Flight Controls Flashcards
(51 cards)
Components
- 3 computers: 2 Flight Control Computers (FCCs) and Backup Flight Control Unit (BFCU) - - 16 actuators: 9 Hydraulic Actuators (HAs) and 7 Electric Backup Hydraulic Actuators (EBHAs) - 16 Remote Electronics Units (REUs)
- Horizontal Stab Control Unit (HSCU)
- Horizontal Stab Trim Actuator (HSTA)
- 2 Flight Control System (FCS) batteries: Electric Backup Hydraulic Actuator (EBHA) battery and Uninterruptable Power Supply (UPS) battery
- Flap Electronic Control Unit (FECU)
- GVIII uses fly-by-wire technology. How does this work?
Pilot inputs are read by a computer that in turn decides how to move control surfaces to best achieve what the pilot wants.
- How is trim accomplished?
Pitch and roll trim is accomplished by actuating switch mounted on sidestick; pedestal mounted PITCH TRIM switch is also used to control pitch.
- What’s the purpose of A/P DISC switch?
It disengages autopilot and stops runaway trim in all three axes.
- What’s the function of FLT CTRL RESET switch?
Used to reset flight control computers, sidesticks, and control surface actuators when directed by checklist.
- What effect does loss of one hydraulic system have on flight controls?
Loss of one spoiler pair.
- What are control laws?
Software in FCCs that translate electrical commands from cockpit control sensors and aircraft motion sensors (inertial/air data) into flight control surface commands.
- How many computers control the fly-by-wire flight control system?
Three (3) computers: two (2) flight control computers for normal operation and Backup Flight Control Unit in case both flight control computers fail.
- What’s the minimum number of FCC channels that can command all flight control surfaces on the aircraft.
One
- What’s the purpose of Backup Flight Control Unit (BFCU)?
It’s designed to provide what Gulfstream calls “get home capability” if both primary FCCs fail.
- What happens once the BFCU becomes active?
It communicates directly with EBHA remote electronics units (REUs) on separate backup data buses, and is active for duration of flight.
- Describe Electric Backup Hydraulic Actuator (EBHA).
It’s a special actuator with self-contained electric motor/pump and hydraulic reservoir.
- What type of sensor input is provided to FCCs?
Input from IRSs, AHRS, ADSs and radio altimeters.
- Describe AOA limiting feature.
In this mode, full stick input commands maximum nose angle-of-attack of 0.95.
- Which mode protects from surface flutter and separation that would occur greater than Vdive speed?
High speed protection
- What’s the auto-retract feature?
It retracts speed brakes at high power settings.
- What enhanced rudder feature occurs automatically following engine failure?
Application of rudder counters uncommanded thrust asymmetry.
- Name the four (4) flight control modes.
Normal, alternate, direct, and backup.
- When would flight control mode change from normal to alternate?
Loss of multiple air data or inertial sensors; may also revert to alternate mode if FCCs lose communication with HSCU.
- What happens if all four (4) FCC channels are invalid?
Flight control system reverts to direct mode.
- What happens if all four (4) FCC channels are unable to compute the control law?
Backup Flight Control Unit (BFCU) activates to provide “get home” capability.
- What term is used to describe the amplification, attenuation, boosting, or magnification that’s applied to forward signal to achieve desired aircraft response?
Gain
- Normal mode has four (4) primary operating sub modes. What are they?
On ground / takeoff stall protection, In flight, AOA limiting, and High speed protection.
- Describe how the flight control system operates in alternate mode.
Pitch, roll, and rudder pedal inputs are multiplied by set of fixed gains to command elevator, ailerons, roll spoilers, and rudder.