KAP140 initiates left turn when first engaged

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Keith M
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KAP140 initiates left turn when first engaged

Postby Keith M » Thu Mar 16, 2017 7:34 pm

Yesterday, after a bit of hand flying, I pressed the AP button on my KAP140 to engage ROL mode, and the plane immediately banked to the left. I was on my own and didn't want to be heads down diagnosing the fault, so other than trying it a couple more times, I continued hand flying. On the ground, the stick moved to the left when the AP button was pressed, so it's a hard fault. Could the turn coordinator cause this behaviour?

The KAP140 Pilot's Guide doesn't give any diagnostic information, but would it indicate an error if the turn coordinator was completely dead?

Thanks in advance for any suggestions.
Keith
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Rich
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Re: KAP140 initiates left turn when first engaged

Postby Rich » Thu Mar 16, 2017 9:44 pm

Problem in the turn coordinator signal (or interface between it and the KAP 140) causes this exact behavior. I haven't had it happen in my plane but have seen it in some 172's.
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Re: KAP140 initiates left turn when first engaged

Postby Keith M » Fri Mar 17, 2017 2:31 pm

Thanks Rich. I've got an appointment to have it checked next week.
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Re: KAP140 initiates left turn when first engaged

Postby BlackMammoth » Thu Apr 13, 2017 3:40 pm

We have had this exact issue! Problem was the "Blind" turn coordinator (not the one on the panel for our steam gauge airplane).

I wish we could ditch the blind turn coordinator and take the output from the Aspen AHRS but apparently that is not covered under the Aspen STC.

PK
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Re: KAP140 initiates left turn when first engaged

Postby Keith M » Sat Apr 15, 2017 7:29 am

The problem with mine was, as Rich predicted, due to a poor connection between the KAP140 and the TC. This is a known issue for which Honeywell have had a free replacement part available for years, but have not widely advertised it. It's exchanged with the original, which takes 2 to 3 weeks, so I plan to do that at the next annual.
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Re: KAP140 initiates left turn when first engaged

Postby Pilot55 » Sat Apr 15, 2017 11:24 am

The KAP140 works even better gpss is turned on with my aspen. never wonders with it on. with it off your better to use heading mode.
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Re: KAP140 initiates left turn when first engaged

Postby Tim H » Sat Apr 15, 2017 11:47 pm

Keith-

Do you have the P/N of the replacement part or a SB from Honeywell that references the issue? How did you get the free part?

Thanks,

Tim
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Re: KAP140 initiates left turn when first engaged

Postby Keith M » Mon Apr 24, 2017 12:58 pm

Tim,

It's a Honeywell SB with reference KAP 140-22-102. I've not been able to find out exactly what it entails, but google found these two links:

http://support.diamond-air.at/fileadmin/uploads/files/after_sales_support/DA42_Twin_Star/Service_Informations/SI42-078-1-Honeywell-SB-KAP140-22-102.pdf

https://www.diamondaviators.net/forum/viewtopic.php?t=3699

The forum comes up with the goods as usual! :)

Keith

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