing against each other!! Not a safe situation! My mechanic thinks that I need to remove one cable and re-route it so that it crosses behind, instead of in front of its mate?? However he is guessing, and there does not seem to be that much tension now at the point where they cross that I would expect the situation to improve any by simply re-routing them... On close inspection, I noticed that the hangers for the lower pulley is asymmetric in shape... both hangers are attached to the side walls facing the same way. This places the two pulleys exactly opposite each other and therefore creates the problem. It would appear to me that one of the hangers should be reversed so that the two bullies are not assembled exactly in line with each other... This would relieve the problem of them rubbing against each other where the two cables cross??

I could not find a suitably enlarged picture in the Cessna manual of this cable assembly.. Does anybody recognize this problem and have a correct solution for us??

Thanks Dave
PS I will post this as a question as well in the maintenance section of the forum..

pasts

jon s blocker · Post by **jon s blocker** » Tue Mar 16, 2004 9:21 pm

Dr Dave,
On one of the pulley brackets, I don't remember which one, there is a spacer between the pivot attach bolts, (for a lack of better term), and the bulkhead. This is supposed to space that pulley out just enough to keep the cables from rubbing on each other, and still keep them lined up. The attach bolts are like eye bolts that have a pivot shaft that goes through them, that is what the pulley bracket pivots on. One set of those bolts has a spacer on it to set the backet out about 1/16 of an inch or so, which should keep the cables from rubbing. Check to see if you can see or feel the spacers on ONE set of bolts, (appears to be a thick washer). If there is none , that is your problem. If you have the spacers, check to see that the proper cable crosses in front of the other. If not then one cable is actually forced against the other. One other case could be that the attach bolts are starting to pull through the bulkhead or have bent the bulkhead enough to allow the cables to rub together. I have seen pictures of these bolts actually pulling completely through the bulkhead! You can put a doubler on the back side of the bulkhead to prevent this. Also do NOT use the compression type spring, as it will only compress so far, the all of the strain goes directly from the cable pulleys to the bulkhead. If this is not clear, PM me and I will try to explain better. By the way, my spacers are on the bottom right pulley, (looking from the tail forward).
Jon

Dr. Dave · Post by **Dr. Dave** » Wed Mar 17, 2004 7:24 am

Thanks Jon.. Your explanation is very clear and makes sence.. I really appreciate this information.. I will pass it on to my mechanic tommorow and let you know if I need any more help..

Thanks again..

Once again the group is such a big help.. Right now this information helps me but because it is accesable to all, it may well help someone else in the future..

Dave

Post by **GAHorn** » Wed Mar 17, 2004 3:29 pm

Jon has addressed the major part of this issue. I responded to your other msg about this, Dave, with other factors regarding the later tailwheel steering system. (Eyebolts are also different. See the IPC pgs 107a and b.)