Section 06 - APU Flashcards
Assume all bus switches in AUTO, APU engine running, AUX PWR switch ON, and BATT 1 & 2 switches ON. If the battery switches were selected to OFF, what would happen to the APU?
There would be no change in APU operation.
Below what altitude is the APU guaranteed to start no later than the second start attempt?
15,000ft
What would happen if APU air is selected on immediately after APU start?
The APU air would turn on immediately
Normal shutdown of the APU is accomplished by pushing what switch?
The APU OVSP-STOP switch
Selecting what APU switch to the off position will close the APU fuel shutoff valve immediately?
The APU Master switch
Prior to starting the APU, how can the position of the right engine lower cowl door be checked?
Visually, or using the indicator light on the APU panel (if installed)
What is the minimum fuel temperature required prior to APU start?
Above -30ºC
If necessary, how can the batteries be warmed most effectively prior to APU start?
Use an external AC power cart to charge and warm the batteries
What is the minimum acceptable battery voltage prior to APU start?
22 volts DC
After APU start, when will the APU generator power the electrical buses?
When the AUX PWR switch is selected ON
How is an APU start manually terminated?
Depress the APU OVSP-STOP switch, which trillers the over speed circuit, resulting in an immediate start abort
Would an APU DIRE message cause the APU to shutdown in-flight or on the ground?
Both on the ground and in-flight
Can the APU provide pressurization in flight?
No
If an APU start attempt on the battery power fails, how long a wait is required in order to try a second attempt?
No waiting is required until it fails a third attempt, then 1 hour
If an APU start attempt on external DC power fails, how long a wait is required in order to try a second attempt?
15 minutes
From where does the APU receive its fuel?
From the motive flow line to the left fuel ejector
How long is the recommended wait for turning on APU air after the APU is started?
2 minutes
After a normal or automatic shutdown of the APU, what must be done in order to re-start the APU
Cycle the APU master switch to OFF, then ON
What is indicated by the red “OIL PRESSURE LOW” light on the APU control panel?
The APU inlet door is fully open
During APU shutdown, when is it acceptable to turn off the APU master switch?
After the APU RPM is less than 10%
When is a specific APU inspection required in regard to normal operation of the APU?
An inspection is required if the APU is operated above 30,000 feet for more than 1 hour per flight, or on more than 5 occasions (not required for aircraft with the 36-150G APU)
What is the maximum permissible APU EGT?
- Up to 60% RPM during the start: 988°C
- 60% to 100% during the start: 821 °C to 732°C (linear decrease)
- Running: 732°C
What is the maximum permissible APU EGT {36-150G)?
- Up to 50% RPM during the start: 973°C
- 51 % to 87% during the start: 973°C to 732°C (linear decrease)
- 87% to 100% during the start: 732°C
- Running: 732°C
What are the APU starting limits?
- With aircraft batteries: 30 seconds per start, 3 attempts, then 20 minutes cool down
- With external DC power: 15 seconds per start, 2 attempts, then 20 minutes cool down
The APU has just been started, Five minutes later, a red “APU FIRE” CAS message illuminates. The fire warning bell is also ringing. Describe the emergency procedure associated with this condition.
- APU Overspeed Test Button - PRESS
- APU Master Switch - OFF
- APU Fire Extinguisher - PRESS
- After 1 minute, APU Fire Test - PRESS
The APU “HIGH OIL TEMP” light has illuminated. Describe the abnormal procedures associated with this condition.
No action is required. The APU will initiate an automatic shutdown
