Gulfstream G650ER Elevator Control System PDF

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL ELEVATOR CONTROL — SYSTEM DESCRIPTION 1. General A. Description The elevator control system provides electrical and mechanical control of the elevator, fault monitoring and annunciation. The aileron system is part of the primary flight control system. The...

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL ELEVATOR CONTROL — SYSTEM DESCRIPTION 1. General A. Description The elevator control system provides electrical and mechanical control of the elevator, fault monitoring and annunciation. The aileron system is part of the primary flight control system. The elevator control surfaces are located on the left and right trailing edge of the horizontal stabilizer. Electronically controlled hydraulic actuators provide power for elevator movement. During flight, aircraft lateral (pitch) control is accomplished by movement of the elevator surfaces located on the horizontal stabilizer, as well as by movement of the entire horizontal stabilizer. The elevators provide aircraft pitch control around the lateral axis. Elevator movement is in unison. When left and right elevator trailing edge goes up with Aft movement of the control column, the nose goes up. When left and right elevator trailing edge goes down with Fwd movement of the control column, the nose goes down. See Figure 1. Movement of the pilot / copilot control column sends commands to the Flight Control Computers (FCCs). The FCCs process the information and sends commands to Remote Electronic Units (REUs) located near the control surface. The REUs control hydraulic actuators that move the elevator surface. Elevator deflection is -24° ±1° up and +13° ±1° down. 2. Subsystems Elevator Interface and Control, 27-31-00, System Description Elevator Cockpit Sensors, 27-32-00, System Description Elevator Hydraulic Actuation, 27-33-00, System Description Elevator System Sensors and Indication, 27-34-00, System Description Elevator System Electronics, 27-35-00, System Description Elevator Autopilot System, 27-36-00, System Description Stall Barrier System, 27-37-00, System Description 3. Subsystem Details A. Elevator Interface and Control Conventional control columns are used by the flightcrew to control aircraft pitch. The control columns are mechanically linked during normal operation so that they always move together. If a jam occurs with one of the columns, either pilot may override the other by exceeding and maintaining the breakaway force. Each control column is connected by control cables to its associated pilot and copilot aileron and elevator control module. The pilot / copilot aileron and elevator control modules contain the following: Mechanical linkages Feel and centering units Electric motors An override mechanism RVDT position sensors The RVDTs provide the commanded position information to the FCCs and Backup Flight Control Unit (BFCU). The FCCs sends control information on Bidirectional ARINC 429 (BD429) digital data buses to the REUs located at each actuator. The REUs command the hydraulic actuators that move the elevator surfaces. 27-30-00 Page 1 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL B. Elevator Cockpit Sensors Elevator movement is sensed by five RVDT sensors in the RVDT cluster on top of the each aileron and elevator control module. The RVDT sensors translate mechanical movement into electronic signals that are provided to the FCCs. The FCCs and BFCU provide excitation signals to the RVDT sensors and receive voltage signals back that are proportional to the displacement of the inceptor. The voltage change indicates the position commands. When changes occur, the FCCs or BFCU command REUs to energize actuators, which move the elevators to the commanded position. The sensors provide data to the following: FCCs BFCU Autopilot (AP) system FDR NOTE: The BFCU commands are ignored by the REUs unless there has been a total failure of both FCCs. C. Elevator Hydraulic Actuation Hydraulic actuation is driven by the FCCs. The FCCs provide position signals to the REUs. The REUs process the signals to drive hydraulic manifold pumps in order to initiate actuator movement to control elevator surface movement. The left and right hydraulic systems provide 3000 psi hydraulic power to the actuator control manifolds. The elevator is controlled by the following two separate and independent actuators: EHSA - Outboard actuator EBHA - Inboard actuator The EBHA actuator consists of an EHSA-type hydraulic part, combined with local Motor Control Electronics (MCE) to drive the hydraulic cylinder / piston in backup mode. The REU in the EBHA system is mounted directly to the hydraulic actuator manifold. The MCE is mounted directly to the electrical backup hydraulic manifold. The associated actuator is located between the hydraulic actuator manifold and the electrical backup manifold. The EBHA actuator has the following dual power source: Hydraulic Electric The EBHA is comprised of an hydraulic cylinder / piston assembly and the following two hydraulic manifolds: HA EB D. Elevator System Sensors and Indication Force sensors (strain gauges) are installed on each column assembly to detect pilot action to override the servos. Each FCC interfaces with one sensor on each column. Detected force changes at the pilot / copilot stations are provided to the FCCs. The FCCs send the demanded position data to the elevator REUs. Each elevator control surface has LVDTs that provides surface position data to the associated REU. The REU compares the demanded ram position against the actual ram position as provided by the ram LVDT. The difference between the demanded and actual ram position becomes the control 27-30-00 Page 2 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL error. The REU then commands the electro-hydraulic servo valve proportional to the ram error until the control error is reduced to zero. E. Elevator System Electronics Pilot and copilot control columns provide the control inputs through RVDT position sensors. The sensors provide data to the FCCs and the BFCU. The FCCs sends control information on BD429 digital data buses to the REUs located at each actuator. The REUs control the hydraulic actuators that move the elevator surfaces. The REUs provide position loop closure and actuator monitoring. For integrity control, the REU has two dissimilar hardware lanes, one for command and one for monitoring. F. Elevator Autopilot System The AP system consists of two servo actuators and two stick shaker motors. The FCCs control the stick shaker motors and the AP system controls the servos. The AP servo is attached to the aileron and elevator control module. One motor and one servo actuator is attached to each column / wheel assembly. A mechanical interconnect allows either motor to drive the movement of both controls. This arrangement allows continuous operation if one side becomes jammed. The AP inputs are supplied through an electric AP servo motor that connects to the flight control mechanical input sector. The AP servo motor is mounted in each control module. The servos move the columns and wheels. Either pilot may override the AP system with sufficient wheel force to override the servo and disconnect the AP. The pilot side servo motor is controlled by Automatic Flight Control System (AFCS) No. 1 located in Modular Avionics Unit (MAU) No. 1. The copilot side motor is controlled by AFCS No. 2 in MAU No. 2. The servo motors are used to directly move the control wheels. There is no direct signal from the AFCS system to the FCC for aircraft control. Instead, the motors control the aircraft by moving the controls in the same manner as the flightcrew in manual control. This method has the benefit of providing the flightcrew visual feedback of what the AFCS system is doing to control the aircraft. G. Stall Barrier System There is one FCC driven stick shaker motor per control column. The stick shaker motors shake the control column during an approaching stall before the maximum Angle of Attack (AOA) is exceeded. This arrangement allows continuous operation in case of a jammed side. When the AOA is trending toward 85% of the maximum allowed AOA, the FCC control law enters AOA limiting and the stick shaker is activated. While in AOA limiting, pitch commands by the pilot / copilot determine the AOA. Full column is the maximum allowed AOA. The AOA limiting is exited by landing the aircraft or by reducing the AOA. The FCC controls activation of the shakers by internally switching the 28 Vdc power to the stick shaker motor. The power for the motor is routed through the FCC and passes through internal switches controlled by FCC software. 4. Operational Summary A. Elevator Control The elevators move in unison with each other to control aircraft pitch around the lateral axis. Elevators are hinged to the left and right horizontal stabilizer rear beams at elevator station 20, elevator station 67, elevator station 104, elevator station 150 and elevator station 202. The elevators are constructed from epoxy graphite and extend from BL 5 - BL 200. The pilot / copilot controls the elevators by moving the control column forward (for aircraft nose pitch down) or aft (for aircraft pitch nose up). When engaged, the AP also supplies pitch control. 27-30-00 Page 3 August 15/14