FCOM Flashcards
The basic element of the APU is a
single-shaft gas turbine that delivers mechanical shafts power for driving the accessory gearbox(electrical generator, starter) and produces bleed air
What is ECB
Electronic Control Box a full authority digital electronic controller
What ECB controlles
- Sequences the start and monitors it
- Monitors speed and temperature
- Monitors bleed air
- Sequences the shutdown
- Controls the automatic shutdown
Which fuel line supplies the APU
The let fuel feed line supplies the APU
What is IGV
Inlet Guide Vanes control bleed air flow, and a fuel-pressure-powered actuator positions the IGVs
What is APU speed
APU speed is always 100% except for air conditioning
The APU speed is 99% if the ambient temperature is
above -18’C or below 35’C
If the aircraft was using APU bleed air, the APU keeps running for cooling period of
60 Seconds
At what % the air inlet flap closes
7%
When AVAIL green light comes on
when N is above 99.5% or 2 seconds after N reaches 95%
APU N amber when
N >= 102%
APU N red when
N >= 107%
APU EGT amber when
EGT >= EGT max -33’C
APU EGT red when
EGT >= EGT max
Maximum EGT during start
1090’C
Maximum EGT with APU running
675’C
Will the APU shutdown automatically in the event of a fire in flight?
No, only on the ground.
In flight, the APU must be shut down manually and the agent manually discharged
What if the aircraft is on the ground and a APU fire is detected?
The APU will automatically shutdown and discharge agent 3 seconds after the fire warning.
A FAULT light with a squib DISCH light would indicate an auto shutdown for a fire
Will an APU fire detection system test shut the APU down?
No, but the APU auto extinguisher test will
What is the relationship between the APU bleed valve, the cross bleed valve and the engine bleed valves?
The position of the APU bleed valve controls the cross-bleed valve (If the switch is in AUTO) and the engine bleed valves. If the APU valve is opened, the cross-bleed valve is opened and engine valves are closed
Why does the green APU AVAIL light remain lighted and the APU generator continue to power the buses after the Master switch is selected OFF?
If the APU bleed valve has been open, the APU will continue to run at reduced RPM for up to two minutes to cool the turbine after Master switch is selected off
What are the APU operating limits?
Remember 15,20,25 and 39
The APU will operate 2 packs to 15,000
1 Pack to 20,000
Battery only APU starts arent allowed above 25,000
Ceiling of 39,000
20,000 is the top of the APU assisted air-start envelop for the engines (if airspeed is < 200kts)
What the cooling period between APU starts?
1 minute cooling period between start attempts and a 1 hour delay after the third start attempts
Can the APU be used with wing anti-ice on?
Yest, but only for electrical power
APU bleed valve should not be opened while using wing anti-ice
What does a FAULT light in the APU Bleed Switch indicate?
An APU bleed air leak. it will be accompanied by ECAM action to ensure the APU bleed valve is closed
What does the APU MASTER SW do?
When selected ON, the
- ECB power up test is initiated
- APU air inlet flap opens
- APU fuel isolation valve opens
- APU fuel pump runs
- ECAM APU page is displayed
APU fuel burn is
290 pounds per hour using both bleed air and the generator
LOW OIL LEVEL indicated the remaining oil quantity allows for normal operation of
approximately 10 hours
