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 ON.

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

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

3 / 15

During autoland, the busses isolate to allow three independent sources to power the three autopilots.

True.

False.

The left IDG powers the left AC transfer bus, the left main DC bus, and the captain’s flight instrument bus The right IDG powers the battery bus and AC standby bus through the main battery charger The backup system powers the right AC transfer bus, the right DC bus, and the first officer’s flight instrument bus.

4 / 15

During autoland, the busses isolate to allow three independent sources to power the three autopilot. In this case which one of the following is the power source for the right AC transfer bus, the right DC bus, and the first officer's flight instrument bus?

Right IDG

Left IDG

Backup System

APY Generator

5 / 15

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

Only the main battery bus will be powered.

All statements are correct.

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

The hot battery bus will be powered.

6 / 15

The standby inverter converts DC power to AC power. The inverter powers the AC standby bus if the right transfer bus is not powered.

False.

True.

The standby inverter converts DC power to AC power. The inverter powers the AC standby bus if the left transfer bus is not powered.

7 / 15

The main battery provides standby power to the following:

The hot battery bus, the battery bus, the captain’s flight instrument bus, the left and center flight control PSAs, and the standby inverter.

The hot battery bus, the battery bus and the captain’s flight instrument bus.

The hot battery bus, the captain’s flight instrument bus, and the standby inverter.

The hot battery bus, the battery bus, the captain’s flight instrument bus and the standby inverter.

8 / 15

When will the RAT auto-deploy?

Both transfer busses unpowered, all three hydraulic systems low, and both engines fail.

Both transfer busses unpowered, both engines fail and C hydraulic system low

Both transfer busses unpowered, and both engines fail.

Both transfer busses unpowered, all three hydraulic systems low, both engines fail and C hydraulic system low

9 / 15

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

APU.

Main AC busses.

Permanent magnet generators.

Battery.

10 / 15

What is the primary source of DC power during normal flight?

DC generators.

Transformer rectifier units.

Main battery.

APU battery.

11 / 15

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

4

7

6

5

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

12 / 15

Which bus powers the main battery charger and the APU battery charger?

Standby bus.

Ground service bus.

Right main bus.

Left main bus.

13 / 15

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

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

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).

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

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

14 / 15

What automatic switching will occur if you start the APU with external power on the BUS TIE system?

The APU connects to the BUS TIE switches but does not power either main bus.

The APU connects to the BUS TIE swıtches and powers the maın bus.

The APU connects to the BUS TIE and replaces secondary external power on the left main bus.

The APU connects to the BUS TIE and replaces primary external power.

15 / 15

Which one of the following is not true about the 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.

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.

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