Auxiliary Power Unit (APU) Operation Quiz
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Questions and Answers

Where is the APU located in an aircraft?

  • In the unpressurized tail cone (correct)
  • Above the passenger cabin
  • Near the main landing gear
  • In the cockpit area

    • What powers the APU starter?

  • Pneumatic power from engines
  • AC power
  • Hydraulic power
  • DC powered electric starting motor (correct)

    • Which function does the APU NOT perform?

  • Serving as the primary engine power source (correct)
  • Providing bleeds air for air conditioning packs
  • Supplying electrical power to the aircraft system
  • Operating engine starters

    • At what altitude is the APU limited to supply only one pack?

    <p>From 15,000 to 20,000 feet</p> Signup and view all the answers

    What is provided by the APU during takeoff to avoid thrust reduction?

    <p>Bleed air for environmental control packs</p> Signup and view all the answers

    What component provides automatic control of the APU?

    <p>Electronic Control Box (ECB)</p> Signup and view all the answers

    What is the maximum aircraft altitude that the APU generator can provide electrical power?

    <p>FL390</p> Signup and view all the answers

    Which of these is a function of the APU during flight?

    <p>Supplying bleed air for engine operation</p> Signup and view all the answers

    Which condition must be met for the APU starter to activate?

    <p>The APU Master switch and Start pushbutton must both be ON.</p> Signup and view all the answers

    What is the maximum altitude for an in-flight battery start of the APU?

    <p>25,000 feet</p> Signup and view all the answers

    Under what condition will the APU fuel flow be controlled by the ECB?

    <p>During normal operation with engine generator power.</p> Signup and view all the answers

    What happens to the APU air intake flap when the APU is shut down?

    <p>It closes automatically.</p> Signup and view all the answers

    Where are the main APU controls located?

    <p>On the overhead panel of the flight deck.</p> Signup and view all the answers

    Which switch must be ON for the APU generator to operate?

    <p>APU GEN switch</p> Signup and view all the answers

    How is the APU fire extinguisher deployed in the event of a fire?

    <p>It is automatically discharged on the ground.</p> Signup and view all the answers

    What indicator appears on the ECAM APU page to confirm the flap is fully open?

    <p>green FLAP OPEN</p> Signup and view all the answers

    What will occur if the APU start button is pressed before the flap is open?

    <p>The start sequence will pause until the flap is open.</p> Signup and view all the answers

    What safety feature is provided for ground operation with the APU?

    <p>The APU can operate without crew supervision.</p> Signup and view all the answers

    What does the APU BLEED pushbutton switch control when the APU is running?

    <p>Supplies APU bleed air to the pneumatic system.</p> Signup and view all the answers

    What is displayed on the ECAM APU page during APU operation?

    <p>APU bleed air configuration and APU generator operation.</p> Signup and view all the answers

    What will prompt an advisory on the ECAM APU system display page?

    <p>Low oil quantity.</p> Signup and view all the answers

    What happens when the APU reaches approximately 95% N?

    <p>The blue ON light in the APU START pushbutton extinguishes.</p> Signup and view all the answers

    What is the purpose of the check valve installed in the output of APU bleed air?

    <p>To prevent backpressure from external sources.</p> Signup and view all the answers

    When should the APU bleed air typically be turned OFF before shutting down the APU?

    <p>Immediately after engine start.</p> Signup and view all the answers

    What indication remains visible during the APU cool-down cycle?

    <p>APU AVAIL memo.</p> Signup and view all the answers

    If the APU bleed was not in use prior to turning the APU MASTER switch to OFF, what will happen?

    <p>The APU will immediately shut down.</p> Signup and view all the answers

    What should be observed on the ECAM APU page as soon as the APU generator is online?

    <p>All generator displays will show normal parameters.</p> Signup and view all the answers

    What effect does pressing the APU BLEED switch to ON have on the ECAM APU page?

    <p>It replaces the APU AVAIL with APU BLEED.</p> Signup and view all the answers

    What happens if you select the APU MASTER switch back to ON during the cool-down cycle?

    <p>The cool-down cycle will be interrupted.</p> Signup and view all the answers

    How long does the APU typically continue to operate for proper cooling after bleed air use?

    <p>60 to 120 seconds.</p> Signup and view all the answers

    Why is it important to monitor the ECAM page after turning off external power?

    <p>To observe APU generator readiness.</p> Signup and view all the answers

    What occurs on the ECAM APU page when the APU bleed air switch is OFF?

    <p>The APU BLEED memo changes back to APU AVAIL.</p> Signup and view all the answers

    Study Notes

    Auxiliary Power Unit (APU) Operation

    • Location: The APU is situated in the unpressurized tail cone, providing self-contained electric and pneumatic power.
    • Self-Sufficiency: It is designed to operate independently without external ground support equipment.
    • Power Generation: A single-spool gas turbine engine, driving an accessory gearbox for electrical and pneumatic outputs.
    • Electrical Provision: Powers the aircraft electrical system, supporting operations like engine starting.
    • Pneumatic Supply (Bleed Air): Provides air for air conditioning packs and engine starters, both on the ground and in flight.

    APU Operation During Ground Operations

    • Electrical Power Source: Can utilize an engine-driven generator or an external power source.
    • Start Sequence (Normal Power):
      • Select the APU MASTER switch.
      • Observe the ECAM APU page display.
      • Watch for the air inlet flap to open (FLAP OPEN).
      • Press the APU START pushbutton.
      • Monitor RPM, EGT, and the AVAIL light.
      • Turn OFF external power to empower the APU generator.
      • Select the APU BLEED switch if needed.

    APU Operation During Flight Operations

    • Maximum Electrical Power: The APU generator can deliver power until approximately FL390.
    • Bleed Air Usage in Flight:
      • Maximum operation for 2 packs up to 15,000 feet, limited to 1 pack between 15,000 and 20,000ft. Actual altitudes dependent on ISA temps. Specific details in the flight manual.
    • Electrical Power during Flight: Can provide power to one side of the aircraft's electrical system if an engine generator is inoperative.
    • Start Sequence (Battery Power): Similar sequence as in ground start, but only the battery powers the APU. Only ECAM page is not available. Also, no exterior power options available.
      • APU MASTER switch on.
      • Observe the START light.
      • Watch APU for RPM at 95%.
      • Monitor for APU AVAIL light.

    APU Shutdown

    • Automatic Cool-Down Cycle: APU will continue running for a period of 60-120 seconds if the bleed air was on before shutdown for complete cooling.
    • Bleed Air Consideration: APU bleed is normally turned off before shutting down the APU.
    • Manual Selection for Shutdown: Turn the APU MASTER switch OFF. If there is no bleed air, the APU shuts down immediately and the display indicates flap closed.

    APU Controls

    • Flight Deck Panel: Includes APU MASTER, START, BLEED, GEN, and FIRE controls/indicators.
    • External Nose Gear: APU Shut-Off button and FIRE warning light.

    APU Indicators and Displays

    • ECAM APU Page: Automatically displayed after start, showing EGT, Compressor RPM, bleed air configuration, generator operation status, and flap position.
    • Warnings and Abnormal Situations: Oil quantity low. Alerts are displayed on the ECAM APU page.
    • E/WD Display: Provides additional information (AVAIL, BLEED).

    APU Safety on the Ground

    • Automatic Operation: Ground Operation is mostly unsupervised once started.
    • Fire Protection: Equipped with fire detection, warnings, and automatic shutdown, and automatic fire extinguisher discharge (on the ground).

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    Description

    Test your knowledge on the operation of the Auxiliary Power Unit (APU) in aircraft. This quiz covers the APU's functions, location, self-sufficiency, and procedures during ground operations. Perfect for aviation students and professionals looking to deepen their understanding of APU systems.

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