ANY plane with the G1000 Nxi (have not tested other autopilots/control systems) will periodically roll (left or right) and begin a spiral dive towards earth.  Watching this occur from outside the plane - there is NO/NONE movement of any control surface which might initiate the roll and dive.  In the cockpit - there is no movement of the yoke or pedals.  The G1000 display shows the proper course, heading, altitude, VS, FLC - none of that changes during the upset. 

This maneuver occurs when on a HDG or GPS and sometime APR course, when climbing, descending, or in level flight. 

Sometimes it does not  occur at all during a 2-hour flight, other times it occurs within minutes of starting a flight and then continues to occur at random intervals of five, ten, or maybe 20-minutes.

After I recover from the flight upset (the elevator trim goes to 95% NoseUp within 10-seconds) and level the plane out and on the exact course shown by the magenta line and press AP - the roll IMMEDIATELY begins again with no control inputs and no control surface movements.  I must hand fly for one to five minutes before the AP will again control the intended flight.

I can verify my CH Yoke and Pedals are NOT commanding any input because I run a monitor program showing the constant signal stream from those devices.  This happens with nothing in the community file - no mods of any kind!

I have verified none of my keys or mice are profiled to command a roll or dive. 

The roll/dive occurs when I am in cockpit view or outside view and happens when I have not touched the controls for many minutes.

This problem began immediately after SU6.

It also occurs in the RY Turbo G36 and the DA62X. 

Any idea what is happening?

Edited November 16, 20214 yr by TacomaSailor

This was happening to me in the early days of flying MSFS.  Happened for some flights and not for others, and most often soon after takeoff.  It was at a time when I was spending time in these new-at-the-time cockpits of several aircraft while on the ground prior to flying.  Studying the features, switches, and switch positions.  I was also studying the G1000 and G3000 (note this was well before the WT NXi) as I was much more familiar with Garmin GNS and GTN GPS units.  I was likely activating and deactivating the AP Master during those studies.  As soon as I began leaving my fingers off of the AP Master until airborne the issue went away for me.  Don't know if that is the issue you are experiencing or not.

Edited November 16, 20214 yr by fppilot

32 minutes ago, TacomaSailor said:

ANY plane with the G1000 Nxi (have not tested other autopilots/control systems) will periodically roll (left or right) and begin a spiral dive towards earth. 

This happens to me also... and I have not been able to link it to any particular event or situation.

I happens quite abruptly and does not disconnect the autopilot.  Just drops a wing without any warning.

In the early days, I could link it to my yoke being slightly off center and a recalibration solved it.

Now I use FSUIPC and tend to have the yoke centered.. but maybe it is sending the odd signal spike regardless.. not sure..   CH Yoke also BTW..

Are you using a button to activate the AP?

I wonder if activating the AP via mouse click on the MFD is in any way different than assigning it to a button..

Edited November 16, 20214 yr by Bert Pieke

Quote

 I was likely activating and deactivating the AP Master during those studies.  As soon as I began leaving my fingers off of the AP Master until airborne the issue went away for me.  Don't know if that is the issue you are experiencing or not.

I am very careful to allow the plane to fly entirely under the AP control with my hands in my lap and my feet on the floor.  During the roll/dive AP appears in the status box and you can see the AP drive the elevator trim to full NoseUp - my only way to regain control is to turn off the AP!

Edited November 16, 20214 yr by TacomaSailor

Bert asked:  "Are you using a button to activate the AP? I wonder if activating the AP via mouse click on the MFD is in any way different than assigning it to a button.."

I've tried all iterations of that question - I can find no correlation with how AP is activated/deactivated.  Nor does the AP mode seem to make a difference. 

Edited November 16, 20214 yr by TacomaSailor
quote is not working ??

There is something peculiar with the MSFS autopilot, in that a yoke input causes the plane to react, without disconnecting the AP.

In the real airplane, you would have to overpower the AP, which then disconnects..

In previous flightsims, AP mode would effectively disconnect the yoke.. but not here..

Have you tried adjusting the deadzone for the yoke?

15 minutes ago, TacomaSailor said:

I've tried all iterations of that question - I can find no correlation with how AP is activated/deactivated.  Nor does the AP mode seem to make a difference. 

To follow up my earlier post, Based on my logs I have not had this happen since mid-October 2020, and was experiencing it regularly prior to that. Also based on my logs I did not record making any changes to controls settings or calibration.  At that time I was using a Saitek Pro Cessna Yoke.  I did not change to my current HC Alpha until January of this year.  So mine vaporized in October 2020 and I can in no way attribute my experience to my controls.  And since it is much more recent I have not had it happen at all with the NXi.

Hope you determine the cause and solution in your case.

Edited November 16, 20214 yr by fppilot

40 minutes ago, TacomaSailor said:

I am very careful to allow the plane to fly entirely under the AP control with my hands in my lap and my feet on the floor.  During the roll/dive AP appears in the status box and you can see the AP drive the elevator trim to full NoseUp - my only way to regain control is to turn off the AP!

Do you have an Xbox controller connected? I had this happen when I touched the controller I use for the drone without noticing it.

49 minutes ago, TacomaSailor said:

I am very careful to allow the plane to fly entirely under the AP control with my hands in my lap and my feet on the floor.  During the roll/dive AP appears in the status box and you can see the AP drive the elevator trim to full NoseUp - my only way to regain control is to turn off the AP!

OK, try this as a test:

- Fly in AP NAV/ALT mode and gently turn your yoke to the left or right (about half ways) and hold it there.

- After about 5 seconds, your wing will drop and without disconnecting the autopilot, the elevator trim will run up and the airplane lose control.

Second test:

- Fly in AP NAV/ALT mode, as before, and turn your yoke all the way to the left or right.

- The autopilot will disconnect.

I believe SU6 introduced the "disconnect" feature, but the "offcenter" bug was not fixed.

 

Edited November 16, 20214 yr by Bert Pieke

Bert -

I verified I have a 5% dead zone in the yoke X/Y axis and the slope of the response curve is quite flat (also tried with several other shapes) in the middle.

I verified that just prior to and during the upset - the signal from the CH yoke fluctuates between 110 and 109 (scale is 0 to 255 - full left to full right).  The yoke fluctuates 109 - 110 during all phases of controlled flight, which never seems to be a problem.

Test 1 (gentle/slight yoke movement) does NOT cause a wing drop - even when sustained for 10 seconds

Test 2 (full left/right yoke deflection) does cause AP breakout.

Verified the above with the C172/G1000, G36 stock, RY Turbo G36, and TBM 930 as it comes from Asobo with NO WT G3000 mod.

The really interesting result from Test 1 and Test 2 is that the yoke movement in the cockpit is REVERSED when the AP is engaged but the aircraft response is appropriate for the intended yoke movement.

e.g - in TBM 930 with AP engaged in NAV/ALT mode - I move the CH Yoke right and the plane rolls right but the cockpit yoke image rolls left.

3 hours ago, TacomaSailor said:

Test 1 (gentle/slight yoke movement) does NOT cause a wing drop - even when sustained for 10 seconds

Hmm, that is interesting.. On my system (CH Yoke), in the G36 with NXi, a 30 degree deflection on the yoke, when held steady, will always cause the wing to drop after a few seconds.  Wonder what is different..

The TBM has a different Garmin suite... so have not tested that.

Just flew the ASOBO/Stock G36 from KSAN -> KBUR with absolutely NO AP problems.  I tried hard to upset the autopilot including many iterations of your tests.  I got the plane into some steep banks while overpowering the AP - but as soon as I released the CH yoke - the AP (G1000Nxi is in the community folder) the plane gently returned to a normal attitude and proper heading.

In the stock G36 - the in cockpit yoke follows the CH yoke movement - so it seems to only be the stock TBM 930 with a reversed yoke movement.

I made NO changes to anything (as a tech support guy - I never believed the user when they said that) between the flight that had all the AP rolling/diving problem and this very stable flight.

All very strange & challenging.  Fortunately - I enjoy debugging/resolving mysteries as much as I do flying. 

5 hours ago, TacomaSailor said:

All very strange & challenging.

Happy to hear you had a good flight.. as did I today.  🙂

Multiplayer, Turbo G36, carefully calibrated yoke, 2.5 hr flight.. no AP issues whatsoever.

Still do not know why, when I turn my yoke it drops a wing, when your AP does not do that... maybe the Rob Young Turbo version has slightly different behavior..

Tomorrow is SU7 and all may well be different again.. 😉

1 hour ago, Bert Pieke said:

when I turn my yoke it drops a wing,

Bert,

Tried a couple of things and if it's any 'comfort', I see the same thing as you with the B36 Turbo and the default DA-62, both of which use the G1000NXi, and also with the default C172 steam gauge. And if I turn the yoke fast and far enough, the AP will turn off -- that may be realistic depending on the particular AP.

The aircraft also responds to yoke pitch changes with the AP on, whether in ALT Hold or PITCH hold.

So it seems something is not right.

Al

Edited November 18, 20214 yr by ark