B777 Electrical

Boeing 777 Electrics

Boeing 777 Electrics

1 / 15

What is the correct electrical panel configuration for normal flight?

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

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

2 / 15

What is the primary source of power for the transfer busses?

Main DC busses.

Engine generators.

Backup generators.

Ram Air Turbine.

3 / 15

The main battery provides standby power to the following:

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

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, 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.

4 / 15

If the RAT is unable to maintain RPM, the RAT generator electrical load is shed until RPM is satisfactory. Power for standby electrical loads is provided by the main battery during deployment of the RAT and when RAT generator loads are shed.

True.

False.

The RAT is deployed automatically if both AC transfer busses lose power in flight. The RAT can be manually deployed by pushing the RAM AIR TURBINE switch on the overhead panel.

5 / 15

When will the RAT auto-deploy?

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

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

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

6 / 15

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

DC busses.

Left transfer bus.

Main AC busses.

Hot battery bus.

7 / 15

Primary power for the flight control DC electrical system comes from permanent magnet generators (PMGs) housed within each backup generator. Variable frequency PMG AC power is used by individual power supply assemblies (PSAs) to provide DC power to the three flight control DC busses. To ensure a high level of system reliability, each PSA also has multiple AC power sources.

False.

True.

To ensure a high level of system reliability, each PSA also has multiple DC power sources (No AC power!). If primary PMG AC power is not available, secondary power for the left and right PSAs is provided by the related main DC bus. Secondary power for the center PSA is provided by the captain’s flight instrument bus. The hot battery bus provides additional backup power for the left and center PSAs only. Each PSA also uses a dedicated battery to prevent power interruptions to the related flight control DC bus. The batteries have limited capacity and are incorporated to supply power for brief periods during PSA power source transfers.

8 / 15

What is the electrical configuration during autoland?

There is no change from normal.

The left transfer bus isolates from the right transfer bus.

The right transfer bus isolates from the right main AC bus.

The left transfer bus isolates from the right main bus.

9 / 15

What is the correct source order for powering left and right main busses in flight?

Respective backup generator - APU generator - opposite backup generator.

Respective IDG - APU generator - opposite IDG.

APU generator - respective IDG - opposite IDG.

Opposite IDG - APU generator - respective IDG.

10 / 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 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.

11 / 15

Which one of the following is not true about the ram air turbine (RAT) generator?

The RAT is deployed automatically if both AC transfer busses lose power in flight.

The RAT generator provides standby power to the C1 and C2 TRUs.

The RAT cannot be manually deployed by pushing the RAM AIR TURBINE switch if any of the AC transfer busses powered.

The RAT can supply electrical and hydraulic power simultaneously.

12 / 15

Which bus operates only on the ground?

The right transfer bus.

The left main AC bus.

The ground handling bus.

The ground service bus.

13 / 15

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

The APU battery and the hot battery bus.

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

The engine fire extinguisher bottles and APU fire extinguisher bottle.

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

14 / 15

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

Left main bus.

Ground service bus.

Right main bus.

Standby bus.

15 / 15

Which one of the following is not true about Electrical Load Management System (ELMS)?

If the electrical loads exceed the power available (airplane or external), ELMS automatically sheds AC loads by priority until the loads are within the capacity of the airplane or ground power generators.

Priority for shedding is galleys first, then utility busses. Utility busses are followed by individual equipment items powered by the main AC busses.

The ELMS provides load management and protection to ensure power is available to critical and essential equipment.

When an additional power source becomes available or the loads decrease, ELMS restores power to shed systems in the same order of shedding(First shed system restored first).

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