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Thread: Rudder Cable Slapping Sounds

  1. #1
    Join Date
    Apr 2019
    Location
    Macomb Township, MI
    Posts
    4

    Default Rudder Cable Slapping Sounds

    Fellow PA-22 flyers, I have a question!

    Lead-up notes:

    • Went to fly my Tri-Pacer, heard slapping noises coming from baggage area when turning yoke left / right (noise isn't new, but for whatever reason this time the noise was louder than it used to be)
    • Didn't fly, instead removed panels and channels in baggage / rear seat area for the rudder cables
    • Cables were rather slack, and when turning the yoke they slapped against the floor panels near the baggage compartment (so that's the source of the sound I heard) - also of note: cables REMAINED on all of the pulleys, even when slack
    • Removed panel in front next to rudder pedals, found hard connection between pedal tube and cable (no springs)
    • Removed strobe light panel on bottom side of aft fuselage, saw rudder pedal cables connected to interconnect / actual rudder movement cables via another hard connection (crimped sleeve)
    • So basically, I see a cable with a hard connection in front and rear with no method of taking slack out of the line


    Questions:
    • This looks to be how it was designed, can anyone confirm that there is no potential to remove slack in the rudder pedal cable line on the base design?
    • Is this a potential issue? (Note: I don't see any place the line is scraping anything, just slapping as it goes limp, cables look just fine, no wear marks or anything)
    • Some designs I think have springs on the rudder cable connection to the pedal tube at the front - is this true? Does it change the way the cables, pedals, or nose-wheel connection operate?



    After looking at everything, I decided this is how it is (everything seemed to match a Univair cable diagram I found online, as well as a few others). I put it all back together and flew it with no problems, just that slapping noise. I have no idea why it became more prominent recently, but it did.

  2. #2
    Join Date
    Feb 2015
    Location
    Weatherford Tx
    Posts
    10

    Default

    Hi Jeff,

    You are right in your assessment. Where the cables attach to the rudder, there is a fitting with several bolt holes, that give (coarse) adjustment for the rudder cables.

    I am not positive about this, but I think you can also make finer adjustments by adjusting the length of the push rods that go from the rudder pedals to the nose gear steering horn.

    To my knowledge, there is no tension specification for the (rudder) cables. I would not have them under any tension, just remove any "excess" slack (very subjective!). Make sure you can go from 'stop to stop' (the 'stops' are located at the rudder horn).

    Conventional models (PA16, PA20, PA22/20) have springs running from the "outside" pedals, forward to the firewall. I think this is not to put any tension on the cables, rather to keep the pedals from 'falling backwards'.

    I also think either later model Tri-pacers (or Colts) have a requirement to have an extension added to the nose gear steering horn, with springs that run back to the mount. (I have just done a review of AD's and SB's, and I can't find any documentation of this)

  3. #3
    Join Date
    Nov 2006
    Location
    Mason, Ohio
    Posts
    341

    Default

    Jeff,

    Paul is correct relative to adjusting the length of the rudder cables. The rudder should hit the stops at the same time the front nose gear hits it's stops and the tabs where the cables attach to the rudder horn should be adjusted to make this happen. If you check the owners manual, you will note that the rudder cables tension is specified as slack, but this is relative. If you want any rudder authority in crosswinds you have to be able to hit the stops. I adjust the rudder cables so they are taunt, but not under tension. If you find you have to adjust the steering rods to further tighten the rudder cables, make sure you can still hit the steering stops and that there is clearance between the rods and the engine mount and carburetor when the front gear is at the steering stops.

    Depending on the year your Tri-pacer was made you can fabricate a kit, that Piper use to sell, that allows for the interconnect between the rudder and the ailerons to be disconnected. This kit requires the use of a Colt steering horn, which are hard to find. There is a drawing on the Drawing CD #14926, which shows the kit and the components. If you need more data on this, let me know

    Tom Anderson

  4. #4
    Join Date
    Apr 2019
    Location
    Macomb Township, MI
    Posts
    4

    Default

    Paul and Tom,
    Thank you both for your replies, both are very helpful.

    I'm going to check the owners manual as was stated to learn a bit more. I'll also check the push rods to the nose gear and see if I have any room for adjustment (considering the comments about hitting stops at both nose gear and rudder simultaneously).

    So, I may sound lazy... but I really like the interconnect. Once I get the plane trimmed out properly (in relatively smooth air that is), I love just being able to steer with my feet. It's like a poor man's auto pilot haha!

    Again, thanks for the advice from both of you. I'll report back if I decide to make some changes.

    -Jeff

  5. #5
    Join Date
    Feb 2015
    Location
    Weatherford Tx
    Posts
    10

    Default

    Hi Jeff,

    It sounds like you are a 'hands on' kind of guy when it comes to maintaining your plane. The SWPC store has several excellent reference sources for guys like us!

    There is a DVD called "SWP Rigging", written by (the late) Frank Rush, our 'Mr Mechanic' for several decades. It covers all the rigging steps on all our models, including rigging the rudder, pedals, and nose steering.

    Also, there is a DVD called "Tips and Techniques", which is a compilation of all technical articles that have been printed in the SWPC News. Easy to search for most any topic.

    Finally, they have a DVD containing MANY (most) of the blueprints that were used for the production of our planes. Extremely valuable for people wanting to maintain their planes. Even if you don't do the actual "wrenching", it is unlikely your mechanic will have the info contained in these blueprints. It's your plane, it is very beneficial to you for your mechanic to have as much info as possible about it.

    I kind of agree with you about the interconnect... I have flown SWP's with and without the interconnect, and have found (for me) it doesn't make much difference, in smooth air you can still make 'course corrections' with just the rudder, and if you want to 'slip' the plane, over powering the interconnect springs is very easy. Still, I have found the interconnects to "assist me" in making coordinated turns (& I need all the help I can get!)

    Just to clarify on the rudder / pedals / nose steering rigging; use the connections at the rudder horns to "coordinate" the pedals to the rudder (pedals aligned evenly, while the rudder is 'straight') Also, to a slight degree, you can adjust the pedals fore or aft a small amount (for 'feel'). Afterwards, make sure the pedals still have enough travel to move the rudder 'stop to stop'. Then adjust the nose steering rods to 'align' the nose steering with the rudder and pedals. Lastly, adjust the nose steering stops (they are adjustable) so that they prevent 'over steering' (with a tow bar) from over stressing the rudder stops. Make sure that (with an air load applied), the steering stops will not prevent full travel of the rudder.

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