KAP 140 problem

Any DA40 related topics

Moderators: Rick, Lance Murray

User avatar
Hans
3 Diamonds Member
3 Diamonds Member
Posts: 130
Joined: Tue Mar 15, 2011 12:25 am
First Name: Hans Wiederkehr
Aircraft Type: DA40
Airports: HWV
Has thanked: 1 time
Been thanked: 2 times

KAP 140 problem

Post by Hans »

Went to fly today and my AP does not work. It goes through the "boot-up" process and then I get dashed lines in the screen, I can adjust alt and baro but the AP button that powers it up does not turn it on or light up, anyone have similar problems ....
Thx
User avatar
c2mlp
3 Diamonds Member
3 Diamonds Member
Posts: 68
Joined: Wed Jun 06, 2012 2:41 pm
First Name: Chris
Aircraft Type: DA40
Aircraft Registration: N681DS (40.611)
Airports: N14
Has thanked: 19 times
Been thanked: 3 times

Re: KAP 140 problem

Post by c2mlp »

I have had exactly the same problem, and other similar problems with my KAP140 this whole winter. I purchased my plane (a 2006 DA40) last June, so this is my first cold weather experience with it. From what I have read on this forum and from my own experience, the cold seems to be the biggest factor as to whether or not the autopilot works. If you did not know, the left series of dashed lines represent lateral autopilot modes, while the right series of dashed lines represent vertical autopilot modes. The autopilot will function in which ever mode is working (if one happens to be out.) However, if both are out, then obviously, no actual autopilot function will work. However, the autopilot is powered up, meaning that the electric trim and altitude annunciator functions will work.

When I started a flight this morning, it was around 20*F out and went down to about 0*F durring cruise. Both modes were dashed out, however, after about a minute of the hidden roll/rate indicator spinning up, the dashed lines for the lateral autopilot modes went out (enabling lateral autopilot modes). However, vertical autopilot modes remained dashed out for the duration of the flight. I do not know if the pitch servo is bad (about $1,600) or if it is simply very sensitive to the cold. I will hold off on replacing it until the weather warms up and see what happens. (The system worked fine in the summer, intermittently in the fall, and rarely in the winter. Not sure if it is dying, or just likes to be warm.)
User avatar
Tim H
4 Diamonds Member
4 Diamonds Member
Posts: 453
Joined: Wed Dec 29, 2010 3:44 pm
First Name: Tim
Aircraft Type: DA40
Aircraft Registration: N233MA
Airports: KMGY
Been thanked: 34 times

Re: KAP 140 problem

Post by Tim H »

Slightly off topic and just wondering aloud here but we (the DA40) have the same set-up as some of the C172s. I wonder if the C172 has the same issues with the KAP140 (cold weather) and the G1000 (red X syndrome). It's the same hardware, just in a different airplane. Would be interesting information.
User avatar
Hans
3 Diamonds Member
3 Diamonds Member
Posts: 130
Joined: Tue Mar 15, 2011 12:25 am
First Name: Hans Wiederkehr
Aircraft Type: DA40
Airports: HWV
Has thanked: 1 time
Been thanked: 2 times

Re: KAP 140 problem

Post by Hans »

Mine is in a heated hanger so I can't say temp has anything to do with it
User avatar
Rich
5 Diamonds Member
5 Diamonds Member
Posts: 4592
Joined: Mon Aug 30, 2010 12:40 pm
First Name: Rich
Aircraft Type: DA40
Aircraft Registration: N40XE
Airports: S39 Prineville OR
Has thanked: 145 times
Been thanked: 1180 times

Re: KAP 140 problem

Post by Rich »

Tim H wrote:Slightly off topic and just wondering aloud here but we (the DA40) have the same set-up as some of the C172s. I wonder if the C172 has the same issues with the KAP140 (cold weather) and the G1000 (red X syndrome). It's the same hardware, just in a different airplane. Would be interesting information.
I've had occasion to use a couple of C-172's at a local FBO that have this A/P and they have more problems than I've had. To the point they've disabled them, by popping the CB's and putting wire ties to prevent activation. Full Disclosure: this is a marginal FBO - their GPS databases are years out of date making IFR GPS Navigation not only illegal, but almost useless in any real-world sense. Even the EGT gauges in some of these are marked INOP.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
User avatar
Bill A.
2 Diamonds Member
2 Diamonds Member
Posts: 33
Joined: Tue May 27, 2014 3:40 am
First Name: Bill Armstrong
Aircraft Type: DA40
Aircraft Registration: N236MA
Airports: KSNA
Has thanked: 3 times
Been thanked: 2 times

Re: KAP 140 problem

Post by Bill A. »

I had the dashed lines show up. Living in SoCal it is definitely not cold weather related. The dashed lines would show up intermittently both on the ground and in the air. The 'failures' would self correct sometimes and sometimes would take a couple of days.

First try at a fix - we replaced the KAP140 box itself. This had no effect. We tried this because it is a 10 minute swap and easy enough to either confirm as faulty or not.

Second thought was that it related to the turn coordinator. However, testing in the plane required an actual 'failure' to be occurring. Of course when we went to test the AP it worked fine. As this seemed like the most likely issue as it caused both the vertical and lateral 'failures' we had it removed and bench tested. Over the course of the test it was 100% clear that the issue was the failure of the turn coordinator and intermittent under speed issues with the gyro. This is why there wasn't a hard failure of the autopilot - as long as the turn coordinator wasn't under speed it was fine - but when it was under speed it would remove that option from the KAP 140 mode selector.

The turn coordinator is 11 years new... So time to replace. The turn coordinator is being replaced tomorrow.
User avatar
johnu
3 Diamonds Member
3 Diamonds Member
Posts: 57
Joined: Sat Aug 21, 2010 7:35 pm
First Name: johnu
Aircraft Type: DA40
Aircraft Registration: N913JD
Airports: KAEG
Has thanked: 14 times
Been thanked: 7 times

Re: KAP 140 problem

Post by johnu »

I regularly fly in the cold at altitude and have my plane in the cold on the ground and have never had an autopilot problem in the 5 years I have had my DA40. However I did have a problem when the turn coordinator was intermittently failing and the autopilot would not work at times. Eventually the turn coordinator failed hard. Changed it and everything worked out. Not sure if this has anything to do with the problem you are seeing though.
User avatar
Bill A.
2 Diamonds Member
2 Diamonds Member
Posts: 33
Joined: Tue May 27, 2014 3:40 am
First Name: Bill Armstrong
Aircraft Type: DA40
Aircraft Registration: N236MA
Airports: KSNA
Has thanked: 3 times
Been thanked: 2 times

Re: KAP 140 problem

Post by Bill A. »

johnu - yes, I think it is the same issue. The turn coordinator is now installed and all is working...

I do have a more general question and can't seem to find the answer. On the G1000 system diagram there is the GRS77 which provides Rate of Turn and Slip/Skid information to the GIA63. There is very little 'diagram' type stuff for the KAP140 but the avionics shop said it was the turn coordinator - does the KAP140 have its own turn coordinator? I ask because I don't recall (and I'm 100% sure I would have noticed) if the PFD information had gone in-op. And obviously when you pull the KAP140 circuit breaker the GRS77 still functions.

And on a similar systems question - on the G1000 system block diagram there is the GSA81, GTA82 and the GSA81 which are all autopilot systems (pitch, trim and roll) - are those systems for the KAP140? Or, are they specific to the the GFC700? I ask because I found another system block diagram that notes that the MFD for the KAP140 installation is the GDU1040 while the MFD for the GFC700 is the GDU 1044B.

Just trying to understand where the KAP140 interfaces with the G1000.
User avatar
Keith M
4 Diamonds Member
4 Diamonds Member
Posts: 363
Joined: Sun Jun 19, 2011 9:54 am
First Name: Keith
Aircraft Type: DA40D
Airports: EGNH
Has thanked: 29 times
Been thanked: 46 times

Re: KAP 140 problem

Post by Keith M »

Bill A. wrote:does the KAP140 have its own turn coordinator?
Yes, it's hidden behind the PFD. The GFC700 doesn't have one, and it has a different PFD to house its control buttons. That turn coordinator allows the KAP140 to keep working in ROL mode if the G1000 fails.
User avatar
johnu
3 Diamonds Member
3 Diamonds Member
Posts: 57
Joined: Sat Aug 21, 2010 7:35 pm
First Name: johnu
Aircraft Type: DA40
Aircraft Registration: N913JD
Airports: KAEG
Has thanked: 14 times
Been thanked: 7 times

Re: KAP 140 problem

Post by johnu »

While I do not have a Garmin cockpit, I have an Aspen Avionics cockpit I do know that for older autpilots that use the turn coordinator most glass cockpit systems use a "hidden" turn corrdinator to run the autopilot. this is because the autopilot was originally certified with the mechanical turn coordinator. Trying to certify it with a digital "glass cockpit" turn corrdinator is often to expenxive if the the manufacturers are different.
Post Reply