Electrical Flashcards
How many engine driven generators does the aircraft have?
Four
How many total generators does the aircraft have?
Five
Is the aircraft primarily AC or DC powered?
DC
What is the purpose of the EDL?
Manages the electrical system during normal and abnormal operation
Describe the main batteries
Two nickel-cadmium batteries 24 V DC, 44 Ah, 1-hour rate
Describe the Backup Battery
One Lead-Acid Battery 24V DC, 5 Ah, 10-hour rate
Which generators are on engine 1?
1 and 3
Which generators are on engine 2?
2 and 4
What is the purpose of the GCUs?
To control and protect their associated generators
What speed N2 do the engine driven generators come on-line during start?
56.4%
What power sources can be used to start the APU?
GPU
Battery 2
Battery 2 assisted by main generators
How long can the main batteries power essential loads in flight?
40 minutes
How long can the main batteries power the aircraft on the ground?
15 minutes
What is the indication when a GPU is plugged into the aircraft but not selected?
The GPU AVAIL instruction illuminates inside the GPU button
What items are powered by the Hot Battery Bus?
Courtesy/Stairs Lights
ELT
Engine Fire Bottles
Fuel Shutoff
Hydraulic Shutoff
Main Door Control
Pressure Refueling
What items are powered by the Backup Hot Bus?
EDL
GCUs
What are some items on the DC buses that would be lost during an electrical emergency?
Autopilot
FMS
IC-600#2
Lavatory
PFDs and MFDs
Pressurization
Radar
What are some items powered by the shed buses?
Coffee maker
Nose wheel landing and taxi lights
Pre Recorded announcements
Recirc fan
Windshield Heat 2
What is the purpose of the Central Bus?
To connect the APU generator to the load buses through the bus tie contactors
What items have a secondary power source on the backup buses?
DAUs
EICAS
IC-600 #1
IRS
What items are on the AC bus?
EGPWS
TCAS
Windshear
When will the ground service bus be powered?
GPU connected to the aircraft, and NOT selected
What is the purpose of the ground service bus?
To provide lighting for cleaning crews without them having to enter the cockpit
Describe the electrical system with four or five generators.
Two networks, all buses powered
Describe the electrical system with three generators
One network, all buses powered
Describe the electrical system with one or two generators
One network, all buses powered except shed buses
Describe the electrical system with no working generators in flight.
Batteries supply power to essential buses, Duration 40 minutes
Describe the electrical system with no working generators on the ground.
Batteries supply power to essential buses and DC buses, Duration 15 minutes
What does the term ELECTRICAL EMERGENCY mean?
Loss of all generators
What does the Shed Bus OVRD knob do?
On the ground only, with one or two generators operating, the shed buses can be powered if this knob is set to the OVRD position
What controls the electrical system bus tie contactors and load shedding?
Electrical Distribution Logic (EDL)
When will a white strip be displayed inside the GPU button?
When the button is pressed in
How does the EDL configure the electrical system during APU start?
Battery 1 contactor opens, isolating the number 1 battery to provide stable power to the backup buses
What happens when the backup button is pressed?
When pressed out, it removes power from the backup buses and prevents the backup battery from charging
When should the Avionics Master buttons be pressed out?
During APU start and prior to aircraft shutdown
What does the Essential Power Button do?
When pressed in, it overrides the EDL and connects the batteries to the essential buses only
If the batteries, APU, and GPU are all connected and operating, which takes priority?
GPU
Can the GPU charge the batteries?
No
If the main battery voltage is below _, it must be replaced
19V
During an electrical emergency, can an ILS approach be flown?
Yes, using the RMU navigation page
