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Frontier > A320 APU > Flashcards

A320 APU Flashcards

1
Q

What can be seen on the APU systems page?

A

-APU GEN
-Bleed air
-N speed
-EGT

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2
Q

What controls the APU?

A

The ECB (electronic control box)

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3
Q

What are the functions of the ECB

A

-Start and shut down sequencing
-APU N speed and EGT monitoring
-Bleed air output monitoring
-Fault monitoring, reporting, and APU auto-shutdown

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4
Q

How much APU use time is left if the LOW OIL LEVEL indication appears?

A

10 hours of APU operation. How much time is remaining can be checked by maintenance.

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5
Q

What happens if the APU senses low oil pressure?

A

No low pressure message is displayed. The ECB automatically shuts off the APU.

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6
Q

How does the APU get fuel?

A

The APU is directly connected to the Engine 1 feed line. Fuel flow is controlled by the ECB.

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7
Q

What would happen if you tried to start/run the APU but there’s no pressure in the engine 1 feed line?

A

The APU has a dedicated DC pump to provide fuel pressure to the APU. The ECB will automatically tell the pump to energize when no fuel pressure is detected. This pump will automatically turn off once fuel pressure is sensed in the line.

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8
Q

What would happen if regardless of APU pump operation, there wasn’t enough fuel pressure to run the APU?

A

A “FUEL LO PR” message would be displayed on the APU page and the APU automatically shuts down.

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9
Q

What powers the ECB and the APU starter motor?

A

The DC Battery Bus, which requires that the BAT pushbuttons are selected to auto (lights out). *once the APU is running the batteries are usually left in auto to allow for automatic fire protection should the APU fail.

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10
Q

How do you turn on the APU?

A

By first pressing the APU MASTER SW pushbutton, waiting a few seconds, then pressing the APU START pushbutton.

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11
Q

What does pressing the APU MASTER SW pushbutton do?

A

It controls the electronic power supply to the APU and turns on the ECB. Doing so illuminates the ON light on the APU MASTER SW pushbutton if AC power is established.

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12
Q

What happens after the ECB self-test?

A

1.) The air intake flap opens
2.) APU fuel isolation valve opens
3.) The integral APU fuel pump starts
4.) Fuel flows to the APU
5.) The APU ECAM page will be displayed

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13
Q

What does the APU START pushbutton do?

A

It engages the APU electric starter. The ON light will illuminate to let you know the APU is starting.

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14
Q

When does the APU “AVAIL” light appear? What does the light mean?

A

It appears shortly after 95% N speed or once it reaches 99.5% N speed. It means that APU bleed air and electrical power are now available for use.

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15
Q

What’s the normal method of shutting down the APU?

A

Pressing the APU MASTER SW pushbutton

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16
Q

If APU bleed air was used, what will happen when you shut off the APU?

A

It will continue running for 60-120 seconds at a reduced to N speed to provide a cooling period.

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17
Q

How long after turning the APU off do you need to wait before turning off the batteries during the securing aircraft checklist? Why?

A

You must wait 2 minutes after APU shutoff to turn off the batteries. This is because after APU shutoff it takes 2 minutes for the APU oil to return to the reservoir. If the batteries are turned off early then not all oil return and can lead to false low oil indications.

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18
Q

What happens if the APU flap fails to close after APU shutdown?

A

The green FLAP OPEN indication flashes

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19
Q

What’s the maximum APU N speed? What happens when the APU reaches this speed?

A

107%. When this happens the ECB automatically shuts off the APU.

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20
Q

At what N speed does the N speed gauge turn amber? Red?

A

102% for amber
107% for red

21
Q

What’s the APU max EGT?

A

It’s computed by the ECB (the exact value depends on N speed and other factors) and displayed on the APU EGT gauge as a red line. There are hard limitations as well on other flash cards.

22
Q

What’s the max EGT during APU start above 35,000’?

A

1,120ºC

23
Q

What’s the max EGT for APU start below 35,000’?

A

1,090ºC

24
Q

Whats the max EGT with the APU running?

A

675ºC

25
Q

What does the amber line on the APU EGT gauge signify?

A

33ºC below maximum EGT

26
Q

Why does the APU not require a constant speed drive?

A

Because the APU runs in a narrow band of RPM’s, unlike the engine driven generators.

27
Q

How can you manually turn off the APU generator?

A

By pressing the APU GEN pushbutton on the electrical overhead panel

28
Q

What can the APU bleed air be used for?

A

Engine start and air conditioning

29
Q

What does lights out on the APU GEN pushbutton mean? On the APU bleed pushbutton?

A

The APU electrics are in automatic mode when the APU GEN pushbutton is dark. This means that in the absence of another electrical source the APU generator will automatically be used.

Unlike the electrics, the APU Bleed air is not automatic and must be manually selected on. So when the APU bleed pushbutton is dark it means that APU bleed air is OFF.

30
Q

Can APU bleed air be used for anti-icing?

A

No, it is prohibited. (Probably. Because it isn’t hot enough to actually provide for anti-ice)

31
Q

What has priority, APU bleed air or engine bleed air?

A

APU bleed air is automatically prioritized over engine bleed air when it’s selected on.

32
Q

How would you perform a bleeds closed takeoff?

A

APU on

33
Q

What must be selected on in order to get the APU bleed air pressure to display instead of “xx”?

A

ADIRU 2 must be selected to NAV in order for the APU bleed air pressure to be displayed.

34
Q

WHat provides fire detection and protection to the APU?

A

A dual loop sensor and a single HALON bottle

35
Q

What needs to be on in order to get fire detection and protect for the APU?

A

The DC battery bus must be powered or no protection will be available. That’s why we usually leave the batteries in auto even once the APU is running.

36
Q

Can the APU fire test be performed on battery power only?

A

Yes, but the indications of a successful test are different. (Refer to the fire detection deck for a better description)

37
Q

Will testing the APU fire detection and protection while the APU is running shut off the APU?

A

Not normally. But the FOM Vol 2, 3.07 says to avoid pushing the fire detection button for more than 3 seconds to avoid it accidentally shutting down the APU and discharging the extinguisher bottle.

38
Q

What will happen if an APU fire is detected on the ground?

A

-APU automatically shuts down
-If the DC batter bus is powered (battery pushbuttons are in the auto position), the Halon extinguisher is automatically discharged
-The external horn sounds to alert ground personnel
-the APU FIRE light on the external power panel is illuminated

39
Q

What happens when an APU fire is detected in flight?

A

The ECB will NOT automatically shut down the APU. The APU must be selected off by the crew in accordance with emergency procedures.

40
Q

What are the indications of an automatic APU shutoff?

A

-A FAULT light on the APU MASTER SW pushbutton
-An ECAM message appears with an automatic shutdown caution

41
Q

Does an APU cooldown occur with an automatic shutdown?

A

No

42
Q

How is a manual, emergency APU shutoff performed?

A

-The flight crew pushing the APU FIRE pushbutton
-The ground crew pushing the APU SHUT OFF pushbutton on the exterior power panel

43
Q

What’s the maximum altitude for a battery start of the APU?

A

25,000’

44
Q

What’s the APU starter motor duty cycle?

A

3 consecutive start attempts. After the 3rd attempt a 60 minute cooldown period must be observed.

45
Q

When both the engines and the APU are on, which one provides bleed air to the packs?

A

The APU, assuming the APU bleed pushbutton is selected

46
Q

What do you need to do when you’re dispatched with one engine generator inoperative?

A

Run the APU for the whole flight as a backup electrical generator

47
Q

Maximum altitude for an engine generator start of the APU?

A

39,800’, the aircrafts maximum altitude.

48
Q

After an APU fire is detected, when will the extinguisher automatically discharge?

A

On the ground. In the air you’ll have to manually selected the bottle to discharge.

Frontier (43 decks)

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