Boeing 787-8 - Page 807

787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Controls -
System Description
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 9.20.7
Flight Control System Secondary Mode
The PFCs automatically revert to secondary mode when inertial or air data is
insufficient to support normal mode or when all slat and flap position data is
unavailable. The ACEs continue to receive and process pilot control inputs, and
send these signals to the three PFCs. The PFCs use simplified computations to
generate flight control surface commands. These simplified commands are sent
back to the ACEs, where they are sent to the control surface actuators. All flight
control surfaces remain operable. The elevator and rudder are more sensitive at
some airspeeds and yaw damping is degraded.
In the secondary mode, the following functions are not available:
The EICAS caution message FLIGHT CONTROL MODE is displayed when the
primary flight control system is in the secondary mode. The secondary mode
cannot be manually selected.
Secondary Mode
• autopilot
• auto speedbrakes
• gust suppression
• overspeed protection
• roll/bank angle protection
• roll/yaw asymmetry compensation
• stall protection
• tail strike protection
Surfaces
Control
SPOILERS
RUDDER
FLAPERONS
AILERONS
ELEVATORS
STABILIZER
- use simplified commands
- redundant
PFCs
Pilot Control Inputs
control in each axis
Provide redundant
ACEs
ACTUATOR
ELECTRONICS
CONTROL
AUTOPILOTS
COMPUTERS
PRIMARY
FLIGHT
Not available
February 15, 2010