B777 Electricals Quiz
The electrical power system of the B777 has two independent electrical systems; the primary electrical system that is the main mega 3-phase system, which aides the flight and the secondary, which is essentially a power generation system, which acts as a back up for the aircraft. B77 electricals quiz below tests your understanding of the subject.
- 1.
What automatic switching will occur if you start the APU with primary and secondary external power on the BUS TIE system?
- A.
The APU connects to the BUS TIE switches but does not power either main bus.
- B.
The APU connects to the BUS TIE and replaces secondary external power on the left main bus.
- C.
The APU connects to the BUS TIE and replaces primary external power.
- D.
The APU powers both main buses.
Correct Answer
B. The APU connects to the BUS TIE and replaces secondary external power on the left main bus. -
- 2.
How are the main AC busses powered if the right engine is started with the APU powering the left bus system and external power powering the right bus system?
- A.
External power continues to supply the right main bus.
- B.
The right engine generator automatically powers both main busses.
- C.
The right engine generator automatically powers the right main bus.
- D.
The right engine generator automatically powers the left main bus.
Correct Answer
C. The right engine generator automatically powers the right main bus. -
- 3.
What will occur if a single IDG is powering both buses, and the PRIMARY EXTERNAL POWER switch is selected ON?
- A.
Primary external power connects to both busses and the IDG power source is removed.
- B.
Primary external power connects to the bus which is normally powered by the non-operating IDG.
- C.
The single IDG will continue to power both busses.
- D.
External power cannot be applied in this situation.
Correct Answer
A. Primary external power connects to both busses and the IDG power source is removed. -
- 4.
Which items below are de-powered if you position the BATTERY switch to OFF during power down?
- A.
The APU battery and hot battery bus
- B.
The engine fire extinguisher bottles and APU fire extinguisher bottle
- C.
The AC standby bus, the Captain's flight instrument bus, and the left and center flight control busses
- D.
The F/O's flight instrument bus and the left and right transfer busses
Correct Answer
C. The AC standby bus, the Captain's flight instrument bus, and the left and center flight control busses -
- 5.
How can you power the ground handling bus before shutdown if primary external power is not available?
- A.
Select the ground handling bus ON.
- B.
The bus is powered as long as the right main bus is powered.
- C.
Connect the secondary external power source.
- D.
Start the APU.
Correct Answer
D. Start the APU. -
- 6.
Which bus operates only on the ground?
- A.
The ground service bus
- B.
The ground handling bus
- C.
The left main AC bus
- D.
The right transfer bus
Correct Answer
B. The ground handling bus -
- 7.
What is the primary source of DC power during normal flight?
- A.
APU battery
- B.
Main battery
- C.
Transformer rectifier units
- D.
DC generators
Correct Answer
C. Transformer rectifier units -
- 8.
What provides DC power on this airplane?
- A.
DC generators
- B.
Standby inverters
- C.
Transfer busses
- D.
Transformer rectifier units
Correct Answer
D. Transformer rectifier units -
- 9.
When does the right transfer bus isolate from the right main bus?
- A.
Never
- B.
During descent
- C.
When system configures to autoland
- D.
When main AC busses are powered
Correct Answer
C. When system configures to autoland -
- 10.
What is the electrical configuration during autoland?
- A.
The right transfer bus isolates from the right main AC bus.
- B.
The left transfer bus isolates from the right main bus.
- C.
There is no change from normal.
- D.
The left transfer bus isolates from the right transfer bus.
Correct Answer
A. The right transfer bus isolates from the right main AC bus. -
- 11.
What is the primary electrical power source for flight control system?
- A.
Battery
- B.
Main AC busses
- C.
Permanent magnet generators
- D.
APU
Correct Answer
C. Permanent magnet generators -
- 12.
What is the secondary source of power for flight control system if one or more PMGs are unpowered?
- A.
Hot battery bus
- B.
DC busses
- C.
Left transfer bus
- D.
Main AC busses
Correct Answer
B. DC busses -
- 13.
What is the primary source of standby power if all normal AC and DC power sources fail?
- A.
APU
- B.
Main battery
- C.
Backup generators
- D.
RAT generator
Correct Answer
D. RAT generator -
- 14.
What is the source of standby electrical power if the RAT sheds electrical power because of low hydraulic pressure?
- A.
APU
- B.
Backup generators
- C.
Main battery
- D.
DC busses
Correct Answer
C. Main battery -
- 15.
Which condition(s) cause the EICAS message ELEC GEN DRIVE L to display?
- A.
Generator drive oil temperature is high.
- B.
Generator drive oil pressure is low.
- C.
GENERATOR CONTROL switch selected to OFF.
- D.
Generator drive oil temperature is high or generator drive oil pressure is low.
Correct Answer
B. Generator drive oil pressure is low. -
- 16.
What is the primary source of power for the transfer busses?
- A.
Ram air turbine
- B.
Backup generators
- C.
Engine generators
- D.
Main DC busses
Correct Answer
C. Engine generators -
- 17.
What is the correct electrical panel configuration for normal flight?
- A.
BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches ON
- B.
BUS TIE switches in AUTO, BATTERY switch OFF, GENERATOR CONTROL switches ON
- C.
BUS TIE switches in ISLN, BATTERY switch ON, GENERATOR CONTROL switches ON
- D.
BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches OFF
Correct Answer
A. BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches ON -
- 18.
What does the green EXTERNAL POWER AVAIL light indicate?
- A.
External power is disconnected from the airplane.
- B.
External power is connected to all the airplane's electrical busses.
- C.
Electrical power is available to the electrical busses but may not be correct.
- D.
External power is connected to the airplane and the voltage and frequency are within limits.
Correct Answer
D. External power is connected to the airplane and the voltage and frequency are within limits. -
- 19.
What items are load shed first by the Electrical Load Management System if the electrical loads exceed the power available?
- A.
The load shedding sequence is galleys first and the utility busses.
- B.
The individual items causing the exceedance are shed first followed by the galleys.
- C.
Only the utility busses load shed.
- D.
All non-essential items on the main AC busses load shed.
Correct Answer
A. The load shedding sequence is galleys first and the utility busses. -
- 20.
What is the alternate source of power for the ground handling bus?
- A.
Secondary external power
- B.
Left transfer bus
- C.
APU
- D.
Right transfer bus
Correct Answer
C. APU -
- 21.
What happens in flight when both transfer busses become unpowered?
- A.
The APU starts automatically, regardless of the APU selector position.
- B.
The RAT powers both transfer busses
- C.
No other power source is available so only the standby bus remains powered until pilot action
- D.
The APU must be manually started and connected to the transfer busses
Correct Answer
A. The APU starts automatically, regardless of the APU selector position. -
- 22.
What components make up the Standby Electrical System?
- A.
The main battery, the standby inverter, the L TRU and R TRU, the RAT generator amd its associated generator control unit
- B.
The main battery, the standby inverter, the APU battery, the L TRU and R TRU
- C.
The main battery, the standby inverter, the RAT generator amd its associated generator control unit
- D.
The main battery, the standby inverter, the L TRU and R TRU
Correct Answer
C. The main battery, the standby inverter, the RAT generator amd its associated generator control unit -
- 23.
Which of the following statements about the standby inverter is not correct?
- A.
The standby inverter converts DC power to AC power.
- B.
The inverter powers the AC standby bus if the left transfer bus is not powered.
- C.
The standby inverter normally receives DC power from the Battery Bus.
- D.
The standby inverter can not receive DC power from the RAT generator through TRU
Correct Answer
D. The standby inverter can not receive DC power from the RAT generator through TRU -
- 24.
The standby inverter converts DC power to AC power. Which bus provides DC power to the Standby Inverter and which AC bus is powered by the Standby Inverter?
- A.
The Battery Bus and the Standby Bus
- B.
The Hot Battery Bus and the Standby Bus
- C.
The Battery Bus and the Captain's Flight Instrument Bus
- D.
The Hot Battery Bus and the L Transfer Bus
Correct Answer
A. The Battery Bus and the Standby Bus -
- 25.
Which system does not have AC power removed when the IFE/PAS switch is placed in the OFF position?
- A.
All In Flight Entertainment systems
- B.
Personal computer power outlets
- C.
Telephones
- D.
Emergency Locator Transmitter
Correct Answer
D. Emergency Locator Transmitter -
- 26.
Which system does not have AC power removed when the CABIN/UTIL switch is placed in the OFF position?
- A.
Utility Busses
- B.
Galleys
- C.
Left forward main tank fuel pump
- D.
Miscellaneous cabin systems loads on the Ground Service Bus
Correct Answer
C. Left forward main tank fuel pump -
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Current Version
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Nov 27, 2018Quiz Edited by
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Jun 23, 2009Quiz Created by
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