81X Posted March 22, 2019 Report Share Posted March 22, 2019 I have a complete, working as removed KFC150 setup minus the HSI that I’ll be getting rid of in the next week or so which could help you with the servo, PM me for details. Regarding the computer, as others have mentioned, check the pins on the harness. It’s a huge pain in the butt to get at, but many of my pins had lost their spring, so to speak, and I had to replace some when I put in my G5 HSI since the unit wouldn’t power up or drive the FD after the install. Quote Link to comment Share on other sites More sharing options...
flyingcheesehead Posted March 23, 2019 Author Report Share Posted March 23, 2019 On 3/22/2019 at 1:12 AM, PT20J said: The red button has two functions: autopilot disconnect and trim interrupt. Only the trim servo power runs through the switch (see attached installstion manual p 2-37) The autopilot disconnect is just a low current signal to the computer. Sorry, I misspoke when I said "all" servos. It is just the trim servo - But if the trim servo happens to kick in just when you hit the disconnect, you're still going to put more current through that switch than it's rated for, so it's better to disconnect the autopilot using the button on the KC192 (the control unit). Just something to be aware of is all. 21 hours ago, 81X said: I have a complete, working as removed KFC150 setup minus the HSI that I’ll be getting rid of in the next week or so which could help you with the servo, PM me for details. Regarding the computer, as others have mentioned, check the pins on the harness. It’s a huge pain in the butt to get at, but many of my pins had lost their spring, so to speak, and I had to replace some when I put in my G5 HSI since the unit wouldn’t power up or drive the FD after the install. Mine's working fine now... But its days are numbered. I'll pull it out in favor of the GFC500 at some point. The pins were one of the steps we went through in the troubleshooting process - They didn't turn out to be the culprit. Definitely a good thing to check and take care of though. 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 24, 2019 Report Share Posted March 24, 2019 21 hours ago, flyingcheesehead said: Sorry, I misspoke when I said "all" servos. It is just the trim servo - But if the trim servo happens to kick in just when you hit the disconnect, you're still going to put more current through that switch than it's rated for, so it's better to disconnect the autopilot using the button on the KC192 (the control unit). Just something to be aware of is all. I see this assertion from time to time, but it makes no sense to me. The trim breaker is 5A. So the trim servo probably draws a couple of amps max. The installation manual only calls for 20 AWG wire. It’s not hard to find a switch the size of the one used with a rating in the 3-5 amp range. Why would Bendix-King use an under rated switch in a critical circuit? Could they have even gotten that certified? Someone is going to have to show me the specs on the switch and the servo before I believe this is not just an oft-repeated OWT. Quote Link to comment Share on other sites More sharing options...
Steve W Posted March 24, 2019 Report Share Posted March 24, 2019 6 minutes ago, PT20J said: Someone is going to have to show me the specs on the switch and the servo before I believe this is not just an oft-repeated OWT. How about just a photo of the switch after it self destructs. Presumably under rated switch and undamped inductive kick from disconnecting. 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 24, 2019 Report Share Posted March 24, 2019 9 minutes ago, Steve W said: How about just a photo of the switch after it self destructs. Presumably under rated switch and undamped inductive kick from disconnecting. That doesn’t really prove anything. Switches can fail for lots of reasons. Show me specs that show that the load exceeds the rating of the switch. Quote Link to comment Share on other sites More sharing options...
Marauder Posted March 24, 2019 Report Share Posted March 24, 2019 How about just a photo of the switch after it self destructs. Presumably under rated switch and undamped inductive kick from disconnecting. Unfortunately you can damage a switch that way by getting liquid in there and I have even seen heavily used top mounted switches collect enough body parts to short out. You want proof? Turn your PC’s keyboard upside down and shake it a few times. Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
Steve W Posted March 24, 2019 Report Share Posted March 24, 2019 5 hours ago, Marauder said: Unfortunately you can damage a switch that way by getting liquid in there and I have even seen heavily used top mounted switches collect enough body parts to short out. You want proof? Turn your PC’s keyboard upside down and shake it a few times. Luckily the one thing King did right for this switch is choosing a totally sealed switch. Quote Link to comment Share on other sites More sharing options...
Marauder Posted March 24, 2019 Report Share Posted March 24, 2019 Luckily the one thing King did right for this switch is choosing a totally sealed switch. I’d like to see that specification. From every environmental spec sheet I have seen from Bendix King they don’t test the servos or even the flight computer for any environmental factors. I doubt the switch got any special treatment. But stranger things have happened. Sent from my iPhone using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
flyingcheesehead Posted March 25, 2019 Author Report Share Posted March 25, 2019 (edited) On 3/24/2019 at 1:00 AM, PT20J said: I see this assertion from time to time, but it makes no sense to me. The trim breaker is 5A. So the trim servo probably draws a couple of amps max. The installation manual only calls for 20 AWG wire. It’s not hard to find a switch the size of the one used with a rating in the 3-5 amp range. Why would Bendix-King use an under rated switch in a critical circuit? Could they have even gotten that certified? Someone is going to have to show me the specs on the switch and the servo before I believe this is not just an oft-repeated OWT. OK, I went digging, because I've heard about this in enough places that it would seem there is probably some element of truth to it. First of all, while the KFC 150 only runs the trim servo through the disconnect, the KFC 225 does run ALL the servos through it. I did verify via the KFC 150 install manual (page 2-37) that the 150 only runs the trim servo through the disconnect switch. The motor is supposed to draw a max of 5A at 14V or 2.5A at 28V, But the disconnect switch is only rated for 3A DC. Also, the switch is rated for 25,000 operations (minimum, not MTBF), yet they tend to fail WAY before that in this application, so something clearly is not right. Now, this still doesn't explain why *my* switch failed because I have a 28V system and it should theoretically be able to handle the 2.5A max of the KS179... But it did fail, and with only about 1500 hours since new on the airplane so unless it was used an average of once per 3.6 minutes, it failed early. Edited March 25, 2019 by flyingcheesehead Quote Link to comment Share on other sites More sharing options...
Marauder Posted March 25, 2019 Report Share Posted March 25, 2019 So now we know where Marauder keeps his ladies, in the keyboard Pieces of them anyways. Sent from my iPad using Tapatalk Pro 1 Quote Link to comment Share on other sites More sharing options...
mooneyflyfast Posted March 25, 2019 Report Share Posted March 25, 2019 I'm a fan of Jake at Bevan Aviation in Wichita for fixing my KFC 200. Repaired the computer and pitch servo at reasonable cost. It works great. 2 Quote Link to comment Share on other sites More sharing options...
flyingcheesehead Posted March 25, 2019 Author Report Share Posted March 25, 2019 9 hours ago, Hyett6420 said: YES finally. the KFC225 is a COMPLETELY different beast to the 150. Peter Holts blog linked to earlier shows that as well. The best example is where he flies over a military installation in France, that LOTS of light aircraft fly over and the only ones that fry are the 225s not the 150s, in fact ive flown over that place several times. we must not confuse the later 225 with the 150. Its like comparing apples with oranges. That doesn't change the fact that they do use the same disconnect switch, which still isn't rated for what the trim servo can pull on a 14V system, nor does it change the fact that those switches are notoriously unreliable on KFC150 installations too. Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 26, 2019 Report Share Posted March 26, 2019 7 hours ago, flyingcheesehead said: That doesn't change the fact that they do use the same disconnect switch, which still isn't rated for what the trim servo can pull on a 14V system, nor does it change the fact that those switches are notoriously unreliable on KFC150 installations too. There may be no way fully settle this. B-K used at least a couple of different servos (KS 179, KS 272) over the years as well as going from 14V to 28V to dual voltage. Maybe the switches are not even all the same except cosmetically. The specs I've seen here and elsewhere are not all that clear. For example, the spec for the KS 272 trim servo in the installation manual I posted previously says "28VDC or 14VDC at 5 amps." This can't be the actual current draw because the installation uses a 5A breaker. Also, the autopilot uses a 10A breaker to feed everything and if roll, pitch and trim servos all draw 5A, the autopilot breaker would be tripping a lot. Without more detailed engineering specifications for each configuration, it's impossible to tell. I still think it is pretty unlikely that Bendix-King underrated the switch. I've flown a lot of them over the last 30 years - many at flight schools where they get used a lot - and never had a failure, but maybe I'm just lucky. I seriously doubt that disconnecting the autopilot with the yoke push button causes it to fail, but you can always avoid it if you are worried about it. But much of the switch is mechanical and mechanical stuff likes to be used occasionally. Personally, when doing the trim preflight test, I use the KAP/KFC 150 method (hold the red button down and see that the trim switch is inop) rather than the KAP 140 method (run the trim and see that the red button stops it). After all, this stuff is old. Skip Quote Link to comment Share on other sites More sharing options...
flyingcheesehead Posted March 26, 2019 Author Report Share Posted March 26, 2019 4 minutes ago, Hyett6420 said: So a switch that fails after 30 years is not reliable? REALLY how often do you re-wire your house, over here its every 10 years. Sorry i do not agree with you on this. My plane has a ways to go before it's 30 years old. And to some extent, yes, I do expect things on an airplane to last 30 years. It would be god-awful expensive to fly if you had to replace every piece of the airplane every 30 years. But this is something I really don't care about. As I just told someone in a PM, I'm going to treat it the same way I treat my engine WRT shock cooling. I personally don't believe shock cooling is a thing (after all, the temp of the engine falls dramatically after you shut it down)... But, it doesn't hurt me to run my engine as if shock cooling IS a thing, just in case I'm wrong. So, I reduce power 2-3" of MP at a time starting 20 miles out, going from cruise to 22 to 20 to 17 to 14" MP, then once the gear is out, down to 2000 and then 1500 RPM. So, in this case, I'm going to try to leave the red button alone, and shut off the autopilot via the AP button instead. Maybe I was just unlucky, but since there are others that seem similarly unlucky WRT this switch, I'll just pretend that the switch is not up to the task, and use the AP button because even if you're right, it doesn't hurt me to be extra nice to it. Quote Link to comment Share on other sites More sharing options...
Pepperjet Posted October 30, 2019 Report Share Posted October 30, 2019 Anyone happen to have a part number for the pilot side, right handle, yoke mounted, KFC 200 autopilot disconnect / trim interrupt switch - with red button? Mine is round and says CS 8109 C2003R with a 3 below it in center of the switch, but nothing comes up on a search. After nearly 38 years, the plastic around the inside edge holding the red button in finally gave up the ghost and a small piece broke off. Have used electric contact cleaner a couple times through the years with good results. Switch has been a little flaky last several years, sometimes disables electric trim. Have had to wiggle it a little after using it to get electric trim to work again. Autopilot function not affected, only electric trim function. Much appreciated. Quote Link to comment Share on other sites More sharing options...
Bob Weber Posted October 30, 2019 Report Share Posted October 30, 2019 (edited) I have a used one I can test, $100 + shipping if it looks good. Bob Weber webairconsulting.com 616 822 1999 Edited October 30, 2019 by Bob Weber added contact info Quote Link to comment Share on other sites More sharing options...
Bob Weber Posted October 30, 2019 Report Share Posted October 30, 2019 I believe the King P/N is 031-0326-00, it would change (I think) to 031-00326-0000 in honeywell numbers. You may want to take a seat before asking the cost... Bob Weber webairconsulting.com 616 822 1999 1 Quote Link to comment Share on other sites More sharing options...
Bob Weber Posted October 30, 2019 Report Share Posted October 30, 2019 WOW I just spoke with one person about the switch and received a call from another that offered more.. SOLD to the guy with a 310! it turns out it is an unused new old stock part. Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 31, 2019 Report Share Posted October 31, 2019 Go capitalism! -a- 1 Quote Link to comment Share on other sites More sharing options...
Bob Weber Posted October 31, 2019 Report Share Posted October 31, 2019 10 minutes ago, carusoam said: Go capitalism! -a- It amazes me how hard it is to save people money, the first guy was beating me up for more info rather than listening to how to fix things. I helped the 310 guy with the switch in a 15 minute call, now he will have a system working better. More importantly, the extra hour he was gladly willing to spend brought him my "pocket full of tools". 1 Quote Link to comment Share on other sites More sharing options...
Lima Whiskey Posted July 23, 2021 Report Share Posted July 23, 2021 A guy in our M20J club accidentally broke the Autopilot Disconnect/Trip Interrupt switch for out King Autopilot 200. The switch C2003R is handled by Textron and sells for $99.95 each. Unfortunately the switches were backordered until mid-August and I am leaving on a cross-country trip to California next Friday. Many thanks go out to Bob Weber at webairconsulting.com 616 822 1999 for helping our mechanic figure out how to get a replacement switch. Even though Bob didn't have a switch, he helped us find one. The good thing is we have replaced the switch. The bad thing is that we had to pay $360 for it (without labor). 1 2 Quote Link to comment Share on other sites More sharing options...
Pepperjet Posted July 24, 2021 Report Share Posted July 24, 2021 13 hours ago, Lima Whiskey said: A guy in our M20J club accidentally broke the Autopilot Disconnect/Trip Interrupt switch for out King Autopilot 200. The switch C2003R is handled by Textron and sells for $99.95 each. Unfortunately the switches were backordered until mid-August and I am leaving on a cross-country trip to California next Friday. Many thanks go out to Bob Weber at webairconsulting.com 616 822 1999 for helping our mechanic figure out how to get a replacement switch. Even though Bob didn't have a switch, he helped us find one. The good thing is we have replaced the switch. The bad thing is that we had to pay $360 for it (without labor). Wish I would have known earlier. Had a few new old stock switches in unopened packages you could have had for $100 including shipping. Quote Link to comment Share on other sites More sharing options...
Lima Whiskey Posted July 24, 2021 Report Share Posted July 24, 2021 I wish I would have known earlier also. I should have posted something looking for the parts. I will do so in the future. 1 Quote Link to comment Share on other sites More sharing options...
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