Gulfstream G650ER Aileron Hydraulic Actuation PDF

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL AILERON HYDRAULIC ACTUATION — SYSTEM DESCRIPTION 1. General A. Description The aileron actuators are powered by 3000 psi from the left and right hydraulic system during normal operation. Hydraulic system pressure is ported from the manifolds to the actuato...

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL AILERON HYDRAULIC ACTUATION — SYSTEM DESCRIPTION 1. General A. Description The aileron actuators are powered by 3000 psi from the left and right hydraulic system during normal operation. Hydraulic system pressure is ported from the manifolds to the actuators. See Figure 1 and Figure 2. Hydraulic actuation is commanded by Flight Control Computers (FCCs) or the Backup Flight Control Unit (BFCU). The FCCs provide position signals to Remote Electronic Units (REUs). Bidirectional ARINC 429 (BD429) digital data buses are installed between FCCs and REUs. Motor Control Electronics (MCEs) receive ARINC 429 data from FCCs using BD429 digital data buses. The REUs process data signals to drive hydraulic manifold valves that initiate actuator movement to control flight surfaces. If both FCCs fail, BFCU provides position signals to REUs using standard ARINC 429 (A429) digital data buses. See Figure 3. The following three types of manifolds drive actuators: EB HA EBHA The following two types of actuator systems are used: EHSA system EBHA system The EHSA system includes a hydraulic cylinder / piston assembly and a separate manifold. The EBHA system has an hydraulic EHSA-type part, with an MCE controlled Integrated Motor Pump Assembly (IMPA) that drives an hydraulic cylinder / piston in backup state. Backup state is used if aircraft hydraulic system fails and adjacent EHSA is unavailable. NOTE: Hydraulic manifolds for EHSA type and EBHA type spoiler actuators are not interchangeable. The same REU fits all locations. Applicable REU software is selected by installation strapping for each location. Actuation system may be in any of the following states: 27-13-00 Page 1 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL TYPE OF CONTROL STATE DESCRIPTION Dual hydraulic EBHA active hydraulic state and EHSA active, both controlled by their REU; force fight alleviation in EBHA REU using EHSA pressure sensors. EHSA only EHSA in hydraulic state is controlled by its REU, EBHA (inop) is in damped bypass state. EBHA only EBHA active in hydraulic state is controlled by its REU, EHSA (inop) is in damped bypass state. EBHA electrical backup EBHA in electric state is controlled by its REU / MCE, EHSA (inop) in damped bypass state is activated by bypass solenoid valve. The MCE works in surface velocity control state, commanded by EBHA REU. MCE MCE backup position control EBHA active in electric state is controlled by MCE backup controller function, EHSA is in damped bypass state. No control Damped bypass EBHA and EHSA in damped bypass state (no REU / MCE control). REU 2. Component Location COMPONENT ATA QTY PER A/C LOCATION Aileron EHSA actuator 27-13-01 2 Wing rear beam Aileron EBHA actuator 27-13-03 2 Wing rear beam Aileron EHSA manifold 27-13-05 2 Wing rear beam Aileron EB manifold 27-13-07 2 Wing rear beam Aileron HA manifold 27-13-09 2 Wing rear beam 3. Component Details A. Aileron EHSA Actuator The aileron EHSA hydraulic actuator is flange-mounted. It employs a toggle link to ensure freedom of motion while providing hinge movement required to deflect ailerons during roll functions. The actuator accepts hydraulic inputs from adjacent aileron EHSA manifold. It provides position data to aileron REU using a single channel main ram LVDT to close the control loop during all operational states. Left and right outboard actuators are EHSAs. An EHSA is controlled electrically by its REU and uses hydraulic power to move control surfaces. Left EHSA REU receives electrical power from a single circuit breaker on left essential dc bus. Right EHSA REU receives electrical power from a single circuit breaker on right essential dc bus. 27-13-00 Page 2 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL The EHSA system has the following three separate components: REU Hydraulic actuator Hydraulic manifold Left and right actuators are separate from REU. For symmetry during failure, both actuators use right aircraft system hydraulic power. Hydraulic actuators contain a single channel LVDT that provides position sensing data to REU. No other electrical components are in the actuator. The EHSA (outboard actuator) has the following three operational states: Active hydraulic (normal) Damped bypass (1) EHSA Active Hydraulic State In EHSA active hydraulic (normal) state, Mode Select Valve (MSV) is energized and allows hydraulic flow from Electro-Hydraulic Servo Valve (EHSV) to actuator. In active hydraulic state, REU energizes a normally open three-way MSV Solenoid Operated Valve (SOV) that moves MSV into active position. Active position connects cylinder ports to EHSV and disconnects cylinder ports from Variable Damping Orifice (VDO). In EHSA active hydraulic state, REU uses internal main ram LVDT signal to determine main ram position and calculates difference between commanded ram position (from FCC or BFCU) and actual ram position to generate an error signal. The REU applies an electrical command current to first stage coils in EHSV that is proportional to error signal. The EHSV command current proportionally increases flow orifice metering area between supply pressure and one cylinder port along with flow orifice metering area between return pressure and opposing cylinder port. Polarity of EHSV command current causes ram to move in a direction that reduces positional error signal until error signal reaches zero. Polarity of EHSV command current in effect determines which cylinder ports (extend or retract) get connected to supply and return pressures. (2) EHSA Damped Bypass State The EHSA system is placed in damped bypass state when MSV is de-energized. Damped bypass state is entered when an REU or aircraft hydraulic system failure occurs. Since actuator is no longer actively controlled, a damping force is used for flutter suppression. The associated EBHA actuator, is also actively controlling the same surface and will overcome the EHSA actuator damping force. In EHSA damped bypass state, actuator may be commanded to shut down through a solenoid valve driving the MSV. The REU de-energizes the three way MSV SOV that moves the MSV so that cylinder ports are disconnected from EHSV and interconnected through VDO. Upon loss of electrical or hydraulic power actuator MSV automatically reverts to damped state. B. Aileron EBHA Actuator The aileron EBHA hydraulic actuator is flange-mounted. It employs a toggle link to ensure freedom of motion while providing the hinge movement required to deflect the aileron during roll functions. The actuator accepts hydraulic inputs from adjacent aileron HA manifold and provides position data to aileron REU and MCE. It uses a dual channel main ram LVDT to close the control loop during all states of operation. The EBHA system includes a hydraulic cylinder / piston assembly and two hydraulic manifolds (HA and EB). A separate hydraulic actuator is located between the EHSA manifold and HA manifold. The 27-13-00 Page 3 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL hydraulic actuator contains a two channel LVDT that provides position sensing data. One channel is connected to the REU and the other to the MCE. There are no other electrical components in the actuator. The MCE receives electrical power from a single 65 amp circuit breaker on the 28 Vdc EBHA bus. The MCE uses the power for its internal electronics and to power the backup electrical motor. The left and right inboard actuators are EBHAs. An EBHA is controlled electrically by its REU and uses hydraulic power to move the control surface. For symmetry during a failure, both EBHA actuators are driven by the left hydraulic system. The EBHA system has the following five separate components: REU MCE Hydraulic actuator Electric backup manifold Hydraulic actuation manifold The left EBHA REU receives electrical power from two separate circuit breakers. One is located on the Uninterruptible Power Supply (UPS) bus and the other on the left main dc bus. The right EBHA REU receives electrical power from two separate circuit breakers. One is located on the UPS bus and the other is on the right main dc bus. If both the EBHA REU and EHSA REU are invalid, the MCE has a limited capability to control the electrical motor and actuator on its own. In that condition, the MCE receives the surface command signals directly from one of the FCCs on the MCE ARINC A429 bus. The MCE receives electrical power from a single 65 amp circuit breaker on the 28 Vdc EBHA bus. The MCE uses the power for its internal electronics and to power the backup electrical motor. The EBHA has the following three states of operation: Active hydraulic (normal) Damped bypass Electrical backup (power select valve de-engerized) (1) Active Hydraulic State In the EBHA active hydraulic state, hydraulic pressure is from the aircraft system. The EHSV modulates the flow of fluid to provide the desired actuator movement. The Power Select Valve (PSV) controls the state between normal and electrical backup. In the normal energized position, the valve allows the EHSV modulated aircraft hydraulic pressure to move the actuator. The de-energized position allows pressure from the self-contained electrical backup hydraulic system to move the actuator. The EBHA active hydraulic state with normal hydraulic power provides closed-loop positional control of the EBHA, using the EHSV. When the EBHA is commanded into active state with normal hydraulic power, the REU and MCE energize a torque motor that positions the twoposition MSV into the active position. The active position connects the cylinder ports to the EHSV and disconnects the cylinder ports from the VDO. The REU and MCE also energize another torque motor that positions the two position PSV into the position for normal hydraulic power. The PSV connects hydraulic system pressure to the EHSV and connects the EHSV extend and retract control ports to the ram using the MSV. (2) Damped Bypass State The EBHA damped bypass state provides for adequate dynamic damping to prevent surface flutter in the event of a loss of all hydraulic pressure or electrical power. The EBHA may be 27-13-00 Page 4 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL commanded into the damped bypass state or the EBHA will default to the damped bypass state if there is a loss of electrical power or hydraulic pressure. A damping force is placed on the actuator since it is no longer being actively controlled but still needs to provide sufficient damping for flutter suppression. The associated EHSA actuator, which is also actively controlling the same surface, will overcome the damping force of the EBHA actuator. (3) Electrical Backup State In the EBHA electrical backup state the EHSV is bypassed and the starting, stopping and reversing of the IMPA modulates the flow of fluid to provide the desired actuator movement. The MSV controls entry into the damped bypass state. In the energized position the MSV allows hydraulic flow during either normal or electrical backup state. Electrical backup control of a surface is only done if both the EHSA and EBHA systems do not function in their normal hydraulic state. There will not be mixed operation where an EHSA is operated in its normal hydraulic state and the EBHA is in electrical backup state. However, the electrical pump function is activated in a warm up state when there has been a hydraulic failure to the EBHA, even when the EHSA is still functioning normally. The warm up state circulates warm hydraulic fluid through the manifold and prevents it from becoming cold soaked. This insures the EBHA is ready to immediately control the surface in the event an EHSA failure. In the EBHA electrical backup state, backup power provides closed-loop positional control of the EBHA using the pump motor. When the EBHA is commanded into active state with electrical backup power, the REU and MCE energize a torque motor that positions the twoposition MSV into the active position. The active position connects the cylinder ports to the pump and disconnects the cylinder ports from the VDO. The REU and MCE de-energize the PSV torque motor, positioning the two-position PSV for backup hydraulic power. The PSV connects the pump extend and retract control ports to ram using the MSV and blocks hydraulic system pressure from the EHSV. In the EBHA electrical backup state, positional control is provided by first comparing the commanded ram position to the actual ram position. The REU demodulates the main ram LVDT signal to determine the main ram position and calculates the difference between the commanded ram position and the actual ram position to generate the error signal. The REU then applies an electrical command current to the MCE, which commands the electrical motor driving the pump that is proportional (within limits) to the error signal. The pump motor command current proportionally increases (within limits) the pump motor velocity. The polarity of the pump motor command determines which cylinder ports (extend or retract) get connected to the inlet and outlet ports of the pump. For proper closed-loop control, the polarity of the pump motor command current causes the ram to move in a direction that reduces the positional error signal until the error signal reaches zero. C. Aileron EHSA Manifold The aileron EHSA manifold is installed at each instance of an EHSA type aileron actuator. The manifold servo valve is commanded by the REU and ports fluid accordingly to the extend or retract chambers of the associated actuator. The manifold output is open loop as all of the command computation is done within the REU. For maintenance purposes, the manifold contains a relief valve that may be manually driven so that the surface may be positioned as needed. The REU is mounted on its associated hydraulic manifold. The REU processes FCC signals and initiates electrical commands to the MSV solenoid and the EHSV. The MSV and EHSV control the flow of hydraulic fluid that moves the actuator. The aileron EHSA manifold includes the following components: 27-13-00 Page 5 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL SOV MSV VDO EHSV and position sensor Fluid pressure sensors Bidirectional Relief Valve (BDRV) Fluid filter Fluid reservoir Anticavitation check valves The REU controls the EHSV to port pressure to the cylinder. The cylinder delivers the force to move the surface. Sensors within the manifold provide status data to the REU. These include the following sensors: EHSV position LVDT Hydraulic supply and return pressure sensors Compensator position LVDT The compensator is a LP spring-loaded accumulator that stores a small hydraulic fluid reserve. The retract and extend cylinder pressure sensors are located in the EHSA manifold, but they provide data only to the EBHA REU. The sensors monitor the hydraulic pressure on both extend and retract chambers of the hydraulic actuator. The EBHA REU monitors similar pressure data from the EBHA actuator and compares the two pressures to insure the two actuators are working together with no force fight issue between the two. Status data in the form of a discrete signal is passed from each REU to the other. This lets the associated REU know if the other is invalid and not actively controlling the surface. D. Aileron EB Manifold The aileron EB manifold is installed at each instance of an EBHA type aileron actuator. The EB manifold contains the following components: EHSV SOV PSV IMPA Anticavitation check valves During all states of operation, the EB manifold is commanded by its electrical interface with the MCE and REU. During normal operation, aircraft hydraulic pressure is controlled by the EHSV to extend or retract the actuator. During the electrical backup state, the IMPA generates hydraulic pressure to extend or retract the actuator based on the direction of motor rotation. The REU processes FCC signals and initiates electrical commands to the PSV solenoid and EHSV in the EB manifold. Those components control the flow of hydraulic fluid that moves the actuator. Sensors within the manifold provide status data to the REU. The EB manifold contains the following sensors: EHSV position LVDT Hydraulic supply and return pressure sensors Hydraulic temperature sensor The MCE is mounted directly to the EB manifold. Each MCE has its own 65 amp circuit breaker on the 28 Vdc EBHA Power Distribution Box (PDB). The MCE uses the power for its internal electronics and to power the IMPA. The MCE controls the operation of the IMPA. It receives motor position and velocity data from the motor resolver. The MCE shall know the validity of both the EBHA REU and the EHSA REU and receives a status discrete from each. If the EBHA REU is active 27-13-00 Page 6 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL and the EHSA REU is inactive, the EBHA REU issues the motor velocity commands to the MCE over the REU to MCE RS-485 data bus. This data bus is referred to as the Motor Control Data Link (MCDL). The MCE passes its internal status monitors to the REU using the MCDL. E. Aileron HA Manifold The aileron HA manifold is installed at each instance of an EBHA type aileron actuator. The HA manifold contains the following components: SOV MSV VDO BDRV Anticavitation check valves Compensator Compensator position LVDT Retract and extend cylinder pressure sensors Return relief valve NOTE: The pressure sensors monitor hydraulic pressure on both extend and retract chambers of the hydraulic actuator. The REU is mounted directly to the HA hydraulic manifold. The HA manifold receives electrical input from the REU. The REU processes FCC signals and initiates electrical commands to the MSV solenoid in the HA manifold. This controls the flow of hydraulic fluid to move the actuator. The BDRV interconnects the extend and retract chambers when the greater of the two chambers exceeds the compensator circuit pressure by more than a preset value. The BDRV limits the maximum load on the actuator, in addition to the maximum pressure in each chamber. The HA manifold interfaces hydraulically with the EB manifold to pressurize the extend and retract ports of the aileron actuator. The HA manifold features a manual override for the return relief valve. This allows maintenance personnel to move the aileron surface when required. 4. Controls and Indications A. Circuit Breakers The system is protected by the following circuit breakers: NOMENCLATURE PANEL LOCATION POWER SOURCE L AIL HA LEER A9 L ESS 28VDC L AIL EBHA SEC LEER B9 L MAIN 28VDC L AIL EBHA PRI REER A3 UPS 28VDC R AIL EBHA PRI REER A4 UPS 28VDC R AIL HA REER A6 R ESS 28VDC R AIL EBHA SEC REER C7 R MAIN 28VDC L AIL EBHA PWR N/A EBHA PDB (tail compartment) EBHA BUS 28VDC R AIL EBHA PWR N/A EBHA PDB (tail compartment) EBHA BUS 28VDC 27-13-00 Page 7 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL B. Solid State Power Controllers The system is protected by the following solid state power controllers: NOMENCLATURE IDENTIFICATION NUMBER POWER SOURCE ROLL TRIM 2702 R ESS 28VDC C. CAS Messages The CAS messages for the system are shown in the following table: MESSAGE COLOR MESSAGE DESCRIPTION FCS Maintenance Required Blue Flight control system maintenance is required. Notify maintenance for corrective action. Roll Control Miscompare Amber Pilot and copilot control wheel positions are different. Continue flight within flight envelope limitations. Aircraft roll response with respect to control wheel input may be reduced. Pilot L-R Brake Pedal Fail Amber Pilot left and right brake pedals failed. Copilot L-R Brake Pedal Fail Amber L-R Inboard Brake Fail Amber Left and right inboard brakes failed. L-R Outboard Brake Fail Amber Left and right outboard brakes failed. Uncommanded Brake Amber Brakes are not commanded. Brake By Wire Fail Amber Brake-by-wire has failed. Retrim Left Wing Down Amber Retrim left wing down. Retrim Right Wing Down Amber Retrim right wing down. L-R Aileron Fail Amber Both REUs failed or loss of aileron command to both ailerons. Continue flight within flight envelope limitations. Attempt FLT CTRL RESET. Roll Authority Limit Amber Roll axis flight control surfaces approaching maximum displacement. Adjust flight condition as necessary. Lateral Coupling Data Invalid Amber Copilot left and right brake pedals failed. Lateral coupling data is invalid. Speed Brake Auto Retract Amber Speed brakes (flight spoilers) automatically retracted with speed brake handle not in RETRACTED position and TLA =90% or angle of attack limiting encountered. Place speed brake handle at RETRACTED position. If unable, speed brakes will be unavailable while message is displayed. Speed Brake Fail Amber Speed brake control failed. Notify maintenance for corrective action. 27-13-00 Page 8 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL MESSAGE COLOR MESSAGE DESCRIPTION FCS Test Fail Amber Flight control system built-in test failed. Notify maintenance for corrective action. Ground Spoiler Red Failure of ground spoiler component or deployed ground spoiler panel. Select ground spoiler switch OFF and perform appropriate procedures. NOTE: The FCC status data required by the flightcrew is shown on the main displays as CAS messages and synoptic page data. 5. Operation A. Aileron Hydraulic Actuation Aileron hydraulic control is accomplished by the following two types of actuators: EHSA EBHA (1) EHSA Operating States An EHSA is controlled electrically by its REU and uses hydraulic power to move the control surface. The EHSA system has the following three separate components: REU Hydraulic manifold Hydraulic actuator The REU is mounted directly to the hydraulic manifold. The left aileron EHSA REU receives electrical power from a single circuit breaker on the left essential dc bus. The right aileron EHSA REU receives electrical power from a single circuit breaker on the right essential dc bus. The REU receives surface position commands from the FCCs on two separate and independent BD429 data buses. One bus is from FCC 1 and the other from FCC 2. The REU processes the FCC signals and initiates electrical commands to the MSV solenoid and the EHSV. The MSV and EHSV control the flow of hydraulic fluid to move the actuator in the desired direction. Sensors within the manifold provide status data to the REU. These include the EHSV position LVDT, hydraulic supply and return pressure sensors and compensator position LVDT. The compensator is a LP spring-loaded accumulator that stores a small hydraulic fluid reserve. The retract and extend cylinder pressure sensors are also located in the EHSA manifold, but they provide data only to the EBHA REU. The sensors monitor the hydraulic pressure on both extend and retract chambers of the hydraulic actuator. The EBHA REU monitors similar pressure data from the EBHA actuator and compares the two pressures to insure the two actuators are working together with no force fight issue between the two. Status data in the form of a discrete signal is passed from each REU to the other. This lets the associated REU know if the other is invalid and not actively controlling the surface. The left and right actuators are separate from the REU. For symmetry during a failure, both EHSAs use hydraulic power from the aircraft right system. The hydraulic actuators contains a single channel LVDT that provides position sensing data to the REU. There are no other electrical components in the actuator. The EHSA (outboard actuator) has the following states of operation: 27-13-00 Page 9 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL Active hydraulic (normal) Damped bypass In the EHSA active hydraulic state, the MSV is energized and allows hydraulic flow from the EHSV to the actuator. In the active hydraulic state, the REU energizes a normally open threeway MSV SOV that moves the MSV into the active position. The active position connects the cylinder ports to the EHSV and disconnects the cylinder ports from the VDO. In EHSA active hydraulic state, the REU uses the internal main ram LVDT signal to determine the main ram position and then calculates the difference between the commanded ram position (from the FCC or the BFCU) and the actual ram position to generate an error signal. The REU applies an electrical command current to the first stage coils in the EHSV that is proportional to the error signal. The EHSV command current proportionally increases the flow orifice metering area between supply pressure and one cylinder port along with the flow orifice metering area between return pressure and the opposing cylinder port. The polarity of the EHSV command current causes the ram to move in a direction that reduces the positional error signal until the error signal reaches zero. The polarity of the EHSV command current in effect determines which cylinder ports (extend or retract) get connected to supply and return pressures. The EHSA system is placed in damped bypass state when the MSV is de-energized. The state is entered when there has been a failure in the REU or the aircraft hydraulic system. A damping force is placed on the actuator since it is no longer being actively controlled, but still needs to provide sufficient damping for flutter suppression. The associated EBHA actuator, is also actively controlling the same surface and will overcome the damping force of the EHSA actuator. In the EHSA damped bypass state, the actuator may be commanded to shut down through a solenoid valve driving the MSV. The REU de-energizes the three way MSV SOV that moves the MSV so that the cylinder ports are disconnected from the EHSV and interconnected through the VDO. Upon loss of electrical or hydraulic power the actuator MSV automatically reverts to the damped state. (2) EBHA Operating States An EBHA is controlled electrically by its REU and uses hydraulic power to move the control surface. The EBHA system has the following five separate components: REU MCE Hydraulic actuator HA manifold EB manifold The REU is mounted directly to the HA hydraulic manifold. Two circuit breakers are provided for each REU to allow separate wire routing from each breaker along the leading and trailing edges of the wing. The two breakers have different power sources to provide redundancy for power bus failures. The left aileron EBHA REU receives electrical power from two separate circuit breakers. One is located on the UPS bus and the other on the left main dc bus. The right aileron EBHA REU also receives electrical power from two separate circuit breakers. One is located on the UPS bus and the other on the right main dc bus. If both the EBHA REU and EHSA REU are invalid, the MCE has a limited capability to control the electrical motor and actuator on its own. In that condition, the MCE receives the surface command signals directly from one of the FCCs on the MCE A429 bus. 27-13-00 Page 10 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL The EBHA REU receives surface position commands from the FCCs on two separate and independent BD429 data buses. One bus is from FCC 1 and the other from FCC 2. The REU processes the FCC signals and initiates electrical commands to the MSV solenoid in the HA manifold and the PSV solenoid and EHSV in the EB manifold. Those components control the flow of hydraulic fluid to move the actuator in the desired direction. The MCE is mounted directly to the EB hydraulic manifold. Each MCE has its own 65 amp circuit breaker on the 28 Vdc EBHA bus. The MCE uses the power for its internal electronics and to power the IMPA. The MCE controls the operation of the backup electrical motor. It receives motor position and velocity data from the motor resolver. The MCE shall know the validity of both the EBHA REU and the EHSA REU and receives a status discrete from each. If the EBHA REU is valid, then the REU issues the motor velocity commands to the MCE using the MCDL. The MCE passes its internal status monitors to the REU over the MCDL. The EBHA actuator is installed between both REUs. The hydraulic actuator contains a two channel LVDT that provides position sensing data. One channel is connected to the REU and the other to the MCE. There are no other electrical components in the actuator. For symmetry during a failure, both EBHAs use hydraulic power from the aircraft left system. The EBHA has the following three states of operation: Active hydraulic (normal) Damped bypass Electrical backup (de-engerized) In the EBHA active hydraulic state, hydraulic pressure is from the aircraft system. The EHSV modulates the flow of fluid to provide the desired actuator movement. The PSV controls the state between normal and electrical backup. In the normal energized position, the valve allows the EHSV modulated aircraft hydraulic pressure to move the actuator. The de-energized position allows pressure from the self-contained electrical backup hydraulic system to move the actuator. The EBHA active hydraulic state with normal hydraulic power provides closed-loop positional control of the EBHA, using the EHSV. When the EBHA is commanded into active state with normal hydraulic power, the REU and MCE energize a torque motor that positions the twoposition MSV into the active position. The active position connects the cylinder ports to the EHSV and disconnects the cylinder ports from the VDO. The REU and MCE also energize another torque motor that positions the two-position PSV into the position for normal hydraulic power. The PSV connects hydraulic system pressure to the EHSV and connects EHSV extend and retract control ports to the ram using the MSV. In the EBHA electrical backup state the EHSV is bypassed and the starting, stopping and reversing of the IMPA modulates the flow of fluid to provide the desired actuator movement. The MSV controls entry into the damped bypass state. In the energized position the MSV allows hydraulic flow during either normal or electrical backup state. Electrical backup control of a surface is only used if both the EHSA and EBHA systems do not function in their normal hydraulic state. There will not be mixed operation where an EHSA is operated in its normal hydraulic state and the EBHA is in electrical backup state. However, the electrical pump function is activated in a warm up state when there has been a hydraulic failure to the EBHA, even when the EHSA is still functioning normally. The warm up state circulates warm hydraulic fluid through the manifold and prevents it from becoming cold soaked. This insures the EBHA is ready to immediately control the surface in the event of an EHSA failure. 27-13-00 Page 11 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL In the EBHA electrical backup state, backup power provides closed-loop positional control of the EBHA, using the IMPA. When the EBHA is commanded into active state with electrical backup power, the REU and MCE energize a torque motor that positions the two-position MSV into the active position. The active position connects the cylinder ports to the pump and disconnects the cylinder ports from the VDO. The REU and MCE de-energize the PSV torque motor, positioning the two-position PSV for backup hydraulic power. The PSV connects the pump extend and retract control ports to ram using the MSV and blocks hydraulic system pressure from the EHSV. In the EBHA electrical backup state, positional control is provided by first comparing the commanded ram position to the actual ram position. The REU demodulates the main ram LVDT signal to determine the main ram position and calculates the difference between the commanded ram position and the actual ram position to generate the error signal. The REU then applies an electrical command current to the MCE, which commands the electrical motor driving the pump that is proportional (within limits) to the error signal. The pump motor command current proportionally increases (within limits) the pump motor velocity. The polarity of the pump motor command determines which cylinder ports (extend or retract) get connected to the inlet and outlet ports of the pump. For proper closed-loop control, the polarity of the pump motor command current causes the ram to move in a direction that reduces the positional error signal until the error signal reaches zero. The EBHA damped bypass state provides for adequate dynamic damping to prevent surface flutter in the event of a loss of all hydraulic pressure or electrical power. The EBHA may be commanded into the damped bypass state or the EBHA will default to the damped bypass state, if there is a loss of electrical power or hydraulic pressure. A damping force is placed on the actuator since it is no longer being actively controlled, but still needs to provide sufficient damping for flutter suppression. The associated EHSA actuator, which is also actively controlling the same surface, will overcome the damping force of the EBHA actuator. 27-13-00 Page 12 August 15/14