787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Controls -
System Description
Copyright © The Boeing Company. See title page for details.
9.20.14 D615Z003-TBC
The stabilizer green band monitor is part of the crew alerting function and helps
confirm that the green band displayed on the stabilizer position indicator is correct
for the actual takeoff weight and CG. based on the gross weight and CG entries in
the FMC. Two nose gear pressure transducers provide actual airplane gross weight
and CG information. The nose gear pressure data is used to determine two separate
sets of validation limits (one for each transducer). The FMC calculated stabilizer
green band is then compared to the validation limits from the transducers. The
EICAS advisory message STAB GREENBAND is displayed if:
• computed green band disagrees with pressure transducer data, or
• the two transducer values are not within the set tolerance, or
• either transducer has failed
Normal Mode Roll Control
In the normal mode, airplane roll control characteristics are similar to
conventional airplanes. Unlike conventional airplanes, the control wheel does not
directly position the lateral surfaces in flight, it instead commands a roll maneuver
with the rate dependent on wheel displacement. The flight control system
automatically positions the ailerons, flaperons, and spoilers to generate the
commanded maneuver. It constantly monitors airplane response to pilot inputs and
repositions the lateral surfaces to carry out these commands. Control wheel forces
increase as control displacement increases. Control wheel forces do not change
with airspeed changes. Airplane roll response to turbulence is minimized by
automatic control surface commands. The ailerons are locked out at high speeds.
Roll Envelope Bank Angle Protection
Bank angle protection reduces the likelihood of exceeding the bank angle
boundary due to external disturbances, system failures, or inappropriate pilot
action. The protection functions operate only in the Normal mode during manual
control and do not reduce pilot control authority.
Bank angle protection provides roll control wheel inputs when airplane bank angle
exceeds the bank angle protection boundary of approximately 35°. If the boundary
is exceeded, the control wheel force rolls the airplane back within 30° of bank.
This roll command can be overridden by the pilot. Maximum control wheel
deflection always commands maximum roll authority. The autopilot disengage
bar disables bank angle protection.
Excessive bank angles are indicated on the PFD bank indicator. The indicator
changes color to amber at bank angles exceeding 35°. (Refer to PFD Attitude
Indications in Chapter 10, Section 10, for additional information.)
August 14, 2009
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