[Solved] Crabbing with auto pilot engaged

[matrosov]

Any idea of why I'm crabbing as illustrated in auto pilot.  My vertical bar is drifting to the left and my yaw to the right and it's not slip coordinated? Thank you for the tips and hints in advance. 
 

Edited January 8, 2022 by oisintierney

[Graeme_77]

I think the fuel imbalance isn't helping you there. It's just in limits, but try fixing that first and then see how it goes. 

[ois650]

Can confirm this is fuel balance as I've had the same when testing. Make sure you don't run your APU for ages on the ground to avoid an imbalance.

 

[matrosov]

Aha that helps. Thank you. Speaking of fuel imbalance is there a QRH that tells me how to transfer from left main to right main?  It's not very apparent like it is in boeing or Airbus. 

[ois650]

The fuel crossflow valve will balance you out

[matrosov]

1 minute ago, oisintierney said:

The fuel crossflow valve will balance you out

Nothing else just open the valve don't mess with boost pumps aux valves aux pumps?

[ois650]

It's a gravity crossflow so no pumps required. 

The manufacturer recommends flying a steady heading sideslip (i.e. one wing low while maintaining a heading). The low wing should be the wing with less fuel. As the fuel indications will be erroneous during the sideslip you must level off and wait thirty seconds before checking them. Obviously sideslips aren't advisable with pax onboard. Best to keep the tanks balanced!

[Graeme_77]

You can also transfer wing tank fuel to the aux tank (from where it goes to both engines), but you need a bit space in the aux to do that.

[matrosov]

So got myself pretty balanced out there is only 100 pounds differential between the tanks and I am still crabbing in cruise.  Any ideas as to what else might be causing it?

 

[Graeme_77]

Can you show the flight controls page on the MFD please when this happens again? Also, you're going to need to fly way faster than that!

[matrosov]

I definitely have gremlins somewhere.  Fresh reinstall of the plane reboot new airframe.  Still crabbing.  And for some reason Vnav doesn't take over speed. Trims are centered.  FMS is correctly programmed as far as I can tell. Plenty of deadzone on the rudder pedals.  And sticks are not noisy.  



 

[CaptCrash]

your rudder is not centered, do you have any rudder pedals or controls bound to the rudder? if so please calibrate them

[matrosov]

Thanks you're right.  I checked rudders fifty times for noise set up dead zone and they  were perfectly fine. as in not noisy.  But when I turned them off completely it worked.  So now I need to figure out how to turn them back on without breaking the plane again.  Any ideas on the FMS not taking over speed management?

[Ed Moore]

I've had this problem before (in DCS actually) and it was a axis I hadn't realised I'd bound to rudder trim ages ago having been just knocked slightly.