APU

Question 1

What does the gas turbine auxiliary power unit (APU) provide?
A. AC and DC electrical power
B. AC electrical power and bleed air
C. DC electrical power and bleed air
D. AC electrical power and failure detection

Answer 1

B

Question 2

How is the oil quantity in the APU oil sump maintained at optimal level?
A. The crew can service APU oil through the oil replenishment system or manually through the gravity oil fill port.
B. The oil replenishment system functions automatically without any crew involvement .
C. The oil sump can be only refilled by maintenance personnel using a pressure oil fill port.
D. The APU oil does not deplete.

Answer 2

A

Question 3

What fuel tank normally supplies the APU?
A. Aft fuel tank
B. APU fuel tank
C. Left wing collector tank
D. Right wing collector tank

Answer 3

D

Question 4

What system does NOT use APU bleed air?

A. Wing anti-ice system(WAI)
B. Main engine starting(MES)
C. Environmental control system (ECS)
D. Fuel tank inerting system (FTIS)

Answer 4

A

Question 5

If a high oil temperature condition occurs while the airplane is in flight:
A. the APU shuts down automatically.
B. the APU remains in operation.
C. the APU shuts down after 60 seconds.
D. an APU FAULT message is shown on the EICAS.

Answer 5

B

Question 6

What happens first in the normal shutdown sequence initiated by selecting the APU rotary switch to the OFF position?
A. The APU shutdown occurs immediately.
B. The APU door opens fully.
C. There is a 90-second cool down period before the actual shutdown occurs.
D. There is a 1-minute cool down period before the actual shutdown occurs.

Answer 6

D

Question 7

APU name

Answer 7

SPU300

Question 8

APU provides :
1 Bleed Air cooling & heating up to
2 Bleed Air for Engine Start up to
3 Bleed Air for fuel tank inserting up to
4 Electric Power

Answer 8

25 000 ft

23 000 ft

25 000 ft

60 KVA - 45 000 ft and 40 KVA till 51 000 ft

Question 9

Where is located and how is operated the APU door

Answer 9

Located on the upper right side of the fuselage
Electrically actuated , controlled by FADEC

Question 10

What is the maximum RPM for starting the APU or for windmilling

Answer 10

7% RPM

Question 11

When can the APU door angle be seen

Answer 11

If a door fault is sensed by the FADEC the APU door angle is displayed in Amber on EICAS page and on Service synoptic and the APU DOOR FAIL CAS message comes on

Question 12

When does an automatic APU shutdown occurs due to door position?

Answer 12

On GROUND if the the door is NOT fully opened
IN FLIGHT if the door is NOT in the position commanded by the FADEC and if the door is opened less the 45 degrees

Question 13

How many speed sensors are in the APU

Answer 13

2

Question 14

When is the FADEC commanding an automated shutdown due to Speed sensors?

Answer 14

1 When an overspeed is sensed by the FADEC
2 With the Failure of both sensors on ground and inflight

Question 15

How many Temp sensors are?

Answer 15

2

Question 16

What are the temp sensors used for?

Answer 16

1 Provides Temp info to FADEC for turbine monitor
2 Fuel schedule trim
3 Bleed Control Valve - BCL, modulation

Question 17

Failure of the Temp sensors

Answer 17

1 On Ground - automatic shutdown
2 In FLIGHT - message APU EGT SENSORS amber CAS comes on

Question 18

Primary components of the APU

Answer 18

1 Wet Oil Sump
2 Gear driven pressure / Scavenge Pump
3 Oil pressure, Temperature & Quantity Sensors
4 Fuel / Oils / Air Heat Exchanger

Question 19

What happens If Oil pressure drops bellow a certain value ON GROUND

Answer 19

1 APU shutdown occurs and
2 APU OIL LO PRESS amber message CAS. Then
3 APU SHUTDOWN blue message CAS

Question 20

What happens If Oil pressure drops bellow a certain value IN FLIGHT

Answer 20

1 APU OIL LO PRESS amber CAS on
2 Protective shutdown is NOT initiated

Question 21

What happens If Oil Temp rises above a certain value ON GROUND

Answer 21

1 APU OIL HI TEMP amber CAS replaced by
2 APU SHUTDOWN blue message CAS

Question 22

What happens If Oil Temp rises above a certain value IN FLIGHT

Answer 22

1 APU OIL HI TEMP amber CAS comes on
2 Protective shutdown is NOT initiated

Question 23

What is the total capacity of the APU OIL SUMP

Answer 23

3.7 quarts (3.6L)

Question 24

At what value the APU LOW OIL QTY come on

Answer 24

3.4 Qaurts (3.3L)
Even if the real quantity is bellow 3.4 Q the lowest value transmitted by FADEC is 3.4
When APU is replenished the value remain at 3.4 Q until the entire gear box is filled up then rises to the 3.7 Q indication

Question 25

When is permitted to service the APU reservoir ?

Answer 25

10 min after shutting down the APU and above -12C

Question 26

Under which condition will the full authority digital engine control (FADEC) command an automatic auxiliary power unit (APU) shutdown?
A. High oil temperature in flight
B. Low oil temperature in flight
C. Failure of both exhaust gas temperature (EGT) sensors in flight
D. Loss of overspeed protection on ground or in flight

Answer 26

D