Electrical Flashcards
In addition to the traditional electrically powered systems, the 787 electrical system also powers…
engine start and pressurization.
wing ice protection and stabilizer trim.
wheel brake systems.
All of the above are correct.
All of the above are correct.
Engine and APU starter/generators function as electrically powered starter motors for start and generators once the engine or APU is running. There are a total of ___________________ starter/generators on the 787.
4 variable frequency
6 constant speed
4 constant speed
6 variable frequency
6 variable frequency
The engine starter generators are designated as…
L1, L2, R1, R2.
left, left 1, right, right 2.
1,2,3,4.
L1, L2, R3, R4.
L1, L2, R1, R2
During normal engine start only one starter/generator is used during the start. The other starter/generator is used as a backup.
True
False
False
The 115 Vac external power system consists of both a forward and aft system. How many receptacles are there for each system?
Three forward, two aft
One forward, one aft
One forward, two aft
Two forward, one aft
Two forward, one aft
The removal of electrical loads in order of priority to stay within the capacity of the available power sources is referred to as…
load inhibit.
load shed.
battery shed.
load priority.
load shed
Three engine driven Permanent Magnet Generators (PMGs) are the primary source of power for the flight control electronics. A secondary source for control power is provided by…
the Permanent Magnet Alternators (PMA).
only the APU battery.
the aircraft battery only.
the 28 Vdc bus distribution system, and the main battery.
the 28 Vdc bus distribution system, and the main battery.
The main AC busses designated L1, L2, R1, and R2 provide…
270 Vdc.
115 Vac.
235 Vac.
28 Vdc
235 Vac.
The aft external power system may be used as the sole electrical source to start the right engine first.
True
False
False
If electrical power is lost in flight, how is the aircraft powered during the time between the power loss and Ram Air Turbine (RAT) deployment?
Main battery
APU battery
Permanent Magnet Alternators (PMAs)
Permanent Magnet Generators (PMGs)
Main battery
Four engine starter/generators function as electrically powered starter motors for start and engine driven generators once the engines are running. The starter/generators are…
variable frequency and utilize a CSD to provide stable output.
directly connected to the engine gearboxes, producing variable power proportional to engine or APU rotor speed.
ganged in pairs through a hydro/electric motor drive.
variable frequency utilizing the engine variable stator vanes to control output.
directly connected to the engine gearboxes, producing variable power proportional to engine or APU rotor speed.
Circuit breakers cannot be opened or closed using the Circuit Breaker Indication and Control (CBIC) display in flight.
True
False
False
Each engine has two ______ variable frequency starter generators.
270 Vdc
115 Vac
28 Vdc
235 Vac
235 Vac
The APU battery functions automatically and has no power switch. The main battery assists the APU battery providing power on the ground for APU start.
False
True
True
In addition to traditional electrically powered systems, the B787 electrical system powers which of the following systems?
Wing ice protection
Pressurization
Wheel brake
All of the above.
All of the above.
Following the loss of all electrical power to the Captain’s and First Officer’s flight instruments in flight, what is the source of standby power until RAT deployment?
Backup generators
APU battery
APU
Main battery
Main battery
What is the primary source of power for the flight control electronics?
Main 235 Vac system
Main battery
28 V DC distribution system
Three Permanent Magnet Generators (PMGs)
Three Permanent Magnet Generators (PMGs)
With only forward external power selected ON, after the APU is started,…
the buses remain powered by external power until the APU starter generators are manually selected on.
the APU energizes the 235 Vac and 115 Vac system while external power continues to energize 28 Vdc system.
the APU generators energize the four main 235 Vac buses, and external power transitions from ON to AVAIL.
external power energizes the 115 Vac and 28 Vdc buses while the APU powers the 235 Vac busses.
the APU generators energize the four main 235 Vac buses, and external power transitions from ON to AVAIL.
Four electrical brake power supply units regulate power for the exclusive use of the airplane electric brake system. The primary and backup power source for the brakes are…
the 28 Vdc bus system and main battery respectively.
the Large Motor Controller and APU battery respectively.
the 115 Vac System and standby battery respectively.
the 235 Vac System and standby battery respectively.
the 28 Vdc bus system and main battery respectively
How is the 28 Vdc system powered when the 235 Vac system is energized?
Four DC generators
Two standby inverters
Auto Transformer Units
Power conversion devices
Power conversion devices
How is the aft external power system used during engine start?
It provides power to the Power Electronics Cooling System (PECS) and the aft galley.
It provides backup power for use during a left engine start.
It provides power to start the APU with external power.
It energizes only the motor controller required to perform a right engine start using external power as the sole power source.
It energizes only the motor controller required to perform a right engine start using external power as the sole power source.
With no other power source connected which electrical mode is active when a single forward external power receptacle is connected but not selected ON?
Ground Service mode
Standby Power mode
Towing Power mode
Ground Handling mode
Ground Handling mode
What electrical power source becomes active if a loss of all electrical power to captain’s and first officer’s flight instruments occurs in flight?
RPDUs
Ram Air Turbine (RAT)
Emergency Bus
APU Generator(s)
Ram Air Turbine (RAT)
The electrical synoptic shows a list of airplane systems affected by load shedding. Equipment that is inhibited or shed is also indicated…
by individual equipment caution messages.
in white on the affected system synoptic (AIR, FUEL, & HYD).
in the ECL Non-normal checklist.
by an individual EICAS message.
in white on the affected system synoptic (AIR, FUEL, & HYD).
If the APU is not available, engine start may be accomplished using external power. At a minimum, ___________________ external power source(s) is (are) required. In this configuration, either engine may be started first, however significant load shedding occurs and engine start time increases.
one 90 kVA
one 180 kVA
one 115 Vac
two 90 kVA
two 90 kVA
The Ram Air Turbine (RAT) deploys automatically with a loss of all electrical power to the captain’s and first officer’s flight instruments.
True
False
True
Two distinct power distribution methods include primary for higher amperage loads and remote for lower amperage loads. The primary power distribution distributes amperage loads greater than 10 amps directly from…
Remote Power Distribution Units (RPDU).
bus power panels located in forward and aft E/E bays.
PCDs.
starter/generators
bus power panels located in forward and aft E/E bays.
What is the power source for the braking system?
Center hydraulic system
Right hydraulic system
28 Vdc
115 Vac
28 Vdc
The airplane’s use of variable frequency power requires large motor loads to be energized by high voltage motor controllers that condition the power for use. The heat created by these high voltage motor controllers is dissipated by the…
Cabin Air Compressor (CAC) cooling air.
Integrated Cooling System (ICS) cooling air.
Power Electronics Cooling System (PECS).
Miscellaneous Equipment Cooling System (MECS).
Power Electronics Cooling System (PECS).
Electrical loads are dynamically managed so that loads are cycled on or off to efficiently use available airplane power. Flight deck control/indication, power transfer functions, and overall load management and protection for the electrical system is provided by the…
Bus Power Control Unit (BPCU).
Permanent Magnet Generators (PMG).
battery bus.
Power Conversion Devices (PCD).
Bus Power Control Unit (BPCU).
In addition to limited lighting and communications capability, Towing Power mode also provides electrical power for brakes. Towing Power mode is activated by…
selecting the BATTERY switch ON.
starting the APU.
selecting the TOWING POWER switch ON.
selecting EXTERNAL POWER switches ON
selecting the TOWING POWER switch ON.
The removal of electrical loads at predefined operational phases because the affected system is not required, or additional power is temporarily needed by another system is referred to as…
battery shed.
load inhibit.
load shed.
load priority.
load inhibit.
A list of airplane systems affected by load shedding can be found on the…
Electronic Checklist (ECL).
electrical synoptic.
Primary Flight Display (PFD).
Navigation Display (ND).
electrical synoptic.
Electrical power to some non-essential loads can be controlled from the flight deck overhead electrical panel. These include the In-Flight Entertainment system and the passenger seat system which are controlled by the_________ switch.
IFE/PASS SEATS
CABIN/UTILITY
BATTERY
FWD EXT PWR switch
IFE/PASS SEATS
With the APU and engine generators off, the External Power On mode is active when…
any external power source is connected with the associated AVAIL light illuminated.
two external power sources are connected and associated AVAIL light is illuminated.
only the aft external power source is connected and selected ON.
at least one forward external power receptacle is connected and selected ON.
at least one forward external power receptacle is connected and selected ON.
The Ground Service mode of the electrical system can be activated by a switch located on the…
overhead panel.
TCP panel.
master attendant panel switch.
ACP panel.
master attendant panel switch.
Three engine driven Permanent Magnet Generators (PMGs) are the primary source of power for the…
EECs.
large motor controllers.
flight control electronics.
APU batteries.
flight control electronics.
Both the main battery and APU battery provide power for towing during battery-only towing operations.
True
False
True
Two engine driven Permanent Magnet Alternators (PMAs) (one per engine) are the primary source of power for the…
flight control electronics.
CACs.
large motor controllers.
EECs.
EECs
The four main 235 Vac buses are designated as…
Bus 1, Bus 2, Bus 3, Bus 4.
Fwd 1, Aft 2, Fwd 3, Aft 4.
L1, L2, R1, R2.
Primary AC 1, Primary AC 2, Secondary AC 3, Secondary AC.
L1, L2, R1, R2.
A generator that has been disconnected from the engine by pushing the respective generator drive disconnect (DRIVE DISC) switch can subsequently be reconnected by the flight crew.
True
False
False
An EICAS message, _______________ (L1, L2, R1, R2) requires the crew to disconnect the generator drive. This action is irreversible by the flight crew.
DRIVE
ELEC GEN OFF
DRIVE DISC
ELEC GEN DRIVE
ELEC GEN DRIVE
The Circuit Breaker Indication and Control (CBIC) page can be shown on…
only the FO’s MFD.
the left AUX display.
any MFD.
only the Captain’s MFD.
any MFD.
While towing the aircraft using the TOWING POWER switch, the current state of charge of the batteries can be observed on the…
Electric synoptic.
AUX panel.
Towing Power panel.
Electrical pane
Towing Power panel.
Electrical power for APU start can be provided by the APU battery, engine generated power or…
forward external power.
aft external power.
aircraft PMAs.
PMGs.
forward external power.
For APU starts with the APU battery as the power source (no engine running and forward external power not ON), the right starter/generator is always used.
True
False
True
In flight, which APU starter/generator is used to supply electrical power?
Both
One or both, depending on the electrical load requirements of the aircraft
Right
Left
One or both, depending on the electrical load requirements of the aircraft
Two engine driven Permanent Magnet Alternators (PMAs) are the primary power source for the EECs. When a PMA is inoperative (including during engine start) a secondary source of power for the EECs is provided by the airplane’s…
battery bus.
28 Vdc bus distribution system.
115 Vac bus distribution system.
235 Vac bus distribution system.
115 Vac bus distribution system.
The majority of the airplane electrical loads are 115 Vac and 28 Vdc energized by the forward E/E bay power panels and Remote Power Distribution Units (RPDUs). A limited number of high voltage 235 Vac electrical loads are energized from the aft E/E bay. What changes power from one voltage or current type (AC/DC) to another?
Power conversion devices
Remote Power Distribution Units (RPDU)
Large motor controllers
Bus Power Control Unit (BPCU)
Power conversion devices
What electrical mode is active when the BATTERY switch is selected ON while the airplane is on the ground and there are no other power sources connected?
On-Ground Battery Only mode
Ground Handling mode
Ground Service mode
Battery mode
On-Ground Battery Only mode
How can the flight crew determine circuit breaker status?
Check the CBIC display.
Open CBs automatically display on EICAS.
Check the Electrical synoptic.
Check the Status page display.
Check the CBIC display.
What type of circuit breakers may be reset via the Circuit Breaker Indication and Control (CBIC) page?
Thermal
Electronic
Mechanical
Circuit breakers can not be reset via the CBIC
Electronic
With the airplane unpowered on the ground, selecting the battery switch to ON, …
initiates the left and right CCR start-up sequence.
powers the left inboard and outboard displays.
initiates the left CCR start-up sequence.
powers the left TCP.
initiates the left CCR start-up sequence.
