B777 Electrical

Boeing 777 Electrics

Boeing 777 Electrics

1 / 15

What does the green EXTERNAL POWER AVAIL light indicate?

Electrical power is available to the electrical busses but may not be correct.

External power is connected to the airplane, correct and ready to power the electrical busses.

External power is connected to all the airplane's electrical busses.

External power is disconnected from the airplane.

2 / 15

What is the correct electrical panel configuration for normal flight?

BUS TIE switches in AUTO, BATTERY switch OFF, GENERATOR CONTROL switches ON.

BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches OFF.

BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches ON.

BUS TIE switches in ISLN, BATTERY switch ON, GENERATOR CONTROL switches ON

3 / 15

Which condition(s) cause the ELEC GEN DRIVE L EICAS message to display?

GENERATOR CONTROL switch selected to OFF.

Either A or B is correct

Generator drive oil pressure is low.

Generator drive oil temperature is high.

4 / 15

On ground no power connected to the airplane. Which items will be powered if you push the BATTERY switch ON?

All statements are correct.

Only the main battery bus will be powered.

The APU controller and the DC fuel pump will be powered.

The hot battery bus will be powered.

5 / 15

What is the source of standby electrical power if the RAT sheds electrical power because of low hydraulic pressure?

DC busses.

APU.

Main battery.

Back up generators.

6 / 15

What is the primary power source for 'fly-by-wire'?

Permanent magnet generators.

APU.

Main AC busses.

Battery.

7 / 15

When does the right transfer bus isolate from the right main bus?

When system configures to autoland.

When main AC busses are powered.

During descent.

Never.

8 / 15

Which one of the following is not true about the Primary External Power?

If a single IDG powers both busses, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to both busses and removes the IDG source.

If both busses are powered from secondary external power, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to the both main busses.

If the APU generator is running, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to the right main bus, leaving the previous source connected to the left main bus.

When the Primary power source voltage and frequency are within limits, the primary external power AVAIL (available) light illuminates.

9 / 15

How can you power the ground handling bus before shutdown if no external power is available?

Deploy the RAT.

Select the ground handling bus ON.

The bus is powered as long as the right main bus is powered.

Start the APU.

10 / 15

How many total AC sources of power does the B777 accommodate?

5

7

6

4

Seven (2 IDG, APU, PRI and SEC external power, 2 BUG).

11 / 15

Which one of the following is not true about the Secondary External Power?

If a single IDG powers both main busses, pushing the SECONDARY EXTERNAL POWER switch ON connects secondary external power to both busses and removes the IDG source.

When the secondary external power source voltage and frequency are within limits, the secondary external power AVAIL (available) light illuminates.

Secondary external power can only power the left main bus.

If the BATTERY switch is ON and no other source is powering the main busses, pushing the SECONDARY EXTERNAL POWER switch ON connects secondary external power to both main busses.

12 / 15

Which one of the following is not true about the backup electrical system?

Backup power is provided by one variable speed, variable frequency generator mounted on each engine.

A frequency converter converts the generator frequency to a constant 400 Hz.

If both IDGs and the APU generator are inoperative, a backup generator powers essential airplane equipment to reduce electrical loading on the backup generator, some of the systems becomes inoperative such as TCAS, Centre tank override/jettison pumps (centre tank fuel is unusable).

Right and Left backup generators power the converter at the same time.

13 / 15

You have a cold airplane (no power connected). Which items will be powered if you push the BATTERY switch ON?

The APU controller and the DC fuel pump will be powered.

Only the main battery bus will be powered.

The hot battery bus will be powered.

14 / 15

The standby electrical system consists of:

The main battery and the RAT generator.

The main battery, the standby inverter, the RAT generator and its associated generator control unit and the C1 and C2 TRUs.

The main battery, the standby inverter, and the RAT generator.

The main battery, the standby inverter, the RAT generator and the C1 and C2 TRUs.

15 / 15

Which one of the following is not true about the DC electrical system?

The left TRU powers the left main DC bus.

The DC electrical system includes the main DC electrical system and the flight control DC electrical system.

The C1 TRU powers the first officer's flight instrument bus.

The main DC electrical system uses four transformer-rectifier units (TRUs) to produce DC power.

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