G650ER™ Operating Manual: Flight Controls System Overview

Aircraft electrical and hydraulic systems

2 (channels 1B and 2A)

FCC Alternate Mode (caution)

All primary flight control surfaces (other than one mid or inboard spoiler pair) remain operational

SPOST (System Power On Self Test)

Flight deck controls, Flight Control Computers, Air Data sensors, Inertial sensors, Flight Control Actuators

The primary flight control surfaces are the two ailerons, six spoilers, two elevators and one rudder.

The flight control surfaces are hydraulically actuated and electrically controlled with fly-by-wire technology.

The main components of the primary FCS are the Flight Control Computers (FCCs) and the Backup Flight Control Unit (BFCU).

The pilot and copilot flight controls (control wheels, columns and rudder pedals) are mechanically linked and designed to operate in unison.

The artificial feel mechanisms provide tactile cues or feedback to the pilots through the flight controls.

The other systems are the flap system (with the Flap Electronic Control Unit and drive system) and the horizontal stabilizer system (with the Horizontal Stabilizer Control Unit and Trim Actuator).

The bungee rods act as a solid link between the wheel and column, allowing control in the event of a mechanical jam on the pilot or copilot side. They will only allow differential inputs if the forces on the pilot and copilot side differ by a large amount due to a jam or opposing inputs.

The pilot and copilot rudder pedals are mechanically connected with a hard link which cannot be overridden.

In the event that both Flight Control Computers (FCCs) are inoperative, the BFCU controls the elevators, ailerons, outboard spoilers (roll control only, no speed brakes), and rudder to allow safe operation of the aircraft.

There are two dual-channel FCCs, and any one of the four FCC channels is independently fully capable of safely operating the entire aircraft Flight Control System. The aircraft may be dispatched with one FCC channel inoperative or the BFCU inoperative with restrictions.

The FCCs house the operational logic, also known as the Control Laws, for the control of the flight control surfaces.

The G650ER aircraft has two dual-channel FCCs, with each of the four channels comprised of a command lane and a monitor lane. This configuration provides four redundant, dissimilar, and independent channels of operation. The monitor lane continuously checks the computations of the command lane, and significant differences between the two lanes cause that channel to be shut down. Any single channel is capable of controlling all flight control surfaces, providing additional redundancy.

The BFCU monitors all four FCC channels and will assume control of the Flight Control System (FCS) within one half of a second if all four channels of the FCCs become unavailable. This provides a backup mode of operation for the flight control system in the event of a complete FCC failure.

The FCCs provide surface position commands directly to each of the seven EBHA Remote Electronics Units (REUs) to allow operation during either normal hydraulic or Electrical Backup operation. The backup mode is not selectable by the flight crew, and the EBHA REUs receive commands from the FCCs to actuate the flight control surfaces in the event of a hydraulic system failure.

The HSTS is responsible for providing pitch trim adjustments to the horizontal stabilizer. It receives position commands from the FCCs and uses the Elevator Backup Hydraulic Actuator (EBHA) to move the horizontal stabilizer and provide the necessary pitch trim adjustments during flight.

The FCCs provide surface position commands directly to each of the seven EBHA REUs to allow operation during either normal hydraulic or Electrical Backup operation. The REUs receive commands from the FCCs and actuate the flight control surfaces, including the rudder and elevator, to control the aircraft's flight.

The flight control system has a Maintenance mode that is not selectable by the flight crew. This mode is entered when certain failure conditions are detected, such as when all four FCC channels become unavailable, and the BFCU takes over control of the flight control system. The Maintenance mode allows for continued safe operation of the aircraft under these failure conditions.

The FCCs provide command inputs to the HSTS based on pitch trim inputs and Control Law commands.

Pitch control would be degraded to a direct mechanical linkage between the pilot's controls and the elevators, without any augmentation from the normal flight control laws.

The HSTS provides automatic and manual trim of the horizontal stabilizer to maintain the desired aircraft pitch attitude. It receives position commands from the FCCs and uses actuators to move the horizontal stabilizer as needed to achieve the commanded position. The HSTS is a critical component for maintaining pitch control and aircraft stability.

The FCCs continuously monitor the health and status of the flight control system, including the sensors and actuators responsible for pitch control. If an abnormal condition is detected, such as a sensor failure or actuator issue, the FCCs will report the issue through the CAS, FCS Synoptic page, and/or the Central Maintenance Computer (CMC). This allows the pilots and maintenance crew to be alerted to the problem and take appropriate action to maintain safe flight.

Entering maintenance mode could cause a temporary loss of augmentation from the flight control laws, resulting in direct control of the flight surfaces.

The REUs, also known as the midboard spoiler REUs, provide dual electrical sources to the flight deck control device sensors and other aircraft sensors and systems. They receive inputs from these sensors and provide the data to the FCCs, which then use it to calculate position commands for the flight control surface actuators. The REUs are a key component in the redundant and robust flight control system architecture.

The REUs provide a backup control path for the rudder and elevator surfaces in case of FCC or other system failures.

The flight control system on the G650ER has extensive built-in test capabilities that can be accessed through the Central Maintenance Computer (CMC). Functions such as system rigging and configuration checks can be performed through the CMC, allowing maintenance personnel to diagnose and troubleshoot issues with the flight control system. The system also reports any abnormal conditions through the CAS, FCS Synoptic page, and CMC, providing valuable information to the maintenance crew.

The FCS would continue to operate normally with the remaining three FCC channels providing full redundancy.

The FCCs are the central components of the primary flight control system on the G650ER. They receive input data from various sensors and systems, including the flight deck controls, air data sensors, and inertial data sensors. The FCCs then use this information to calculate the appropriate position commands for the 16 flight control surface actuators. They also monitor the health and status of the entire flight control system, reporting any abnormal conditions through the aircraft's various systems.

The FCC system implements control laws to blend and prioritize the inputs from the pilot and co-pilot flight controls.

The flight control system on the G650ER has a highly redundant design, with multiple communication buses and backup systems. The buses connecting the FCCs to the flight control surface actuators have redundancy that allows the system to continue operating even after damage from events like birdstrikes or engine rotor bursts. Communication between the FCCs and other critical components, such as the Backup Flight Control Unit (BFCU), Horizontal Stabilizer Trim System (HSTS), and various actuators, is primarily through ARINC 429 digital communication buses. This robust architecture ensures the flight control system can maintain safe and reliable operation in a wide range of scenarios.