B777 Electrical

Boeing 777 Electrics

Boeing 777 Electrics

1 / 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

APY Generator

Backup System

Left IDG

2 / 15

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

DC busses.

Main battery.

Back up generators.

APU.

3 / 15

Which one of the following is not true about the APU generator?

In flight, when both transfer busses are unpowered, the APU starts automatically, regardless of APU selector position.

The APU generator cannot power both main busses at the same time.

The APU generator is electrically identical to the IDG generators.

If no other power source is available when the APU generator becomes available, the APU generator automatically connects to both main AC busses.

4 / 15

What is the secondary source of power for 'fly-by-wire' if one or more PMGs are unpowered?

Main AC busses.

DC busses.

Hot battery bus.

Left transfer bus.

5 / 15

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

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

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.

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.

6 / 15

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

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

Start the APU.

Select the ground handling bus ON.

Deploy the RAT.

7 / 15

Which items below are de-powered if you position the BATTERY switch to OFF during power down?

The standby bus, Captain's displays and left AIMS.

The battery bus, Fırst Offıcer’s dısplay and the rıght AIMS.

The APU battery and the hot battery bus.

The engine fire extinguisher bottles and APU fire extinguisher bottle.

8 / 15

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

Right main bus.

Left main bus.

Ground service bus.

Standby bus.

9 / 15

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

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.

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 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.

10 / 15

How are the busses powered if the right engine is started with the APU powering the left bus system and external power powering the right bus system?

External power continues to supply the right main bus.

The right engine generator powers both main busses.

The right engine genrator automatically powers the right main bus.

There is no automatic switching till the left engine is started.

11 / 15

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

Variable frequency PMG AC power is used by individual power supply assemblies (PSAs) to provide DC power to the three flight control DC busses.

Primary power for the flight control DC electrical system comes from permanent magnet generators (PMGs) housed within each backup generator.

Each PSA also uses a dedicated battery to prevent power interruptions to the related flight control DC bus.

Variable frequency PMG AC power is the unique power source for the power supply assemblies (PSAs).

12 / 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 and replaces secondary external power on the left main bus.

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

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

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

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

Which one of the following is not true about integrated drive generators (IDGs)?

The IDG can be reconnected by the flight crew by pushing the respective DRIVE DISCONNECT switch.

The DRIVE light illuminates and the EICAS message ELEC GEN DRIVE L or R displays when low oil pressure is detected in an IDG.

The IDG can be electrically disconnected from the busses by pushing the GENERATOR CONTROL switch to OFF.

The IDG drive can be disconnected from the engine by pushing the respective DRIVE DISCONNECT switch.

15 / 15

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

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

The left TRU powers the left main DC bus.

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

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

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