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DIY - Rudder Cable Replacement

Posted: Thu Feb 02, 2012 9:55 pm
by ricksigler
Intro:

First, a big thank you to Lance Murray for letting me pick his brain. He replaced his rudder cables recently and provided valuable information.

I liken the rudder cable replacement process to the colonoscopy that I get every five years. I don’t look forward to it, I’m very happy when it’s over, and I begin dreading the next one the very next day.

My biggest gripe during the whole process was cutting and replacing pristine rudder cables. The idiot that determined that the cables should be replaced every five years should have his/her head examined, and any credentials they might hold revoked. In my opinion, the rudder cables shouldn’t be replaced (if at all) until approximately 2000 hours. The cable ends could be inspected every five years, which would be more than adequate since that is the place where any problems would probably develop. I would guess that it would be virtuously impossible for the cables to break or fray in any other place. When you consider that the cables and eye ends are tested to withstand more than 2000 lbs., it makes no sense to replace them at five years. How much pressure do you think you could place on the rudder with one leg even if a wind gust happened to hit the rudder?

I found the removal and re-installation of the front seats to be the most difficult and frustrating task. After completing the process and learning a few tricks, I don’t think the removal and re-installation of the seats is difficult. I spent approximately six hours per day for five and one half days replacing the cables. I estimate that approximately two hours a day was spent chatting with the A&P. The only help I had was lifting the rear seat out, lifting it back in and safety wiring the turnbuckles (the A&P insisted on doing that). I believe that with this guide and someone to help when needed, the whole process could be completed in much less time.

So, with my big gripe off my chest and some preliminaries, here’s a step by step guide to replacing the rudder cables:

Step 1:

Print out and study the following pages from the AMM (I had the September 20, 2007 version, but checked the latest version and there doesn’t appear to be any differences):

Cable tension - Chapter 06-00-00 page 10 (33.7 lbs. +/- 4.5 lbs.).

Remove/Install rudder cables - Chapter 27-20-00 pages 205 – 211, Chapter 27-20-00 Figures 3, 4 & 5 pages 5, 8 & 102.

Seat removal/install - Chapter 25-10-00 pages 201 – 205, Chapter 25-10-00 Figures 1 & 2 pages 2 & 4. It is important to note that the manual does not cover the removal of the front seats for 2007 and forward models because of the AMSAFE seat belts. Since my DA40 is a 2007 model this caused me a lot of wasted time trying to figure out how to get the seats out.

Nicopress instructions: http://l-36.com/manuals/Nico-Press-Tool.pdf

Instruction 32: http://versales.com/ns/nicopress/instruction32.pdf


Step 2:

Order your parts. I obtained mine from Aircraft Spruce and ordered more than I needed because I wasn’t sure exactly how much I needed. I keep accurate measurements of the cables and as measured from the outside of the eye to the outside of the eye, these are the exact measurements of the cables I removed:

Pilot outboard, firewall to yoke – 5’ 1 3/8”
Pilot inboard, firewall to yoke – 3’ 9 3/4”
Copilot outboard, firewall to yoke – 5’ 1 1/4”
Copilot inboard, firewall to yoke – 3’ 9 1/4”
Pilot, yoke to turnbuckle – 3’ 1 1/2”
Copilot, yoke to turnbuckle – 3’ 1 3/8”
Pilot, turnbuckle to rudder – 13’ 6 3/8”
Copilot, turnbuckle to rudder – 13’ 6 1/8”

There are eight separate cables, so you’ll need 16 thimbles, 16 sleeves and 16 pieces of
heat shrink wrap 1 1/4” long. I purchased 10mm heat shrink wrap from Harbor Freight. It was very inexpensive. If you use a swaging tool that requires three crimps instead of the two that I used, you could probably use 3/8” heat shrink wrap. Here’s a copy of the AS invoice with the part numbers:

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I would not order the go/no go gauge again because all you need is a caliper that measures .0345”. Here’s a photo of the gauge and caliper:

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Step 3:

Assemble your tools. Your A&P may have some or all of the tools you’ll need, but here’s what I put together:

Swaging tool - Nicopress and Locoloc make the real expensive versions (over $200 new). I purchased the import version from Home Depot for $19.97 plus tax. Here’s their link: http://www.homedepot.com/h_d1/N-5yc1v/R ... ogId=10053. You might be able to get an expensive version on Ebay for a reasonable price, but I don’t think you’ll be any better off. For the Nicopress you can use models 51-M-850, 64-CGMP, 63-VXPM or 51-MJ. I didn’t research the Locoloc models. The import appears to be similar to the 51-MJ because two crimps are required instead of three primarily because of the thickness of the blades. If you do any research, you’ll find a lot of advice to only use Nicopress tools with Nicopress sleeves, etc. But, here is research showing that there is no difference between the tools and sleeves: http://www.delberthall.com/loadlab/swaging.html
Cable cutter (Felco C-7 purchased off Ebay for a total of $26)
Heat gun
Cable tension gauge (hope you’re A&P has one because they are way expensive)
Awl (used to align holes and hold sleeves on bolts in place)
Small needle nose vice grips
1/4" & 3/8” metric socket sets with extensions
Open and closed end 10mm and 13mm wrenches
Socket drive 3mm allen wrench (you can use a regular allen wrench, but it’s more difficult)
Cable ties (use to hold the cable in the sleeve for crimping)
Phillips screwdriver
Small work light
Slip joint pliers
Lineman pliers
Diagonal wire cutters
Block of wood 3/4" x 2” x 10”
Measuring tape
Masking tape
Additional miscellaneous tools I’ll probably mention later, but can’t think of now.

Step 4:

Preassemble your cables. I wish I had the information necessary to do this before starting the project. Cut your cables to the lengths shown above and add about 6” to 1’ to cover minor differences between my cables, yours and the loop around the thimble. Install one thimble, sleeve and heat shrink wrap on each of the eight cables. Since I had no help in doing this, I used cable ties to help hold the thimble and sleeve in place. The cable wants to expand and is tough to hold in place. This is an area where a helper would really be valuable. Here’s a photo of my solution:

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If you’re using a three crimp tool, the first crimp is in the middle of the sleeve, the second near the thimble and the last on the outside. If you’re using a two crimp tool, the first crimp is near the thimble and the second is on the outside. Use masking tape to tape the other end of the cable to prevent any fraying before you slide the cable through the Teflon tubes.

Step 5:

Move the rudder pedals fully aft to give you room to work. Then take the interior out of the airplane. Start with the back baggage area. Remove the pads held in place with Velcro to expose the fasteners. Use your phillips screwdriver to pop out the fittings. Pull the baggage area straight towards the front of the plane. It took some effort to get the piece under the top of the seat belt shoulder straps, but it finally came out. Lift the baggage tube out through the passenger window. Remove the molding that covers the tow bar storage compartment with the 3mm socket drive. Next, the real fun part. Remove the front seats. I started with the pilot seat, but it doesn’t make any difference. Do not rely on the AMM for 2007 models and forward. It does not address the AMSAFE connections. Remove the seat cushions that are held in place with Velcro. Take out the four bolts at the front of the seat with a 10mm socket.

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Next remove the access panel on the seat bottom using the 3mm allen socket drive. You could probably get away without removing the access panel. Here’s where I made a mistake. I removed the two bolts in the seat bottom. Don’t do that. Instead, pull the Velcro heater vent out that is located behind the seat and on the floor.

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Then remove the two bolts and washers that attach the mounting brackets to the side of the plane and to the center console. They have self locking nuts, so you don’t have to access the nuts. Use a 13mm socket to remove these two bolts and washers. Now the seat will be loose, but before you remove it, push the seat slightly forward until you can see the AMSAFE cable.

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You must disconnect the cable before removing the seat. The connector is released by pushing the red tab to its unlock position and then pushing down on the yellow locking clip. Once you’ve got the cable released you can remove the seat. The seat is very tight and I think the best way to get it out is to tilt it inboard and pull forward. Notice the seat outside the plane and the AMSAFE cable in the photo. Leave the seats attached to the lap belt. The passenger seat comes out the same way.

Step 6:

Remove the rear seats. This chore is not very difficult. Remove the seat cushion that is held in place with Velcro. Remove the five bolts that hold the rear shelf in place with a 10mm socket.

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Remove the six bolts in the seat bottom (10mm). There are three closely spaced on either side of the seat bottom, going through a plate.

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Remove the two bolts that hold the front of the seat with the 10mm socket.

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Next, tilt the rear seat forward and reach under the seat with a 13mm wrench. Use a 13mm socket on the seat bottom to remove the bolt, washers and lock nuts that hold the shoulder straps in place.

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Tilt the rear seat up on the copilot’s side and pull up the rear shelf (the rear shelf will flex). Use one person on the rear and another on the front to slide the seat forward and through the front canopy opening. You might be able to get it through the passenger opening, but it seemed easier to go through the front. More photos:

Step 7:

Remove the cables from the firewall to the yoke and install the new cables. By now, you’ll see that the job is not going to be easy because of the cramped quarters. I did one cable at a time starting with the pilot’s outboard cable. This one proved to be the most difficult because of the bolt and nut on the yoke. I’ll describe the removal of this cable because it is the most difficult. After you do this one, the others from the firewall to yoke are similar, but not as hard. First, disconnect the cable from the firewall. Use the work light. I propped the rudder pedal backward by wedging the 2 x 10 board against the pedal and against the nuts on the bottom of the dash to relieve the spring tension and give me room to work. You could probably remove the springs, but I didn’t want to risk it. This task is difficult because you’re outside the plane, reaching in with one hand. Use the needle nose vise grip to grip one end of the bolt.

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Note the position of the cable in the mounting bracket. There are five different holes in the bracket used for some adjustment. Use a 10mm socket to loosen and remove the bolt, nut, washers, sleeve and cable end. Now move to the yoke. This is the difficult part. Cut the safety wire on the turnbuckles and loosen the tension on the cables by turning the turnbuckles (they are hand tight).

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Next, go to the copilot’s side and prop the yoke over to the pilot’s side.

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Locate the outboard cable attachment point on the yoke.

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Use your 10mm wrenches to take off the lock nut. Now, the hard part. The bolt does not want to come out because there is not enough room to slide it out. I finally got it out, but found out you really don’t need to completely remove it. The cable end is held in place by the bolt, nut, sleeve and a brass cone. All you need to do is to pull the bolt up enough to pull the cable end and cone out. Leave the bolt and sleeve in place. Make sure you note the position of the brass cone on the four attachment points on the yoke so you can replace them properly. Now use the cable cutter and cut the perfectly good and pristine cable at the firewall end. Slide it out and prepare your new cable. I made my cables exactly the same length as the factory originals although I couldn’t figure out why there were slight differences in the factory lengths between the pilot and copilot sides. To get the exact length, I taped the “old” cable back together and clamped it in a vise. Then I attached the new cable to the old one with a bolt through the thimbles.

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I moved out about a foot from the eyes and taped both cables together. Next, I placed the sleeve and thimble on the end of the cable. I pulled it into position and cut the cable to length, removed the un-crimped sleeve and the thimble and taped the cut end again to prevent fraying. Now that you have the cable to the correct length, install it from the yoke to the firewall. Remember that you already should have installed one thimble, sleeve and heat shrink wrap on the yoke cable end. Pull the cable around the pulley, through the Teflon tube and through the S tube at the pedal. Slide the heat shrink wrap on the cable, remove the masking tape, install the thimble and sleeve and heat the wrap. This is a little difficult, but I did it by myself. With a helper it would be much easier. Install the cable end on the yoke with the brass cone, sleeve, etc. I left the four firewall ends loose so I could move the yoke easily and installed them after all connections were made at the yoke. To install the cables to the firewall move to the firewall end and install the cable end to the U bracket in the same hole from which you removed it. Here’s the trick to getting the sleeve, cable end, bolt, washers and nut in place with one hand: Use slip joint pliers to grip the U bracket and squeeze it together. This will bend it in slightly and allow you to place the sleeve and cable end in the bracket and the bracket will hold it in place. Use the awl to line it up correctly and them put the bolt, washers and nut on. Use the needle nose vise grips and 10mm socket to tighten the nut.

Step 8:

Remove and install cables from the yoke to the turnbuckle. By now you should have a pretty good idea of how to proceed. Use the same method to remove and replace the cables you used in step 6. Just don’t forget the heat shrink wrap before crimping the final end. The big difference in this step is that you have to deal with the turnbuckle. I got the old cable off the turnbuckle by using two pliers to hold and bend the thimble until I had enough room to use the cable cutter to cut the cable between the sleeve and thimble. I ran the cable from the yoke to the turnbuckle meaning that I had to crimp the cable end in the plane. It wasn’t really difficult, but you are doing it in the plane. In addition, you have to put the thimble on the eye of the turnbuckle. Press it on and it will pop into place, but after you do it the thimble will be spread apart somewhat. I used a pair of pliers to gently squeeze the thimble back together.

Step 9:

Remove and install the cables from the turnbuckle to the rudder. The only problem here is getting the cable end removed from the rudder. The bolt holding the cable end hits the rudder when you try to remove it and you can’t get the sleeve and brass cone out. The solution is very easy: Remove the two lock nuts from the rudder at the bottom bracket leaving the grounding strap in place.

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The rudder will remain attached by the grounding strap and the pivot pin in the top of the rudder. Slide the bottom of the rudder off the bracket. You can then push the bolt up and get the cable ends off. I installed the cable from the turnbuckle to the rudder. I was able to attach the turnbuckle to the cable outside the plane and also the cable end at the rudder.

Step 10:

Reconnect the turnbuckle. I used the 2 x 10 board to clamp the pilot’s rudder pedals together and keep them aligned.

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I then centered the rudder by sight and adjusted the turnbuckles by hand to keep equal pressure on them. I ended up with one turnbuckle being shorter than the other by a slight amount. Use the cable tension gauge to set the correct tension (really easy to use). You can now release the clamps on the rudder pedals and test your work. The rudder should easily go from stop to stop just by using your hands to push the pedals. If that works, safety wire the turnbuckle.

Step 11:

Install the back seats. No big deal here. Just remember to install the shoulder straps in the correct position before installing the remaining bolts. The three bolts on either side of the seat bottom were a little difficult, but use the awl to align the holes.

Step 12:

Install the front seats. Make sure that you connect the AMSAFE cord before you attach any bolts to the seat. After you get the cord connected and the bolts on the bracket sides and front edge, attach the heating duct to the outlet and put it back in place. Re-install the access panels.

Step 13:

Finish installing the interior and give thanks that you’re finally done and won’t have to face the process for five years.

Re: DIY - Rudder Cable Replacement

Posted: Thu Feb 02, 2012 11:21 pm
by Gary
Welcome and thanks Rick. I nominate you for having the most useful first post in the history of this forum.

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 12:24 am
by Graham
Wow, I second that!

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 2:22 am
by Rick
Yeah, WOW! You should get a couple of extra diamonds right off the top for that one!

I sure wish I'd had those instructions a couple of years ago when I did mine - there's a number of really good tips in there!

Thanks, Rick - and WELCOME! :thumbsup:

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 4:18 am
by Gary
Rick wrote:Yeah, WOW! You should get a couple of extra diamonds right off the top for that one!

I sure wish I'd had those instructions a couple of years ago when I did mine - there's a number of really good tips in there!

Thanks, Rick - and WELCOME! :thumbsup:
No kidding. He has already contributed more to this forum than I have.

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 6:06 am
by Lance Murray
Congratulations Rick. You finished. Great writeup, this will come in handy for when I do this again and have forgotten all that I taught you. :-D

Doing it yourself is a little like performing your own root canal but in the end I am happy that I did it myself. I am sure you are also.

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 8:26 am
by Kai
Welcome to DAN and Thank you, Rick! Great post!

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 11:24 am
by Aart
hey Rick,
Could you come over and do mine next year? Mallorca is a great place to spend a week or so.
Thanks for your contribution.

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 12:19 pm
by Rick
This post makes me wonder if we should have a "How To" forum to collect posts such as this. People could add writeup like this, things like "how to change a tire", or "how to change your oil", etc. It seems like we already have a number of posts like this sprinkled around the DAN (although probably none as detailed!). Any thoughts?

Re: DIY - Rudder Cable Replacement

Posted: Fri Feb 03, 2012 3:50 pm
by carym
Aart wrote:hey Rick,
Could you come over and do mine next year? Mallorca is a great place to spend a week or so.
Thanks for your contribution.
Aart,
Keep this a secrete, but there is no need to do this in the DA42 (at least for US registered aircraft).

Cary