787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Controls -
System Description
Copyright © The Boeing Company. See title page for details.
9.20.16 D615Z003-TBC
For severe asymmetric conditions where the initial automatic lateral control input
is very large, the EICAS caution message ROLL LEFT/RIGHT AUTHORITY, is
displayed to inform the crew of the limited roll control available.
Automatic lateral and rudder inputs are only available in the normal flight control
mode and can be overridden by manual control wheel or rudder pedal inputs.
Wheel to Rudder Cross–Tie
The wheel to rudder cross–tie function is available in the secondary and direct
modes. This function reduces maximum sideslip and vertical fin loads.
In the normal mode, wheel to rudder cross-tie is not required, the flight control
system automatically controls sideslip and fin loads.
Yaw Damping
In the normal mode, the roll/yaw control laws provide turn coordination and
Dutch roll damping.
Gust Suppression
Vertical gust suppression enhances ride quality in the presence of vertical gusts
and turbulence. It utilizes symmetric deflection of the flaperons and elevators to
alleviate gust acceleration. This function is active only with the autopilot engaged
in Altitude Hold or VNAV level flight modes.
Lateral gust suppression improves ride quality and can reduce pilot work load on
approach by automatic application of discrete yaw commands in response to
lateral gusts and turbulence.
Operation of vertical and lateral gust suppression does not result in control wheel,
control column, or rudder pedal movement.
Vertical and lateral gust suppression are only available in the Normal mode.
Rudder Trim
Manual rudder trim operation is provided in all three flight control modes by a
rudder trim selector located on the aft aisle stand. Two rudder trim rates are
available. A low rate is commanded with the selector rotated to the detent, and a
high rate is commanded when rotated past the detent. Manual trim inputs are
automatically zeroed during takeoff roll, when groundspeed exceeds 30 knots and
further manual trim inputs are inhibited until in the air. Manual rudder trim is also
inhibited with the autopilot yaw engaged (LAND 3) on approach. To provide pilot
awareness, the pedals move to reflect the amount of manual rudder trim applied.
February 15, 2010
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