Auxiliary Power Unit Flashcards
What is the APU automatically controlled by?
ESU - Electronic Sequencing Unit
Can the APU bleed air be selcetd on with the engine bleeds on?
Yes, but they will only provide air if the engines are off otherwise the engine pressure exceeds the pressure output from the APU and engine bleed aire will be used
With the APU generator operating, which buses are powered?
All DC buses
How is the APU generator load monitored?
On DC Monitor, select GEN 2 and press Load Button on the APU panel
What is the indication of an APU loop fault?
Amber FAULT on APU panel iluminates, red CHECK FIRE DET light iluminates, red MASTER WARNING light iluminates
Will the APU operate in flight?
No
What are the starter limits?
one on, two off, one on, two off, one one thirty minutes off
How can the APU be shut down?
Remove Bleed Air and Generator then press APU PWR, or press the OVERSPEED TEST swithc or press the APU Fire Test button
How is APU fire protection provided?
Fire Sensing Loop and Fire Extinguishing Bottle
What are the indications of an APU fire?
FIRE Warning light, CHECK FIRE DET Warning light, MASTER WARNING light, APU Caution light,MASTER CAUTION Swithch light, BTL Advisory light iluminates and then goes out if bottle fires, APU FUEL VALVE CLOSED light, RUN Switch light off
What does the bottle light mean?
Indicates the extinguishing bottle is full when the system is armed, or system if being tested. Light goes out when the bottle is discharged
What does RBY OHT light mean?
Together with the APU caution light warns of an overheat in the rear bay
What does the APU caution light mean?
Indicates ESU has detected a fault and shuts down the APU, it will also come on during an APU fire test and during and overspeed test
What does a CHECK FIREDET warning light mean?
APU or engine fire detected, or during APU and Engine fire detection test, or a fault condition exists in engine fire loop or APU fire loop sensor
Where does the APU get its fuel?
From the #1 fuel system
