Chapter 6 - Electrical Flashcards Preview

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Flashcards in Chapter 6 - Electrical Deck (33):
1

What do the APU GEN and GEN CONT switches do ?

They ARM to close the breaker when power is available.

2

When do the APU GEN and GEN CONT OFF light illuminate ?

Whenever the breaker is open (because power is not available).

3

What does the BUS TIE switch do ?

It arms:
- The AC bus tie
- The DC bus tie
- The respective flight instrument transfer bus

4

When does the bus tie ISLN light illuminate ?

When the AC bus tie breaker is open.
Not in case of the DC bus tie.

5

How can the load shed circuitry be reset ?

By recycling the UTILITY BUS switch.

6

When does the generator DRIVE light illuminate ?

When the oil pressure is low OR oil temperature is high.

7

Can a generator disconnect be reset in-flight ?

No.

8

When does the standby power OFF light illuminates ?

When the AC or DC standby bus or the battery bus is not powered.

9

When does the battery OFF light illuminate ?

When the battery switch is off.

10

Can one AC source power the whole electrical load ?

No. Two sources are required for the full load.

11

If APU is running and external power is connected, is the APU powering the main busses ?

No.

12

What is priority of AC power sources ?

- Ground power
- IDG
- APU
- Opposite IDG

13

Are there any indications or EICAS messages for a galley bus which is not powered.

No. Only when the utility bus is not powered as well.

14

Which bus powers the GND SVC bus ?

R MAIN AC BUS.

15

How is the GND HANDLING bus powered ?

From the APU GEN or from external power.

16

What happens above 200 ft in case of loss of a generator during an autoland ?

> 200ft, the bus ties close again. The L main AC system powers the center autopilot. NO LAND 3 is shown.

17

During autoland, how is the center autopilot powered ?

By the standby power system.

18

What happens with the AC bus ties during autoland ?

They open.

19

How are the flight instruments powered in case of loss of both generators ?

By the HDG.

20

Are the transfer busses powered in case of loss of both generators ?

Yes, by the HDG.

21

What is the order of AC load shedding ?

- Galley bus
- Utility bus
- Main AC items

22

Is load shedding automatically reverted ?

Yes.

23

Before engine start, two load sheddings may occur:

- one electric hydraulic pump
- center tank fuel pumps

24

During engine start, one load shedding may occur:

Utility busses

25

What happens on the ground, when the engines are shut down, and the thrust levers are advanced ?

It may cause inadvertent load shedding of the utility busses. Solution: return the thrust levers to idle, and recyle the UTILITY BUS switches.

26

Is the DC bus tie armed when only one BUS TIE switch is in auto ?

No.

27

The standby power system consists of:

battery bus
hot battery bus
AC standby bus
DC standby bus

28

How is the battery bus powered ?

By the L DC bus or the main battery.

29

How is the DC standby bus powered ?

By the L DC bus or by a combination of:
- the main battery AND APU battery.

30

How is the AC standby bus powered ?

By the L AC TRANSFER BUS or by a combination of:
- the main battery AND APU battery + inverter

31

When is the HDG activated ?

When the L AND the R MAIN AC bus are not powered.

32

Is the amount of power of the HDG more than that of full batteries ? What is the consequence ?

No. Consequence is that initially BAT DISCH for both batteries may occur.

33

What busses are lost in case of a failure of L AC main bus ?

L AC transfer bus
L utility bus
L galley bus