Turn Coordinator and KAP-140

[Tim H]

The KAP-140 gets some information from the "hidden" turn coordinator (mounted behind the MFD). How can I tell if the TC is going bad?

The TC in my old Skyhawk got progressivly lazier in turns, but never actually failed. If this happens in DA40, I would never know. And there is no practical way to monitor it since it is hidden.

Anyone have any experience with a "failed" TC and a KAP-140?

[Jean]

Hello Tim,
We replaced the TB coordinator a little time after buying our DA 40.
The problems we encountered were:
1. Lousy final approach handling
2. Some times KAP 140 would not initialize, we only had dashes on the led screen. Some times KAP 140 would fail in flight (again showing dashes), we had to pull the CB off and on again to restart.
3. The avionics shop noticed that the time for the TB red flag to go away was abnormally long. I guess this is what you should check if you want to monitor your T&B. Tou need to remove the PFD.
It was replace by a new one.

We recieved a new T&B from Diamond Maint.
It is a 1394T100-12RB
the one installed in the N446DC
is a 1394T100-12RZ

The new (Diamond certified) T&B has a brushless motor.We haven't experienced any problems since, except swinging in short final (we usually take it by hand before reaching minimums on ILS approaches).
Would sure prefer a GFC700 but KAP 140 does a good job.

[Gasser]

I am bringing this post back from the dead to report a similar problem.

I'm almost done with my instrument training and have noticed a progressive decline in the planes ability to turn using the heading bug. It should turn standard rate but over the last several months its decreased to almost nill and I have to help it with the CWS button. It's really only turning 1/4 standard rate.
Initially the null valve was off center so it wouldn't turn right but would left and wouldn't fly the correct heading. Once that was centered it was all even but would turn 3/4 rate at best but this last flight was almost none or very slow.

I think we are going to put in a new one and ill report back.

Anybody else deal with this. I'm pretty tired of fixing squawks. Hopefully this is the last one for a bit. To top it off, got a flat tire on landing yesterday even after one of the softest landings I've ever made. When it rains it pours I guess.

Jeff

[Hans]

My TC went and had to replace it .... All dashes... Was around 1k with a trade-in... Helped my mechanic it's a plug and play part

[Gasser]

My TC went and had to replace it .... All dashes... Was around 1k with a trade-in... Helped my mechanic it's a plug and play part

Tell me about all dashes??

I'm not getting any warning or red Xs. Only symptom I'm seeing is the plane will not turn correctly with the heading knob. Did you notice anything like this before it failed completely?

I hate to change it if its fine. Any way to test it? My avionics guy says that's pretty much the only other thing it could be since we've fixed everything else.

Any thoughts?

[Hans]

There were dashes horizontal across the screen I think 2 groups of 3 or 4.....no warning just turned it on one day and got nothing. My avionics guy used some kind of diagnostic plug to confirm that it was the TC....and it was....good luck brushless is 5-6 hundred dollars more....

[Gasser]

There were dashes horizontal across the screen I think 2 groups of 3 or 4.....no warning just turned it on one day and got nothing. My avionics guy used some kind of diagnostic plug to confirm that it was the TC....and it was....good luck brushless is 5-6 hundred dollars more....

Ok, thanks. Ill post what they find.

[nrenno]

My DA 40 with KAP 140 has been turing slowly to the left when in roll mode. Is this normal?

[Gasser]

What I fixed first was to have your avionics shop center your null valve. This even out my turns. I still think mine is slowly dieing as in heading mode it won't hold a standard rate turn. It does 3/4 rate at the moment. I've heard this might be normal for the KAP 140. At least its the same on both sides now.

[Rick]

What I fixed first was to have your avionics shop center your null valve. This even out my turns. I still think mine is slowly dieing as in heading mode it won't hold a standard rate turn. It does 3/4 rate at the moment. I've heard this might be normal for the KAP 140. At least its the same on both sides now.

FWIW, my KAP140 always did 3/4 rate turns, too. There's no adjustment for that in the KAP, either.