Electrical Flashcards
During cruise, you notice a BAT DISCHARGE light illuminated. When you check the batt voltage, what would you expect to see as normal?
22-30 volts
How long can a fully charged battery / batteries provide standby power?
Single: 30 min
Dual: 60 min
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?
IDG low oil press caused by 1 of:
- IDG fail
- Engine shutdown
- IDG auto disconnect for high oil temp
- IDG disconnected thru generator drive DISCONNECT switch
Assess any related info and reference QRH
Why does QRH direct the generator drive DISCONNECT switch to be placed in Disconnect position?
Reduces risk by preventing further IDG 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 BUS TRANSFER switch is in AUTO, the source powering the opposite transfer bus automatically picks up the unpowered bus through the bus tie breaker
While in cruise, you receive a MASTER CAUTION/ELEC and notice a TR UNIT light on the overhead panel. What could have caused it?
1) TR 1 failed, or
2) Both TR 2 and TR 3 failed
While in cruise, you receive a MC/ELEC and the following lights on the overhead panel:
- TRANSFER BUS OFF (both)
- SOURCE OFF (both)
- GEN OFF BUS (both)
What provides power to essential systems immediately?
Standby Power System:
- AC standby bus powered from batteries via static inverter
- DC standby bus, battery bus, hot battery bus, and switched hot battery bus are powered directly from the battery(ies)
What does the STANDBY PWR OFF light indicate?
Illuminated (amber) = 1 or more of following buses are unpowered:
- AC standby bus
- DC standby bus
- Battery bus
With a loss of both IDGs, what other source of electrical power may be available?
APU generator can meet all ground and most flight power requirements.
What should you consider for starting the APU in flight following loss of both IDGs?
APU start attempts are not recommended >25,000’
With both buses off, only 1 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 it is the nearest suitable airport, as directed by AOM and QRH.
