777 AIRCRAFT MAINTENANCE MANUAL
AUXILIARY POWER SYSTEM -APU GENERATOR
EFFECTIVITY BEJ ALL 49-00-00
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D633W101-BEJ Jan 05/2002
AUXILIARY POWER SYSTEM -CONTROLS
APU Flight Deck Controls
These control the APU from the flight deck:
*
The APU selector
*
The APU maintenance switch
*
The APU fire switch.
You use the APU selector on the electrical panel (P5) to start and shut down the APU.
You use the APU maintenance switch on the P61 overhead maintenance panel to supply power to the APUC when the APU selector is OFF. This permits the APUC to show APU indications on the status and maintenance page formats.
You can shutdown the APU with the APU fire switch on the cargo fire/engine control panel (P5).
Auxiliary Shutdown Control Switch
You can shutdown the APU from outside the airplane with the APU fire shutdown switch. This switch is on the P40 service and APU shutdown panel on the nose landing gear strut.
EFFECTIVITY BEJ ALL 49-00-00
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D633W101-BEJ Sep 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
AUXILIARY POWER SYSTEM -CONTROLS
EFFECTIVITY BEJ ALL 49-00-00
Page 15
D633W101-BEJ Jan 05/2002
AUXILIARY POWER SYSTEM -OPERATION
Pre-Start
The left main fuel tank must contain a minimum of 950 pounds (430 kg) of fuel to start and operate the APU for one hour.
The battery switch on the electrical panel (P5) must be in the ON position before you can start the APU.
The APU GEN switch on the electrical panel should be in the ON position before you start the APU.
If electrical power is available, you should do a test of the fire detection system before you start the APU. You do this test with the fire/OVHT test switch on the cargo fire panel (P5).
If electrical power is available, you should also do a check of the APU oil quantity. You can see the APU oil quantity on the status display or on the APU maintenance page.
Start
You can start the APU with the electric starter motor or the air turbine starter. If pneumatic power is available, the APUC will normally select the air turbine starter to start the APU.
The APU BLEED switch on the bleed air/pressurization Panel (P5) must be in the AUTO position to do a pneumatic start.
You move the APU selector from OFF to START to start the APU. After you move the APU selector to START, you hold the APU selector at the START position for one second and manually move the APU selector to ON. The start is automatic. It is recommended that you do not release the APU selector from the START position to the ON position. Damage to the internal contacts in the APU selector can cause an APU no start problem.
The APU FAULT light below the APU selector will flash one time during APU start. The APU RUNNING memo message shows on the EICAS engine primary format when the APU speed is greater than 95 percent RPM.
Normal Operation
The APU operates at 100 percent RPM. The status page shows EGT, RPM, and oil system data.
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AUXILIARY POWER SYSTEM -OPERATION
BEJ 001-004
Normal Shutdown
You move the APU selector to OFF to shutdown the APU. The APU stays at 100 percent RPM for 15 seconds after you move the selector. The APU then decreases speed from 100 percent RPM to 70 percent RPM for 10 seconds (deceleration rate of 3 percent RPM for each second in a 10 second interval) and stays at 70 percent RPM for 80 seonds. The memo message APU COOLDOWN shows during this period. After the 105 second cooldown period, the APU then decreases speed from 70 percent RPM to 0 percent RPM (APU shutdown). The APU FAULT light flashes one time during APU shutdown.
BEJ 005-999
Normal Shutdown
You move the APU selector to OFF to shutdown the APU. The APU stays at 100 percent RPM for 15 seconds after you move the selector. The APU then decreases speed from 100 percent RPM to 84.8 percent RPM for 8 seconds (deceleration rate of 1.9 percent RPM for each second in a 8 second interval). The APU then decreases speed from 84.8 percent RPM to 70 percent RPM for 82 seconds (deceleration rate of approximately 0.2 percent RPM for each second in a 82 second interval). The memo message APU COOLDOWN shows during this period. After the 105 second cooldown period, the APU then decreases speed from 70 percent RPM to 0 percent RPM (APU shutdown). The APU FAULT light flashes one time during APU shutdown.
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