Electrical Flashcards

1
Q

Identify the location of the GROUND SERVICE bus switch

A

In the cabin on the forward flight attendant panel.

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2
Q

Recall the main AC power sources.

A
  • The Left and Right Engine Integrated Drive Generators (Engines Operating)
  • The APU Generator
  • External Power
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3
Q

Recall when the hydraulic driven generator activates (HDG equipped aircraft only).

A
  • The Hydraulic Driven Generator (HDG) activates automatically when both the Left and Right main AC busses are unpowered.
  • The HDG is powered by the Left hydraulic system on the
    757 if installed.
  • The HDG is powered by the Center hydraulic system on the
    767-300 and ER if installed.
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4
Q

List the components powered by the ground service bus.

A
  • The main battery charger.
  • The APU battery charger.
  • Miscellaneous cabin and system loads.
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5
Q

Identify how the ground handling bus can be powered

A

The ground handling bus can be powered only on the ground and only from the APU generator or from the external power source (AVAIL light illuminated

Note:
To accept late bags after pushback, the 757 must have APU power to operate the cargo doors.

To accept late bags after pushback, the 767 must have APU power to operate the right side cargo doors.

The manual bulk cargo door on the 767 can be used with no
power requirements.

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6
Q

Explain the function of the battery (BAT) switch

A

Unpowered airplane on the ground:

BAT switch off (ON not visible)
* Turns battery power off.

BAT switch ON
* Turns battery power on.
* Allows the APU to be started
* A few annunciator lights illuminate

Powered airplane on the ground or in flight, and AC power is removed or lost:

  • The battery bus and standby busses are powered.
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7
Q

Recall how long the battery will last on standby power

A
  • 30 minutes minimum powering standby AC and DC busses.

Note: The 757-300, the MAIN and APU batteries are paralleled for a standby power operation of 90 minutes.

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8
Q

Recall how landing gear extension and flap operation are affected if battery power is lost on a 767 without an operating HDG.

A
  • The flaps and gear CANNOT be extended.

Note:
- The normal landing gear and flap extension methods require
Center hydraulic pressure. Pressure will not be available.
- The alternate landing gear and flap extension methods require
electrical power. Power will not be available.

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9
Q

Identify where to find the major systems NOT available when operating on HDG power.

A
  • The QRH identifies the major systems NOT available when
    operating on HDG power.
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10
Q

Recall the meaning of an illuminated L/R UTILITY BUS OFF light and the conditions that cause the utility busses to load shed

A
  • Illuminated (amber) – the utility and galley busses are
    unpowered

Utility Bus load shedding
* Both thrust levers advanced on the ground with a single power source.

  • Overload.
  • Single generator operation in-flight.
  • Starting engines with the APU providing electrical power
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11
Q

Recall that galley power can shed without illumination of the L / R UTILITY BUS OFF lights. (Utility busses are still powered)

A
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12
Q

Recall what an EXT PWR AVAIL and an ON light indicates.

A

External Power Available (AVAIL) light

  • Illuminated (white) – external power is plugged in and the power quality is acceptable.

External Power ON light

  • Illuminated (white) – external power is powering the busses.
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13
Q

Recall what is indicated by an AC BUS OFF light.

A
  • Illuminated (amber) – the respective AC bus is unpowered.
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14
Q

Explain the meaning of a generator DRIVE light.

A
  • Illuminated (amber) –
  • The generator drive oil temperature is high
  • The generator drive oil pressure is low.
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15
Q

Explain the meaning of an illuminated APU GEN (generator) OFF light on the overhead electrical panel. (Switch ON)

A
  • The APU generator breaker is open because of a fault with the APU running.
  • The APU GEN switch is selected OFF.
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16
Q

Recall the meaning of a BAT discharge (DISCH) light.

A
  • Illuminated (amber) – the main battery is discharging
17
Q

Explain the meaning of an illuminated STBY POWER bus OFF light

A

Illuminated (amber) – standby AC and /or DC bus not powered.

18
Q

Explain the operation of the STBY POWER selector.

A
  • OFF – the standby busses are unpowered.
  • AUTO – the standby busses transfer to battery power if normal AC power is lost.
  • BAT – the standby busses are powered from the main battery
19
Q

Explain the function of the L/R GEN CONT (generator control)
switch.

A

Generator Control (GEN CONT) switches

  • ON (bar in view) –
  • Arms the generator control breaker to close automatically when generator power is available.
  • OFF (bar not visible):
  • Opens the generator control breaker.
  • Resets the fault trip circuitry
20
Q

Explain the function of the BUS TIE switches.

A
  • Provides power to both the main AC and DC Busses
  • Isolates faults
21
Q

Recall the function of the FLT INSTR BUS PWR switch (767 ER
only).

A
  • Off (ALTN not visible) – allows the hydraulic driven generator to power the Captain’s flight instruments
  • ALTN – allows the hydraulic driven generator to power the First Officer’s flight instruments