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How is the APU panel set up for normal operations – Prior to starting
Aircraft Battery ON, DC start pump or right tank fuel pump ON
How do you start the APU and establish power on a cold dark airplane?
Aircraft Battery, DC start pump or right tank fuel pump.APU master switch to run and verify APU GEN OFF message appears on annunciator.Next move the APU master switch to the momentary start position and release to run.APU oil pressure low illuminates and should extinguish around 35% but up to 95%.Check the Freqs and Volts. APU GEN OFF extinguishes. Once AC power is established right AC pump can be selected on and DC Pump turned OFF.
What are the APU start limitations?
- 1st 90 sec on, 5 min off
- 2nd 90 sec ON, 5 min OFF
- 3rd 90 sec ON, 60 min OFF for cooling
The APU is started, but the APU generator is not online – What do you do?
Connect the APU Generator to the Buses
External Power is powering the electrical system prior to starting the APU. When the APU is started, which power source will power the electrical system with the APU bus switches on?
How does the Battery Switch affect APU operation?
Battery must be On for APU to operate. APU will shutdown if battery is turned OFF
Does the APU Master Switch shut down the APU immediately when turned OFF?
60 second cool down begins after that total shutdown happens.
What else shuts the APU down?
APU FIRE Switch to OFF & Agent ARM
What causes the APU to shut down automatically?
- A fire is sensed.
- The oil pressure falls below a predetermined value
- The turbine over speeds
Explain the doors panel on the APU?
- RAM DOOR is used for APU Start.
- -closes at 95%RPM and is a scoop underneath the fuselage.Non RAM Door opens after the RAM Door Closes Flush with the bottom of the fuselage.
Explain the memory items for an APU fire?
- APU Fire CONT Switch…. OFF & Agent ARM
- If APU FIRE annunciator remains illuminated:
- APU FIRE Agent 1 or 2 switch…..DISCH
- If APU FIRE annunciator remains illuminated after 30 Sec:Remaining APU FiRE Agent switch…..DISCH
Can you fight an APU fire during the pre-flight walk around?
- YES, through the APU ground Control Panel.
- Flip switch to APU SHutOFF, then DISCH the bottles.