Default C172 G1000 Autopilot aileron oscillation problem (video included)

Bug Reporting Hub Resolved
, , , ,
1

Are you using Developer Mode or made changes in it?

No, this is not developer mode.

Have you disabled/removed all your mods and addons?

Yes, I do not have any add-ons or mods of any kind. This is all stock MSFS 2020.

Brief description of the issue:

The title really says it all: Default C172 G1000 Autopilot aileron oscillation problem. When autopilot is engaged in the default C172 (G1000), the ailerons have an oscillation problem (see video). For this occasion (this has happened several times on several different flights after restarting MSFS), I’m at 10,500 feet following a GPS path on Nav mode with altitude mode set. Video begins with AP engaged, then you can see that the oscillation stops when AP is disengaged. Then it starts again when reengaged.

Provide Screenshot(s)/video(s) of the issue encountered:

https://youtu.be/yFfgek76rDg

Detailed steps to reproduce the issue encountered:

Load default C172 (G1000) and fly to 10,500 and engage autopilot with nav mode to follow a flight path in the G1000.

PC specs and/or peripheral set up if relevant:

Not relevant. I’m on a PC.

Build Version # when you first started experiencing this issue:

1.29.30.0

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

2

Do you have the same issue if you follow the OP’s steps to reproduce it?

Yes

Provide extra information to complete the original description of the issue:

The only thing I can add is that this behavior occurs in all weather conditions, at all speeds above stall, and at all altitudes in the stock C172 G1000 when the AP is engaged… a steady, rhythmic oscillation that stops immediately when AP is disengaged, then the effect of the actual turbulence (if any) is felt. “Wing rock” returns as soon as AP is re-engaged.

If relevant, provide additional screenshots/video:

OP’s video shows it perfectly.

3

Edit: Tonight I am trying to recreate it and the autopilot WAS smooth as silk at the same altitude with indicated airspeed about 10kts higher than what is in the video posted in the original post. So original post/problem happens at about 90 kts.

Tonight my autopilot was smooth at 100 kts. But the IAS has dropped to 90 knots and the oscillation is happening again.

So maybe this is a clue that the airspeed has something to do with it.

4

I have found that when this happens dropping a notch of flaps will gradually stop the oscillations after a while, and then I can retract the flaps and flight is normal, until the next time.

1 Like
6

I am also having this issue. As soon as I turn off autopilot oscillation stops. Turning autopilot back on causes it to start again.

7

Are you using Developer Mode or made changes in it?

NO

Have you disabled/removed all your mods and addons?

YES

Brief description of the issue:

Cessna 172/G1000 rocking side to side back and forth when AUTOPILOT is on trying to follow the GPS. I did not test other NAV modes, just GPS.

It is NOT TURBULENCE. Notice in the video how it immediately stops shaking when the autopilot is turned off and shakes again when AP is turned on.

I did a 1-hour flight, and it did this the whole time while on cruise with the AP on. Very frustrating and annoying.

Another way I was able to stabilize it was moving the joystick to the side with AP still on until it stops shaking. But it’s not permanent. After a bit, it starts doing it again.

UPDATE: Someone mentioned it could be the new CFD in the C172. I tested the Cirrus SR22 and Kodiak and they do not have this issue.

Provide Screenshot(s)/video(s) of the issue encountered:

https://youtu.be/SSS_Oq2LKjA

UPDATE: Someone mentioned it could be the controller. I made another uncut video WITHOUT ANY CONTROLLER connected to rule out any controller interference. The issue PERSISTS (11:00): https://youtu.be/PXdpLeoc5qA (details in my reply bellow)

Detailed steps to reproduce the issue encountered:

Turn on the autopilot with NAV following the GPS.

Route tested: (SNPU MAPMI UKPAD PUDVA REDAD SBCF) at 8000ft cruise and real life weather.

PC specs and/or peripheral set up if relevant:

RTX 3080 TI, Logitech X56 HOTAS, Windows 11, DirectX 12, 4K, Ultra Settings

Build Version # when you first started experiencing this issue:

Happening with latest updated version as of Jan 22, 2023.

I saw other people reporting the same issue since April 2022 here, but the issue persists: Cessna 172 Autopilot Shaking

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

8

Cannot reproduce - I have a full VKB setup and it’s rock solid in crosswind and Live WX. Recommend checking your controller axes and see if you have a noisy potentiometer. Windows Gaming Controller Applet will show you your axes and any noise/uncommanded inputs using the bar graphs.

I had a TM Airbus with the factory problem of a loose wiring bundle for the rudder axis - it was the only axis that wasn’t a Hall Sensor. It did exactly that during AP.

9

@CasualClick I’ll test again but I do not think it’s the controller. It’s a brand new controller just unboxed this week and axis look very stable. If it was the controller, why is it rock solid in my video with the AUTOPILOT OFF? If the controller was shaking, shouldn’t it shake the plane when I have manual controls? Why does it only shake with AP on?

Also, I’m almost sure I’ve seen this before with my old controller, and other people reported the same problem also with AUTOPILOT ON.

It doesn’t happen every flight or even the whole time in the same flight. In this flight for example, AP was stable after takeoff. Shaking started closer to my cruise altitude and continued pretty much the entire cruise. When doing the approach thru GPS then ILS it was stable again on both.

10

Oh I could make the rudder axis stable for a while by going to one rudder end extreme or another, then slowly ride the axis and return to center. But I released the control and the stick attempted to remain at center (as most controllers do by design), you’d see the rudder axis twitch on the Applet readout. That could be done with AP On or Off. The twitching would get so bad it would force the AP to disconnect on it’s own.

11

@CasualClick I tested again and confirmed it is NOT THE CONTROLLER.

Here’s the troubleshooting I did.

  • Exact same flight. After takeoff, engaged AP and it was stable up to the cruise altitude of 8000ft.
  • Flew stable for about 2 minutes cruising at 8000 and started shaking again on it’s own without me touching the controller.
  • if I disable AP, It’s stable again. If re-enable AP, starts shaking.
  • I checked the windows controller settings and Logitech app and the axis are stable.
  • I set a ridiculously high dead zone for the stick axes and makes no difference.
  • I fully DISCONNECT both the stick and throttle from USB and it’s still shaking. I disable AP clicking the G1000 with the mouse and it stops shaking. Enable AP again with the mouse and it shakes again.
  • After about 5 minutes cruising with AP on at 8000 it stops shaking again without me doing anything. A minute later, starts shaking again on it’s own. Disable AP, no shake… and so on…
12

@CasualClick tested again and recorded WITHOUT any controller connected, just used the mouse to click around the cockpit. I also included the route tested in the original post if anyone wants to try to reproduce. (SNPU MAPMI UKPAD PUDVA REDAD SBCF)

Here’s the definitive proof it’s not the controller, most likely some random bug with the autopilot:

  • Notice how even tho the climb is relatively stable, it’s already hinting at the problem on multiple occasions at a smaller scale. Almost feels like it’s over correcting for any small wind bumps with big oscillations side to side. (There’s almost no wind tho)
  • At around 11:00 is when the issue really starts, and you can see it goes away as soon as I click to disable the AP.
  • At 13:42 you can see there’s no controller connected.

Let me know if you have other ideas. Hope this helps the team troubleshoot this issue.

(the sim froze when I first tried to switch to the external camera, but it came back)

13

I do not recall ever having seen behaviour like that. As a test and to make sure my memory wasn’t playing me tricks, I just went for a quick flight with the C172. At similar altitude, it did not do anything close to what I saw in your video. I then even went a bit overboard with weather: went for mid summer. only 2,500 ft over land, high temperature, 20kt wind, all to try and get a lot of turbulence. And yes, there was some bumping around, but not the strange aileron and yoke behaviour that your plane exhibited.

In looking at your aircraft, it almost seemed as if there was something fighting the AP. Do you have any assistances enabled?

14

@SlabsFly All assistances are off except, the new helicopter and glider stuff that came enabled by default, Assisted Controller Sensitivity which I think only applies to Xbox controller and the Auto Rudder. I’ll test with those off but don’t think it’s the issue since it happens even without any controller enabled.

I don’t think it’s the weather either. In my second video there’s almost no wind. The behavior doesn’t even look like a natural light or severe turbulence. It’s not a normal shake. Looks like a deliberate oscillation from side to side.

Did you test the same route I provided? Are you using DX 11 or 12? Thanks!

15

Sorry no, I did not do the same route as I did not think it would be THAT location specific: will try that.

So no copilot, no nothing? Really strange then!

16

OK, downright weird: I got the same rocking motion on doing this flight once I got to cruising altitude! Never seen it before!

1 Like
17

@SlabsFly Did another video with more tests:

  • Tried HDG instead of GPS, same issue. So I dont think the issue is specific to following this GPS route.
  • Disabled auto-rudder and controller sensitivity, same issue.
  • Changed from real weather to clear skies, same issue, so I don’t think issue is the weather.
  • Checked the co-pilot menu, everything is off.

Notice how when AP is off, the plane just receives the normal effects from moving thru the air. The yoke and pedals are not moving at all. Doesn’t seem like there’s anything that could be “fighting” the AP. We would see it in the controls when AP is off. It really seems the AP is just doing something weird when it’s on.

UPDATE

  • Just tested with the CIRRUS SR22 and the KODIAK 100. The issue does NOT happen even flying thru clouds and rain! I waited many minutes after cruise and no side-to-side oscillation at all at any moment of the flight. So far, the issue seems to be specific to the C172 and not general to the G1000.
18

Told ya! Glad someone was able to reproduce it!

The issue is frequent but random. In my last test it only really started some time after cruise. But before in my second video, you can see it already starting during climb and getting worse after cruise.

19

Well, this might help narrow it down then. Neither of those aircraft have the new computational fluid dynamic (CFD) feature. However the C172 G1000 does.

Probably some interaction with CFD is my guess.

20

Interesting! I didn’t think of that.

What other aircraft currently has the CFD so we can test?

21

From the link I posted:

NPS: New Propeller Simulation
CFD: Computational Fluid Dynamics
SBS: Soft Body Simulation

// Airplanes //

  • NPS_____________: Aerosoft Twin Otter
  • ______CFD ______ : Airbus A310-300
  • NPS_____________: Beechcraft King Air 350i
  • NPS__CFD_______: BlackBox BN2 Islander
  • NPS__CFD_______: BlackBox Trislander
  • NPS__CFD_______: Bonanza G36 improvement project
  • NPS__CFD_______: Camair 480
  • NPS_____________: Cessna 152
  • NPS__CFD___SBS : Cessna 172 G1000 (other variants not confirmed)
  • NPS_____________: Cessna 208 B Grand Caravan EX
  • ______CFD ______ : Cessna Citation Longitude
  • ______CFD ______ : Curtiss JN-4 Jenny
  • NPS__CFD_______: DA40-NGX Improvement Mod
  • NPS__CFD_______: DA62X Improvement Mod
  • NPS__CFD_______: DC Designs PT-17 Stearman
  • ______CFD ______ : DG Aviation DG-1001E neo
  • ______CFD ______ : DG Aviation LS8-18
  • ______CFD ______ : Douglas DC-3
  • NPS__CFD_______: FlyingIron F6F-5 Hellcat
  • NPS__CFD_______: FlyingIron P-38L
  • NPS_____________: FlyingIron Spitfire MkIX
  • NPS_____________: Freedom Fox, Fox2
  • NPS__CFD_______: FSReborn Sting S4
  • NPS__CFD_______: GotGravel Monster NXCub, Savage Grravel, Savage Carbon
  • ______CFD ______ : GotFriends Discus-2c
  • ______CFD ______ : Grumman G-21A Goose
  • NPS__CFD_______: iniBuilds P-40F WarHawk
  • NPS_____________: Milviz Cessna 310
  • NPS_____________: Robin DR-400-140b Dauphin mod
  • NPS__CFD_______: Savoia-Marchetti S.55
  • NPS_____________: Van’s RV-7 and RV-7A