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 drive
• Single stage impeller with a stage 2 axial-flow turbine
• Independent Oil system

Question 3

What controls the APU?

Answer 3

A dedicated FADEC

Question 4

What battery is used for 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 crossfeed valve

Question 6

What fuel pump is used for APU Start?

Answer 6

Batteries ‘ON’ only - DC fuel pump in right tank
AC powered airplane - ACMP 2
Right Engine running - Ejector fuel pump

Question 7

Will the APU shutdown automatically 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 for 1 minute)

Question 9

Can the APU shutdown be cancelled?

Answer 9

Yes, by moving the START switch back to ON beofre 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 shutdown immediately

Question 12

When will automatic shutdown of the APU occur?

Answer 12

Ground
-Over/Under speed
-FADEC Critical fault
-Fire
-EGT Overheat
High/Low oil pressure
-Sensor Fault
Flight
-Over/Under Speed
-FADEC critical fault

Question 13

Can the APU be started after a critical fault?

Answer 13

No