APU operation requires:
- APU fire switch on the overheat/fire panel must be IN
- APU fire control handle on the APU ground control panel must be IN
- Battery switch must be ON
The APU Electronics Control Unit (ECU) provides:
- Automatic shutdown protection for overspeed conditions, low oil pressure and high oil temperature.
- Automatic shutdown protection for APU fire, fuel control unit failure and EGT exceedance.
- Automatic control of APU speed through the electronic fuel unit.
The APU can supply both transfer busses:
On the ground or in the air.
APU cooling air:
Enters through a cooling air inlet above the APU exhaust outlet.
During APU operation, fuel is automatically heated to prevent icing?
True
Moving the battery switch to OFF automatically shuts down the APU?
On the ground or in the air.
The APU generator ammeter:
It is displayed in a digital readout format on the electrical panel.
It is recommennded to operate the APU for _____ before using it as a bleed air source.
2 full minute.
During the APU start cycle, the APU EGT indication may fluctuate from 0º to 1100º C prior to normal EGT rise and the LOW OIL PRESSURE light may cycle on and off several times. These indications have no adverse effect on starting the APU. It is not necessary to monitor EGT during start.
True.
Electrical power to start the APU comes from?
The No.1 Transfer bus if available. If AC power is not available, battery power is used.
If the APU is the only source of electrical power:
In flight, the galley busses are automatically shed
The APU switch OFF position has an automatic shutdown delay of:
60 seconds.
The APU is capable of supplying bleed air for both air conditioning packs:
On the ground or in the air.
The APU may be used as an electrical and pneumatic source simultaneously up to:
10 000 feet.
The APU start cycle may take up to:
120 seconds.
The APU may be used as a pneumatic source up to:
17 000 feet.
The APU will shutdown on the ground if:
The battery switch is placed to OFF.
When the APU is started using battery power only, there is a normal indication on the electrical metering panel that the APU generator has come online and is ready to be selected.
False.
If the APU GEN OFF BUS light fails to illuminate by the end of the start cycle:
The FAULT light illuminates.
In flight, if the APU is the only source of electrical power, all galley busses are automatically shed. If electrical load still exceeds design limits, both main busses automatically shed until the load is within design limits. On the ground, the APU attempts to carry a full electrical load. If an overload condition is sensed, the APU sheds galley busses first, and then both main busses until the load is within limits.
True.
The APU OVERSPEED light illuminated indicates:
- APU RPM limit has been exceeded, resulting in an automatic shutdown
- The overspeed shutdown protection feature has failed a self-test during a normal APU
shutdown.
Of the four lights located on the APU control panel, which light will NOT cause an automatic shutdown of the APU when it illuminates?
MAINT.
The APU starts, operates and can supply electrical power alone up to:
41,000 feet.
The blue APU MAINT light means that:
APU may be operated.
