APU Flashcards
The APU supplies pneumatic power for:
Main engine Starts and Air Conditioning
The APU is equipped with a:
40 KVA generator
The APU ECU controls the APU during:
All phases of operation
The APU control system ensures priority is given to:
Electric loads
Pressurized fuel is supplied to the APU by the:
APU fuel pump
APU RPM is displayed on the
EICAS status page
APU “AVAIL” will illuminate at
99% RPM and two seconds later
The APU gauges ( RPM and EGT ) appear on EICAS when
APU POWER/FUEL switch/light is pressed in
“APU overspeed “ warning message is displayed when RPM exceeds
106%
Where is the APU located?
Tail cone
What is the purpose of the internal bypass valve
Allows the APU to continue to run if APU pump fails
APU rpm is displayed on the
EICAS status page
APU Bleed air is controlled by modulating
APU LVC
APU bleed pressure read out can be monitored on
EICAS “ECS” Synoptics page
APU intake door is located
Upper right hand side of aircraft
APU secondary function(s)
Supplies bleed air for air conditioning
Supplies air for main and engine starting
If APU door is open or unknown position airspeed is restricted to
220 KIAS
What is the max operating altitude for the APU?
41,000 feet
APU intake door is located:
Upper right-hand side of aircraft
An APU fire will be extinguished automatically when:
On the ground.
Max altitude for starting the APU.
37,000 feet.
What tank does the APU fuel pump draw from?
The left collector tank.
What batteries are required to start the APU in flight?
The APU battery and the main battery, both need a minimum of 22 volts.
How long does the APU need to warm up before RTL (ready to load for pneumatic loading).
60 seconds (99% RPM + 60 seconds)
What happens if you push the “ APU fire push” switch light???
1) arms squib
2) closes fuel SOV
3) closes LCV (load control valve) ( which is pressurized air control)
4) trips APU Generator (off)
The APU door position is displayed on the
EICAS status page
What is the LCV ?
Load Control Valve: Modulates to Control bleed air for air conditioning. ACSC
What happens if you push the PWR fuel switch light ?
It initiates the APU pre-start sequence.
Explain what your looking for on the APU pre-start check ?
Push the PWR FUEL switch light. ECU and Fuel pump activate. SOV opens. EICAS displays will show: APU IN BITE (for 5 seconds) DOOR OPEN (APU door open) RPM and EGT pop up on ED2
Where are the two APU remote cut-off switches located?
One is on the external services panel, the other is inside the APU compartment.
