Podcast
Questions and Answers
What is the primary reason hydraulic power is used in high-speed aircraft flight control systems?
What is the primary reason hydraulic power is used in high-speed aircraft flight control systems?
- To reduce pilot workload by automating control inputs.
- To enhance or replace mechanical systems due to increased loads and effort required for operation. (correct)
- To simplify the design and maintenance of flight control systems.
- To decrease the overall weight of the aircraft.
Which of the following is a critical design consideration for hydraulic flight control systems?
Which of the following is a critical design consideration for hydraulic flight control systems?
- Reducing the complexity of hydraulic lines and connections.
- Minimizing the use of electronic components.
- Improving performance, response, stability, irreversibility, safety and reliability. (correct)
- Ensuring reversibility of control inputs for enhanced maneuverability.
What is a Power Control Unit (PCU) in the context of hydraulic flight control systems?
What is a Power Control Unit (PCU) in the context of hydraulic flight control systems?
- A mechanical linkage that connects the pilot's controls to the control surfaces.
- An actuator within hydraulic flight control systems. (correct)
- A unit that regulates the electrical power supply to the flight control system.
- A sensor that monitors the pressure and temperature of the hydraulic fluid.
What is the purpose of the 'self-nulling' feature in hydraulic flight control systems?
What is the purpose of the 'self-nulling' feature in hydraulic flight control systems?
In a servo boosted flight control system, what happens to the movement of the control system if the hydraulic system fails?
In a servo boosted flight control system, what happens to the movement of the control system if the hydraulic system fails?
Which of the following best describes a servo boosted flight control system?
Which of the following best describes a servo boosted flight control system?
What is the main function of the spool valve in the Bell 206 hydraulic servo operation?
What is the main function of the spool valve in the Bell 206 hydraulic servo operation?
What happens to the actuator valve, rod, and piston assembly once the desired position is reached in the Bell 206 hydraulic servo operation?
What happens to the actuator valve, rod, and piston assembly once the desired position is reached in the Bell 206 hydraulic servo operation?
What term describes the action of shutting off fluid flow into and out of the actuator once the desired position is reached in the Bell 206 hydraulic servo operation?
What term describes the action of shutting off fluid flow into and out of the actuator once the desired position is reached in the Bell 206 hydraulic servo operation?
In a hydro-mechanical flight control system, what is the relationship between mechanical control and hydraulic operation?
In a hydro-mechanical flight control system, what is the relationship between mechanical control and hydraulic operation?
What is a key characteristic of hydro-mechanical flight control systems regarding redundancy?
What is a key characteristic of hydro-mechanical flight control systems regarding redundancy?
What is the purpose of control tabs in the context of manual reversion in hydraulic flight control systems?
What is the purpose of control tabs in the context of manual reversion in hydraulic flight control systems?
What component is responsible for hydraulically moving the control surface in a hydro-mechanical flight control system?
What component is responsible for hydraulically moving the control surface in a hydro-mechanical flight control system?
What is a disadvantage of hydro-mechanical flight control systems?
What is a disadvantage of hydro-mechanical flight control systems?
In the CRJ hydraulic system, what is the purpose of the Ram Air Turbine (RAT)?
In the CRJ hydraulic system, what is the purpose of the Ram Air Turbine (RAT)?
What information does the Hydraulic Synoptic Page on the CRJ flight deck provide to the flight crew?
What information does the Hydraulic Synoptic Page on the CRJ flight deck provide to the flight crew?
On the CRJ, which overhead panel switches control the activation of the hydraulic systems?
On the CRJ, which overhead panel switches control the activation of the hydraulic systems?
In the CRJ 200 aileron control system, what is the function of the aileron damper?
In the CRJ 200 aileron control system, what is the function of the aileron damper?
What is the purpose of the roll disconnect handle in the CRJ 200 aileron control system?
What is the purpose of the roll disconnect handle in the CRJ 200 aileron control system?
What is the function of the Power Control Units (PCU) in the aileron control system?
What is the function of the Power Control Units (PCU) in the aileron control system?
In the CRJ elevator control system, what is the function of the 'stick pusher' assembly?
In the CRJ elevator control system, what is the function of the 'stick pusher' assembly?
What is the purpose of the load limiter in the CRJ elevator and rudder control systems?
What is the purpose of the load limiter in the CRJ elevator and rudder control systems?
What is the primary function of the yaw damper in the CRJ rudder control system?
What is the primary function of the yaw damper in the CRJ rudder control system?
What does the Elevator Position Indicator on the flight control display typically indicate?
What does the Elevator Position Indicator on the flight control display typically indicate?
What does the presence of Elevator Flutter Damper Outlines on the flight control display indicate?
What does the presence of Elevator Flutter Damper Outlines on the flight control display indicate?
In the CRJ 200 flight control system, how is manual reversion typically achieved in the event of a hydraulic failure affecting the ailerons?
In the CRJ 200 flight control system, how is manual reversion typically achieved in the event of a hydraulic failure affecting the ailerons?
Why is it important for aircraft hydraulic flight control systems to have multiple levels of redundancy?
Why is it important for aircraft hydraulic flight control systems to have multiple levels of redundancy?
Apart from servo boosted and hydro-mechanical, which of the following describes another type of hydraulic flight control system?
Apart from servo boosted and hydro-mechanical, which of the following describes another type of hydraulic flight control system?
Flashcards
Hydraulic Flight Control Systems
Hydraulic Flight Control Systems
Systems on high speed aircraft using hydraulic power for increased loads & efforts.
Servo Boosted Flight Controls
Servo Boosted Flight Controls
Standard mechanical system positions a control valve on hydraulic actuator for assistance.
Manual Reversion
Manual Reversion
Flight control system where movement is available even with hydraulic system failure.
Hydro-Mechanical Flight Controls
Hydro-Mechanical Flight Controls
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Self-Nulling
Self-Nulling
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Valve Assemble
Valve Assemble
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Ram Air Turbine (RAT)
Ram Air Turbine (RAT)
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Overhead Panel Switches
Overhead Panel Switches
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Hydraulic Lines/Components Disadvantages
Hydraulic Lines/Components Disadvantages
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Hydraulic Lines/Components Advantages
Hydraulic Lines/Components Advantages
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Study Notes
Hydraulic Flight Control Systems
- Hydraulic power can enhance or replace standard mechanical flight control systems for high-speed aircraft
- Hydraulic systems accommodate increased loads and effort required to operate such aircraft
- These systems enhance performance, response, stability, irreversibility, safety, and reliability
Types of Hydraulic Flight Control Systems
- Servo boosted systems
- Hydro-mechanical systems
- Fly-by-wire systems
Flight Control Actuators
- All hydraulic flight control system actuators, like Power Control Units (PCU), Electro-Hydraulic Servo Units (EHSU) or Servo Assemblies, include a built-in or individual valve assembly
- All valves must shut off or stop moving once they achieve the desired position
- This is known as "SELF-NULLING"
Mechanical System Without Hydraulics
- Control stick
- Quadrant
- Cable
- Push rod
- Elevator
Hydraulic Servo Operation in Bell 206
- Input from the pilot moves a spool valve at the end of actuator valve, rod, and piston assembly
- Hydraulic fluid flows in one side of the actuator and drains from the other
- The cylinder is stationary, promoting movement of the piston, rod, and valve assembly
- As the actuator valve, rod, and piston move in the desired direction, with no additional input it returns the valve to the neutral postion
- Fluid flow into and out of the actuator stops when it gets to its intended spot
Servo Boosted Systems
- It is essentially a standard mechanical system that positions a control valve on a hydraulic actuator
- Hydraulics "piggyback" on the mechanical system
- This concept is similar to automotive power steering systems, where steering is still possible without engine power, though more difficult
- With servo-boosted flight controls, movement is still available via manual reversion if the hydraulic system fails
Hydro-Mechanical Systems
- System is mechanically controlled, and hydraulically operated
- There is high dependency on hydraulic availability for operation
- High levels of redundancy with multiple systems/actuators and/or mechanical reversion using trim
- Control is achieved hydraulically through the mechanical positioning of a servo valve in an actuator
- These systems have very little or no reversibility
- Manual reversion often involves control tabs if a flight control surface experiences hydraulic failure
- High hydraulic redundancy can make manual reversion unnecessary
CRJ Hydraulic System and Redundancy
- CRJ Hydraulic System distributes power to different parts of the aircraft
- Hydraulic systems can be chosen individually via overhead panel switches
CRJ 200 Flight Control System
- Some components of the CRJ 200 Flight Control System
- Aileron
- Elevator
- Rudder
- Flight spoiler
- Horizontal Stabilizer
- Autopilot Servo Actuator
Flight Control Position Indication
- Flight Control Position on the navigation display indicates
- White scale represents position of flight control surface
- Aileron position -Top tick mark represents -24.6 degrees -Center tick mark represents 0 degrees -Bottom tick mark represents +20.8 degrees
- Elevator Position -Top tick mark represents -23.6 degrees -Center tick mark represents 0 degrees -Bottom tick mark represents +18.4 degrees
- Rudder position indicator -Left tick mark is 25/33 degrees -Center tick mark represents 0 degree -Right tick mark represents 25/33 degrees
CRJ Aileron Control System
- Aileron control system components
- Pilot Aileron control column
- Copilot aileron control column
- Primary and secondary mechanical stops
- Aileron cable circuits
- Aileron Power Control Units (PCU)
- Spoileron
Aileron Power Control Units (PCU)
- Include components like pressure ports, return ports, check valves, actuators, control valves, compensators, and relief valves.
Hydro-Mechanical: Advantages
- Increased redundancy and reliability
- Improved performance and handling characteristics
Hydro-Mechanical: Disadvantages
- Added weight and cost due to hydraulic lines and components
- Greater difficulty in troubleshooting
- Working with hydraulic fluid
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