APU

Question 1

What causes an automatic EMER. SHUTDOWN of the APU? When is this facility available?

Answer 1

• APU fire on the ground.

- Pressing the APU fire on the exterior panel.

Question 2

Why would the APU continue to run after being selected OFF?

Answer 2

If using APU bleed air, the APU keeps running for cooling period of 60sec.

Question 3

What happens if excessive EGT is sensed?

Answer 3

FAULT amber light, and a caution appears on ECAM. Followed by an automatic shutdown.

Question 4

AUTO SHUTDOWN is available during which phases of flight? And EMER SHUTDOWN (Fire)

Answer 4

1500’ – 800’

Question 5

What causes the FLAP to OPEN? What does the message FLAP OPEN mean exactly?

Answer 5

• When MASTER SW p/b is pressed.
• In green when APU air intake flap is fully open.
• In amber after 3min APU has been switched OFF.

Question 6

What happens if the START button is pressed immediately after the MASTER button is pressed?

Answer 6

• Green light comes on when N is >99.5% or 2sec after N reaches 95%
• APU can now be used for electrics and/or bleed

Question 7

What is the Maximum altitude for APU start?

Answer 7

• 41,000’ by electrical power
• 25,000’ by battery only
• 14,500’ on the ground

Question 8

What are the altitude limitations for the use of APU bleed & packs?

Answer 8

2 packs: 15,000’

1 pack: 22,500’

Question 9

What would you do if the SD showed LO OIL LVL?

Answer 9

• Refill the oil
• Low APU oil when the aircraft is on the ground, and the APU is not running.
• The APU may be started ad operated even if the LOW OIL LEVEL ECAM advisory is displayed.
• Maintenance action is required within next 10hrs of APU operation.

Question 10

What is the APU start limitation?

Answer 10

After 3 starter motor duty cycles, wait 60min before attempting 3 more cycles.

Question 11

One.

Answer 11

How many generators has the APU?

Question 12

The APU AVAIL appears in green when APU N is above 95%.

Answer 12

When does the APU AVAIL appear green?

Question 13

The basic element of the APU is a single-shaft gas turbine that delivers mechanical shaft power for driving the accessory gearbox (electrical generator starter etc.) and produces bleed air (engine starting and pneumatic supply).

Answer 13

What is the basic element of the APU?

Question 14

The APU will run for a cooling period because you have been using the APU bleed.

Answer 14

You switched the APU off. Why do you still have the APU AVAIL indications?

Question 15

The APU can be started at any altitude using normal aircraft electrical power.

Answer 15

The APU may be started up to which altitude?

Question 16

The ECB is a full-authority digital electronic controller that performs the bulk of the APU system logic for all modes of engine operation such as: Sequences the start and monitor it monitors speed and temperature monitors bleed air sequences the shutdown and controls the automatic shutdown.

Answer 16

What is the purpose of the Electronic Control Box (ECB)?

Question 17

APU fire warnings operate in the cockpit and in the nose gear bay the AVAIL light goes out the FAULT light comes on the APU shuts down and the APU fire extinguisher discharges.

Answer 17

What occurs in case of an APU fire with no crew in the cockpit?

Question 18

In flight the APU backs up the electrical system and the air conditioning and it can be used to start the engines.

Answer 18

What is the purpose of the APU in flight?

Question 19

The left fuel feed line supplies the APU. The required pressure is normally available from the tank pumps. If pressure is not available (batteries only or pumps off) the APU FUEL PUMP starts automatically. The ECB controls the fuel flow.

Answer 19

How does the APU fuel system work?

Question 20

When selected to OFF the APU generator field is de-energized.

Answer 20

What is the function of the APU GEN pushbutton located on the overhead electrical panel?

Question 21

The left fuel feed line supplies the APU normally via the tank pumps. The APU FUEL PUMP starts automatically if pressure is not available (batteries only or pumps off).

Answer 21

How does the fuel supply work for the APU?

Question 22

20,000 Feet

Answer 22

What is the highest altitude the APU can supply bleed air for engine start while providing electrical power?

Question 23

Electric

Answer 23

Does APU air or electric have priority?

Question 24

The APU is available to provide electrical power and/or bleed air

Answer 24

What does the green “AVAIL” light on the APU start pushbutton indicate?

Question 25

25,000 Feet

Answer 25

The APU generator can supply 100% electrical load to what altitude?

Question 26

25,000 Feet

Answer 26

What is the highest altitude the APU can supply bleed air to one pack while providing electrical power?

Question 27

15,000 Feet

Answer 27

What is the highest altitude the APU can supply bleed air to two packs while providing electrical power?

Question 28

- Electrically powers the APU system (Blue ON light in the pushbutton)- Electronic Control Box (ECB) performs a power up test- APU ECAM page appears (if EXT or ENG GEN AC power is available)- APU air intake flap opens- APU fuel isolation valve opens- APU fuel pump operates (if no tank pumps are on)

Answer 28

What happens when the APU MASTER sw pushbutton is selected ON?

Question 29

EXT PWR

Answer 29

With the APU green AVAIL light ON and the EXT PWR blue ON light illuminated, which system is powering the aircraft?

Question 30

- Blue "ON" light illuminates- When APU air intake flap opens the starter is energized- Ignition is turned ON 1.5 seconds after starter is energized- Starter is de-energized and ignition turned off at 55% N- Blue "ON" light in start button extinguishes- Green "AVAIL" light illuminates 2 seconds after 95% N or above 99.5% N- APU page disappears from the ECAM 10 seconds later

Answer 30

What happens when you push the APU START pushbutton?

Question 31

APU

Answer 31

With the APU green "AVAIL" light ON and the EXT PWR green "AVAIL" light on, with system is powering the aircraft?

Question 32

- APU BLEED pushbutton OFF- APU MASTER sw OFF- APU will cool down and then shut down

Answer 32

With the APU running and supplying bleed air, how do you shut it down?

Question 33

The APU will shut down

Answer 33

If a mechanic pressed the APU AUTO EXTING TEST pushbutton, what would occur?

Question 34

Yes, press the APU MASTER sw pushbutton

Answer 34

During the cool down cycle can you still use the APU?

Question 35

An ECB commanded auto shutdown of the APU has occurred

Answer 35

What does an amber "FAULT" light in the APU MASTER sw pushbutton indicate?