Electrical

Question 1

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

Answer 1

About 15 minutes.

Question 2

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

Answer 2

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.

Question 3

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

Answer 3

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.

Question 4

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

Answer 4

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).

Question 5

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

Answer 5

19V

Question 6

What is the minimum battery temperature to start the APU?

Answer 6

-20ºC

Question 7

What is the voltage range required to select the GPU?

Answer 7

26V - 29V

Question 8

What does GPU AVAIL in the GPU select button indicate?

Answer 8

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

Question 9

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

Answer 9

Battery #2

Question 10

What amperage generates the EICAS caution message APU GEN OVLD?

Answer 10

When the APU amperage exceeds 400A.

Question 11

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

Answer 11

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.

Question 12

When are the Shed Buses powered?

Answer 12

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.

Question 13

When is the Ground Service Bus powered?

Answer 13

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

Question 14

How can the batteries be recharged?

Answer 14

Can be recharged by the APU or Engine Generators.

Question 15

What is powered by the AC Bus?

Answer 15

TCAS, EGPWS, and Windshear

Question 16

Describe the normal visual indication of loss of all generators?

Answer 16

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

Question 17

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

Answer 17

About 40 minutes.

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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.

Question 21

Describe the company Circuit Breaker Policy?

Answer 21

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.

Question 22

Can the GPU be used to recharge the batteries?

Answer 22

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

Question 23

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

Answer 23

TCAS, EGPWS, and Windshear

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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.

Question 26

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

Answer 26

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

Question 27

Is DME available in essential power mode?

Answer 27

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

Question 28

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

Answer 28

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.

Question 29

What happens when the ESS PWR button is pressed?

Answer 29

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

Question 30

How is the overhead circuit breaker panel organized?

Answer 30

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

Question 31

What is the Rule of 4?

Answer 31

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

Question 32

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

Answer 32

After the APU RPM exceeds 95% for 7 seconds.

Question 33

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

Answer 33

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.

Question 34

Describe the different ways to start the APU?

Answer 34

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.

Question 35

What buses are powered in essential power mode?

Answer 35

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

Question 36

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

Answer 36

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