Aircraft flight controls Flashcards
What is the function of the AFCS?
Combines with the flight director as an autopilot flight director system.
It interfaces with navigation systems for auto navigation on pre-programmed track and flight profiles.
Operating Principles of the AFCS?
Obtains navigation info from the IRS/GPS
Transmits that to servos (hydraulic or electric)
Obtains feedback of flight control position
Displays a/c attitude via flight director.
What are the AFCS inputs?
- ADC: speed and mach
- Encoding altimeter
- Rate gyro yaw dampner
- IRS heading
- FMS track
When do AFCS warnings occur?
Autopilot disengage
- When a pilot input is detected
- When the switch is activated
- If turbulence is sevre
- System Malfunction
Purpose of yaw dampeners?
Required to control dutch roll and limit pilot inputs as airspeed increases
Inputs for a yaw dampner?
- Primary control system
- IRS rate gyro
- ADC
- Gust pressure transducers for gust suppresion
- Rudder ratio charger
What is the automatic trim system?
Required to automatically adjust the pitch trim with autopilot engaged.
Auto trim principles?
- Confined to pitch trim
- Trim servomotor operated in parallel with A/P pitch control servo
- Limited to the half rate of manual trimming
- typically adjust tailplane incidence
What is a pitch trim servomotor?
- Separate hydraulic screw-type actuator
- Electric motor actuator
What is the STAB TRIM panel?
Provides pilots with two trim switches and provides ability to isolate 2 hydraulic systems.
What is a power control unit?
- A pilot/spool valve and the actuator is incorporated into the same unit, ie a power control unit
How is redundancy provided in powered flight controls?
Redundancy is in the form of multiple actuators and multiple hydraulic systems, there is also an emergency hydraulic system.
If there is complete hydraulic failure pilots main have to resort to manual reversion
Explain the powered flight control of fly by wire?
- Pilots controls and movements are transmitted electrically to the actuators, transmission is either with synchros or using digitals data bus
- Envelope control is maintained by computers.
What do control valves do in the fly by wire systems>
Direct fluid to the actuators into the actuator body.
