Auxiliary Power Unit (APU) Flashcards
How is the DC Starter-Generator cooled?
air cooled
How many volts and amps is the DC Starter-Generator?
28 volt DC, 400 amps
What provides the APU power for starting?
the DC Starter-Generator receives power from the right main 28 volt DC bus, which can be powered by either the main battery or external DC power
Where does the APU draw air for operation?
through a screened inlet duct on the right rear of the fuselage
How are APU exhaust gases ejected?
through an upward pointing outlet at the aft end of the tail cone
When does the APU fire detection and automatic extinguishing system monitor the APU and its compartment?
continuously when electrical power is supplied to the system (right essential 28 volt DC bus)
What does the APU PWR switchlight do?
arms the APU start circuits and opens the fuel shutoff valve, performs self test, closes fuel shutoff valve
When should the APU RUN light illuminate during start?
approximately 20 seconds after STARTER light extinguishes and APU is running at full operating speed
When does the APU WARN light illuminate?
the APU is running and the generator is not providing power (not selected on, generator malfunction)
What has a higher priority for the APU, generator or bleed air?
the generator has load priority over bleed air
Where is the APU fuel supplied from?
left wing collector bay through an APU fuel shutoff valve
How does the APU maintain fuel pressure?
a gravity fed, APU-driven fuel pump
What controls APU fuel scheduling?
automatically controlled by APU FADEC
When is the APU fuel shutoff valve automatically closed?
PWR switchlight pushed off APU fire EXTG switchlight pushed FIRE TEST button pushed Aircraft becomes airborne APU fault GEN OHT
How is the APU Starter-Generator cooled?
cooled by air entering through a metal mesh screen located at the bottom forward section of the tail cone and exiting through the tail cone right side door
