Engine Systems and Fuel Management
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Questions and Answers

What is the primary function of the fuel return valve (FRV) in the heat management system?

  • To regulate the fuel flow to the combustion chamber
  • To cool the IDG oil by mixing hot return fuel with cold fuel (correct)
  • To increase fuel pressure before injection
  • To provide emergency fuel shutoff during overspeed conditions

    • How does the overspeed protection system function in the context of engine operation?

  • It routes all excess fuel directly to the combustion chamber
  • It activates the FADEC to control fuel flow during overspeed
  • It automatically shuts down the engine when overspeed occurs
  • It uses a governor and flywheel to mechanically manage fuel supply (correct)

    • What initiates the closure of the LP shutoff valve during an emergency shutdown?

  • Manual activation by the pilots via a switch
  • High engine temperature detection
  • Automatic regulation by the FADEC system
  • Pressing the fire push button (correct)

    • What is the role of the Full Authority Digital Engine Control (FADEC) in the engine system?

    <p>To directly manage thrust and optimize engine operation</p> Signup and view all the answers

    How is the power supply for each ECU in the FADEC system generated?

    <p>Through a three-phase permanent magnet alternator when engine N2 &gt; 15%</p> Signup and view all the answers

    What is the primary function of the fuel metering valve (FMV) in the engine fuel system?

    <p>To allow only metered fuel to pass to the nozzle</p> Signup and view all the answers

    Which component follows the high-pressure (HP) pump in the fuel system to ensure cleanliness of the fuel?

    <p>Wash screen filter</p> Signup and view all the answers

    How does the servo fuel contribute to the operation of the engine?

    <p>By actuating components such as the turbine clearance control</p> Signup and view all the answers

    What role does the hydro-mechanical unit (HMU) play in the fuel system?

    <p>It controls the delivery of fuel to the combustion chamber</p> Signup and view all the answers

    What is the purpose of the fuel heat exchanger in the fuel system?

    <p>To maintain optimal fuel viscosity and prevent ice formation</p> Signup and view all the answers

    Study Notes

    Fuel System Overview

    • Engine fuel system is essential for aircraft operation
    • System components are mostly installed on the left side of the fan compartment
    • It consists of a primary fuel system connected to the airframe and a secondary fuel system connected to the engine

    Main Functions of the Engine Fuel System

    • Function One: Provide fuel flow to combustion chamber and sustain combustion for engine thrust.
      • This involves fuel flow from the main tanks via the LP pump, heating, filtering, and pressurization by HP pump.
      • Metered fuel passes through the FMV to the nozzle and combustion chamber.
    • Function Two: Servo fuel (pressurized fuel) actuates compressor airflow control, turbine clearance control, and the FMV.
      • Servo fuel passes through a wash screen filter and servo fuel heater to remove ice particles.
      • Servo fuel drives the actuators (TBV, VSV, VBV, LPTACC, HPTACC) controlled by the ECU.
    • Function Three: Heat Management
      • Engine oil is cooled using the oil/fuel heat exchanger.
      • Integrated drive generator (IDG) oil is cooled using the IDG cooler
      • Bypass valve in the Hydro Mechanical Unit (HMU) redirects servo fuel to cool IDG oil.
      • Fuel return valve (FRV) is controlled by the ECU and uses servo fuel to mix hot return fuel with cold fuel to reduce thermal stress.

    Engine Protection

    • Overspeed Protection:
      • Mechanically controlled by governor, flywheel, and bypass valve.
      • Independent of FADEC.
      • Bypasses fuel to reduce fuel flow in case of increased speed.
      • FADEC receives a signal if N2 exceeds 45%.
    • Emergency Shutdown:
      • Fire push button closes the LP shutoff valve to shut down the engine.
    • High Pressure Shut Off Valve:
      • Supplied by pilots and controlled by pressure, it shuts off fuel to the combustion chamber.
    • Normal Shutdown:
      • The engine master switch turns off the LP and HP fuel shutoff valves and FRV.
      • ECU drives the FRV to close.

    FADEC System

    • Full Authority Digital Engine Control (FADEC): Regulates and schedules engine systems for thrust control and engine optimization.
      • Interfaces with aircraft signals.
    • FADEC System:
      • Consists of two channels of electronic control units (ECUs) per engine.
      • ECU is the FADEC computer, located on the engine fan case.
    • Power Supply:
      • ECUs are powered by a three-phase permanent magnet alternator when N2 > 15%.
      • The FADEC control alternator provides independent power to both ECU channels.

    FADEC System Functions

    - Power management control
- Variable Bleed Valves (VBVs) control
    • Other Components
      • Hydro Mechanical Unit (HMU)
      • Fuel Control Unit (FCU)
      • Fuel metering valve (FMV)
      • LP pump
      • HP pump
      • Oil/fuel heat exchanger

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    Description

    This quiz covers essential concepts related to engine systems, focusing on fuel management and control components. Participants will explore the functions of various valves, the Full Authority Digital Engine Control (FADEC), and the importance of cleanliness in the fuel system. Test your knowledge on how these elements work together to ensure optimal engine performance.

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