Gulfstream G650ER Elevator Interface and Control PDF

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL ELEVATOR INTERFACE AND CONTROL — SYSTEM DESCRIPTION 1. General A. Description The elevator control system provides electrical and mechanical control of the elevator, fault monitoring and annunciation. Conventional control columns are used by the flightcrew...

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL ELEVATOR INTERFACE AND CONTROL — SYSTEM DESCRIPTION 1. General A. Description The elevator control system provides electrical and mechanical control of the elevator, fault monitoring and annunciation. Conventional control columns are used by the flightcrew to control aircraft pitch. The elevator system is part of the primary flight control system, which is an integrated three axis Fly-By-Wire (FBW) system that provides the following control: Pitch control through the elevator control system. See Elevator Control, 27-30-00, System Description. The pitch control function is supported by the horizontal stabilizer control system. See Horizontal Stabilizer Control, 27-40-00, System Description Yaw control through the rudder control system. See Rudder Control, 27-20-00, System Description Roll control through the aileron control system. See Aileron Control, 27-10-00, System Description. The roll control function is supported by the spoiler control system. See Spoiler Control System, 27-60-00, System Description The control columns are mechanically linked during normal operation so that they always move together. If a jam occurs with one of the control columns, either pilot may override the other by exceeding and maintaining the breakaway force. Each control column is connected by the elevator force sensor pushrod to its associated pilot / copilot aileron and elevator control module below the cockpit floor. See Figure 1 and Figure 2. Aircraft pitch control is accomplished through elevator surfaces on the horizontal stabilizer. Electrically controlled hydraulic actuators provide power for elevator surface movement. See Figure 4. Pilot and copilot control columns provide the control inputs through the RVDT position sensors. See Elevator Cockpit Sensors, 27-32-00, System Description for more information on the RVDTs. The commanded position information is provided to the two Flight Control Computers (FCCs) and the Backup Flight Control Unit (BFCU). The computers transmit the information on ARINC 429 (A429) digital data buses to the Remote Electronic Units (REUs) located at each actuator. The REUs command the hydraulic actuators that move the elevator surfaces. NOTE: The BFCU commands are ignored by the REUs unless there is a total failure of both FCCs. 2. Component Location COMPONENT ATA QTY PER A/C LOCATION Control column 27-31-01 2 Cockpit Elevator control override pushrod 27-31-03 2 Below cockpit floor, upper pushrod aft of pilot / copilot aileron and elevator control module assemblies Elevator 27-31-05 2 Trailing edge of horizontal stabilizer 27-31-00 Page 1 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL 3. Component Details A. Control Column The control column is part of the wheel / column assembly. The conventional control column provides the pilot / copilot a mechanical interface to the control modules. The control column travel is limited by over travel mechanical stops in the control modules. The pilot / copilot control pitch by moving the control column in the direction of the desired pitch as follows: Forward moves the nose down Aft moves the nose up The FBW system has artificial feel design for human factors operation. Dampers provide smooth operation and alleviate oscillations. The damping force is provided by two dampers connected to each control column. Movement of the control column moves the column pushrod that connects to the pilot / copilot control module assemblies. The control modules are located at the aft end of the cockpit under the floor and include the following: RVDT position sensors Force sensors Stick shaker motors Autopilot (AP) servo motors (1) RVDT Position Sensors Movement of either control column is sensed by 10 RVDT sensors (two RVDT clusters with five sensors per cluster). The sensors are contained within a mechanical enclosure, called the RVDT cluster. The RVDT cluster is a part of the control module assembly. The control module contains a common shaft along the vertical center line that simultaneously drives all five sensors. The sensors are located concentrically around the shaft. The control column drives the RVDT cluster through the primary flight control cables and mechanical linkage. For each RVDT cluster, the wheel position data is supplied as follows: Two RVDTs provide data to FCC No. 1 Two RVDTs provide data to FCC No. 2 One RVDT provides data to the BFCU The FCCs and the BFCU provide the excitation signal to their designated RVDTs and receive a voltage signal back that is proportional to the control wheel positions. The RVDTs translate the sensor movement into electronic signals. The FCCs interpret the electronic signals from the RVDTs and sends commands through bidirectional A429 digital data buses in a wiring harness to the REUs located at each elevator actuator. The REUs command the hydraulic actuators that move the elevator surfaces. Two separate and independent actuators are located at each elevator surface. The outboard actuator is the EHSA and the inboard is the EBHA. (2) Force Sensors The applied force on each control column is measured by its own force sensor. The elevator force sensor is on the pushrod and is attached to the column and the control module. Each sensor is a two channel strain gauge, with one channel connected to FCC No. 1 and the other channel connected to FCC No. 2. The FCCs provide an excitation signal to the sensor and then receives a voltage signal back that is proportional to the applied force. Control column force information is used by the AP system and the FDR. The FCCs provide the information on an A429 data bus to the Honeywell Modular Avionics Unit (MAU), where 27-31-00 Page 2 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL the AP modules reside. The AP uses the force information to automatically disconnect and return manual control. The MAUs transmit the force information on a digital data bus to the FDR. (3) Stick Shaker Each control column is equipped with an electrically powered stick shaker installed at the lower end of each column below the floor mounts. Motors are used to shake the control columns during an approaching stall, before the maximum Angle of Attack (AOA) is exceeded. The FCC provides discrete signals that control the stick shaker and control warning lights. When the AOA is trending toward 85% of maximum, the FCC control law enters AOA limiting and the stick shakers are activated. The 28 Vdc power for the stick shaker motor enters the FCC and passes through internal switches controlled by the FCC software. The motor for the pilot stick shaker is powered by the left essential DC bus. The copilot shaker is powered by the right main DC bus. (4) Autopilot Servo An 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 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. Either motor drives the movement of both control columns, due to the mechanical interconnect. B. Elevator Control Override Pushrod The override pushrods are installed between the column mount and control module. The pushrods are spring-loaded such that there are sufficient breakout forces to prevent the pushrods from extending or collapsing under normal operations. If a failure presents itself to where either the pilot / copilot pitch controls are jammed, the pilot with the operational controls shall be able to provide an input force of large enough magnitude to cause the spring to breakout and allow for column travel. Movement of the control column is transferred to the control module, resulting in elevator movement. C. Elevator The elevators are installed on the aft edge of the horizontal stabilizer. Pitch control is accomplished by the elevators, as well as by movement of the entire horizontal stabilizer. In normal operation, the FCCs use A429 digital data buses to transmit the commanded position to the REUs located at each actuator. In all operational modes, elevator surface control is achieved by means of the following: Conventional pilot / copilot control columns Pilot / copilot elevator RVDT positions sensors FCCs REUs Motor control electronics EHSAs and EBHAs attached to the elevator Based on the pilot / copilot control column displacement, RVDT position sensors generate electrical commands to the FCCs. The FCCs process the RVDTs electrical commands and send augmented, 27-31-00 Page 3 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL shaped and scaled digital commands via a data bus to each elevator REU. Based on the FCCs commands, each REU provides electrical commands to its associated actuator, causing the elevator surface to move as commanded. Elevators provide aircraft pitch control during normal operating conditions. The aircraft pitch command is initiated when either control column is moved forward or aft. The motion is transmitted by pushrods to the aileron and elevator control module, where signals are generated and provided to the FCCs. The FCCs send the electronics signals to the REUs located in the tail. The REUs control the actuators that actuate the elevators. In normal operation each elevator surface is controlled by the following two types of actuators that are simultaneously pressurized in an active / active configuration: EHSA - Left and right outboard EBHA - Left and right inboard (1) Control Wheel Trim Switches Each control wheel contains two separate and independent pitch trim switches. Both switches shall be actuated simultaneously to initiate the trim function. This prevents the single point failure of one switch giving an uncommanded trim signal. Actuating both switches in an up or down direction from the center neutral position allows up or down pitch trim. See Figure 3. Both control wheel trim switches are single-pole, center-off switches. Each pole provides trim signals in the form of ground / open discretes to the two FCCs. In the normal in air mode, the FCC trims with the elevators and commands the Horizontal Stabilizer Control Unit (HSCU) as required for the elevator off load function. In the normal on ground mode, alternate mode or direct mode, the FCC trims by commanding the HSCU to move the horizontal stabilizer. (2) Trim Control Module Switches The trim control module contains three sets of trim switches, one set for each aircraft axis. In addition, there is a roll trim motor control switch and a rudder trim centering switch. See Figure 5. Two separate and independent switches are used to accomplish the pitch trim function. Actuating both switches in a nose down or nose up direction from the center neutral position allows up or down pitch trim. Both switches shall be actuated simultaneously to initiate the trim function. This prevents the single point failure of one switch giving an uncommanded trim signal. Both pedestal pitch trim switches are double-pole, double-throw switches. One pole of each switch provides trim signals in the form of ground / open discretes to the two FCCs. The second pole provides trim signals in the form of ground / open discretes to the HSCU. Those signals are used for the backup (secondary) stabilizer control function. The control panel switches are labeled BACKUP PITCH. The backup (secondary) stabilizer control mode is entered when there is a loss of communication between the FCC and HSCU. If the HSCU does not receive data from the FCCs, it automatically transitions to backup mode. If the FCC does not receive data from the HSCU, it ignores the pedestal pitch trim switch commands and discontinues the elevator off load function. In backup stabilizer mode the FCC is bypassed and the HSCU takes trim commands directly from the pedestal pitch trim switches and commands the corresponding horizontal stabilizer movement. 27-31-00 Page 4 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL 4. Controls and Indications A. Circuit Breakers The system is protected by the following circuit breakers: NOMENCLATURE PANEL LOCATION POWER SOURCE L ELEV HA LEER A8 L ESS 28VDC L ELEV EBHA PRI REER B3 UPS 28VDC R ELEV EBHA PRI REER B4 UPS 28VDC L ELEV EBHA SEC REER B8 R MAIN 28VDC R ELEV HA REER B8 R ESS 28VDC R ELEV EBHA SEC REER C8 L MAIN 28VDC L ELEV EBHA PWR N/A EBHA PDB (tail compartment) EBHA BUS 28VDC R ELEV EBHA PWR N/A EBHA PDB (tail compartment) EBHA BUS 28VDC B. CAS Messages The CAS messages for the system are shown in the following table: MESSAGE COLOR MESSAGE DESCRIPTION Stall Reference Speed Increase Blue Stall protection speed increased because of wing anti-ice fail and possible ice accretion on wings. Verify increased landing reference speed and increased landing distance. AP Trim Fail Blue AP trim has failed. AP Inhibit-Stall Blue AP inhibit-stall is active. Pitch Trim Nose Down Limit Blue Pitch trim at nose down limit. Adjust pitch trim as necessary. Pitch Trim Nose Up Limit Blue Pitch trim at nose up limit. Adjust pitch trim as necessary. Stick Shaker 1-2 Fail Blue Stick shaker 1 and 2 have failed. AP Inhibit-Manual Trim Active Blue Go Around Pitch Blue Go around pitch is active. Stall Protection Active Amber AOA limiting mode is active. Adjust flight condition as necessary. Stall Protection Unavailable Amber AOA data unavailable or flight control mode other than normal. Continue flight within flight envelope limitations, minimum airspeed velocity reference. Retrim Left Wing Down Amber Retrim left wing down. AP inhibit-manual trim is active. 27-31-00 Page 5 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL MESSAGE COLOR MESSAGE DESCRIPTION Retrim Right Wing Down Amber Retrim right wing down. L-R Elevator Fail Amber Both REUs failed or loss of elevator command to both elevators. Continue flight within flight envelope limitations. Attempt FLT CTRL RESET. Elevator Single Actuator Amber Single elevator actuator failed. Notify maintenance for corrective action. Attempt FLT CTRL RESET. Vertical Coupling Data Invalid Amber Pitch Authority Limit Amber Pitch axis flight control surfaces approaching maximum displacement. Adjust flight condition as necessary. Amber Pilot and copilot pitch control column positions are different. Continue flight within flight envelope limitations. Aircraft pitch response with respect to control column input may be reduced. Pitch Control Miscompare NOTE: Vertical coupling data is invalid. The FCC status information required by the flightcrew is shown on the main displays as CAS messages and synoptic page data. 5. Operation A. Elevator Interface and Control The control column allows the pilot / copilot to control pitch by moving the control column in the direction of desired pitch (forward nose down, aft nose up). Total column travel is 18°. A control column head universal joint connects the control column to the control column torque tube through a yoke and a fork (left horn for the pilot side, right horn for the copilot) connection. The elevators move in unison with each other to control aircraft pitch around the lateral axis. Elevator deflection is -24° ±1° up and +13° ±1° down. 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. (1) Elevator Trim The FCCs interface with five cockpit switches for the trim function. A split button switch is located in the left horn for the pilot side, right horn for the copilot of each control wheel. Each split button switch has two contacts, up and down, center position is off. Another switch is in the trim control module located in the pedestal. There is also an AP trim disconnect switch (marked AP DISC) on the left horn of each control wheel. The AP trim disconnect switches have the following two contacts: Normally open Normally closed The elevator trim function is accomplished by manually activating a pitch trim switch. Based on the electrical command signals from the pitch trim switch, the horizontal stabilizer trim system and actuator move the horizontal stabilizer surface to longitudinally trim the aircraft. Although pitch trim is initially accomplished with elevator movement, at a predetermined amount of trim the horizontal stabilizer moves to off load and neutralize the elevator. 27-31-00 Page 6 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL All elevator trim control module switches provide signals to the FCCs in order to command the elevators. The trim switches also provide a backup pitch trim capability by directly providing signals to the HSCU to control the horizontal stabilizer. When the elevator command exceeds a preset value for a predetermined time (for example 1° for 30 seconds), the FCCs simultaneously do the following: Provide a rate command to the HSCU Command the elevator to the faired position (0° relative to the horizontal stabilizer surface) (2) Autopilot The AP supplies aircraft pitch control. Autopilot inputs are supplied through an electric servo motor that connects to the control module. In autoflight mode the columns are positioned by two AP servo actuators operating in active / standby configuration. The FCCs receive the AP position commands through the column RVDTs. The FCCs monitor pilot / copilot forces to detect any attempt to override the servos. See Aileron Autopilot System, 27-16-00, System Description. 27-31-00 Page 7 August 15/14