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KFC150 fail; what to do


MooneyBe

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Acknowledging that there are a plethora of KFC150 commentaries on MS, coming back to the well for more. 

Our panel: G500 with GTN 750, GNS 430, KFC 150, KAS 297B (and then a bunch of Garmin gear for XM, traffic, etc but not really pertinent). 

Our problem: We were in the decent yesterday (around 2200 feet) when the KFC 150 failed (basically powered down). It did not pop a circuit breaker--just failed/turned off. The KAS 297B altitude preselect was still 'on' and indicating it was receiving but had 4 horizontal bars across and would not allow for any inputs/would no display an altitude. The electric trim was still functional. After landing, the electric trim rocker switch also failed (i.e. it would click itself off after being turned on but again, no circuit breakers would pop). It's worth noting that the panel mounted thermometer was about as hot as I've seen it with the temp just below the dash/above the annunciator panel at 115 degrees). 

Diagnosis: We went back today following some calls and were able to isolate the problem to the KFC 150. The electric trim switch would stay 'on' (and requires the A/P circuit breaker to be in), the altitude preselect will not work (though it powers on), and the KFC 150 will just not power on (no lights no nothing). 

Question: Has anyone else had their KFC system fail like this (it feels to me like a failure that will require some level of overhaul...) and what was the price to fix? At this point seeing some of the other horror stories pouring 5-10k into a KFC repair when a GFC 500/G5 all in is 19k makes me wonder. And I know executive autopilots on the WC is well liked--any suggestions closer to home in Northern Virginia?

Thanks, as always! 

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BeechTalk people recommend first calling Bob Weber and seeing what advice he may offer.  He apparently has over 40 years experience with autopilots.  His web address is:

https://webairconsulting.com/services/

Basically almost anything that has to do with the KFC 150, figure 5K at least, if you take it to an Avionics shop specializing in Autopilots. 

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depending on what dash # you have, if its a kap dash 15 like we had it was estimated a 5K for repair of ckt board, if its earlier we had a loaner while waiting to up grade to a new auto pilot. there are plenty of trade ins available, just plug in mooney modules from your box or maybe its time to trade up

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First detail, your trim switch is actually a switch circuit breaker combo. So the fact that it does not stay on is because the breaker part is tripping.

Second point, it is not necessarily a $5K bill every time a king autopilot glitches. I had a roll servo go out. It was sent to Mid Continent for a $600 repair. My shop was another $400.

The bottom line is you need a competent technician to trouble shoot the system. It could be anything and other people’s experience with similar symptoms don’t matter much. An incompetent technician won’t do the debug and will send all of your components out for overhaul when the real problem is a chafed wire and all of your components were fine.

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Similar issue four years ago with our KAP 150. While flying along I heard a pop and saw smoke coming out of the head unit. Sent it to Autopilots Central and it turned out to be a capacitor, which luckily they still had a steady supply of. Here's a picture of the blown capacitor and the invoice.

IMG_2469.JPG

 

APC.jpg

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If the KC192 won't PFT and has no annunciations I would be checking power and ground to the unit.  There is also a small pico fuse inside the unit.  If you have a -15 unit repair capabilities will be limited to 2 shops, Bendix King and Duncan Aviation.  If it is the older -03 unit they can still be field repaired.  

I have seen the caps explode before and there is also a issue with units manufactured in the 93-97 year range where they will have capacitors leaking in the power-supply circuit.  The circuit traces are so small in some of the areas that the electrolyte just eats up the trace.  If you don't catch the cap leakage early on you can have a big problem with board damage.

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On 9/5/2020 at 11:05 AM, MooneyBe said:

Acknowledging that there are a plethora of KFC150 commentaries on MS, coming back to the well for more. 

Our panel: G500 with GTN 750, GNS 430, KFC 150, KAS 297B (and then a bunch of Garmin gear for XM, traffic, etc but not really pertinent). 

Our problem: We were in the decent yesterday (around 2200 feet) when the KFC 150 failed (basically powered down). It did not pop a circuit breaker--just failed/turned off. The KAS 297B altitude preselect was still 'on' and indicating it was receiving but had 4 horizontal bars across and would not allow for any inputs/would no display an altitude. The electric trim was still functional. After landing, the electric trim rocker switch also failed (i.e. it would click itself off after being turned on but again, no circuit breakers would pop). It's worth noting that the panel mounted thermometer was about as hot as I've seen it with the temp just below the dash/above the annunciator panel at 115 degrees). 

Diagnosis: We went back today following some calls and were able to isolate the problem to the KFC 150. The electric trim switch would stay 'on' (and requires the A/P circuit breaker to be in), the altitude preselect will not work (though it powers on), and the KFC 150 will just not power on (no lights no nothing). 

Question: Has anyone else had their KFC system fail like this (it feels to me like a failure that will require some level of overhaul...) and what was the price to fix? At this point seeing some of the other horror stories pouring 5-10k into a KFC repair when a GFC 500/G5 all in is 19k makes me wonder. And I know executive autopilots on the WC is well liked--any suggestions closer to home in Northern Virginia?

Thanks, as always! 

I would call Autopilot's Central and ask for Tex.  He is a great resource for these and knows the 150 very well.  Even if you talk to Mike, he knows a great bit and has resources to help also.  

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