Autopilot

Any DA40 related topics

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rhoab
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Autopilot

Post by rhoab »

Any ideas for why when I engage autopilot the default ROL function puts the plane into a 10-20degree bank to the right? When I switch over to HDG or NAV mode it works fine on the bug or needle.
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Rick
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Re: Autopilot

Post by Rick »

Brian,

I'm assuming you have the KAP140 autopilot, and maybe a G1000? With this configuration, I believe the autopilot ROL mode is driven by the turn-and-bank indicator. With the G1000, you have one, but it's hidden behind the PFD. My first guess would be that your T&B indicator is not working correctly.
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rhoab
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Re: Autopilot

Post by rhoab »

Thanks.. I have a steam gauge and the KAP140. I haven't noticed any turn coordinator defect but I'll have to look at the position during my next engage.
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Eric N
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Re: Autopilot

Post by Eric N »

I believe the comment about the turn-and-bank indication is correct; if flight is uncoordinated when ROL mode is engaged the AP will fly banked. This trait, if that's the right word, is referenced in the very complete Jeppesen G1000 course, and is true of both the KAP140 and GFC700. Our KAP140 has a funny quirk in that if you tell it to go direct to other than the next waypoint, it will briefly bank in the wrong direction before turning on course. Queer but apparently harmless.
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Rick
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Re: Autopilot

Post by Rick »

Eric N wrote:Our KAP140 has a funny quirk in that if you tell it to go direct to other than the next waypoint, it will briefly bank in the wrong direction before turning on course. Queer but apparently harmless.
I have seen that with our KAP140, also. Sometimes even just coming out of HDG mode into NAV mode, on course, it will decide to turn 10 or 15 deg left, and then back right on course again... Now that I think about it, both of my KAP140's had this same behavior, so maybe it's just "normal" for that autopilot?
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Jean
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Re: Autopilot

Post by Jean »

Rick wrote:
Eric N wrote:Our KAP140 has a funny quirk in that if you tell it to go direct to other than the next waypoint, it will briefly bank in the wrong direction before turning on course. Queer but apparently harmless.
I have seen that with our KAP140, also. Sometimes even just coming out of HDG mode into NAV mode, on course, it will decide to turn 10 or 15 deg left, and then back right on course again... Now that I think about it, both of my KAP140's had this same behavior, so maybe it's just "normal" for that autopilot?
Same for me
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Steve
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Re: Autopilot

Post by Steve »

Rick wrote:
Eric N wrote:Our KAP140 has a funny quirk in that if you tell it to go direct to other than the next waypoint, it will briefly bank in the wrong direction before turning on course. Queer but apparently harmless.
I have seen that with our KAP140, also. Sometimes even just coming out of HDG mode into NAV mode, on course, it will decide to turn 10 or 15 deg left, and then back right on course again... Now that I think about it, both of my KAP140's had this same behavior, so maybe it's just "normal" for that autopilot?
I've been flying behind my KAP140 for ten years and never seen that behavior...

Steve
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Re: Autopilot

Post by carym »

Just flew home yesterday from DCA to IND in an Embraer 145. I had foreflight on my iPad and noticed that when we were to make a turn the plane initially turned in the wrong direction before turning in the correct direction. I have noticed the same thing occurs on occasion in my DA42 with the KAP140, but not everytime. When it happens it wakes me up enough to put my finger on the red switch because on a rare occasion it will not turn to the correct direction. I don't underwtand why, but this phenomenon reminds me that I can't completely trust the autopilot.

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Re: Autopilot

Post by ScottF »

I too have been having issues with my KAP-140. After several calls to Honeywell i found there was a service bulletin (Honeywell KC 140-22-102) that effects all KAP-140's installed in Diamonds before 2008. The details of the bulletin states intermittent operation. I've pulled mine and sent to them, not received back but anyone having issues may want to check that out. Scott
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Re: Autopilot

Post by Rick »

ScottF wrote:I too have been having issues with my KAP-140. After several calls to Honeywell i found there was a service bulletin (Honeywell KC 140-22-102) that effects all KAP-140's installed in Diamonds before 2008. The details of the bulletin states intermittent operation. I've pulled mine and sent to them, not received back but anyone having issues may want to check that out. Scott
Hi Scott, and welcome to the forum!

Thanks for the Service Bulletin reference. I believe this SB is for a problem where the cover plate on the KC140 unit interferes with the AP on/off button, and sometimes causes the button to be pressed. This would be very annoying if you had such a problem, as the AP would randomly turn itself off (or maybe even on???) for no apparent reason. However, I don't think this problem could cause the strange turning issue (or the other porpoising issue, for that matter) that many of us are experiencing.

I hope you get your KC140 back soon. What issues were you having before you sent it in?
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