Engines and APU Flashcards
Max altitude for inflight APU start?
Max certified altitude
APU bleed air available up to what altitude?
17000ft
What two batteries are required for APU start?
APU battery and aircraft main battery
What fuel manifold provides fuel to APU?
Left fuel manifold
What is fuel pumps and power sources used for APU fuel? (2)
- Dedicated DC fuel pump if no AC power available and APU selector placed to on
- When AC power is available then uses left forward AC fuel pump regardless of if switch is turned on
How is APU unit protected from thermal shock on shutdown?
Time delay allowing for cooldown (shuts down straight away if APU bleed valve been closed for a while, if not it delays shutdown)
How cancel the APU shutdown if switch inadvertently moved to off (and run light still on)?
Momentarily move selector to start cancels the shutdown
What happens to APU on the ground if battery switch moved to off? Why need to be careful?
In flight?
APU will shutdown after cooldown period but no fire detection will be available prior to shutdown
In flight it will not shut down APU
What does amber FAULT light on APU mean and how reset the fault circuitry?
Fault is sensed and APU will shut down immediately
Reset by moving APU selector to OFF
When does APU Fault light momentarily come on for normal operations?
When APU fuel valve is not in commanded position so therefore during start and shutdown it comes on momentarily
Two main services provided by APU?
Electrics and pneumatics.
Where is the external APU control panel?
On nose wheel strut
If you see APU FUEL VALVE on EICAS should you attempt APU start?
No
If the APU experiences a FAULT on start can you attempt one restart?
Yes, provided fault light extinguishes when moved to OFF before attempting next start
What EGT should you wait for (motoring) during start before you put fuel on?
100deg C EGT
What % N3 does starter cut out occur?
47% N3
Light off should occur how long after fuel on during start?
20sec
N3 should be stabilised within how many seconds of start?
90sec
In AUTO position, when do ignitors come on? (2)
When engine anti ice is turned on or flaps out of the up position
Two occasions when continuous ignition is used?
- Heavy rain
- Severe turbulence
Difference between CONT and FLT positions on ignition switch?
Cont is continuous for just one ignitor, FLT is for both ignitors
Which inflight start envelopes are given?
The one closest to current flight level and next two down
What does x-bleed above N3 mean for inflight start?
Means x-bleed from live engine is required
What does l or R STARTER CUTOUT mean and actions?
Start valve has not closed at 47% N3, starter remains in GND, and starter must be moved manually to Auto
What must happen before you can move from reverse idle to full reverse thrust on the reverse levers?
Reversers must have moved to the open position
What two additional two things does moving the reverse thrust levers to reverse idle do on landing?
- Disengages auto throttle
2. Deploys the speedbrake
