Electrical Flashcards
During cruise, you notice a BAT DISCHARGE light illuminated. When you check the battery voltage, what would you expect to see as normal?
22-30 volts
How long can a fully charged battery/batteries provide standby power?
Single battery: 30 mins minimum
Dual battery: 60 mins minimum
You receive a MASTER CAUTION/ELEC and
notice a DRIVE light illuminated on the overhead
panel. What has occurred and what should be your
next course of action?
Integrated drive generator (IDG) low oil pressure
caused by one of the following:
• IDG failure
• Engine shutdown
• IDG automatic disconnect due to high oil
temperature
• IDG disconnected through generator drive
DISCONNECT switch
Carefully assess any related information. Reference
the QRH for corrective action
Why does the QRH direct the generator drive
DISCONNECT switch to be placed in the Disconnect
position?
Disconnection reduces risk by preventing further
generator drive damage.
What does a SOURCE OFF light indicate?
No source has been manually selected to power the
related transfer bus, or the manually selected source has been disconnected
How is the transfer bus powered if the
respective IDG is disconnected?
If the BUS TRANSFER switch is in the AUTO
position, the source powering the opposite transfer
bus automatically picks up the unpowered transfer
bus through the bus tie breaker
While in cruise flight, you receive a MASTER
CAUTION/ELEC and notice a TR UNIT light
illuminated on the overhead panel. What could have
caused it?
• TR1 failed; or
• TR2 and TR3 failed
While in cruise flight, you receive a MASTER
CAUTION/ELEC and the following lights on the
overhead panel: TRANSFER BUS OFF (both),
SOURCE OFF (both), and GEN OFF BUS
(both). What provides power to essential systems
immediately?
Standby power system:
• The AC standby bus is powered from the
batteries via the static inverter.
• The DC standby bus, battery bus, hot battery
bus, and switched hot battery bus are
powered directly from the battery/batteries
What does the STANDBY PWR OFF light
indicate?
Illuminated (amber) – One or more of the following
buses are unpowered:
• AC standby bus
• DC standby bus
• Battery bus
With a LOSS OF BOTH ENGINE DRIVEN
GENERATORS, what other source of electrical power
may be available?
As the only power source, the APU generator can
meet electrical power requirements for all ground
conditions and most flight conditions
What considerations should you consider for
starting the APU in flight following a LOSS OF BOTH
ENGINE DRIVEN GENERATORS?
• APU start attempts are not recommended
above 25,000 feet
• With both busses off, only one start attempt is
recommended. Multiple start attempts
reduce standby power capacity
If the APU generator is the only remaining
source of AC power, can you continue to your
destination?
Only if the destination airport is the nearest suitable
airport to you, as directed by the AOM and QRH
