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767 > 6 - Electrical > Flashcards

6 - Electrical Flashcards

1
Q

What does the APU Generator (APU GEN) Control Switch do?

A
  • arms APU generator breaker to automatically close
  • opens APU generator breaker
  • resets fault trip circuitry
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2
Q

What do the BUS TIE Switches do?

A
  • arms/opens automatic AC bus tie circuits
  • arms/opens automatic DC bus tie circuits
  • arms/opens automatic flight instrument transfer bus circuits
  • resets fault trip circuitry

(Flight instrument transfer bus auto transfer for BUS OFF only if BUS TIE switch is in AUTO)

(Both BUS TIE breakers must be in AUTO for DC bus tie breaker to work)

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3
Q

What do the Generator Control (GEN CONT) Switches do?

A
  • arms the generator breaker to close automatically when generator power is available
  • opens generator breaker
  • resets fault trip circuitry
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4
Q

External Power Available (AVAIL) Light

Illuminated (white) –

A

external power is plugged in and power quality is acceptable

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5
Q

What do the UTILITY BUS Switches do?

A
  • connects/disconnects utility and galley busses to main AC bus
  • resets overload/load shed circuitry
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6
Q

What happens when you push a GEN DRIVE DISC Switch?

A
  • disconnects generator drive from the engine

* requires maintenance action on the ground to reconnect the generator drive.

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7
Q

What does a Generator DRIVE light indicate?

A
  • the generator drive oil temperature is high

* the generator drive oil pressure is low

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8
Q

What happens with the BAT switch ON:

  • Unpowered airplane
  • Powered airplane (when AC power is lost/removed)
A
  • a few annunciator lights illuminate
  • allows the APU to be started

• the standby and battery busses are powered (with STBY POWER in AUTO)

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9
Q

What happens if AC power is lost with Standby (STBY) POWER Selector in AUTO?

How long will it last?

A

the standby busses transfer to battery power (Main and APU)

90 min

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10
Q

A hydraulic driven generator operates _____ as a backup source of power in the event _____

A

automatically (no time limit)

both main AC busses lose power

(less than 1/10 the power of an engine driven generator)

(may have BAT DISCH light because HDG DC output low)

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11
Q

The source order for powering left/right main busses is:

A
  • respective IDG
  • APU generator
  • opposite IDG
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12
Q

The ground service bus is normally powered by _____

Alternate sources of power for the ground service bus are _____

A

right main bus

  • the APU generator
  • external power
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13
Q

The ground service bus powers:

A
  • the main battery charger
  • the APU battery charger
  • miscellaneous cabin and system loads
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14
Q

The ground handling bus is powered (only on the ground) by _____ , and powers ______

A

APU generator or external power source

cargo handling and equipment

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15
Q

During autoland, the busses isolate to allow three independent sources to power the three autopilots:
• the left main system powers _____
• the right main system powers _____
• _____ powers the center autopilot

A
  • the left autopilot and the captain’s flight instrument transfer bus
  • the right autopilot and the first officer’s flight instrument transfer bus
  • the battery/standby system

(Reverts to normal for autopilot GA or disengage)

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16
Q

Normally, the captain’s flight instruments are powered by _____ and the first officer’s flight instruments are powered by _____

If the bus tie breakers are in AUTO, the flight instrument transfer busses transfer to _____

If power is lost to both main AC busses, the captain’s flight instruments are powered by _____

A

left main AC Bus

right main AC Bus

opposite main AC bus

hydraulic driven generator.

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17
Q

Left and right AC transfer busses power items considered necessary for ETOPS (which are not powered by the battery/standby system)

Transfer busses are normally powered by _____ ,
but also can be powered by _____ when both AC busses are unpowered

A

associated main AC busses

Hydraulic Driven Generator

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18
Q

The main DC electrical system uses _____ to produce DC power, which are powered by _____

A

transformer-rectifier units (TRUs)

main AC busses

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19
Q

The TRUs operate isolated from one another

If one TRU fails, the ______ closes to keep both DC busses powered

Both _____ switches must be in AUTO for the _____ to close

A

DC bus tie breaker

BUS TIE

DC bus tie breaker

20
Q

Where are the flight deck controls for the main DC electrical system located?

A

There are no flight deck controls for the main DC electrical system

21
Q

The Battery/Standby Power System consists of the following busses:

A
  • the hot battery bus
  • the battery bus
  • the standby AC bus
  • the standby DC bus
22
Q

What is the power source for the hot battery bus?

A
  • Main battery

- Battery charger powered from the ground service bus

23
Q

Prior to establishing electrical power _____ powers the hot battery bus

After establishing electrical power _____ powers the hot battery bus

A

main battery

main battery charger (powered by the Ground Service Bus)

24
Q

After establishing electrical power _____ powers the battery bus, and _____ provides a backup source of power

A

left DC system

main battery

25
Q

What does the HDG (Hydraulic Driven Generator) power? (7, 4-AC, 3-DC)

A
  • CA Flight Instrument Transfer bus
  • L AC Transfer bus
  • R AC Transfer bus
  • Stby AC bus
  • Stby DC bus
  • Battery bus
  • Hot Battery bus

(L FMC, flap posit, auto press controllers, stby engine indications, ISFD, CA pitot heat)

26
Q

What happens if you get an APU FAULT light?

A

immediate automatic shutdown (no cool down)

27
Q

How long can the Main Battery power the STBY Power system?

A

30 min

CBT says 90 min for Main and APU batteries

28
Q

On STBY Power if battery is depleted (30 min), what is the effect on flaps and gear?

A

C ADP pneumatic supply valve closes with loss of DC power. No way to hydraulically operate flaps and gear.

29
Q

What happens when you place BAT switch to ON?

A

allows battery to power Battery Bus if no other source is available

30
Q

What happens with STBY POWER selector to AUTO?

A

the STBY busses transfer to battery power if normal AC power is lost

(AC STBY bus normally powered by L AC bus. If L AC power is lost, DC tie bus powers STBY Inverter. If both AC busses are unpowered, main BAT powers STBY Inverter)

(DC STBY bus normally powered by L DC bus)

31
Q

What does a STBY POWER OFF light mean?

A

loss of power to STBY AC and/or STBY DC bus

32
Q

What does a Bus Tie ISLN light mean? Due to _____ (2)

A

BTB open due to a fault or switch OFF

33
Q

What does a GEN Drive Disc DRIVE light mean?

A

high oil temp or low oil press

34
Q

What does a Gen Cont OFF light mean?

A

generator breaker open

35
Q

When do utility busses shed? (4)

The galley bus is powered by the left utility bus, and has no direct controls or indications

A

BOSS

B - both T/Ls TO range on ground with engines shutdown

O - overload of available electrical power

S - starting engines

S - single GEN source

36
Q

What is max altitude for APU power?

A

FL 431

37
Q

What happens to the APU if you get an APU FAULT light?

A

immediate automatic shutdown with no cool down

38
Q

APU Starter limit

A

3 attempts in 60 min

39
Q

What happens if BAT Switch is turned OFF with APU running?

A

APU shutdown after cool down cycle without fire detection

40
Q

Hot Battery Bus powers (10)

regardless of BAT switch position

A
  • Clock time base
  • IRS emergency power
  • Equipment cooling ground warning
  • Fire extinguisher bottles
  • Fueling system
  • APU fuel shutoff valve
  • Wing spar fuel shutoff valve
  • Alternate landing gear extension
  • Parking brake valve
  • RAT manual deployment
41
Q

What is powered from the Battery Bus? (5)

A
  • Fire detection
  • PA system
  • Fuel quantity indicating system
  • Stby engine indications
  • Alternate stab trim
42
Q

What is powered by the STBY POWER system? (5)

A
  • Stby instruments
  • L VHF, VOR, RDMI
  • C ILS
  • Instrument panel flood lights
  • Manual pressurization control
43
Q

Normal load shedding during engine start (3)

A
  • an electric hydraulic pump
  • center tank fuel pumps
  • utility buses
44
Q

How is the Ground Handling Bus powered and what is on the bus?

A

EXT (AVAIL) or APU

  • Cargo systems
  • Cargo lights
  • Maint access lights
  • Fueling systems
45
Q

How is the Ground Service Bus powered and what is on the bus?

A
  • R main bus
  • APU
  • EXT
  • Main/APU battery chargers
  • Left forward fuel pump
  • Cabin lighting and outlets
  • Misc cabin and system loads
46
Q

What happens with a L or R BUS OFF light illuminates?

only if BUS TIE switches in AUTO

A
  • Flight instrumental transfer bus switches to other bus
  • DC bus tie closes to keep the DC busses powered
  • (L bus fail) Stby AC bus powered from the Stby Inverter
  • (R bus fail) Lower EICAS screen blanks
47
Q

If EXT power is powering both main busses what happens when the APU is started and APU GEN becomes available?

What happens if IDGs or APU Gen are powering both main busses and EXT is selected ON?

A

Nothing. EXT continues to power both busses until switched off.

EXT powers both main busses

767 (21 decks)

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