Kodiak: Problems in AP with ILS and RNAV?

Hello guys
Did anyone with the Kodiak from SWS approach airports in autopilot, glideslope ILS or RNAV?
I did it a few times now, it “works”, but the plane does not fly the glideslope very well.
Instead of flying it smoothly, it basically does left and right curves around the centerline of the glideslope.
Meaning often quite a bit off from the center line to the left… then corrects, overshoots to the right a lot… corrects back, overshoots to the left again, etc etc.
Anyone having the same problem?
Kind regards

P.S. I mainly tried it on LSZH, RWY 14, in case somebody wants to do the same
But it happened in other places too.

EDIT: Please check post Nr. 21 here below. There I uploaded videos to illustrate the behaviour.

No problems so far with the couple of ILS procedures I’ve tried. BTW it can’t do left and right curves around the glideslope centre line because the glideslope is the vertical up/down component of an ILS. From your description your issue is with the localiser portion of the ILS.

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Thanks. Well yeah, true, the GS (height) seems to work fine.
But left and right curves are pretty annyoing and so far I don’t have that with any other plane with the G1000.
Which is odd.

Which airports did you try and worked fine?

I notice this aircraft can start to wallow a bit on autopilot if your speed is too slow. What is your speed and flap setting on ILS approach? Stall speed (Vs) at full flap is around 60kts, so if you use 1.3 Vs as your approach speed, you should be approaching at a minimum speed of 78kts with full flap.

I had the same problem, on every approach ILS or GP, the plane would start to sharply veer left at about 500 feet, sometimes it would try to correct by swinging left and right, trying to get back on the loc part of the approach. Sometimes it would drop the left wing and into an unrecoverable stall.

After some thinking, I think this is due to flying the plane to close to stall speed.

Solution seems to be to slow the plane down to about 77 to 80 kts, but no more.

Then, over the runway threshold slowly flare to bleed off speed to about 68-70.

That seems to work better.

Maybe others can see what numbers work for them and then post here.

Can you post your vref and vapp speeds, please. Stock G 1000 or WT G 1000 NXi?

Interesting. I was definitelly over 80 kts, more like 90 - 100 knots (when still rather far from the airport of course) and it already started to go left and right all the time. Basically flying S-curves instead of staying on the LOC.
Stock G1000, not the NXi.

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Maybe try it with the NXi?

Just tried the ILS 15 into LSZH. 110.50

Gideslope is fine, but there is somthing wrong with the Localizer.
Using current Navigraph Nav data .
Std G1000 GPS in Kodiak ( Not Nxi ) PMS50 GNS530 GPS in C172

BOTH the KODIAK and the C172 steam cannot lock correct onto the Localizer.
It almost locks, there is some weak lock, but it does not center & hold the Localizer course.

Suspect the Airport is the cause - so to confirm would need to repeat both planes at a known “Good” airport.

There is a difference right there. The Nxi has its own autopilot implementation I believe so that may be making the difference over the current default. The Nxi will become the default at some point so might as well start to get used to it now and hopefully it resolves this issue as well.

I just flew into Malmö airport , an RNAV approach, and the plane tracked the GP with no problems.

I was at full flaps at around 80 kts.

Obviously, it could also be airport specific.

Yeah but SWS says they focus on the stock G1000. NOT the NXi.

Without any other definitive proof, I suspect the airport LSZH 15

Will watch with interest to see what you guys figure it out to be …

I had the same problem with the plane swinging around the approach while using the WT G 1000 NXi, so I’m not sure it has something to do with the Garmin.

There is no LSZH 15. Do you mean 16?
I have not tried that one, because in reality, RNY 14 (not 15 or 16) is used for the approach from that direction. It’s the main RWY for landing on LSZH.

I flew into EDAH Heringsdorf - and ILS approach to RW 28 - at the 500 callout, plane veers to the left.

I flew into a small Swedish airport - ESMX, Smaland airport, RNAV approach, at about 500 feet, plane veers sharply to the left, drops the left and wing, and enters an unrecoverable death spiral.

In both cases I was very close to the edge of the low-speed performance envelope.

Ok I will try that 80kts and fullflaps trick. Which Malmö RNY did you try?

RW 35 - no issue. Rocksolid tracking of the GP right down to the runway threshold.

Please report your findings.

Just tried the 01 into KDCA.

C172 ROCK solid, needles center and remain centered the whole way on with a very positive lock, and no oscillation.

Kodiak GS OK, Loc needle stays pegged to right, either side of the localizer track.

Something is messed up …

What will it do if you fly a GPS approach? For the autopilot itself it would be quite similar but the guidance is different.