procharger Posted February 4, 2014 Report Share Posted February 4, 2014 What is the best way to see if the rudder trim is working correctly, mine doesn't seem to have much effect thanks?? Link to comment Share on other sites More sharing options...
Al Downs Posted February 4, 2014 Report Share Posted February 4, 2014 I have the same complaint. My rudder and aeliron trim seems have little to no effect when I try to use them. Link to comment Share on other sites More sharing options...
Anticept Posted February 4, 2014 Report Share Posted February 4, 2014 Rudder and aileron trim, if you are referring to a CTLS, has significant movement before any appreciable change occurs. I've had to spin the wheel on mine over several times before it adjusted on both our CTLS aircraft, and then i have to spin it in the other direction a full spin before it starts undoing. I've been wanting to have a closer look at the trim mechanism, but haven't had the time. Link to comment Share on other sites More sharing options...
Tom Baker Posted February 5, 2014 Report Share Posted February 5, 2014 What is the best way to see if the rudder trim is working correctly, mine doesn't seem to have much affect thanks?? The rudder trim has a tube that goes across the tunnel, and it is mounted on bearings on each end. In the center of the tube is an arm that is connected to the trim wheel. When you turn the trim wheel it raises and lowers the arm rotating the tube. There are 2 other arms on each end of the tube. They are mounted at a 45° angle with one pointing forward and the other pointing aft. On the end of these 2 arms is a small pulley that the rudder cables ride on. When you turn the trim wheel one of these arms moves higher putting more tension on that rudder cable, and the other move lower reducing the tension on the other cable. The airplane will turn toward the dirrection of the cable that has increasing tension. When near nuetral the change in cable tension for each side is small, but it increases the farther you move the trim. I did have one airplane that the cable fell off the pulley during maintenance, and it was way out of rudder trim. The aileron trim works by increasing spring tension on one side of the aileron control pulling against a static spring on the other side. Link to comment Share on other sites More sharing options...
FredG Posted February 5, 2014 Report Share Posted February 5, 2014 With my nose wheel held off of the ground, I see the "center" position of the rudder (i.e., the position of the rudder when no pressure applied to the rudder pedals) move when the rudder trim wheel is turned (2006 CTsw). One full rotation of the wheel makes a visible change in the position of the rudder. I have not made any measurements of the amount of deflection. In flight, my rudder trim is effective and definitely moves the ball when the trim wheel is turned. Link to comment Share on other sites More sharing options...
Jim Posted February 5, 2014 Report Share Posted February 5, 2014 It helps to wiggle the rudder pedals slightly as you move the rudder trim in flight. Link to comment Share on other sites More sharing options...
procharger Posted February 5, 2014 Author Report Share Posted February 5, 2014 I guess what i am asking, if i hold the nose off the ground how much should the rudder move and how many turns of the trim wheel should it take to get that movement? Link to comment Share on other sites More sharing options...
Roger Lee Posted February 5, 2014 Report Share Posted February 5, 2014 What some are missing is the proper rudder tension from side to side. If it is too loose your rudder trim wheel will have little affect. The rudder should have 24-26 lbs of pressure from the center out to 8.5" to the left and to the right. I have found many down around 15 ft/lbs and one down around 11 ft/lbs. You need to hold the rudder peddles in the neutral position. (i have a tool for this) Then measure out from the center of the rudder position and mark 8.5" out on both sides of the rudder. Attach a string and pull the rudder left then right and observe the tension. It should be around 24-26 lbs. This is shown and described in the maint. manual. If yours is too loose then trim is poor and peddles can feel loose when trying to hold the ball centered. You make the adjustment up in the front tunnel with the turnbuckles. If this is your first time you will have turned knuckles when done. Most rudder trims that I see when at rest on the ground is the top edge of the rudder pointing to the left about 1"-1.5". Link to comment Share on other sites More sharing options...
Jim Posted February 5, 2014 Report Share Posted February 5, 2014 Rudder and Aileron trim are pretty useless. Just fuel imbalance alone can play dice with the weight of the wings and the side pressure felt on the stick when the fuel gets too imbalanced. But elevator trim is almost a second stick when used to climb, cruise, and land. Alleviating necessary pressure on the stick and ensure the nose goes where you want it to without undo work and overload makes for much smoother work. The electric trim on the CTLSi is an incredible tool! I beg to differ. I fly half the time with a passenger and half the time without. I'd be fighting the airplane half the time if I didn't readjust the rudder and aileron trim. Link to comment Share on other sites More sharing options...
procharger Posted February 5, 2014 Author Report Share Posted February 5, 2014 Roger where do you attach the string?? Can I use a digital fish scale? Thanks Link to comment Share on other sites More sharing options...
Roger Lee Posted February 5, 2014 Report Share Posted February 5, 2014 I use a digital fish scale. I'll take a picture of my rope setup. Bottom line tape or attach a heavy string to one side and pull the opposite direction to measure that sides ft/lb setting. Link to comment Share on other sites More sharing options...
BMcCand - N248CT Posted February 6, 2014 Report Share Posted February 6, 2014 Roger, I would also appreciate a picture of the setup. I have not used a cable tensiometer because I can't find a long enough cable run to fit a tool over the cable. Measurement at the rudder tip would be superior for the CTSW. Do you compute the lever arm of the bearing to cable, then bearing to rudder tip to compute tension at rudder tip? Your note above said ft/lbs , not lbs. The manual speaks of the cable wire tension. Please educate us ! Thanks, Bill McCandless Link to comment Share on other sites More sharing options...
Roger Lee Posted February 6, 2014 Report Share Posted February 6, 2014 Sorry I shouldn't have said ft/lbs, but just lbs. I corrected it. When I get back out to the hangar I'll try and take a picture. It is easy to setup. One you can take a small rope and just tape it to one side of the rudder and run it around the edge and pull from there. I take a small rope about 2' long and put a loop in each end. Then you can run one end through the hole on the upper pin attachment for the rudder and when the loop comes out the other side drop a dowel rod in the loop and pull it back from the other side to pull the dowel rod up tight against the rudder at the opening. The dowel rod will keep the rope from pulling back through the hole.Then attach the scale in the other loop and pull it around the edge of the rudder. You can now put the loop and either side of the rudder by moving the dowel rod from side to side so you can pull either direction. The first way works too, you just have to make sure to tape it really well to keep the rope from pulling off. p.s. I'll try and remember to take a picture of my peddle lock bar tool. Link to comment Share on other sites More sharing options...
procharger Posted February 8, 2014 Author Report Share Posted February 8, 2014 Roger FISH pounds would have worked Link to comment Share on other sites More sharing options...
Runtoeat Posted January 25, 2015 Report Share Posted January 25, 2015 Question regarding checking the effort to move the rudder. Should the rudder pedals be kept in a neutral position and not be allowed to move by a helper while a 2nd person checks the effort to pull the rudder left/right? If the rudder cables are improperly tensioned (i.e., "low tension"), can the effort to move the rudder sometimes be noticeably different right to left? For example, might one find the effort to move the rudder to the right be 15 lbs. and the effort to move to the left be 25 lb.? Would just the tension of the left cable be increased since this is the cable that provides the resistance for right movement of the rudder? Or, would both turnbuckles be adjusted equally? Link to comment Share on other sites More sharing options...
FredG Posted January 25, 2015 Report Share Posted January 25, 2015 Dick, if you look at the rudder control mechanism, both left and right rudder application compress the rudder centering spring (under the panel, between the rudder pedals) by the same amount. Given this design, it is hard to see how the rudder control mechanism would require asymmetric rudder application forces in order to move the rudder the same amount to the left and to the right and when starting from a fully neutral - zero trim - setting (static, of course, not including yaw forces of flight). I would be concerned that some part of the mechanism had developed more resistance to motion in one direction versus the other. 2006 CTsw E-LSA Link to comment Share on other sites More sharing options...
Roger Lee Posted January 25, 2015 Report Share Posted January 25, 2015 Depending on the spring and its adjustment you can have asymmetric forces on the rudder. That's one reason your supposed to use a scale on the rudder when doing adjustments. Link to comment Share on other sites More sharing options...
Runtoeat Posted January 25, 2015 Report Share Posted January 25, 2015 Fred and Roger. No issues seen - just trying to figure out how the system works. Loose rudder control rods to the front wheel have been found and the clinch nuts to the inside rod ends were backed off the rods. Now that this has been found and corrected (I've got 4" longer arms from stretching inside the tunnel to get two the damn clinch nuts!), I'm going to have the system inspected with a good look-see to make sure it is adjusted correctly. As I have now learned and as you both know, this is not your simple, basic rudder system. It is involved. You guys have kind of verified what I suspect which is there is the common spring which provides load when left and right rudder are used. My assessment is that one cable can have less tension than the other and this may result in requiring more travel of one of the rudder pedals or may result in less effort to move one of the pedals if the cables aren't tensioned equally. Do you feel this Is an accurate statement? Link to comment Share on other sites More sharing options...
Tom Baker Posted January 25, 2015 Report Share Posted January 25, 2015 The rudder trim system works by increasing tension on one cable while decreasing tension on the other. Because of this I would expect there to be a difference in tension required to move the rudder. Link to comment Share on other sites More sharing options...
Runtoeat Posted January 25, 2015 Report Share Posted January 25, 2015 Tom, thanks for joining in. With the control rods to the front unbolted and allowed to go forward of the strut, the cables now hang slack. When the rods are fastened to the strut, I observe that this slack is taken up and the cables are again tight. As you indicate, as one rudder is pushed, this pulls on the cable involved forward while the opposite cable moves rearward. The hard thing to envision is how these interact with the tensioning spring thru the paddles and pins from the bellcranks. After reading the MM for "Coarse Adjustment", it is indicated that the 4 rod ends of both cable turnbuckles should be loosened and the rod ends turned in or out to increase or decrease cable tension. This basically answers my question by advising that all 4 rod ends should be moved out or in equally for adjustment and there isn't a need for a differential adjustment between the two turnbuckles. If, after the dust settles and the rudder is found to be off center, then there is an adjustment for this too. Should I determine that my rudder is not offering correct resistance when given the "Roger Lee" fish scale pull test, perhaps I'll only need to do the "Fine Adjustment" provided by working with the steering push rods. Or, if lucky, I'll not need any adjustment but this has not been my history so far when working on my CT. Roger, you might be getting a call........:-) Link to comment Share on other sites More sharing options...
FredG Posted January 25, 2015 Report Share Posted January 25, 2015 Dick and Tom, unless there is unusual and asymmetric friction in the system, I do not see how, at zero airspeed, the two rudder control cables can have different tensions even if the trim is set in a non-neutral position. Since the rudder, (1) is attached to the fuselage by a low friction (we hope) pivot allowing left and right motion, and (2) has the two cables attached to it to control its left and right motion, any difference in cable tension would simply result in motion of the rudder until the tension in the two cables equalized. In flight, under the influence of relative wind, unequal cable tension would occur, as the slipstream attempts to push the rudder out of the trimmed position and back to neutral (the position of lowest drag). Compression of the rudder centering spring provides the force that pushes the rudder against the relative wind (which is why our planes have no trim tab exposed to the relative wind on the rudder itself). My opinions are for discussion only and are not a recommendation for maintenance. Link to comment Share on other sites More sharing options...
Runtoeat Posted January 25, 2015 Report Share Posted January 25, 2015 Hi Fred. I agree with your logic regarding the compliant pivot back at the rudder but was wondering about the equalization of the cables at the front of the system inside the tunnel. I went back to my hangar and took another hard look at the system inside the tunnel. Now, I see that this is basically free to find it's equalization due to a pin and paddle setup down at the spring. With this, the single spring keeps the two cables equally tensioned. If more or less tension is needed, the turnbuckles are adjusted for coarse changes and the steering rods are "tweaked" for fine changes. I lingered in my fridgid hangar long enough to get my camera down into the tunnel to snap a few shots of the rudder trim idler wheels back in the tunnel. Some have indicated that the rudder cables had become dislodged from one or both of the idler wheels and I was worried that the possibility existed that this might be my case. The reason for this apprehension was due to an almost complete fall-off of effort to turn the trim wheel when it is at "center". I guess this is just the nature of this system and is nothing to worry about. I start to feel resistance from the trim wheel after about 1/2 turn in either direction from "centered". Looks like I need to do some housecleaning down inside that tunnel! Link to comment Share on other sites More sharing options...
John Vance Posted November 28, 2015 Report Share Posted November 28, 2015 Tom, thanks for joining in. With the control rods to the front unbolted and allowed to go forward of the strut, the cables now hang slack. When the rods are fastened to the strut, I observe that this slack is taken up and the cables are again tight. As you indicate, as one rudder is pushed, this pulls on the cable involved forward while the opposite cable moves rearward. The hard thing to envision is how these interact with the tensioning spring thru the paddles and pins from the bellcranks. After reading the MM for "Coarse Adjustment", it is indicated that the 4 rod ends of both cable turnbuckles should be loosened and the rod ends turned in or out to increase or decrease cable tension. This basically answers my question by advising that all 4 rod ends should be moved out or in equally for adjustment and there isn't a need for a differential adjustment between the two turnbuckles. If, after the dust settles and the rudder is found to be off center, then there is an adjustment for this too. Should I determine that my rudder is not offering correct resistance when given the "Roger Lee" fish scale pull test, perhaps I'll only need to do the "Fine Adjustment" provided by working with the steering push rods. Or, if lucky, I'll not need any adjustment but this has not been my history so far when working on my CT. Roger, you might be getting a call........:-) Hi Dick - A couple of weeks ago, I thought I had a problem with mis-adjustment of the nose wheel control rods (AKA the "fine adjustment") on my CTLS. I thought so because I noticed a that the airplane pulls to the left on the ground after landing (among other things). I noticed recently that with rudder trim set to neutral (on the ground), and after pushing the tail down to raise the NW and then releasing, the rudder has a pronounced deflection to the left. No measurement required - it's obvious. So I think I need to reset neutral rudder position and am interested in your "after the dust settles" comment above. I've not seen a full schematic of the rudder control system, so don't know how it all works together. My question is whether setting the "neutral position" stop plate per the MM affects other adjustments, i.e. 1) control cable tension, 2) rudder pedal position, or 3) nose wheel angle. I'm hoping that no "coarse adjustment" is required to set things right, but I suspect that's not the case, at least for items 2 & 3. Do I have that right? If you or anyone else knows where to find a good schematic for the rudder system, I'd be interested in that as well. Thanks John Link to comment Share on other sites More sharing options...
Doug G. Posted November 29, 2015 Report Share Posted November 29, 2015 Download the parts and assembly manual. It shows the layout of the parts. The procedure is in the Maintenance Manual. Are you a repairman? Link to comment Share on other sites More sharing options...
Runtoeat Posted November 29, 2015 Report Share Posted November 29, 2015 Hi John. i'll make some comments based on my personal experience with my CTSW but perhaps those with technical knowledge will jump in to provide some expert recommendations for you. I read your post a few times to let what you are experiencing "sink in". Your post indicates that your CT is pulling to the left "on the ground after landing". You don't indicate there was any adjustment of the steering rods to correct this. You also state that after adjusting for "neutral" rudder trim while sitting, the rudder takes a noticeable bias to the left when the nose is lifted. Question: Does your nose wheel keep a "straight ahead" position when the nose is lifted? If the front wheel remains straight but the rudder takes a left bias during "neutral" trim, I would suggest that you follow the MM directions for centering the rudder. My CTSW rudder had a right bias which my mechanic adjusted by re-positioning the rudder stop plate shown on page 3-62 in the CTLS MM. I do not recall this correction affecting the alignment of my front wheel nor did it affect the tension of the rudder pedals or rudder cable. The CTLS MM manual says to move the plate towards the engine to adjust the neutral position of the rudder to the left. Using this example, you would want to move the stop plate away from the engine to adjust your rudder to the right. My notes indicate my rudder stop was moved away from the engine to move the rudder to the left on my CTSW. Needless to say, if your front wheel has a left bias after raising it off the ground, this will cause your CT to taxi left. Turning your left rod end out from the rod and your right rod end in towards the rod will correct this. If the rod ends are turned in and out equally, this will not affect the tension on your rudder cables. I know you are working with a mechanic, as I also do for this type of maintenance, but I'm always good for throwing my 2 cents into the ring so give me a call if you would like to discuss. Link to comment Share on other sites More sharing options...
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