Study Guide APU

Question 1

What kind of APU is on the aircraft?

Answer 1

Sundstrand APS 2300

Question 2

Describe the APU

Answer 2

• Constant speed
• Single Stage impeller with a 2 stage axial flow turbine
• Independent oil system

Question 3

What controls the APU?

Answer 3

A dedicated FADEC

Question 4

What battery is used for the APU start?

Answer 4

• BATT 2 powers the starter

- BATT 1 powers the FADEC and EICAS for monitoring

Question 5

What is the fuel source for the APU?

Answer 5

• Right fuel tank.

- Left fuel tank through the cross feed.

Question 6

What fuel pump is used for APU start?

Answer 6

• Batteries only: DC fuel pump in right tank
• AC powered airplane: ACMP 2
• Right engine running: Ejector fuel pump

Question 7

Will the APU shutdown automtically if speed and acceleration rate isn’t reached in starting cycle time?

Answer 7

Yes

Question 8

What does moving the APU start switch to “OFF” do?

Answer 8

• Initiates normal APU shutdown
• 1 minute cool down
• No pneumatics (electrics only for 1 minute)

Question 9

Can the APU shutdown be cancelled?

Answer 9

Yes, by moving the START switch back to “ON” before the 1 minute cool down is over.

Question 10

How is the APU shutdown immediately?

Answer 10

• APU emergency stop button

- No 1 minute cool down period

Question 11

What will happen if batteries are turned off during the 1 minute cool down period?

Answer 11

-APU will shut down immediately

Question 12

When will automtiac shutdown of the APU occur?

Answer 12

Ground
  Overspeed
  Underspeed
  FADEC critical fault
  Fire
  Overheat
  Low oil pressure

Flight
Overspeed
Underspeed
FADEC critical fault

Question 13

Can the APU be started after a critical fault?

Answer 13

No