Random roll oscillations with AP engaged

[biscyane 0]

First off, I would like to say I am very happy with the aircraft, but this issue is staring to irritate me.

In level cruise flight with AP engaged and on course, the aircraft will start doing wild roll oscillations (almost reminds me of a dutch roll, except the airplane stays mostly coordinated and doesn't change altitude except as a result of the EXTREME bank angles), sometimes going up to and past 60 degrees of bank.  It goes in both directions, and occasionally seems to correct, then rolls again!

I have replicated the problem with and without my weather software (REX), and it only happens after being in cruise for an extended time (over an hour).

Attached is a screenshot of my VC with the MCP showing, during one of these extreme roll events, as well as the flight track.

 

 

 

 

Thanks for your help!
Steven W.

Sorry for the repeat post, AVSIM was giving me issues.

Steven W

[froy 0]

This happened to me too.

Was cruising at FL320 over Turkey enroute OMDB-KATL.

Real time weather with FSGRW.

Switched AP and FD off/on. Reengaged VNAV/LNAV. Then it continued normally.

[erik44067 0]

I don't know if this is similar, but wanted to throw it out there.  In the PMDG 737, when I fly really long legs (an hour plus between waypoints) it will start doing the back and forth thing.  I've never let it go too long, correcting it by going back direct to the current waypoint, or killing the A/P.  As long as I have a waypoint every couple hundred miles, I have not had it be an issue.

 

Were you flying really long legs between waypoints when this happens?

 

If I get a long trip in the 777 before resolution, I'll post my observations...

[falcon999 24]

Can we get the details of your aircraft configuration and route?

 

Thank you

[hopskip 253]

I see a caution light there, is that related to the cold and dark panel save state or something else?

[adamant365 28]

Do a search for "S Turns" and I believe you will find a wealth of information on the subject as well as the solution.

 

You can almost certainly blame your Wx engine for sudden changes and also the FSX turbulence effects.