I am a new subscriber to this forum and your thread caught my attention. I have a Series 6 that was completed in early 2002 and now has over 600 hours on the Hobbs. During that period I have replaced the trim rocker switch twice. The contacts detorate over a short period due to the continual actuation in cruise. I know that this problem be could be reduced if I had slowed the actuator speed with a series restistor. I have read where this has been done before. If anyone on the forum has done this successfully, I would like to know what restinance value they found most effective.
I would also like to know the make and model of the actuator provided for the Series 6 without having to remove it. It sounds loud while operated with the engine not running. I'm trying to find out what is the normal running current, and if it requires periodic lubercation.
Hi John, I suspect John King has joined us from what I can gather from your post. Welcome John haven't heard from you in awhile. Your expertise with all things Kitfox will be appreciated here. Now on to your question, I met an auto electrics guy at Sun n Fun years ago when I was building my Series 5 and he designed a 2 speed system for our trim setup and was kind enough to send me a wiring diagram. I incorporated the system into my airplane and have been very happy with its operation. I have a DPDT(double pole double throw) toggle switch mounted in the center console next to the trim rocker switch for Fast/SLow trim. I keep it in the fast position for pattern work and switch to slow for cruise operations. I find that my setup slows the trim down by about half. Full throw full up to full down in fast mode is about 7 or 8 seconds , and in slow about 13 or 14 seconds. Attached you will find all the information you need to install this setup. I used option "C" or the max retard option for mine. John, I would like to purchase another rocker switch to have in standby should mine ever crap out. Do you remember where you purchased yours and what the part number was for an exact duplicate of what we have? Thanks Bruce Lina N199CL
You got the name right. Thanks for the information on the trim speed control system. That ballast resistor has a resistance range of 1.2 to 5.0 ohms. I am still trying to find out what the make and model number is of the actuator arm in the Series 6.
John, I would like to have a backup rocker switch in my parts inventory, do you recall where you got your replacement switches and if so what the part number for the switch was. Also I will see if I can find out about the actuator for you. Thanks Bruce
I actually ordered two types of DPDT switches from Granger on the Internet: <http://www.granger.com>
One was a Rocker for $21.89 and the other was a Toggle for $18.94 The Rocker is slightly smaller in length and width than the one provided by SkyStar. The Toggle uses a 1/2" mounting hole. They are both made by Hubbell Wiring Device-Kellems.
Rocker = Granger #3JC10 and Toggle = Granger #3HZ95
They are both rated at 15 amp inductive. I am not that impressed with with either of them, especially based on cost, and I think 15 amps is not suited for our application over the long haul. I just ordered a DPDT Rocker switch from Spruce A/C that is rated for 20 amps and at a cost of only $8.40. The Spruce P/N is 14-225. I will give that one a try. Note: all of the switches are spade terminal type, not terminal lugs.
I am seriously thinking of designing a relay operating trim system in an effort to reduce the current flow through the switch contacts. My failure modes have been pitted switch contacts. The switch will only activate the relay coils. That combined with the speed control you suggested ought to be the most reliable speed selected electric trim system. Finding the proper 12 VDC relays will be the biggest problem. I would mount the relays and ballast resistor in a small metal box with a terminal board attached somewhere behing the instrument panel with easy access.
Anyway, that's my current thinking.
--
John
Warrenton, VA
N993JK
Good idea John, a relay sounds like a smart move and one that should extend rocker switch life given the constant use the trim actuator gets in a Kitfox (for trim rather than flaps as in an RV). Here is the relay board commonly used in RVs, seems like this would be perfect for our application. cat-med_flap-board.jpg
Sorry to bump this 13 year old thread but thought I would post because its still an issue. I have a Series 6 and had this intermittent trim problem at around 90 hours flight time. This thread mentions two causes of the intermittent trim problem: 1) gunk in trim motor's commutator and brushes and 2) arcing in the switch.
First a warning. Although others seem to have successfully taken the trim motor apart, cleaned it, and put it back together, it's not for the faint of heart. As careful as I was during disassembly, four washers fell out leaving me scratching my head as to the proper order and I didn't want to guess. Other problem is that getting the brushes back properly is very difficult. My suggestion is to do what I did and just order another trim motor assembly from John McBean.
In my case, the problem turned out to be arcing in the switch (see photos). I was initially fooled into thinking the switch was fine because when I removed the connector to the trim motor and measured the voltages there I got +12V with down trim activated and -12V with up trim activated. The issue though was that because of the worn contacts, the resistance was too high. Replaced the switch, and all worked fine.
Since this problem has not been reported since 2008, my guess is that only the Skystar kits that had the old arc-prone trim switch. The new rocker switch from John McBean is different.
John, here is a place to start for the trim actuator www.motionsystem.com. I suspect that ours is a model 85615/85616 however I am not positive about this. We will need someone who is still building to see if they can find a model number on their actuator as mine is buried in a completed airplane. Bruce Lina N199CL
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".
Re: Intermittent Electric Trim Actuator
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