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 two 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 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 crossfeed valve

Question 6

What fuel pump is used for APU start?

Answer 6

Batteries ‘ON’: Only DC fuel pump in right tnak
AC power: 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
one minute cool down
No pneumatics (electric for one minute)

Question 9

Can the APU shutdown be cancelled?

Answer 9

Yes, by moving start switch back to on

Question 10

How is the APU shut down immediately?

Answer 10

APU emergency stop button

No one 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:
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