Rudder Cables & warning

[Metal Master]

Rudder Cables, a Warning!!! And a Question.

I have read about rudder cables in the 170 book in the last couple of days but I thought this would be an interesting thing to note. I just finished riveting the tail section (the area below the stabilizer) back on to the fuselage the day before yesterday and started inspecting the Rudder, Elevator and Elevator trim cables. The cables were fairly dirty and probably original but for the most part looked intact and not rusted. However after cleaning with a cloth and light lubricant to remove the dirt I started flexing the cable to inspect the strands this is what I found. A good drawing is depicted of the condition of my cables in the inspection guide lines in AC 43.13-1B in section Seven paragraph 7-149 a., through o. Figure 7-16 is exactly what the rudder cables looked like in my aircraft. More over the cable looked normal from all appearances before bending in the prescribed manor of inspection. The cables were extreamly fraid. In fact I did not inspect further because it was apparent that the cable would snap into two pieces if I it forced further and I want keep the cable intact in the event I need to use it as model for manufacturing a new cable.
This was a flying aircraft one year 3 months ago and it has been inside for the past four months. It was apparent from working in the rear of the aircraft that at one time in the distant past the drain holes were plugged in the tail of the aircraft and that the tail had been filled with muddy water up to the exit holes for the rudder cables below the stabilizer. This area can only be inspected through the exit holes for the cables and the elevator push pull tube without removing the stabilizer. This is where the rusted corroded part of the cable was located. The cable has to be removed from this area to accomplish an inspection of the cable. This requires that the cable be disconnected from the front end and then pulled out of the aft end of the aircraft. This could be accomplished with out removing the stabilizer and the fair leads once the pulleys at the forward end of the fuselage are removed.
The previous owner of this aircraft was probably lucky that he ground looped it. I am sure I could break this cable with a very low amount of strain and it has most likely been that way for a while. Warning!!! If you are not sure of the condition of your aircrafts control cables. Take the time to have them thoroughly inspected. This was an accident waiting to happen.
Now does any one know of a source for ready-made cables? I will be taking these cables up to University Swaging in Seattle to have new ones made exactly the same as the originals. I have had cables made for other aircraft at University Swaging before but it took some time to get it done, as they are a major manufacturer for many aircraft companies that need to have production runs of cables made.
I am going to hate this but I will probably just replace all of the cables in the aircraft.

[johneeb]

Jim,

Here picture from 43-13 page 7-35, so we can all see what to look for.

I bought new McFarlane cables from McFarlane (http://www.mcfarlaneaviation.com) and later found that Beuco (800-325-6163) sells McFarlane cables at a discount.

Johneb

[GAHorn]

Thanks, John for posting that info. McFarlane is one of the best in the buisiness. I have seen them mfr cables for an airplane that actually was a "parts"-plane and had goofy, botched-up, homemade/adapted cables installed. McFarlane not only accepted the return of their own new cables (which actually were correct replacement parts as depicted in the IPC,) but at no additional cost custom mfr'd cables to fit the customer's aircraft.....which had a completely custom cable-routing created by mismatched serialed subassemblies,.... but which also was actually overseas! They even covered the return freight (despite no error on their part!)
Good company, and fine products.

[Metal Master]

Thanks Guy's

Jim

[buchanan]

It looks like I got beat to the punch. I bought a set of stainless for my '55 170 from Mc Farlane. (785) 594-2741 located in Kansas. They cost $1,133.82. This was a month ago.

Best...........Buck

[Metal Master]

It looks like I got beat to the punch. I bought a set of stainless for my '55 170 from Mc Farlane. (785) 594-2741 located in Kansas. They cost $1,133.82. This was a month ago.

Best...........Buck

Was that for a complete set? If so I do not think thats to pricey. I will probably order them next week. I have been removing the old cables measuring them & taking digital pictures and taking notes as I remove them.

Jim

[buchanan]

Yup, for a complete set. My IA friend has used them for a long time and speaks highly of them as did George.

Buck

[johneeb]

I did a little better than Buc as I got my complete set delivered to Chicago area from McFarlane for $1052.93 (invoice date 12/01/2003).

I have been told by the sales lady at Bueco that Bueco sells McFarlane products at a discount.

Johneb

They cables fit rite and so far, about 15 hours, have held together.

[Jeff Palmer]

Dang! That's expensive. My mechanic got me some new ones about 3 years ago. I think they were about $300.00. He had me soak them in some stuff before I installed them. That year I just had finished my BFR and my instructor showed me how the 170 can make these flat turns by giving it full rudder one way and full aelorons the other. He slammed me against the door with the force of the turn. I didn't know it would do that. We laughted at that. Then, at my next annual, I replaced my front rudder pulleys. They were fretted. It was then I saw the cable was popping out some strans. When I took it out and twisted it, a whole bunch of them popped out. It's lucky we didn't pop a cable with that flat turn. I check my cables, at the front pulley, really good now. Use a nylon stocking. It will snag on the smallest little fray.

[Metal Master]

After looking at their online catalog that $1,133.82 is the price to replace every cable in the aircraft not just the rudder cables. The most expensive cable in there on line catalog was about $130 for one of the aileron cables over all a pretty good deal. The trim cables appear to come with new chain with them. The difference between galvanized steel set and stainless steel is around $60.OO with the stainless being the more expensive.
Until I read their web sight I would have bought the stainless cables but now I think I will put the Galvanized steel in.
Their web sight allows you to look up the set you need by the make model & serial number of your aircraft.

Jim

[N1478D]

Hi Jim,

Would there be a good way to break the cable/pulley issue up so that the cost and effort could be spread over multiple annuals? If so, which systems would you do first and what would be the groups? Or, is it the type of project that's best done all at once, inspect/replace all pulleys and cables that need it?

[BloomerJohn]

Had the same experience with my 140. We checked another on the field and found the same!! We discovered an inspection technique that began by removing the turnbuckle behind the rear seat bulkhead, securly attaching a smaller pulling wire to the end, then pulling the rudder cable out of the rear far enough to do a proper inspection.
Nice catch.
John

[mrpibb]

dont forget your other cables, I found this on my last annual, all i did was give it a little twist and several stands popped out at me!!
http://www.sandhillaviation.com/flapcable.jpg

[Metal Master]

Hi Jim,

Would there be a good way to break the cable/pulley issue up so that the cost and effort could be spread over multiple annuals? If so, which systems would you do first and what would be the groups? Or, is it the type of project that's best done all at once, inspect/replace all pulleys and cables that need it?

I think that in the case of my 170 that I just do not have a good feeling about any of the systems cables. So far every cable has passed inspection except the rudder cable. The areas of most concern are those not easily accessible. For example either area inboard and out board of the wing root and the tail cone area aft of the bell crank. I still have to inspect my flap & aileron cables.
I would recommend breaking it down like this and in this order.
· Rudder System: Remove enough to get the forward end of the cables disconnected and the first two pulleys attached to the forward side of the main gear bulkhead. Disconnect it at the rudder and pull enough out to get the aft end of the cable toughly inspected. Crawl down the tail, remove the remaining pulleys clean and lubricate them. Note that except for the fairleads in the system two of which are under the stabilizer the rudder cable is now almost completely removed.
· Aileron System: Disconnect the aileron cables at the outer end. If you measure the tension on the system before the cables are disconnected and only disconnect the turn barrel on the follow through cable it makes re-rigging much easier. Pull enough of the cable out of the wing into the fuselage to thoroughly inspect the areas that pass through the wing root and upper cabin.
· Elevator System: This is the easiest system to get to, the cables start in the cabin and end in the tail forward of the Stabilizer. Disconnect the cables at the forward end at the elevator drive bell crank. Crawl down the tail and disconnect the elevator cables at the rear bulkhead bell crank. While in the tail took a good look at the top end of the elevator bell crank brackets where they are riveted to the bulkhead. They are prone to cracking in this area. Crawl out of the tail and pull the cables out into the passenger compartment. Now the cables can be pulled back and forth through the cabin area thoroughly inspected. If time and expenses allow remove all pulleys clean and inspect.
· Elevator Trim System Cables: The most difficult system to deal with. Mostly because once the cables are taken off of the sprockets it takes a lot of running back and forth from the tail to the cabin to get everything set up again. Disconnect the cable at the turn barrel and attach a string to one each end so it is easy to pull back to the cabin. Before you completely remove the turn barrel put a plastic tie wrap over the chain at the front trim wheel as close to the drive sprocket as possible and tighten it so that the cables will not com off of the sprocket. Remove the cover over the sprocket at the stabilizer on the trim actuator and pull the chain off of the sprocket. Depending on the condition of the screws in the bracket cover this can be a lot of work. If the screws are rusted in either the clamp are on the actuator you may end up spending hours here just getting this sprocket chain thing accomplished. Most likely you will end up having to remove the trim actuator completely and servicing it. Once the cables are lose you can pull them far enough forward and aft to inspect them enough by crawling into the tail and cabin. Unlike their 172 brethren the 170 only has a small access hole in the top of the stabilizer where the trim cables make 90 degree turn. The cables can be pulled inboard from this access hole and inspected. Be careful when re-installing the cables from here back to the trim actuator. It is easy to get the chain on up side down and get the trim moving the wrong direction. I put a piece of triple wrapped masking tape on the top cable only to identify it as the one on the top of the sprocket before I remove it.
· Flap System: I save the flap system for last but it probably makes sense to do this system at the same time as the ailerons.
o 170 *170A: Remove the cover on the top of the wing root. Disconnect the flap cable from the end at the flap handle. Pull enough of the cable out to inspect the area in the cabin. Pull enough out at the flap drive at the wing to inspect those areas of the cable that pass through the wing root. While the cable is loose pull the cable out at each section where it passes through the cabin overhead to allow physical inspection of each section of the cable.
o 170B: Remove the turn barrel on the two drive cable connections closest to the flap handle. Disconnect the cables at the flap bell cranks in the wing. Pull enough cable inboard and out board and through the floor to inspect the cable thoroughly.
In all cases follow the rigging instructions in the 100 series maintenance manual for re-rigging the systems. In the case of the 170 & 170A the aileron, elevator, and flap control systems run through a pulley set that has a common axel at the back of the passenger cabin that will not allow you to take cable tension off of one system and remove those pulleys with out affecting the other system. So it makes it difficult to service those pulleys during any one systems work. The 170B’s aileron and flap cables run through the rear doorpost, which is not the case with the 170 & 170A.

I hope this helps. I know it is rather brief and most likely will open a bigger can of worms but it is a beginning.

Jim

[Romeo Tango]

After getting a split flap during a preflight, I replaced all of my cables during annual. I figured I'd only do it once in my lifetime, so I would do it right. I also replaced as much of the attaching hardware as could reasonably be reached or removed (eyes, bolts, nuts, etc.) The entire kit of hardware was another $125 or so, and brings everything up to new.

I did have one issue - the trim was not installed so that neutral trim is neutral on the trim wheel markings.