Eclipse 500 System Manual page 437

Section 16. Autoflight
16.5.4 Pitch Auto Trim
Pitch Auto Trim is enabled whenever the autopilot is engaged. If a high level of
mistrim is reached, an autopilot disconnect could immediately be followed by a
dangerous pitch excursion. The Pitch Auto Trim system ensures that a significant
buildup of mistrim force is prevented by transferring aerodynamic loading from the
elevator to the pitch trim tabs. In the event that Auto Pitch Trim fails, the autopilot will
remain engaged and a PITCH TRIM FAIL caution message will be posted notifying
the pilot of the failure.
16.5.5 Yaw Damper
The Yaw Damper (YD) function is to reduce the natural tendency of the aircraft to
exhibit Dutch Roll at certain airspeed and altitude combinations. The yaw damper
servo will move the rudder to counteract the aircraft movements leading to Dutch
Roll. The servo has as much authority as the rudder can travel.
ENGAGEMENT
The yaw damper engagement envelope is the same as the autopilot. The yaw
damper is engaged manually by pressing the YAW DAMP button on the autopilot
control panel, but will always automatically engage when the autopilot is selected and
the yaw damper wasn't already engaged. Once engaged green YD text appears on
the upper left-hand portion of the ADI on each PFD.
DISENGAGEMENT-AUTOMATIC AND MANUAL
When the autopilot is disconnected the yaw damper will remain engaged. Automatic
disengagement occurs for the same conditions that trigger automatic autopilot
disengagement. Manual yaw damper engagement is accomplished by pressing the
YD OFF/ON button on the autopilot control panel with the autopilot already
disengaged, or by pressing the ALL INTERRUPT switch on the sidestick.
16.5.6 Autothrottle
When engaged, the autothrottle controls the position of the throttles, which in turn
controls engine thrust. When coupled with the rest of the autopilot modes, the
autoflight system is able to track airspeed, or if necessary automatically activate as
part of the over and underspeed protection.
Version 2.0 April 2007
Figure 286. Flight Director-Flight Director Only
Figure 287. Flight Director- Autopilot Engaged
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