julesmusician
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Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 6:40 am

That little switch on the A/pilot that says YD - Yaw damping - are there any guidelines when and when not to use it? Is it used throughout flight or just at certain times and is it used/not used on approach and if so why?

Thanks,

J
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
HT1000
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RE: Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 6:57 am

In Air Tahiti SOP (ATR 42 & 72) we engage YD just after take off (at the same time we retract the landing gear) and disconnect it passing 500 Ft AGL before landing to have full authority on the rudder .

AP and YD on , if you disengage YD then AP will disconnect.

Seb.
Few Were Born With It. Even Fewer Know What To Do With It.
 
julesmusician
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RE: Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 7:08 am

talking of full control of the rudder, if doing a full autoland with a big crosswind at some point the aircraft has to be straightened up on the runway - does the autoland do it or is it a pilot input?
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
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Jetlagged
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RE: Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 8:00 am

Most swept wing aircraft will have the Y/D engaged before takeoff and throughout the flight until shutdown. The Y/D does not have full authority over the rudder (maybe 5%-10%), and there's no feedback to the rudder pedals.

For autopilots with full autoland capability, the rudder is controlled automatically during flare and rollout. It will kick off the drift angle at a couple of feet gear height above ground (on a 747-200). Then it maintains the runway centreline using the localiser signal.

Some older autoland capable autopilots do not have a rudder actuator, so cannot perform an autoland in crosswind. This isn't usually a problem, because if there's much of a wind it's unlikely there will be Cat III visibility conditions.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Stoicescu
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RE: Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 1:43 pm

I might be wrong but I think there is no autoland on 747-200. It might be something similar but is not actually autoland.
 
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CCA
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RE: Yaw Damping Switch On Autopilots

Wed Nov 02, 2005 8:06 pm

Quoting Stoicescu (Reply 4):
I might be wrong but I think there is no autoland on 747-200. It might be something similar but is not actually autoland.

I've done autolands in the classic, I'm not sure what other type of autoland you mean?
Rgds CCA

[Edited 2005-11-02 12:16:12]
P1 in A330, A340, A346, B742, B744, B748.
 
DeltaGuy
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RE: Yaw Damping Switch On Autopilots

Thu Nov 03, 2005 1:23 am

Quoting Julesmusician (Thread starter):
That little switch on the A/pilot that says YD - Yaw damping

Most larger jets (MD-88, 757, etc), don't have the switch on the AP panel..usually on the overhead.

DeltaGuy
"The cockpit, what is it?" "It's the little room in the front of the plane where the pilot sits, but that's not importan
 
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Jetlagged
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RE: Yaw Damping Switch On Autopilots

Thu Nov 03, 2005 2:43 am

Quoting Stoicescu (Reply 4):
I might be wrong but I think there is no autoland on 747-200. It might be something similar but is not actually autoland.

No, you're wrong. Some 747-200's have triple channel fail operational autopilots with full Cat IIIc autoland capability. These have a rudder actuator for "kick off drift" and roll-out control. BA wouldn't have been able to operate from misty LHR and LGW without them. The remaining 747 classics only had a dual autopilot which still is capable of autoland, but with no crosswind capability, because no rudder autopilot actuator is installed. So there is a FLARE mode, but no roll-out mode, so the AP must be disengaged at touch down.

In the US, where Cat III operation is less common, most 747-200's had the third autopilot channel (C) disabled, or not fitted at all. However autoland capability is still there.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
David L
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RE: Yaw Damping Switch On Autopilots

Thu Nov 03, 2005 3:01 am

Quoting Jetlagged (Reply 3):
Then it maintains the runway centreline using the localiser signal.

After a full autoland, is it necessary to disconnect the autopilot before turning off the runway or doesn't it matter? Does the FMC/autopilot just stop caring at that point?
 
DeltaGuy
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RE: Yaw Damping Switch On Autopilots

Thu Nov 03, 2005 7:36 am

Quoting David L (Reply 8):
Does the FMC/autopilot just stop caring at that point?

FMS will usually give you a "END OF ROUTE" Msg. You can turn the autopilot switch to on at the gate if you want to (737, for example), it doesn't seem to mind too much. Now, is it going to do something, that's a little different.

DeltaGuy
"The cockpit, what is it?" "It's the little room in the front of the plane where the pilot sits, but that's not importan
 
David L
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RE: Yaw Damping Switch On Autopilots

Thu Nov 03, 2005 8:36 am

Quoting DeltaGuy (Reply 9):
FMS will usually give you a "END OF ROUTE" Msg.

I guessed the autopilot pretty much left the building at that point. So, there's nothing wrong with leaving it engaged while you taxi to the gate?

FMC/FMS - I do tend to confuse those.

Thanks.

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