B744 ELECTRICAL

Question 1

Name some important items on the Main Hot Battery Bus:

Answer 1

Spar Valves
APU and Lower Cargo Fire Extinguishers
Engine Fire Extinguishers
Fire unlock switches

Question 2

When I place the BAT switch to ON, what busses are powered? (DARK airplane)

Answer 2

• 2 HOT BAT Buses (Main and APU)

- 2 BAT Buses (Main and APU)

Question 3

When I place the STBY PWR selector to AUTO, what Buses are powered & how?

Answer 3

Main and APU Stby Buses,

through the Invertors from the Main and APU Buses

Question 4

What items are on the MAIN Stby Bus?

Answer 4

Primary EICAS 
Left FMS-CDU 
Left EIU  
Left ILS  
Left VOR

Question 5

What items are on the APU Stby Bus?

Answer 5

Left PFD / Left ND / Left FMC

Question 6

What powers the MAIN Stby Bus during normal operations?

Answer 6

AC Bus 3

Question 7

What powers the APU Stby Bus during normal operations?

Answer 7

CA Xfer Bus

Question 8

What is the source of power to the BAT Chargers?

Answer 8

Ground Service Bus

Question 9

What is the main power source to the Grd Service Bus?

Answer 9

AC Bus 1

Question 10

What is the purpose of the “Ground Service” switch located next to the L1 Door?

Answer 10

When AC Bus 1 is not powered, the Grd Serv Bus can be powered from the same source as the Grd Handling Bus by pushing the switch

Question 11

What is the main source of power for the CA Xfer Bus? Backup?

Answer 11

AC Bus 3

AC Bus 1

Question 12

What is the main source of power for the FO Xfer Bus? Backup?

Answer 12

AC Bus 2

AC Bus 1

Question 13

When is the Ground Handling Bus powered?

Answer 13

On the ground, anytime APU 1 or EXT 1 is AVAIL or ON

Question 14

What are some of the items on the Ground Handling Bus?

Answer 14

Lower Cargo Handling and Lights
Fueling system
AUX Hyd Demand Pump #4

Question 15

When is the Main Deck Cargo handling Bus powered?

Answer 15

On the ground, anytime APU 2 or EXT 2 is AVAIL

Question 16

What happens when you push a BTB switch?

Answer 16

Push OFF: opens the BTB and respective DCIR and resets Fault Logic circuitry
Push AUTO: arms the automatic AC bus tie circuitry and closes DCIR

Question 17

What items are powered in flight with loss of all Normal AC Power (Loss of all Gens)?

Answer 17

Left FMC 
Left PFD 
Left ND
Left VHF Comm 
Primary EICAS 
CA Pitot Heat
NAI
Dome Lights
L and R interphone panels

Question 18

Can I fly an ILS with loss of all Normal AC Power?

Answer 18

Yes, BUT no FD or A/P

Question 19

Can I trim with loss of all Normal AC Power?

Answer 19

Yes, using Alternate switches (through a separate control channel)

Question 20

Can I get the Gear & Flaps down with loss of all Normal AC Power?

Answer 20

Yes, the Gear through its normal Hydraulic mode and the TE Flaps through the Primary mode. The LE Flaps will NOT extend prompting a Flaps Drive message (25 Kt additive to VREF – QRH)

Question 21

What about Reverse, Speedbrakes & Anti-Skid with loss of all Normal AC Power?

Answer 21

No Reverse, No Auto Speedbrakes (manual OK), and no Anti-Skid