Electrical

Question 1

Name some important items on the MAIN HOT BATT BUS.

Answer 1

1 Fuel spar valves
2 Engine, APU & lower cargo fire extinguishers
3 Fire override switches

Question 2

(Dark Aircraft) When the BATTERY switch selected ON which busses are powered?

Answer 2

MAIN & APU hot battery busses
MAIN & APU battery busses

Question 3

After the BATTERY switch has been selected ON, selecting the STANDBY POWER switch to AUTO powers which busses and how?

Answer 3

The MAIN STBY bus and APU STBY bus are powered by their respective battery bus and invertors.

Question 4

What items are powered by the APU STBY bus?

Answer 4

Left FMC, ND & PFD

Question 5

What items are powered by the MAIN STBY bus?

Answer 5

Primary EICAS
Left EIU, CDU, ILS, VOR & VHF

Question 6

With the loss of all generators which systems are inoperative?

Answer 6

LE flaps, anti-skid, reversers, auto-speedbrakes

Question 7

How is the MAIN STBY bus powered in normal operations?

Answer 7

AC BUS 3.

Question 8

How is the APU STBY bus powered during normal operations?

Answer 8

CAPT XFER BUS.

Question 9

What is the source of power to the MAIN & APU BATTERY CHARGERS?

Answer 9

GROUND SERVICES BUS.

Question 10

In flight how is the GROUND SERVICES BUS powered?

Answer 10

by AC BUS 1

Question 11

What is the purpose of the GROUND SERVICES switch located next to the L1 door?

Answer 11

When AC BUS 1 is not powered, selecting the GROUND SERVICES switch ON powers the GROUND SERVICES BUS from the samr source as the GROUND HANDLING BUS.

Question 12

What is the CAPT XFER BUS normal and backup power source?

Answer 12

Normally powered by AC BUS 3. If AC BUS 3 is unpowered, AC BUS 1 powers the CAPT XFER BUS.

Question 13

What is the FO XFER BUS normal and backup power source?

Answer 13

Normally powered by AC BUS 2. If AC BUS 1 is unpowered, AC BUS 1 powers the FO XFER BUS.

Question 14

When is the GROUND HANDLING BUS powered?

Answer 14

On the ground anytime EXT PWR 1 or APU GEN 1 is AVAIL or ON.

Question 15

Name some of the items powered by the GROUND HANDLING BUS.

Answer 15

1 Lower cargo handling and lights
2 Fueling system
AUX HYDR DEMAND PUMP 4

Question 16

When is the MAIN DECK CARGO HANDLING BUS powered?

Answer 16

On the ground anytime EXT PWR 2 or APU GEN 2 is AVAIL.

Question 17

What happens when a BTB is in ISLN and in AUTO?

Answer 17

In ISLN the selected BTB and respective DCIR open and fault logic circuitry is reset.
In AUTO the automatic AC bus tie circuitry is armed and the respective DCIR is closed.

Question 18

In flight with the loss of all normal AC power which items are powered? (loss of all generators)

Answer 18

Left FMC, PFD, ND, VHF
Primary EICAS, CAPT pitot heat, NAI, dome lights & left/right interphone panels.

Question 19

Can an ILS be flown with the loss of all normal AC power?

Answer 19

Yes but no FD or AP

Question 20

Can the aircraft be trimmed with the loss of all normal AC power?

Answer 20

Yes using the ALTN trim switches.

Question 21

Can the gear and flaps be extended with the loss of all normal AC power?

Answer 21

Yes. The gear though the normal hydraulic system and the TE flaps through the primary mode. LE flaps will not extend (prompting a FLAP DRIVE EICAS message).

Question 22

Will reverse, speedbrakes and anti-skid be available with the loss of all normal AC power?

Answer 22

No reverse or anti-skid. Speedbrakes only available manually.