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28 Cards in this Set
- Front
- Back
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What is the power source for APU control, fire detection and protection?
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Battery Complex
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What is the minimum battery voltage?
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22 Volts
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How does the Battery Switch affect APU operation?
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The Battery Switch must be on and remain on to start and operate the APU. Turning off the Battery Switch with the APU running will cause it to shut down.
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When must the APU fire warning system be tested?
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on the first flight of each zulu day
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What is the maximum time allowed for the APU fire test?
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1 min.
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If the first APU fire test is unsuccessful, how long must you wait before another attempt?
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4 min.
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How do you fire test the APU if it's already running?
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First position the Auto Fire Shutdown Switch to OFF.
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What are the internal and external fire warning indications?
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a cockpit fire baell,
a red light in the Fire Handle, two master FIRE WARN lights on the glareshield, a flashing red light on the external panel, and an intermittent horn in the nose wheel well. |
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What is the APU start duty limit?
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1 min On, 4 min Off (1st three attempts)
1 min On, 30 min Off (after 4th start attempt) |
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When is an APU start or shutdown prohibited?
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during refueling operations
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What happens when the APU Master Switch is positioned to ON?
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The fuel shutoff valve opens and the APU light illuminates if AC power is available.
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How is fuel provided to the APU?
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Fuel can be either gravity fed from the No. 2 fuel tank or pressure fed from any tank through the crossfeed manifold.
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What happens when the APU Master Switch is positioned to START?
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The starter is energized, the APU CRANK light illuminates, and the DC ammeter shows a discharge.
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How soon must the APU EGT rise after starter engagement?
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15 seconds
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How soon must the APU CRANK light extinguish after EGT rise?
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30 seconds on most or 45 seconds on TAFCUs
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What are the voltage and frequency limitations for the APU and External Power?
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Voltage 115 +/-5
Frequency 405-410 (unloaded), 400 +/-8 (loaded) |
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When the generator Breaker is closed, where does power get connected to the electrical system?
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To the bus.
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What are the maximum amp loads for the APU and External Power?
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APU: 165 amps
External Power: 200 amps |
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What is the limitation before a pneumatic load?
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APU must stabilize for 1 Minute before a pneumatic load
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What is the name of the APU bleed valve? When does it open?
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The air load control valve opens when the APU is on speed and at least one Engine 2 Bleed Switch is open.
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When would you operate both packs by the APU?
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Operate both packs when the OAT is 25F or greater. Below 25F a single pack supplies warmer air than both packs.
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What happens if the flow multiplier overheats?
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The APU BLEED light illuminates and the air load control valve closes.
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What causes an automatic APU shutdown?
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Fire
Low Oil Pressure Overspeed |
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What the phase ones for an APU Fire?
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APU Fire Handle - PULL
APU Bottle Discharge Button - PUSH |
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What happens when the Fire Handle is pulled?
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It shuts off fuel, pneumatics, electrics, and arms the Bottle Discharge System
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What is the minimum APU fire bottle pressure?
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400 psi at 70F +/-3 psi per degree
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What happens when the APU EGT is too high?
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First the air load control valve closes to reduce the pneumatic load, then the fuel control unit reduces the fuel flow to slow down the APU
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What is the limitation prior to shutdown?
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Operate without a pneumatic load for at least 1 Min.
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