Gulfstream G650ER Flight Control Computer PDF

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL FLIGHT CONTROL COMPUTER — SYSTEM DESCRIPTION 1. General A. Description The three axis Fly-By-Wire (FBW) flight control system includes two Flight Control Computers (FCCs) and a Backup Flight Control Unit (BFCU). The BFCU is used only when there has been a...

GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL FLIGHT CONTROL COMPUTER — SYSTEM DESCRIPTION 1. General A. Description The three axis Fly-By-Wire (FBW) flight control system includes two Flight Control Computers (FCCs) and a Backup Flight Control Unit (BFCU). The BFCU is used only when there has been a total failure of all four FCC channels. See Backup Flight Control, 27-02-00, System Description for more information on the BFCU. The FCCs provide a communication link between the Primary Flight Control System (PFCS) and all other applicable aircraft system resources. The FCCs are the source of higher level flight control capabilities such as airspeed scaling, stall protection and high-speed protection. The FCCs also perform system health monitoring and checks. The FCC system provides digital commands to the following: Ailerons (2) Spoilers (6) Elevators (2) Rudder Horizontal Stabilizer Control Unit (HSCU) The FCCs are the central components of the FBW system. They receive sensor data from a variety of aircraft systems and control inputs from the cockpit inceptors. The FCCs support the cockpit control sensors and process the signals to allow the same command to be seen at each Remote Electronics Unit (REU) for a specific flight surface. The FCCs process the data using control laws and transmit commands to the REUs that control the actuation electronics located at each control surface. There are two channels in each FCC. There is a channel A and channel B. Each channel consists of the following two lanes: Command lane (COM) Monitor lane (MON) Channel A hardware is different from channel B. Command lane software is different from monitor lane software. Each FCC module has command lane software and monitor lane software installed and it chooses which executable to run based on where it is located in the FCC rack. Direct mode is the control law that is executed when the FCC enters simple state. This is as a result of a four channel command / monitor miscompare and is therefore only applicable in the case of a fault on all four channels. As long as one of the four FCC channels is operating correctly, the system functions in one of the following modes: Direct mode (includes normal mode and alternate mode control laws) Simple state (includes direct mode control laws) Maintenance mode If all four FCC command / monitor pairs disagree, the FCCs attempt to revert to the direct mode. If the last FCC channel fails due to a command / monitor disagree, all four channels attempt to restart through a hardware reset. The reset results in the FCC processors selecting the direct mode FCC control law. This requires minimal input sensor logic, a simple control law and reduced built-in test command / monitor comparisons. If all four FCC channels are unable to compute the control law after three attempts, the control reverts to the BFCU. Normal is the default mode when all primary flight control system resources are available. The mode provides augmented pitch control through a speed and maneuver stability control law that 27-01-00 Page 1 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL requires aircraft angular rates, load factor and air data signals from external aircraft systems. When the Angle of Attack (AOA) is trending toward 85% of maximum, AOA limiting is activated. At that point the column will begin to control AOA as opposed to the load factor or airspeed. A full aft column will provide the maximum AOA. Normal mode roll and yaw control is implemented such that the wheel and rudder inputs result in a gain scheduled deflection of aileron, spoiler and rudder surfaces. The amount of gain is based on the particular flight condition. In addition, a yaw damper function is superimposed on the pilot rudder. The FCCs interface with avionics for CAS display and fault reporting. Functions such as electronic rigging, software uploading and configuration checking are provided by the PFCS using either portable interface equipment or interfaces with avionics equipment. 2. Component Location COMPONENT ATA QTY PER A/C LOCATION Flight Control Computer Channel A MON Module 27-01-01 2 Right side flight control computer rack in LEER and REER Flight Control Computer Channel A COM Module 27-01-01 2 Right side flight control computer rack in LEER and REER Flight Control Computer Channel B COM Module 27-01-01 2 Left side flight control computer rack in LEER and REER Flight Control Computer Channel B MON Module 27-01-01 2 Left side flight control computer rack in LEER and REER Flight Control Computer Fan Module 27-01-03 2 Center of flight control computer rack in LEER and REER Flight Control Reset Switch 27-01-05 1 Pedestal 3. Component Details A. Flight Control Computer Channel A MON Module The FBW flight control system is driven by FCCs located in separate EERs. See Figure 1. One FCC chassis is located in the LEER, the other chassis is located in the REER. Each FCC chassis contains the following components interconnected by a common backplane board: FCC channel B COM module FCC channel B MON module Fan module FCC channel A MON module FCC channel A COM module NOTE: The fan module is there to improve mean time between failure of the overall FCC and is not required to cool the FCC in order to meet environmental temp requirements. Each channel controls one of the fans. The LEER and REER FCCs are interchangeable. If interchanged, the FCC software will be programmed for the specific location. Program pins are used to program the FCC location. 27-01-00 Page 2 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL Each FCC includes the following two independent and redundant channels (a total of four control channels): Channel A (FCC 1 / FCC 2) Channel B (FCC 1 / FCC 2) NOTE: Channel A and B modules are not interchangeable because of dissimilar hardware. However, like modules (channel A COM / MON or channel B COM / MON) in a particular channel are interchangeable. All FCC channels active; however, only two are normally engaged for control of surfaces. The other two are active but not engaged. The two lanes operate as self-checking pairs to ensure the integrity of control. Each channel has its own 28 Vdc power input, computing and input / output resources. The standby channel is ready to take control at any point should something happen to the active channel. Between the two channels of the same FCC, only one channel at a time will transmit to a given REUs bus. Each channel (A / B) has the following two processing lanes: Command Monitor NOTE: Four control channels, times two processing lanes each, equals eight lanes of communication. Like modules (channel A COM / MON or channel B COM / MON) have identical hardware, but different software (C and ADA language compilers). Each module contains both sets of software and will function as either command or monitor when configured to do so. The modules check their location in the chassis at power up on ground and self configure as command or monitor modules. Each FCC receives input data buses from avionics, such as the following: Aircraft sensors Maintenance Autopilot (AP), etc. Each FCC also receives input data buses from aircraft systems, such as the following: Flaps Landing gear Braking Engines, etc. The FCCs provides output data buses to the following: REUs HSCU Modular Avionics Units (MAUs) NOTE: The MAUs hosts the AP, crew alert and maintenance functions. The FCCs performs data concentration / consolidation for the following: Flap Electronic Control Unit (FECU) Nose Wheel Steering (NWS) unit The FCCs receives trim inputs from trim buttons installed in the following three locations: The pilot wheel The copilot wheel The cockpit center pedestal 27-01-00 Page 3 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL Each trim button is split. Each half moves one switch with two contacts. The roll trim switches directly command the roll trim motor to move the wheel assembly to offset from the neutral position. A single roll trim actuator is mounted in the pilot side aileron and elevator control module and is used for normal aileron trim control. The trim actuator contains an internal RVDT sensor that measures its position. The RVDT data is sent to the display to indicate the amount of trim input from the pilot. The trim switch applies 28 Vdc to the trim actuator. The trim actuator rotates the mechanical ground point of the lateral system. The aileron RVDT cluster is biased by the amount of the ground rotation. The FCC sends biased RVDT cluster output to the REU. Each FCC contains preprogrammed control laws that provide digital commands to the following control units: REUs - Control the primary flight control surfaces HSCU - Controls the stabilizer NOTE: The HSCU along with the horizontal stabilizer trim actuator are part of the Horizontal Stabilizer Trim System (HSTS). The HSTS is considered a subsystem of the PFCS. The horizontal stabilizer has two modes, Normal or Secondary. If the FCCs are in their Normal air mode, then the stabilizer shall be in its Normal mode. Under those conditions, the stabilizer is rate commanded by the FCC to off load the elevators. The pitch trim switches (controlled by the pilot) move the elevators and not the stabilizer. There is no direct pilot control of the stabilizer in Normal mode. If the FCCs are in either Alternate or Direct mode and there is normal communication between the FCCs and the HSCU, the stabilizer remains in Normal mode. Stabilizer control is by direct pilot input using the BACKUP PITCH trim switches located on the trim control module. It is still controlled through the FCC, which provides two fixed command rates. If communication between the FCCs and the HSCU is lost, the stabilizer is placed in Secondary mode. In that mode the BACKUP PITCH trim switch inputs to the HSCU are used to move the stabilizer directly and the FCC is not involved. The HSCU moves the stabilizer at a constant predetermined rate. (1) ARINC 429 Receive Connections The FCCs receive ARINC 429 (A429) bus data from a variety of aircraft systems that includes, but is not limited to the following: Inertial reference system Attitude heading reference system Air data system Radar altimeters MAU AP cards MAU central maintenance system FECU HSCU Brake control unit Landing gear control unit FADEC (2) ARINC 429 Transmit Connections The FCC transmits data to aircraft systems on the following three separate A429 buses: External 1 - Primarily provides CAS and FDR data via MAUs External 2 - Primarily provides Central Maintenance Computer (CMC) data via MAUs Control - Provides actual control data only to the horizontal stabilizer 27-01-00 Page 4 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL The control bus also transmits data to the AP cards of the MAUs, NWS and flap system, but it does not control these systems. The FCCs transmit voted rudder pedal position, based on RVDT readings, to the NWS. (3) Discrete Signal Connections Discrete signal connections to the FCCs come primarily from switches located on various cockpit control panels. They include the following: Flap handle switches Throttle quadrant assembly switches AP disconnect switches Landing gear control handle switches Flight control reset switch Flight control maintenance switch Ground spoiler arm switch Ground spoiler flap override Pilot and copilot pitch trim switches Yaw trim switches Roll pitch trim switches (4) Flight Control Computer Crosstalk Each FCC channel has three separate crosstalk A429 buses on the command lane for data exchange with the other FCC channels. There is also one A429 bus from each monitor lane that transmits to the command lane of the same channel. That connection is entirely internal to the FCC. Validity discretes are exchanged among command and monitor lanes. Each FCC channel receives the command lane buses 1 and 2 of the three other channels. This results in both internal and external connections for those buses. The command lane bus 3 is different in that it is not received by the other channel of the same FCC. Command and monitor lanes exchange data to consolidate control and engagement logics, fault detection and to monitor FCC integrity. It does this by verifying the computations are the same for both lanes. If the FCC integrity is not ensured, the validity of each lane is set to false. The FCC channels exchange data to compute engagement priority logic for control of the outputs and for synchronization and control law voting. The exchanged data is consolidated with the transmitter validity discrete signal. B. Flight Control Computer Channel A COM Module See Flight Control Computer Channel A MON Module component details. C. Flight Control Computer Channel B COM Module See Flight Control Computer Channel A MON Module component details. D. Flight Control Computer Channel B MON Module See Flight Control Computer Channel A MON Module component details. E. Flight Control Computer Fan Module Each FCC chassis includes one cooling module that contains two fans. The fans provide cooling air to the FCC modules. F. Flight Control Reset Switch The PFCS reset module contains the FLT CTRL RESET switch. The reset module is located in the pedestal. If there is a loss of input resources (air data or inertial data), the FCCs downgrade to the 27-01-00 Page 5 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL alternate mode. This mode provides simple high / low gain scheduling and no AOA protection. The FLT CTRL RESET switch can also be used to recover REUs that have become inactive due to a fault or temporary loss of hydraulics and to reset REU bus selection. The FLT CTRL RESET switch input is used to clear latched faults in the FCC. The FCC also uses the FLT CTRL RESET switch input to generate a reset command to all REUs. Similarly the REUs will clear latched faults upon receipt of the reset. NOTE: The FCC FLT CTRL RESET switch cannot initiate a reset from the direct mode to the normal mode. 4. Controls and Indications A. Circuit Breakers The system is protected by the following circuit breakers: NOMENCLATURE PANEL LOCATION POWER SOURCE FCC 1A REER FLIGHT CONTROLS FCS UPS BUS 28VDC FCC 2B REER FLIGHT CONTROLS FCS UPS BUS 28VDC FCC 2A REER FLIGHT CONTROLS R ESS 28VDC FCC 1B LEER FLIGHT CONTROLS L ESS 28VDC B. CAS Messages The CAS messages for the system are shown in the following table: MESSAGE COLOR MESSAGE DESCRIPTION FCC Single Channel Fail Blue Single FCC channel has failed. Takeoff and landing is not inhibited. Log for maintenance action. Amber Channels A and B of both FCC 1 and FCC 2 have experienced communications / monitor failure. Takeoff and landing is not inhibited. Continue flight within flight envelope limitations. Stall protection [AOA limiting] is not available. FCC Alternate Mode Amber Less than two valid inertial reference signals, or less than two valid air data sources. Takeoff and landing is not inhibited. Continue flight within flight envelope limitations. Stall protection [AOA limiting] not available. Attempt FLT CTRL RESET. FCC Multi-Channel Fail Amber Two or three out of the four FCC channels have failed. Takeoff and landing is not inhibited. Notify maintenance for corrective action. Attempt FLT CTRL RESET. BFCU Active Amber Generated when all four FCCs stop communicating with CAS in combination with the BFCU setting its engaged discrete. FCC Direct Mode 27-01-00 Page 6 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL MESSAGE COLOR MESSAGE DESCRIPTION High Speed Protect Active Amber Computed based on the consolidated variable representing the control laws. Stall Protection Active Amber Computed based on control law variables representing the stick shaker on commanded conditions. Yaw Damper Fail Amber Computed based on validity of the inertial data and FCC mode of operation. FCS Maintenance Required Amber Computed based on FCC validity variables and FCC alternate mode variables regardless of how many FCC channels are active. Amber Computed based FCC variable representing ground maintenance state as well as based on FCC inputs from all REUs and HSCU representing maintenance mode operation. FCS Maintenance Mode 5. Operation A. Flight Control Computer At power up the FCCs starts in the initialization state. Each lane of an FCC channel performs various tasks that initialize the hardware circuitry involved in input / output processing. One lane will test internal program pins to determine the FCC location (command or monitor). The FCCs interface with the external aircraft systems through A429 data buses and discrete signals. Only the FCC to REU interface uses a bidirectional BD429 bus. Both FCCs exchange data with each other on the crosstalk A429 buses and through the validity discrete signals. The FCC operational modes/states are not based on control law mode but control law mode is determined through FCC operational state. The FCCs have the follow three operating states: Normal Simple Ground (1) Normal Mode Normal is the default mode when all primary flight control system resources are available. This mode provides augmented pitch control through a speed and maneuver stability control law that requires aircraft angular rates, load factor and air data signals from external aircraft systems. When the AOA is trending toward 85% of maximum, the AOA limiting is activated. At that point the column begins to control the AOA as opposed to the load factor or airspeed. A full aft column provides the maximum AOA. Normal mode roll (aileron) and yaw (rudder) control is implemented such that the wheel and rudder inputs result in a gain scheduled deflection of aileron, spoiler and rudder surfaces. The amount of gain is based on the particular flight condition. In addition, a yaw damper function is superimposed on the pilot rudder. (2) Ground Mode The FCC downgrades to the alternate mode if air data, inertial data or normal communication with the HSCU is lost. In this mode the airspeed, angular rates and load factor are no longer 27-01-00 Page 7 November 15/19 GULFSTREAM G650ER SYSTEM DESCRIPTION MANUAL used for pitch axis control. The column, pedal and wheel commands become simple gain scheduled signals from the pilot inceptors to the surface. The gain schedule is based on either flap handle or landing gear position. The fixed high gain is used when the aircraft is in the landing configuration. Fixed low gain is used in the high-speed region. When AOA limiting and AP are not available, the yaw (rudder) damper may be available. The flight control reset switch may be used to upgrade from alternate mode to normal mode provided the faults that caused entry to alternate mode have been cleared. Reset clears monitors in FCC, actuators. (3) Simple Mode The FCCs enter direct mode if all four FCC command / monitor lanes disagree. A disagreement may be the result of a common software fault. The direct mode is similar to the alternate mode. The control laws used are identical, but the FCCs operate in a more simple manner. Direct mode has reduced redundancy management (cross comparison of various data inputs to insure validity). The flight control reset switch cannot initiate an upgrade from direct to normal mode. 27-01-00 Page 8 November 15/19