APU Flashcards
APU Electrical power and bleed air avlb:
At 95%RPM + 7 seconds
APU ground safe mode (5)
IRS..................OFF Batteries.........OFF Emg. Lights....OFF APU Bleed......OFF APU Gen.........ON
APU will automatically shut down In the Air for? (7)
Overspeed, Under Speed, Failure to start, Failure to accelerate, Failure to light, Loss of ESU (FADEC) signal, ESU (FADEC) failure
APU automatically shut down On Ground (12)
Fire, Over temperature, Over speed, Under speed, Failure to start, Failure to accelerate, Failure to light, Loss of ESU (FADEC) signal, ESU (FADEC) failure, Loss of pressure, High oil temp, Loss of EGT
APU starter cutout
Models 11, 14
(11) 70% RPM
(14) 50% RPM
APU is supplied with electrical power by the:
- Central DC Bus
2. Essential DC Bus
If pressure too high in a bleed valve
Where does it escape?
Thru Anti-Surge valve
controlled by FADEC, ESU
What is APU?
Auxiliary Power Unit
- Single stage centrifugal compressor
- Reverse flow annular combustion chamber
- Single stage radial turbine
Differences between
APU: T-62T-40C11
APU: T-62T-40C14
(11) ESU (Electronic Sequence Unit)
(Flow limiting venture) Runs at 103%
(14) Fedec, Modulating bleed valve. Runs at 100%
When will APU shut down after fire detected?
On ground only 10 sec after the fire is detected
Where does APU gets fuel?
2, right fuel tank
What are the 2 air vents under the APU cowling?
- Left side is for the starter generator intake
* Right side is for APU compartment cooling
How does ESU (c11) test the overspeed protection?
When stop button is pressed, a signal is sent to the ESU to simulate an overspeed condition, which will shut down the APU
When does FADEC (c14) test the overspeed protection?
During FADEC power up
How many volts do you need for APU start?
Min 22 volts
