APU Flashcards
The APU is a self contained, single shaft, gas turbine engine with its own internal oil and fuel systems that provides the aircraft with….?
Pneumatic and electrical power
On the ground the APU supplies….?
Bleed Air for starting engines and air-conditioning, and
Electrical power
In flight the APU provides….?
- Back up to electrical system
- Back up to air conditioning
- Can be used to start engines
From where can the APU obtain power for starting?
- Aircraft batteries
- normal electrical system
- Ground service
Max altitude to assist engine start?
20 000ft
Max Altitude for air conditioning and pressurisation (single pack operation)?
a) YUD
B) all others
a) 22 500 ft (YUD)
b) 20 000 ft
Max Altitude for air conditioning (dual pack operation)
15 000ft
Is the use of APU bleed air for wing anti-ice permitted?
NO!
APU Battery Restart limit (Elec Emer Config)?
25 000ft
What is the APU operation and Normal restart envelope?
Can be operated and restarted throughout the aircrafts normal flight envelope.
Except starting APU on batteries (Elec Emer) limited to 25 000ft
Are the any limits on when the APU can supply electrical power?
No,
only limited to the aircrafts flight envelope
After 3 consecutive APU starts, Flight crew must wait ____mins before a new start attempt?
60mins
Max N speed
107%
Max EGT for starting?
a) YUD
b) others
a) YUD:
<35000ft -1090 deg C
>35000ft -1120 deg C
b) Others:
<25000ft -900 deg C
>25000ft -982 deg C
Max APU for running?
a) YUD
b) others
a) YUD:
675 deg C
b)
with 5 sec confirmation for shutdown: 682 deg C
for immediate shutdown:
700 - 742 deg C depending on ambient temperature
Is APU allowed to be start / shutdown during refuelling/defuelling?
Yes
If APU failed to start or following an automatic shutdown, during refuel / defuel. Is APU now allowed to be started?
No.
Do not start APU
What should be done with the APU if a fuel spill occurs?
Perform normal APU shutdown
The electronic control box (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 Start and Shutdown
- Monitors Start, Temp, Speed and Bleed air
- Controls automatic shutdown
What controls the Electric starter?
The ECB.
Electronic Control Box
When will the starter engage?
When the:
- air intake is fully open, and
- MASTER SW and START pb are ON
Which fuel feed line supplies the APU?
Left side
Which fuel pumps normally provide required pressure for APU?
Tank pumps
When would the tank pumps not be available to provide pressure for APU?
Batteries only, or
Pumps OFF
