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Thread: Intermittent Electric Trim Actuator

  1. #11
    Senior Member jdmcbean's Avatar
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    Default Re: Intermittent Electric Trim Actuator

    Please do not contact Motion Systems. They want nothing to do with aircraft. Not unusal.

    If there is a way we can help please let us know.

    Good tip Randy on the Circuit Board.

    Welcome aboard John.. Wondered how you and Chuck have been.

    We also have rocker switches as well...
    Last edited by jdmcbean; 12-21-2008 at 03:04 PM.
    John McBean
    www.kitfoxaircraft.com
    208.337.5111

    "The Sky is not the Limit... It's a Playground"

  2. #12
    Administrator RandyL's Avatar
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    Default Re: Intermittent Electric Trim Actuator

    Ditto on not mentioning the word "aircraft" to Motion Systems -- they stopped supplying Van's Aircraft for that reason. I needed a specially configured actuator for my RV-3 and said it was for the "automatic trunk lift on my show car".
    Randy Lervold
    TeamKitfox.com Admin Emeritus
    Day job: www.dynonavionics.com

  3. #13
    canelson's Avatar
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    Default Re: Intermittent Electric Trim Actuator

    Motion Systems is the correct make and the website is listed in an earlier post. The model # of the unit in my Series 6 did not match anything that they have on their website. I thought I wrote the model number down when I had it out to clean it but I can't seem to find it. I'll keep looking. Craig

  4. #14

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    Default Re: Intermittent Electric Trim Actuator

    Bruce,

    With the help of a mirror, a bright light and long arms I was able to read the part number of the motor on my trim actuator and the date 11-23-99. The name "Motion" was on the gear box. I called Motion Systems and described the unit. He said it was their actuator unit P/N 85615. I described to him the trim circuit in the Kitfox and what my problem was (failure of the trim switch due to arching of contacts). He stated the current in-rush when the contacts first close can initally exceed several amps causing arching and eventually weld the contacts together. The normal current flow in the 85615 model is less than 1 amp and varies with load.

    I told him I wanted to add a series resistor to slow down the motor and relays to actuate the motor in lieu of the switch. I gave him the following current readings based on my tests in my Bird.

    UP = 0.58 amp w/o resistor
    DWN = 0.36 amp w/o resistor
    UP = 0.54 amp with 8 ohm resistor
    DWN = 0.32 amp with 8 ohm resistor

    He stated that they were typical readings depending on load and that realays are the way to go for that application. I also asked about actuator luberication and he said that they use a perminate luberication that does not requird any periodic maintance.

    I also called VAN's about their Flap Control Circuit board referenced by Randyl. They had no circuit drawings available, but felt that it could be used in the Kitfox trim sustem. I ordered one and will test it out combined with the 8 0hm ballast resistor.

    BTW, the two DPDT switches I mentioned earlier and the one I ordered from Spruce A/C are all smaller than the hole available in the Kitfox center console. If the new circuit design with relays and the resistor works out, I just may use the same type make switch I had before. I should't be a problem any more due to the use of the relays.

    I have developed a new circuit diagram for the use of the relays and speed resistor, and if the VAN's circuit board works out I will modify it accordinally and send in a copy.

    John

  5. #15

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    Default Re: Intermittent Electric Trim Actuator

    John,

    Great to hear from you. Chuck Tippett and I are still flying and doing great. Chuck has his commercial now and is also a Sport Pilot flight instructor. As you probably already read by now, I called Motion Systems
    in an effort to help identify the trim actuator and ask about maintenance. They were very friendly and informative and did not hesitate in answering my questions. They did say that they no longer provide the actuators for aviation applications due to past libaility concerns.

    If the circuit design I am working with on the Series 6 trim system does all I hope it will, I will provide you all the details. In that application I will probably use the same switch you provide. Good to hear your business is back on line. Let me know if I can help in any way, like showing prospective buyers what a Kitfox looks and feels like.

    John

  6. #16
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    Default Re: Intermittent Electric Trim Actuator

    John, Excellent detective work on finding out about the actuator. Do us all a favor and keep photos and possibly a schematic of your work with the trim switching system that you come up with . Sounds like a mod that we all may be interested in retrofitting in to our airplanes. For those of you on the list who may be relatively new to the Kitfox aircraft. John King is one of the legends of the Kitfox line. He has built some beautiful Kitfoxes and has led some Kitfox expeditions to Alaska and Canada. So I would advise you all to listen up when John posts on this forum because he is a wealth of information for the rest of us. John , hope I didn't embarass you but I want this list to know that we are lucky to have you chime in from time to time. Bruce Lina N199CL

  7. #17

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    Default Re: Intermittent Electric Trim Actuator

    Bruce,

    Just a little more information on that ballast resistor you mentioned. It is actually two seperate resistors encased in a ceramic housing with the resistor spade terminals sticking out of the bottom of the housing. One resistor is 2 ohms and the other is 6 ohms. By a combination of jumpers you can get a variation of resistances from less than 2 ohms to 8 ohms. I also found that the 8 ohm combination provided the slowest and best trim speed for my desires.

    It is a very hefty resistor and can tolerate the current required to drive the actuator. It's size is 3 1/8" x 1 1/2" x 5/8" not including the spade terminals. It weights 3.0 ounces. It is sold through NAPA and manufactured by Echlin under P/N ICR24 and sells for $7.10 retail.

    John
    Warrenton, VA

  8. #18
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    Default Re: Intermittent Electric Trim Actuator

    I had the intermittent trim problem as well, and found it was gunk
    on the commutator, and brushes. Cleaned it up, and has worked fine
    since. I also bench ran the motor for a couple hours at full speed to
    seat the brushes.

    On the matter of trim speed, a better solution is to use a Pulse
    Width Modulator circuit. That said, the ballast resistor solution is
    simple, and most likely will work fine (as per Bruce's system).
    The difference is that a pulse width modulator will reduce speed
    while maintaining motor torque. A resistor will reduce torque, and
    increase motor heat.

    I found replacing the factory supplied Rocker switch with a better
    switch was all I need to solve trim sensitivity problems. Since the
    better quality switch allows a simple tap to adjust trim. So I've
    never needed to slow down the motor. The grey black switch has
    such strong springs it's hard to just tap in a minor adjustment.

    Jeff

  9. #19
    Administrator RandyL's Avatar
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    Default Re: Intermittent Electric Trim Actuator

    Jeff,
    Do you have a supplier and p/n for the better quality switch? And does it fit in the same hole as the Kitfox supplied switch?
    Randy Lervold
    TeamKitfox.com Admin Emeritus
    Day job: www.dynonavionics.com

  10. #20
    Senior Member
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    Default Re: Intermittent Electric Trim Actuator

    in fact here's a model railroad (yes that's what I said), controller
    pre-made which would probably work just great. It claims 12VDC
    at 30 amps continuous which should work fine.

    http://www.bakatronics.com/shop/item.aspx?itemid=581

    Regards,
    Jeff

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