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35 Cards in this Set
- Front
- Back
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Where is the APU located?
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In the unpressurized tail cone of the airplane.
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What happens if an APU operation limit is exceeded?
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If a limit is exceeded, the APU controller automatically shuts down the APU with no cool down cycle.
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If the APU fails to start where are the APU Start Cycle Restrictions listed?
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COM (Limitations).
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How many generators are driven by the APU?
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Two.
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What is the minimum number of APU generators required to operate the entire aircraft electrical system?
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One, but normally use two to power the synchronous bus.
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The APU produces enough bleed air to operate how many packs?
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Three.
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On aircraft 6301 - 6310, what fuel pump (AC power ON) supplies fuel to the APU?
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Aft boost pump in main tank 2.
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On aircraft 6311 and beyond, what fuel pump (AC power ON) supplies fuel to the APU?
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Main tank 2 and 3 aft boost pumps.
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How many batteries are required to operate the APU system?
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Two, the main and the APU batteries. (The battery switch must be ON).
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What happens if the APU controller detects an APU fire while operating?
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The APU automatically shuts down without a cool-down period. Unlike other aircraft the fire extinguisher must be manually activated.
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Can the APU be started in flight?
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No.
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From where can the APU be shut down?
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Flightdeck or the APU Ground Control panel in the right body gear wheel well.
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When does the APU DC fuel pump activate?
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If AC power is not available, the DC fuel pump in main tank 2 activates when the APU selector turns through the ON position during an APU start.
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After turning the APU selector to START, how do you know the APU is running?
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Primary EICAS Memo message APU RUNNING; APU generator AVAIL lights; duct pressures on Primary EICAS; Status page: APU EGT, N1, N2, OIL QTY.
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What does an APU generator AVAIL light indicate?
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APU generator output voltage and frequency are within normal limits.
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How is APU electrical power applied to the aircraft’s electrical system?
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First push APU GEN 1 switch to ON and verify AVAIL light changes to ON/flow bar. Then do the same procedure with APU GEN 2 switch.
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Can the two APU generators be paralleled?
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No, separated by the split system breaker (SSB).
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What does the APU EICAS Caution message indicate?
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Automatic fault shutdown with the APU selector ON, or APU N1 exceeds 95 percent with APU selector OFF.
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The APU EICAS Caution message is displayed. What does rotating the APU selector from ON to OFF, prior to re-starting the APU, accomplish?
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Resets fault circuitry.
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What allows both APU GEN 1 and APU GEN 2 to simultaneously power the synchronous bus?
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A split system breaker is installed to divide the synchronous bus into left (main busses 1 and 2) and right (main busses 3 and 4) sides.
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When does the APU bleed air valve open?
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With the APU Bleed switch ON, the valve opens when the APU is operating at the proper RPM (APU RUNNING EICAS Memo message displayed) and sufficient APU pneumatic pressure is available.
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Does the APU shut down immediately when OFF is selected?
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No. A cool down period (60 seconds) is required for all shutdowns except an APU fault or fire.
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If the APU is supplying pneumatic air, what happens when the APU is selected OFF?
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The APU bleed air valve closes and a time delayed cooling period occurs prior to APU shutdown.
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What is the purpose of the cool down cycle during a normal APU shutdown?
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To protect the APU from thermal shock.
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Will selecting the Battery switch OFF cause the APU to automatically shutdown?
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Yes, placing the Battery switch OFF will cause the APU to shut down with NO cool down cycle.
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What APU capabilities are lost if the Battery switch is selected OFF?
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APU fire detection, APU control, and cool down cycle.
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How is a normal APU shutdown initiated?
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Turn APU selector from ON to OFF position.
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How much time should elapse after selecting the APU to OFF before turning the Battery switch to OFF?
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A complete shutdown sequence with fire detection capability requires at least two minutes.
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What Secondary EICAS display allows the crew to watch the APU EGT, N1, N2 and OIL QTY?
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The STATUS page.
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When the APU shuts down due to an APU fire signal, will there be a cool down cycle?
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No.
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How is APU fault protection circuitry reset?
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By turning the APU selector to OFF except when shutdown is due to APU bleed duct leak.
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Is electrical power from the APU generators available during the cool down period?
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No. The First Officer should wait until all four IDGs are on line before selecting the APU selector OFF to initiate the BEFORE TAXI flow.
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Where is the APU Ground Control panel located?
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Right body gear wheel well.
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What APU control functions are available at the APU Ground Control panel?
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APU fire control and remote shutdown.
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If the APU selector is turned OFF, but the APU is still running in the cool down cycle, can the APU be restarted by re-selecting START/ON?
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No, even though it will appear that it is still running because it is in the cool down cycle.
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