AFS Topic 1 Module 1 DIFF
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Questions and Answers

What is the primary function of the swash plate in a hydraulic pump?

  • To protect the engine driven pump and hydraulic system
  • To draw fluid from the in port
  • To eject fluid into the out port
  • To regulate the amount of fluid expelled during each stroke (correct)

    • What happens to the shaft if the pump seizes or is prevented from rotating?

  • It increases in speed
  • It stops rotating
  • It breaks into two parts
  • It shears, preventing further damage (correct)

    • What is the purpose of quill drive shafts?

  • To reduce the pressure in the system
  • To increase the efficiency of the pump
  • To provide a sacrificial shear section (correct)
  • To filter out contaminants

    • What is the primary reason for using filters in a hydraulic system?

    <p>To filter out any particles that may enter the hydraulic system</p> Signup and view all the answers

    What is the consequence of not filtering out contaminants in a hydraulic system?

    <p>Damage to seals and cylinder walls, leading to internal leakage</p> Signup and view all the answers

    Where can filters be installed in a hydraulic system?

    <p>In the pressure and/or return lines</p> Signup and view all the answers

    What is the most commonly employed filter type for aircraft hydraulic systems?

    <p>Micronic filter</p> Signup and view all the answers

    When are filters typically inspected?

    <p>During routine servicing or trouble shooting</p> Signup and view all the answers

    What is the primary function of the reservoir in a hydraulic system?

    <p>To ensure a good supply of fluid to the pump</p> Signup and view all the answers

    What happens to the unused fluid in a hydraulic system?

    <p>It is stored in the reservoir</p> Signup and view all the answers

    What is the purpose of a standpipe in a hydraulic reservoir?

    <p>To draw emergency fluid from the bottom of the tank</p> Signup and view all the answers

    What is the result of thermal expansion in a hydraulic system?

    <p>The fluid volume increases</p> Signup and view all the answers

    What is the function of the power pump in a hydraulic system?

    <p>To force the fluid through the system</p> Signup and view all the answers

    Why is it necessary to provide a reserve of fluid in the reservoir?

    <p>All of the above</p> Signup and view all the answers

    What is a common feature of sophisticated hydraulic reservoir designs?

    <p>All of the above</p> Signup and view all the answers

    What is the primary function of a by-pass valve in a hydraulic system?

    <p>To allow unfiltered fluid to flow through the system in case of filter blockage</p> Signup and view all the answers

    What is the purpose of a differential pressure indicator in a hydraulic system?

    <p>To indicate when the filter is becoming blocked or when there is a differential pressure across the filter</p> Signup and view all the answers

    What is the purpose of an accumulator in a hydraulic system?

    <p>To store hydraulic fluid under pressure</p> Signup and view all the answers

    Why is unfiltered fluid better than no fluid in a hydraulic system?

    <p>Because it allows the system to continue operating</p> Signup and view all the answers

    What is the purpose of a manual indicator or warning light in some filters?

    <p>To indicate when the filter is blocked</p> Signup and view all the answers

    What is a characteristic of a double-acting balanced linear actuator?

    <p>The surface area on both sides of the piston is the same</p> Signup and view all the answers

    What is the purpose of a heat exchanger in a hydraulic system?

    <p>To cool the hydraulic fluid</p> Signup and view all the answers

    What type of actuator is used in a servo actuator in a flight control system?

    <p>Double-acting balanced linear actuator</p> Signup and view all the answers

    What is a typical application of a rotary actuator?

    <p>Retracting a light aircraft's landing gear</p> Signup and view all the answers

    Where are heat exchangers typically located in a hydraulic system?

    <p>In the return side of the hydraulic system</p> Signup and view all the answers

    What happens to the hydraulic fluid as the sub-systems operate?

    <p>It becomes heated</p> Signup and view all the answers

    What is the mechanism by which a rotary actuator operates?

    <p>The rack of teeth on the piston meshes with those in a pinion gear</p> Signup and view all the answers

    What is the primary purpose of the electro-hydraulic pump in the No. 1 system?

    <p>To pressurise the No. 1 user services during ground maintenance/testing</p> Signup and view all the answers

    Which of the following systems does the No. 2 system not supply?

    <p>Spoilers</p> Signup and view all the answers

    What is the purpose of the pressure relief valves in both systems?

    <p>To prevent over-pressurisation</p> Signup and view all the answers

    What is the function of the hand pump circuit in both systems?

    <p>To be used during ground maintenance/ground testing</p> Signup and view all the answers

    What is the primary function of the No. 1 system?

    <p>To supply the primary and secondary flying controls, and the general services</p> Signup and view all the answers

    What is the purpose of the engine driven pumps in the hydraulic system?

    <p>To pressurise the systems</p> Signup and view all the answers

    What is the function of the reservoirs in the hydraulic system?

    <p>To store the fluid</p> Signup and view all the answers

    What are the primary flying controls supplied by the No. 1 system?

    <p>Ailerons, elevator, and rudder</p> Signup and view all the answers

    What is the primary purpose of having an air space above the fluid level in a reservoir?

    <p>To accommodate thermal expansion of the fluid</p> Signup and view all the answers

    What is a characteristic of non-pressurised reservoirs?

    <p>They are used in aircraft that do not fly at high altitudes</p> Signup and view all the answers

    What is a consequence of not having a means of fluid replenishment in a reservoir?

    <p>The system will not be able to function</p> Signup and view all the answers

    Why are reservoirs not designed to be completely filled?

    <p>To allow for thermal expansion of the fluid</p> Signup and view all the answers

    What is a characteristic of reservoirs used in aircraft that fly at high altitudes?

    <p>They are pressurised</p> Signup and view all the answers

    What is the purpose of a dipstick on a filler cap?

    <p>To indicate the fluid level in the reservoir</p> Signup and view all the answers

    What is an advantage of using multiple reservoirs in an aircraft?

    <p>It allows for redundant systems to be used</p> Signup and view all the answers

    Why are non-pressurised reservoirs usually located at the highest point in the hydraulic system?

    <p>To prevent cavitation of the pump</p> Signup and view all the answers

    What happens when the pressure of the fluid in the sub-system builds up to an excess amount?

    <p>The relief valve opens and excess fluid is relieved.</p> Signup and view all the answers

    What is the purpose of a sequence valve in a hydraulic system?

    <p>To time the operation of certain hydraulic sub-systems in a proper sequence.</p> Signup and view all the answers

    What is the function of the pressure reducing valve?

    <p>To meter fluid to the sub-system.</p> Signup and view all the answers

    What happens to the shuttle assembly when the pressure of the fluid in the sub-system returns to an acceptable amount?

    <p>It returns to a balanced position.</p> Signup and view all the answers

    What is the function of the relief valve incorporated within the pressure reducing valve?

    <p>To relieve excess fluid from the system.</p> Signup and view all the answers

    What is the purpose of the sequence valve in the landing gear door sub-system?

    <p>To time the operation of the doors and gear in a proper sequence.</p> Signup and view all the answers

    What is the result when the shuttle assembly moves to the left?

    <p>A passage to a return is opened and excess fluid is relieved.</p> Signup and view all the answers

    What is the relationship between the pressure reducing valve and the relief valve?

    <p>The relief valve is incorporated within the pressure reducing valve.</p> Signup and view all the answers

    What is the primary function of a flow control valve in a hydraulic system?

    <p>To control the flow of fluid within the system</p> Signup and view all the answers

    What is the mechanism by which a check valve allows fluid to flow?

    <p>The fluid flow forces the cone back off the seat</p> Signup and view all the answers

    What is the purpose of a sequencing valve?

    <p>To sequence the operation of multiple hydraulic components</p> Signup and view all the answers

    What is the function of a relief valve in a hydraulic system?

    <p>To relieve excess pressure in the system</p> Signup and view all the answers

    What is the purpose of a shuttle valve?

    <p>To direct fluid to one of multiple paths</p> Signup and view all the answers

    What is the function of a restrictor valve?

    <p>To reduce the flow rate of fluid</p> Signup and view all the answers

    What is the purpose of a hydraulic fuse?

    <p>To act as a safety device in the event of a hydraulic failure</p> Signup and view all the answers

    What is the primary difference between a cone-type check valve and a ball-type check valve?

    <p>The shape of the valve</p> Signup and view all the answers

    What is the primary advantage of quick disconnect couplings in plumbing systems?

    <p>Reducing system fluid or gas loss</p> Signup and view all the answers

    What is the characteristic of screw type fittings?

    <p>Having a set of teeth protruding from the rim of one half of the coupling</p> Signup and view all the answers

    What is the purpose of the indicator pin in an Inst-O-Matic coupling?

    <p>To indicate that the coupling is fully engaged</p> Signup and view all the answers

    What is the function of the self-sealing valve in quick disconnect fittings?

    <p>To eliminate system fluid or gas loss</p> Signup and view all the answers

    What type of quick disconnect fittings are identified by three equally spaced indicating pins?

    <p>Quick threading</p> Signup and view all the answers

    What is the primary reason for the development of quick disconnect couplings?

    <p>To accommodate compact high-performance aircraft and aerospace ground equipment</p> Signup and view all the answers

    What is the mechanism by which an Inst-O-Matic coupling operates?

    <p>By operating a pullback sleeve to release a set of retaining ball bearings</p> Signup and view all the answers

    What is a common feature of quick disconnect couplings?

    <p>Providing ease and speed of connecting and disconnecting plumbing systems</p> Signup and view all the answers

    What is the purpose of the micro switch in the hydraulic reservoir?

    <p>To detect low fluid level and cut pressure supplies to secondary flight controls</p> Signup and view all the answers

    What is the function of the three flexible hoses connected to the engine driven pump?

    <p>To supply hydraulic fluid to the user services, suction from the reservoir, and return/case drain to the reservoir</p> Signup and view all the answers

    What is the characteristic of the engine driven pump?

    <p>It is a self-idling pump</p> Signup and view all the answers

    What is the purpose of the non-return valve in the hydraulic system?

    <p>To route the pressure output from the pump into the system</p> Signup and view all the answers

    What is the function of the system accumulator?

    <p>To store hydraulic fluid under pressure</p> Signup and view all the answers

    What is the location of the engine driven pump in the aircraft?

    <p>In the rear fuselage</p> Signup and view all the answers

    What is the purpose of the V-band clamp in the hydraulic system?

    <p>To secure the pump to the gearbox</p> Signup and view all the answers

    What is the purpose of the dial indicator on the hydraulic reservoir?

    <p>To provide a visual indication of the fluid level</p> Signup and view all the answers

    Study Notes

    Hydraulic Systems Overview

    • Hydraulic systems use fluid to transmit power and motion.
    • Fluid flows from the reservoir to the power pump, where it is forced through the system and eventually returns to the reservoir.

    Reservoir Functions

    • Ensure a good supply of fluid to the pump
    • Cater for ram displacement
    • Allow for thermal expansion
    • Provide a reserve of fluid to allow for small leakage
    • Provide a means of filling and checking the system
    • Allow a space for trapped air to settle out (in certain systems only)
    • Provide a means of cooling the fluid when the pump is not under demand
    • Provide an emergency supply of fluid to a hand pump (in certain systems only)

    Accumulators

    • The primary purpose of an accumulator is to store hydraulic fluid under pressure.
    • Accumulators store fluid that is not being used in the system, allowing for a reserve of fluid in case of an emergency.

    Filters

    • Hydraulic filters are required to filter out any particles that may enter the hydraulic system.
    • Filters can be installed in the pressure and/or return lines.
    • The most commonly employed filter type for aircraft hydraulic systems is the micronic filter.
    • A by-pass valve incorporated in the filter head will allow unfiltered fluid to flow over the top of the element in the event of filter element blockage.
    • Some filters have a manual indicator or a warning light to show when the filter is blocked.

    Actuators

    • Double-acting balanced actuators have the same surface area on both sides of the piston.
    • An example of a double-acting balanced actuator is a servo actuator in a flight control system.
    • Rotary actuators use a piston with a rack of teeth cut in its shaft, and the teeth mesh with those in a pinion gear that rotates as the piston moves left or right.
    • An example of the incorporation of a rotary actuator is when there is a requirement to retract a light aircraft's landing gear.

    Heat Exchangers

    • A heat exchanger is a component that transfers heat from one body to another.
    • Heat exchangers are used to cool the hydraulic fluid in the hydraulic system.
    • Heat exchangers are usually located in the return side of the hydraulic system.
    • Heat exchangers are available in various forms, including air cooled and fuel cooled heat exchangers.

    Hydraulic System Layout and Operation

    • Hydraulic power is used to operate the ailerons, spoilers, rudder, elevators, flaps, and slats, landing gear, nose wheel steering, and wheel brakes.
    • The GENFLY Trainer Hydraulic System has two independently pressurized systems, logically termed No.1 and No.2.
    • Fluid is stored in individual reservoirs and is pressurized by engine-driven pumps (EDPs).
    • Pressure relief valves are used in both systems to prevent over-pressurization, and filters are used to prevent contamination.
    • No. 1 system supplies the primary flying controls, secondary flying controls, and general services.
    • No. 2 system supplies a tandem supply to the primary and secondary flying controls supplied by No. 1 system, except the spoilers.

    Reservoirs

    • There are two basic types of reservoirs: in-line and integral, which can be further classified as pressurized or non-pressurized.
    • Reservoirs are not designed to be completely filled, but have an air space above the fluid level to allow for expansion of the fluid when heated during system operation.
    • Reservoirs provide a means of checking the fluid level and replenishing the fluid.
    • The quantity indicating method can be a dipstick on the filler cap or a remote indicating system to display the quantity on the aircraft's flight deck.
    • Replenishment is normally accomplished by adding fluid directly to the reservoir through a filler opening.

    Types of Reservoirs

    • Non-pressurized reservoirs are designed for aircraft that do not fly at high altitudes or engage in violent maneuvers, such as helicopters.
    • Non-pressurized reservoirs are usually located at the highest point in the hydraulic system, providing a head of fluid pressure to the hydraulic pumps at all times.
    • Pressurized reservoirs are used in aircraft that fly at high altitudes or engage in violent maneuvers.

    Valve Types

    • There are several types of valves used in hydraulic systems, including:
      • Flow control valves
      • Check valves
      • Relief valves
      • Selector valves
      • Pressure reducing valves
      • Sequencing valves
      • Restrictor valves
      • Hydraulic fuses
      • Shuttle valves

    Flow Control Valves

    • Flow control valves are used to control the flow of fluid within the system.
    • They can be fully opened to allow full flow or partially closed to restrict flow.

    Check Valves

    • Check valves are non-return valves that allow fluids to flow in one direction only.
    • They are used to prevent backflow in the system.

    Pressure Reducing Valves

    • Pressure reducing valves are used to meter fluid to a sub-system.
    • They are equipped with a relief valve that opens to relieve excess pressure in the sub-system.

    Sequence Valves

    • Sequence valves are used to time the operation of certain hydraulic sub-systems in a proper sequence.
    • They are used in applications such as landing gear door sub-systems.

    Quick Disconnect Couplings

    • Quick disconnect couplings are used to connect and disconnect plumbing systems quickly and easily.
    • There are three types of quick disconnect fittings: screw type, quick threading, and Inst-O-Matic.

    Engine Driven Pump (EDP)

    • The engine driven pump is located in the rear fuselage and is driven by the No.1 engine gearbox.
    • It is secured to the gearbox by a V-band clamp and connected to the hydraulic system by three flexible hoses with self-sealing quick release couplings.
    • The pump is the self-idling swashplate type, which automatically idles when the required operating pressure is developed.

    Accumulator

    • The system accumulator is located in the centre fuselage.
    • It consists of a cylinder and a freely floating separator piston.

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    Description

    This quiz covers the layout and operation of the hydraulic system on a BAE Hawk aircraft, including its components and functions. It is designed for aviation technical training.

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