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 minutes minimum
Dual battery: 60 minutes 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) 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 asses any related info. Reference 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 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 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.
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.
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 ft
-With both busses off, only one start attempt is recommended. Multiple start attempts reduce standby power capacity.
