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Systems + Gen Ops > Electrical > Flashcards

Electrical Flashcards

1
Q

How long do the batteries last as the sole source of electrical power while on the ground?

A

About 15 minutes.

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2
Q

Describe the amplified procedure for selecting Batteries to AUTO during the Power Up Check?

A

Select the battery knobs to the AUTO position. Confirm the “AURAL UNIT OK” message is heard. Select the electrical systems page on the MFD to verify that the batteries have at least 24V and a temperature at or above -20° C.

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3
Q

Describe the amplified procedure for the Backup Battery check during the Power Up Check?

A

For the XR aircraft first flight of the day, deselect the backup battery button and ensure that the ISIS remains energized. The BKUP BATT OFF BUS caution message will appear when the backup battery is de-selected. This is a normal indication.

Contact maintenance if the ISIS goes blank.

Re-select the backup battery button.

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4
Q

Describe the amplified procedure for the MFD System Pages checked with regards to the Electrical Page during the Before Start Check?

A

On the electrical page, verify that all indications are normal for the current configuration of the electrical system (e.g., battery voltages and temperatures, generator amperages and voltages, GPU voltage).

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5
Q

What is the minimum battery voltage required to start the APU?

A

19V

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6
Q

What is the minimum battery temperature to start the APU?

A

-20ºC

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7
Q

What is the voltage range required to select the GPU?

A

26V - 29V

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8
Q

What does GPU AVAIL in the GPU select button indicate?

A

Indicates that the GPU is available. However, before selecting, make sure voltage is between 26 and 29V.

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9
Q

Which battery is used to provide power during a battery-assist APU start?

A

Battery #2

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10
Q

What amperage generates the EICAS caution message APU GEN OVLD?

A

When the APU amperage exceeds 400A.

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11
Q

Above what APU amperage is crewmember action required? What action is required?

A

If the load on the APU generator exceeds 500 amps, turn the #1 BATT knob to OFF. Once 3 minutes have passed or the load decreases below 400 amps, whichever occurs later, turn the #1 BATT knob back to AUTO.

This procedure will prevent the electrical system’s overcurrent protection from activating, which may cause the system to revert to essential power mode.

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12
Q

When are the Shed Buses powered?

A
  1. Rule of 3 - when at least 3 generators are online.
  2. APU running with the Shed Bus knob set to OVRD.
  3. GPU plugged in and selected.
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13
Q

When is the Ground Service Bus powered?

A

When the GPU is plugged in, not selected, and Batteries set to OFF.

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14
Q

How can the batteries be recharged?

A

Can be recharged by the APU or Engine Generators.

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15
Q

What is powered by the AC Bus?

A

TCAS, EGPWS, and Windshear

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16
Q

Describe the normal visual indication of loss of all generators?

A

Donut Hole - EICAS, RMU 1 and 2, and ISIS are powered.

17
Q

How long do the batteries last as the sole source of electrical power during loss of all generators?

A

About 40 minutes.

18
Q

What approaches may/may not be flown in essential power?

A

In essential power only Localizer and VOR approaches can be flown. No DME or RNAV available.

19
Q

What is the meaning of the EICAS caution message ELEC EMERG ABNORMAL?

A

The system went into essential power mode, even though the generators may still be online.

20
Q

What is the meaning of the EICAS caution message ELEC ESS XFER FAIL?

A

The system has failed to properly transfer into essential power mode following the loss of all generators. Some instruments may still be online. You have more than the normal Donut Hole.

21
Q

Describe the company Circuit Breaker Policy?

A

Tripped on Ground:
If a circuit breaker is tripped on the ground, do not reset until contacting Maintenance Control to discover the cause.

Tripped in Flight:
A circuit breaker must not be reset unless doing so is consistent with QRH procedures or unless the PIC determines that resetting the circuit breaker is necessary for the safe completion of the flight.

Resetting Circuit Breaker:
Before attempting to reset/cycle the breaker, a three minute cool down period is required.

If the circuit breaker trips again, DO NOT ATTEMPT ANOTHER RESET/CYCLE!

Resetting the fuel pump circuits for the fuel quantity indicating system is prohibited.

22
Q

Can the GPU be used to recharge the batteries?

A

No. BC1 and BC2 open automatically when the GPU is selected and supplying power.

23
Q

What items are powered from the inverter via 115 VAC Bus?

A

TCAS, EGPWS, and Windshear

24
Q

Which electrical bus supplies power to the ISIS on the 145XR? 145LR?

A

On the 145XR, ISIS is powered by the Backup Battery Hot Bus. On the 145LR, the ISIS is essentially powered.

25
Q

Under what conditions are shed buses powered while on the ground assuming the SHED BUS knob is not in the OFF position?

A
  1. With GPU powering the aircraft and the shed bus switch in the auto or override position.
  2. With at least one generator online and the shed bus in the override position.
  3. With 3 or more generators online.
26
Q

What criteria must be established to have the shed buses powered in flight?

A

At least 3 generators must be online for shed bus power in flight.

27
Q

Is DME available in essential power mode?

A

No, but VOR or Localizer based approaches may be flown so long as DME is not required.

28
Q

What is the purpose of de-selecting the backup battery on the first flight of the day for XR aircraft?

A

De-selecting the backup battery button isolates the backup battery and the backup battery hot bus, which allows for a visual confirmation that the backup battery is charged.

If the test is done after selecting the GPU or starting the APU, the backup battery system will not isolate and the test is not valid.

29
Q

What happens when the ESS PWR button is pressed?

A

It forces the electrical system into essential power mode regardless of the Electrical Distribution Logic (EDL).

30
Q

How is the overhead circuit breaker panel organized?

A

Panel is divided into buses. Rows are labeled with letters. Columns are labeled with numbers.

31
Q

What is the Rule of 4?

A

You must have 4 generators online to have two independent electrical systems.

32
Q

During starting of the APU, when does the APU generator come online?

A

After the APU RPM exceeds 95% for 7 seconds.

33
Q

If both the GPU is selected and APU is running, which will power the aircraft?

A

GPU is king. As long as the GPU is connected, it will power the airplane over other sources. No matter what, power will be drawn from the GPU.

34
Q

Describe the different ways to start the APU?

A
  1. Can start APU from GPU.
  2. Can start APU from Battery #2
  3. Can start APU from Battery #2 assisted by another generator online.
35
Q

What buses are powered in essential power mode?

A

Central DC Bus, Hot Bus 1 and 2, Essential DC Bus 1 and 2, Backup Essential Bus, and Backup Hot Bus.

36
Q

If the system goes inadvertently into essential power mode on the ground, what should be done?

A

QRH is used to reset the system only on the ground. Then contact maintenance.

Systems + Gen Ops (21 decks)

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