HORIZONTAL STABILIZER ACTUATION.pdf

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL HORIZONTAL STABILIZER ACTUATION — SYSTEM DESCRIPTION 1. General A. Description The horizontal stabilizer is trimmed such that the elevators remain within a specified tolerance of the faired position. This is called the elevator off-load function. The Fligh...

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL HORIZONTAL STABILIZER ACTUATION — SYSTEM DESCRIPTION 1. General A. Description The horizontal stabilizer is trimmed such that the elevators remain within a specified tolerance of the faired position. This is called the elevator off-load function. The Flight Control Computer (FCC) determines when the stabilizer is to be trimmed. The horizontal stabilizer is controlled and monitored by the Horizontal Stabilizer Control Unit (HSCU). In normal operation, the HSCU receives rate command inputs from the FCC. The HSCU will convert this command to an Horizontal Stabilizer Trim Actuator (HSTA) motor command. The horizontal stabilizer trim system converts three-phase 115 Vac from the right main ac and emergency ac buses to 270 Vdc, pulse width modulated power to drive the HSTA. The HSTA, located in the vertical stabilizer, is electrically controlled and electrically actuated to position the horizontal stabilizer. The horizontal stabilizer may be actuated directly, through the FCC, via the BACKUP PITCH trim switches while on ground stationary condition is valid. See Figure 1. NOTE: Both BACKUP PITCH trim switches have to be actuated simultaneously. The dual channel HSCU monitors and controls the HSTA. Each HSCU channel is made of one command and one monitor lane. Each HSCU channel receives rate commands from one FCC over a standard ARINC 429 (A429) bus. The more capable HSCU channel controls the HSTA. Each channel of the HSCU provides the electronic drive for one electric motor and control of the two motor brakes. If there is a failure in the two FCC to HSCU buses, the HSCU takes its commands from the BACKUP PITCH trim switches located on the pedestal. The horizontal stabilizer is displaced by a dual load path electromechanical actuator driven by two identical and independent electric motors in a torque-summed arrangement, operating in active / standby mode. Each motor is fitted with one friction brake with dual solenoid control input. The motor brake assemblies provide actuation of the HSTA. The motor brakes operate in active / standby configuration. One motor is capable of fully controlling the HSTA. The motor brakes interface with the gear train in a torque-summed arrangement through an inertial slip clutch. The gear train is a single gear train connecting the motor brake assemblies to the ballscrew. The HSTA irreversibility is provided by a mechanical no-back device mounted on the HSTA ballscrew and by electromechanical brakes on each motor brake assembly. Either the no-back device or the motor brakes are capable of providing HSTA irreversibility under application of the defined limit load. The HSTA has two fully independent load paths (primary and secondary). In normal operation, only the primary path will carry the HSTA operating and static loads, while the secondary path remains unloaded. If a structural failure occurs in the primary load path, the secondary path immediately engages to carry the static loads. The HSTA will then lock up, holding the horizontal stabilizer in the last commanded position for the remainder of the flight. After a lockup, if the trim actuator is commanded to move, the stabilizer system detects the failure to move and annunciates the failure to the flight and maintenance crews. 2. Component Location COMPONENT ATA QTY PER A/C LOCATION Horizontal stabilizer trim actuator 27-43-01 1 Vertical stabilizer 27-43-00 Page 1 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL COMPONENT ATA QTY PER A/C LOCATION Horizontal stabilizer trim actuator motor 27-43-03 2 On HSTA 3. Component Details A. Horizontal Stabilizer Trim Actuator The HSTA is a gimbal-mounted, irreversible, dual load path ballscrew device installed in the empennage of the aircraft. Extension and retraction of the actuator controls the angle of incidence of the horizontal stabilizer and thereby the longitudinal attitude and trim speed of the aircraft. The HSTA receives 270 Vdc inputs from the HSCU that drive two electrical motor brakes in an active / standby configuration. The motors turn the ballscrew through a slip clutch and gear train and feeds back motor position to the HSCU through brushless resolvers. Stabilizer positional feedback is independently provided to the HSCU by two mechanical position resolvers, one driven by each ballscrew load path. The HSTA incorporates a fail-safe design with two independent dual channel sensors that provide stabilizer position data. The actuator has the following two fully independent load paths: Primary load (normal) Secondary load The dual load path design ensures no single failure will prevent the actuators ability to react load. The HSTA has extend and retract stops to limit actuator motion in the event of control loop failure. A torque limiting slip clutch limits the load imparted to aircraft structure. A tie rod lock assembly prevents motion following a primary load path failure. In normal conditions, only the primary load path carries the actuator operating and static loads, while the secondary load path remains unloaded. If a failure occurs in the primary load path, the secondary load path immediately engages. After a failure, the actuator locks, holding the horizontal stabilizer in the last commanded position for the remainder of the flight. When the locked actuator is commanded to move, the stabilizer system detects and annunciates the failure. Actuator irreversibility is provided by the following: A mechanical no-back device mounted on the actuator ballscrew Electromechanical brakes on each motor brake assembly B. Horizontal Stabilizer Actuator Motor The horizontal stabilizer actuator motor is a 270 Vdc brushless motor with an integral electromechanical brake and brushless resolver. The motor brake assembly interfaces with the HSCU using two D38999, Type III electrical connectors. One connector supplies the required 270 Vdc inputs. The other provides feedback of the resolver and brake signals. The HSTA contains two motors, each of which is capable of providing the output necessary to drive the actuator at full capacity. Each horizontal stabilizer actuator motor assembly has an electromechanical brake with a dual solenoid. The brake consists of spring-loaded friction discs to provide braking torque. The remaining parts are stainless steel, with magnetic or high strength stainless steel used where required. Multiple springs are used to ensure no single point failure affects the brake function. There are two identical and independent electric motor brake assemblies. The brushless motors have 270 Vdc armature windings. Each motor consists of a four-pole design with a three-phase, Y-winding, without a center tap. A single motor is capable of operating the trim actuator. The motor 27-43-00 Page 2 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL brakes are installed and interface with the gear train in a torque-summed arrangement through an inertial slip clutch. A single gear train connects the motor brake assemblies to the ballscrew. 4. Controls and Indications A. Circuit Breakers The system is protected by the following circuit breakers: NOMENCLATURE PANEL LOCATION POWER SOURCE STAB CH 1 REER E1 EMERG BUS 115VAC STAB 2 DC REER A7 R ESS 28VDC STAB 1 DC LEER B10 L ESS 28VDC STAB CH 2 PDB PDB / EER R MAIN BUS 115VAC B. CAS Messages The CAS messages for the system are shown in the following table: MESSAGE COLOR MESSAGE DESCRIPTION Stabilizer Rigging Complete Blue Rigging is valid for the current aircraft. Message occurs when in maintenance mode after autorigging is satisfactorily completed. No action required. Stabilizer Maintenance Required Blue The HSCU has flagged a maintenance item. System redundancy has not been lost. Stabilizer Failed Amber Horizontal stabilizer not responding to movement commands or surface position information is unreliable or unavailable. If flight control system is in normal mode, BACKUP PITCH trim switch on control wheel adjusts elevator trim position. NOTE The backup pitch trim switch on the trim control module shall not be used. Stabilizer Channel Fail Stabilizer Primary Trim Fail Amber Amber A horizontal stabilizer control channel has failed. Notify maintenance for corrective action. Loss of valid pitch trim communication from the FCCs to the HSCU. Continue flight using BACKUP PITCH trim switch. BACKUP PITCH trim switch on control wheel will be inoperative. NOTE This message may be accompanied by FCC Alternate Mode (amber). NOTE: The FCC status information required by the flightcrew is shown on the main displays as CAS messages and synoptic page data. 27-43-00 Page 3 August 15/14 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL 5. Operation A. Horizontal Stabilizer Actuation The horizontal stabilizer is displaced by a dual load path electromechanical actuator driven by two electric motors in a torque-summed arrangement operating in active / standby configuration. Each motor is fitted with one friction brake with dual solenoid control input. There are four resolvers for position feedback to the HSCU. While in air, pitch trim is initially accomplished with elevator movement. At a predetermined amount of elevator trim, the horizontal stabilizer is moved to off load and neutralize the elevator. The FCCs provide rate commands to the HSCU while simultaneously commanding the elevator to the faired position. While on ground and stationary, the stabilizer will be commanded directly through the FCC via the BACKUP PITCH trim switches. The trim control panel switches provide signals to the HSCU. This provides a backup pitch trim capability by directly controlling the horizontal stabilizer. Both BACKUP PITCH trim switches (1 and 2) shall be actuated at the same time for the trim to work. 27-43-00 Page 4 August 15/14