moosebreath Posted October 30, 2017 Report Share Posted October 30, 2017 My autopilot has a case of faulty disconnect switch disease. The symptoms are the classic horn sounding at power up and failure to complete the self test. This goes on until the plane warms up, you recycle the power a few times, cycle the disconnect switch a few times, or maybe until the planets align. Once the self test completes the unit works perfectly for the whole day. The hanger elves have a replacement disconnect switch. It is clear to access the switch that you remove the screw on the top of the switch cluster. Then it appears you must remove the two screws on the trim switch and remove that switch to get to the second screw holding the upper cover. The question is ... how exactly do you do that? I can pull out the trim switch a small way but not far enough to get to the lower screw. I would have to use a very small right angle screw driver to loosen it. I do not want to pull with force on the trim switch. Hopefully someone out there who has done the job can tell me the secret. Quote Link to comment Share on other sites More sharing options...
DonMuncy Posted October 30, 2017 Report Share Posted October 30, 2017 Working from a position of extreme ignorance, I'm not sure what you have described would convince me you have a faulty disconnect switch. If it were easy to change, it might be worth it to do so, but I would try to make sure before I went to that effort. Quote Link to comment Share on other sites More sharing options...
moosebreath Posted October 30, 2017 Author Report Share Posted October 30, 2017 It almost certainly is the problem. The contacts in the switch are known to degrade with use causing either partial contact or a high resistance in the closed portion of the switch. The full power for all the servos is routed through that switch it does not operate a relay. Hence when it gets a bit worn the slightly lower voltage at startup causes a fault in the KFC computer. A lot of other folks have has similar faults corrected by switch replacement. It IS easy to change if one gets the cover off! Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted October 30, 2017 Report Share Posted October 30, 2017 It's usually the Trim Switch on the yoke. There are three microswitches inside and some small spring clips that people who really know what they are doing can replace. (I had Central Texas Avionics do mine.) Quote Link to comment Share on other sites More sharing options...
Will.iam Posted November 20, 2021 Report Share Posted November 20, 2021 On 10/29/2017 at 10:53 PM, LANCECASPER said: It's usually the Trim Switch on the yoke. There are three microswitches inside and some small spring clips that people who really know what they are doing can replace. (I had Central Texas Avionics do mine.) Central Texas Avionics no longer will do a switch replacement as the owner said it was a grey area due to the parts not being TSO and the owner doesn’t want to take the liability risk. Stupid lawyers suing every company that has money now the companies just stop working on parts that could be a liability. This will drive more people to. Experimental airplanes when there are no parts manufactured due to liability. Anybody have another shop suggestion that will fix the trim switch? Mine is very loose and I have the same symptoms of the autopilot failing the test until it warms up or I wiggle the switch just right to make it pass the test then the autopilot works for the rest of the flight. Quote Link to comment Share on other sites More sharing options...
Bob Weber Posted November 20, 2021 Report Share Posted November 20, 2021 On 10/29/2017 at 8:33 PM, moosebreath said: My autopilot has a case of faulty disconnect switch disease. The symptoms are the classic horn sounding at power up and failure to complete the self test. This goes on until the plane warms up, you recycle the power a few times, cycle the disconnect switch a few times, or maybe until the planets align. Once the self test completes the unit works perfectly for the whole day. The hanger elves have a replacement disconnect switch. It is clear to access the switch that you remove the screw on the top of the switch cluster. Then it appears you must remove the two screws on the trim switch and remove that switch to get to the second screw holding the upper cover. The question is ... how exactly do you do that? I can pull out the trim switch a small way but not far enough to get to the lower screw. I would have to use a very small right angle screw driver to loosen it. I do not want to pull with force on the trim switch. Hopefully someone out there who has done the job can tell me the secret. Give me a call 616 822 1999 and I can walk you right thru figuring out what's wrong, and the most efficient solution. Bob Weber WebAirConsulting.com Quote Link to comment Share on other sites More sharing options...
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