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KFC 200 head removal


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Hi Folks. I had an issue with our KFC 200 yesterday. It appears to be working perfectly except that it will not engage when you flip the switch up. I can hear it "touching" in the box, but will not stay engaged. If I hold it up, it does not stay engaged either. I read in another forum that it is likely a faulty switch as all other items appear to be working perfectly.

My question is, if we need to remove the head unit from the center pedestal, how is that done. I want to prep the easy stuff, then have my A&P come in to do the actual removal, but want to give him the easiest way to do it so he can save time. I have reached out to AP Central to get their advice, just waiting to hear back from their tech folks.

Thanks in advance everyone.

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5 hours ago, mwilton1 said:

Hi Folks. I had an issue with our KFC 200 yesterday. It appears to be working perfectly except that it will not engage when you flip the switch up. I can hear it "touching" in the box, but will not stay engaged. If I hold it up, it does not stay engaged either. I read in another forum that it is likely a faulty switch as all other items appear to be working perfectly.

My question is, if we need to remove the head unit from the center pedestal, how is that done. I want to prep the easy stuff, then have my A&P come in to do the actual removal, but want to give him the easiest way to do it so he can save time. I have reached out to AP Central to get their advice, just waiting to hear back from their tech folks.

Thanks in advance everyone.

Mike you will need a 5/64th hex key

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Folks, I think we might have found the culprit, but need some insight. I had been having some interemitent issues with my electric trip yoke switch. Sometimes, it would not command nose up. Nose down works fine. I had not dealt with it as I normally use the wheel to trim, which is a habit I had when I owned a Cessna 340. I didnt try it, but I suspect the switch failed fully around the time my Autopilot shut off and would not engage.

Tonight I took and tried to clean the switch. I put some switch cleaner into it and though it clicks when depressed, the trim wheel would only move a little then stop. That was also intermitent. I took the switch out of the yoke and apart. I tried a bunch of combinations using only the little buttons being pushed and it appears the nose up switch is not functioning.

I now have 2 questions. 1) Does anyone have a good source for the switch as it will need to be replace and 2) would this defective switch be the reason our autopilot will not engage?

Thanks for everyone's input. I have included a couple pictures of the switch wiring, just incase it might be a missed wire and not the switches themselves.

Mike

 

 

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Helps to know what AP the electric trim switch is connected to...

The BK trim switch is famous for causing problems...

It is also famous for being able to swap out the internal switches that do the work...

Identical switches, commercially available...

PP thoughts only, not a mechanic...

Best regards,

-a- 

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Just now, mwilton1 said:

It is for a KFC 200 Autopilot. Tried searching around for the King switch, but seem they are pretty scarce.

Mike

BK standard... hard to find, and outrageously priced...   :)

If the KFC200 used the same switch arrangement as all the other BK APs...

There should be part numbers on the micro switches themselves... enough to be able to find them at the electronics warehouses of the internet...

They use pairs of switches to keep the trim system from sticking when a single switch stops operating correctly....

Keep that in mind when you have a stuck trim switch... know how to shut it off...

We had an MSer have a stuck trim switch, that turned into a stuck trim at the extreme end of the trim range...

Post more pics when able...

Best regards,

-a-

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Found the switches online. Since the whole switch assembly is not available (or so it seems), this is likely my best option. 

Any input on if this would be causing our autopilot issue?

Thanks, Mike

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Just now, mwilton1 said:

Found the switches online. Since the whole switch assembly is not available (or so it seems), this is likely my best option. 

Any input on if this would be causing our autopilot issue?

Thanks, Mike


The AP does a complete test at start up... If you leave the electric trim power switch off... the AP senses a failure, and does not come to life...

Expect with the trim switch not working as you have described... The AP may be sensing that as well...

Switches are pretty easy to test for continuity...

Best regards,

-a-

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Thanks. I did some testing with a multimeter and the other two seem to be working fine. The one engages the clutch and the other provides nose down trim. I guess if the system senses the nose up trim switch as faulty, it would keep the system from engaging. Sounds correct. I ordered 3 new switches tonight. Hopefully that will solve the problem. All other parts of the King switch seem ok. 

 

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