Electrical Flashcards
What is the purpose of the Cabin Utility switch
Powers cabin and utility systems
What does the AVAIL light mean on the external power switch
Power is connected and acceptable
What does the DRIVE light on the IDG switch mean
IDG oil pressure is low
When will the IDG Drive disconnect automatically
High oil temperature ONLY
When will the IDG Drive require manual disconnection
Low oil pressure
Main AC power sources
- Left and right IDG
- APU
- External power
If no other sources of power will the APU power both main transfer buses
Yes
With APU and Primary External power how are the buses powered
- APU powers Left Main AC bus
- Primary powers the right main AC bus
When will the APU automatically start
Both transfer buses are unpowered
Primary external power normally powers which bus
Right Main bus
Secondary external power normally powers which bus
Left main bus
What is the order of priority for powering the main transfer buses
- Respective IDG
- APU
- Opposite IDG
Main buses power individual components such as
- Cooling vent fans
- Recirc fans
- Lavatory/Galley fans
- Electric hydraulic pumps
- IFE
What does the ground service bus power
- Main battery charger
- APU battery charger
- Miscellaneous cabin systems
What is the Ground Handling bus used for
- Fueling operations
- Cargo operations
How are the three buses powered for LAND 3 operations
- Left IDG powers left AC bus
- Right IDG powers the battery bus
- Backup system powers the right AC bus
How many backup generators can be delivering power at once
One
Backup generators automatically provide power when
- Only one main AC generator (Including APU)
- Power lost to both AC buses
- Approach mode is selected for autoland
- Testing
How many PMG’s
2 on each Backup Generator
What is inoperative when backup generators are being used to power the main buses
- HF radio
- Center tank override pumps (No jettison ctr tank)
- Exterior lights excluding landing lights
- Non essential cabin lighting
- Supernumerary cabin lighting
- Cabin temp control is degraded
What powers the DC TRUs
AC main buses
What do the C1 and C2 TRU power
C1 - Captains flight instruments and battery charger
C2 - First officers flight instruments
Each is a back up power source for the other
What order will the ELMS load shed
- Galley buses
- Utility buses
- Individual components as required
What powers the flight control DC electrical sysytem
- Primary power PMG’s in the backup generators
- Secondary power
When do the back up generators work
- Power lost to one or more main AC bus
- Only one generator source available
- Approach mode selected for autoland
- Testing the back up system
