Electrical

Question 1

What is the secondary power source for the Main Standby bus?

Answer 1

Main standby inverter

Question 2

During autoland below 1500’, automatic isolation of which buses occurs?

Answer 2

AC and DC buses 1, 2, 3

Question 3

What is the secondary power source for the FO transfer bus?

Answer 3

AC Bus 1

Question 4

What does the main deck cargo handling bus power?

Answer 4

Nose and side cargo doors

Question 5

When is the main deck cargo handling bus powered?

Answer 5

APU Gen 2 or Ext PWR 2 is AVAIL

Question 6

What does the ground service bus power

Answer 6

Flight deck flood, nav and service lights, and battery chargers

Question 7

If AC bus 1 is unpowered on the ground how can the Ground Service Bus be powered?

Answer 7

GND SERVICE switch at Door 1L

Question 8

How is the Ground Service Bus normally powered?

Answer 8

AC bus 1

Question 9

What does the Ground Handling Bus power?

Answer 9

Lower lobe cargo handling equipment and lights and AUX hydraulic pump 4 (and 1 if installed)

Question 10

When is the Ground Handling Bus powered?

Answer 10

When APU GEN 1 or EXT PWR 1 is avail or ON

Question 11

How is the Main Standby Bus normally powered?

Answer 11

AC Bus 3

Question 12

What is the secondary power source for the Captain Transfer Bus?

Answer 12

AC Bus 1

Question 13

How is the FO transfer bus normally powered

Answer 13

AC Bus 2

Question 14

What does the Main Standby Bus power?

Answer 14

Left: EIU, CDU, ILS, VOR, ADC, Transponder, EFIS panel

Question 15

The Split System Breaker opens and divides the synchronous bus allowing what to happen?

Answer 15

Separate APU or EXT sources to power each side

Question 16

Which bus powers fire detection for the APU and engines?

Answer 16

APU Battery Bus

Question 17

What buses isolate when a BTB is manually selected to ISLN?

Answer 17

The associated AC and DC buses

Question 18

The synchronous bus allows how many IDGs to be connected at the same time?

Answer 18

4

Question 19

What is the purpose of the sync bus?

Answer 19

prevent an AC bus from becoming unpowered if its respective generator fails

Question 20

How does each AC bus connect to the synchronous bus?

Answer 20

BTB

Question 21

Which sources of power may be connected to the synchronous bus at the same time

Answer 21

All four IDGs

Question 22

When will the generator DRIVE light illuminate? and when would an IDG automatically disconnect?

Answer 22

IDG oil temp high

Question 23

What are the main sources of AC power?

Answer 23

4 IDGs, 2 APU generators, 2 Ext Pwr sources

Question 24

How is the Captain Transfer bus normally powered?

Answer 24

AC bus 3

Question 25

The FO Transfer bus is normally powered by which AC bus?

Answer 25

AC bus 2

Question 26

What conditions would cause the generator DRIVE light to illuminate in the Generator Drive Disconnect (DRIVE DISC) switch (accompanied by the EICAS message ELEC DRIVE) provide the engine is operating?

Answer 26

GCB open due to uncontrollable generator frequency fault and IDG oil temperature high

Question 27

Which bus provides power for all fire extinguishing

Answer 27

Main hot battery bus

Question 28

The main and APU battery busses are normally powered by which DC bus?

Answer 28

DC bus 3

Question 29

If an AC bus is unpowered or TRU fails, what powers the respective DC bus?

Answer 29

DC tie bus

Question 30

The APU standby bus powers which equipment items?

Answer 30

Left FMC, ND, PFD

Question 31

With the battery switch ON, Standby power selector OFF and no other electrical sources are connected or available, which buses are powered?

Answer 31

Main and APU battery and hot battery buses

Question 32

With the Battery switch ON, standby power selector in AUTO and the Captain Transfer Bus not powered, what is the power source for the APU standby bus?

Answer 32

APU Standby inverter

Question 33

What is the normal power source for the APU standby bus?

Answer 33

Captain Transfer bus

Question 34

The main standby bus is normally powered by which AC bus?

Answer 34

AC bus 3

Question 35

Assume the aircraft dispatches with AC gen 2 inoperative. During automatic ILS approach once below 1500' AGL and LAND 3 is displayed on the AFDS which AC bus would power the sync bus?

Answer 35

AC bus 4

Question 36

The main deck cargo handling bus is powered on the ground only when what conditions are met?

Answer 36

When APU GEN 2 or EXT PWR 2 is AVAIL

Question 37

How is the APU Standby bus normally powered?

Answer 37

Captain transfer bus

Question 38

If both AC bus 1 and 3 are unpowered what is the power source for the Captain Transfer bus?

Answer 38

The bus will be unpowered

Question 39

If AC bus 3 is unpowered, which AC bus would then power the Captain transfer bus?

Answer 39

AC bus 1

Question 40

The Captain tranfer bus is normally powered by which AC bus?

Answer 40

AC bus 3

Question 41

On the ground, with only External PWR 1 AVAIL light illuminated (AC Bus 1 unpowered), how can the ground service bus be powered?

Answer 41

Through the ground service switch (cabin panel door 1L)

Question 42

The ground service bus is powered on the ground and in flight whenever which AC bus is powered?

Answer 42

AC bus 1

Question 43

With external power connected to each side of the electrical system (SSB open), when engine 4 and 3 are started, what is the configuration of the SSB?

Answer 43

OPEN

Question 44

What condition would disconnect the IDG automatically if not manually disconnected by the flight crew?

Answer 44

Excessive oil temperature

Question 45

How is each DC bus normally powered?

Answer 45

Its respective AC bus through its TRU

Question 46

The APU and Main batteries will provide Standby power for how long?

Answer 46

Minimum of 30 minutes

Question 47

Which bus powers fire protection for the APU and all engines?

Answer 47

Main hot battery bus

Question 48

What is the secondary power source for the APU standby bus?

Answer 48

APU standby inverter

Question 49

During automatic ILS approach, once below 1500' AGL and LAND 3 is displayed on the AFDS which AC bus powers the sync bus

Answer 49

AC bus 4

Question 50

What are the main sources of DC electrical power?

Answer 50

Four TRU's, main battery and APU battery