APU & Electrical System Flashcards
When does the EICAS memo message APU RUNNING display?
When APU selector is ON and APU N1 RPM exceeds 95% N1
Is electrical power available from the APU in flight?
NO
Can the APU be operated in flight?
Yes, when left running for takeoff it can be operated in flight up to 20,000’
How long should you wait before turning the battery switch OFF after the APU selector is rotated to OFF, and why?
2 minutes,
Allows a complete shutdown sequence, with fire detection capability
What are the main AC electrical power sources on the LCF aircraft?
Four IDGs
Two external power sources
What is the function of the standby power switch in the Auto Position?
Allows the main and APU standby busses to be powered from available sources
What does the AVAIL light indicate on the External and APU PWR switches?
Related power source is plugged in and available and the power quality is acceptable.
When is the main cargo deck handling bus powered?
When the AVAIL light is displayed on the APU2 or EXT2 switches
What are some of the equipment items powered by the utility busses?
5 fuel pumps
Galley equipment
What happens when you push a generator drive disconnect (DRIVE DISC) switch?
Disconnects IDG from engine when above idle speed
Opens related Generator Control Breaker (GCB)
What condition would automatically disconnect the IDG if not manually disconnected by the flight crew?
Excessively high drive oil temperature
What does a bus ISLN light illuminated indicate?
BTB open
AC bus isolated from synchronous bus
How do you reconnect an IDG that has been disconnected?
Maintenance action required
IDG cannot be restored in flight
How is the electrical system configured during an automatic ILS approach (AUTOLAND)?
AC and DC busses 1,2, and 3 isolated from Sync Bus and DC Tie Bus
AC and DC busses 4 continue to power synchronous bus and DC tie bus
What are the main AC electrical power sources?
Four IDGs
Two Auxiliary power sources
Two External power sources
