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Mesa ERJ E-JET 175 > Electrical Systems > Flashcards

Electrical Systems Flashcards

1
Q

What is the purpose of the DC GPU receptacle?

A

For APU start (the DC Fuel Pump in Right Tank) when batteries < 22.5VDC

or If battery temp is < 20C

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2
Q

How many volts are the NiCad Batteries normally?

A

22.8 V

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3
Q

DC TIES AUTO Selection does what?

A

System Logic from SPDA

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4
Q

Can the flight crew reset the ICC and SPDA remote electronic CBs?

A

ICC CB’s can only be reset by maintenance on the ground

SPDA CB’s can be reset via the MCDU

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5
Q

What type of circuit breakers can be reset by crew via MCDU?

A

Electric Circuit breakers in the SPDA’s (Secondary Power Distribution Assembly)

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6
Q

What busses does RAT power?

A

AC ESS BUS

STANDBY AC BUS

DC ESS buses via TRU ESS

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7
Q

What Hydraulic pump does the RAT ensure remains powered?

A

HYD PUMP 3A ( ACMP 3A)

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8
Q

Should the RAT deploy automatically following loss of all AC power ?

A

Yes after 8 seconds

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9
Q

What is the AC electrical system’s priority?

A

Onside (IDG)

Inside (APU)

Outside (GPU)

CrossSide (Other IDG)

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10
Q

If Batteries begin to discharge because the RAT does not deploy is there an EICAS message?

A

Yes BATTERY DISCHARGING

Manual Deployment required

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11
Q

How long will the aircraft’s batteries last with no recharging?

A

10 minutes

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12
Q

The DC GPU is used when?

A

Battery 2 temp less than 20 or battery no longer available for APU start.

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13
Q

What manages the electrical system?

A

4 Integrated Control Centers (ICC)

2 Secondary Power Distribution Assemblies (SPDA)

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14
Q

What is an SPDA?

A

Secondary Power Distribution Assembly

An electrical load management unit (powered by the ICC’s) that distributes electrical loads to aircraft systems according to the distribution logic

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15
Q

What are the two types of CBs?

A

Thermal and Electrical

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16
Q

What does Batt 1 Off selection do?

On?

A

Off - Opens the BC 1 contactor.

On - Closes BC1 Contactor

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17
Q

How long after deployment before the RAT will supply power?

A

8 seconds

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18
Q

After selecting DISC on the IDG selector does this cause the amber light adjacent to the knob to extinguish?

A

Yes

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19
Q

Cockpit circuit breakers are Non Remote and are Thermal or Electronic?

A

Non Remote Thermal breakers

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20
Q

What components power the DC system?

A
  • 2 NiCad batteries
  • 3 Transformer Rectifier Units (TRU)
  • DC GPU receptacle
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21
Q

What does the RAT power?

A

ESS BUSSES

(Directly powers AC ESS wich powers TRU ESS, which powers DC ESS BUS 3 which powers DC ESS BUS 1 and 2 through ETC 1 and 2)

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22
Q

How does Batt 2 Auto function?

A

Closes BC 2 contactor connecting Battery 2 to the ESS DC Bus 2 as long as APU Start is not being commanded using Battery #2.

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23
Q

Is there a total loss of power during the 8 second RAT deployment?

A

No Batteries supply power to the DC ESS BUSSES and AC STANDBY Bus

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24
Q

What happens if a power generating source fails?

A

Bus ties automatically connect to provide no system degradation.

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25
Q

How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?

A

GPU button displays AVAIL and the GPU icon is presented on the electrical synoptic page. Once the GPU button is pushed in the button will display “In USE”, provided another AC power source is not available.

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26
Q

What monitors and controls the IDG’s?

A

Each has a Generator Control Unit (GCU)

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27
Q

Can one IDG supply the entire electrical system?

A

Yes

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28
Q

TRU ESS OFF Selection does what?

A

Opens the TRU ESS Contactor

29
Q

How many networks make up the electrical system on the airplane? Why?

A
  • 2 independent networks
  • Redundancy and fault isolation
30
Q

Can the Thermal breakers in the ICC’s be monitored by the MCDU’s

A

Yes. All CB’s in all electronic bays can be monitored.

31
Q

What is the purpose of the Transformer Rectifier Units?

A

To convert 115 VAC to 28 VDC

32
Q

TRU 2 OFF Selection does what?

A

Opens 2 contactors TRU 2 Contactor and ESS 2 Contactor

33
Q

What powers the Ram Air Turbine (RAT)?

A

Airflow turns the RAT propeller which spins the turbine Inside

34
Q

What is the minimum battery temp for APU start?

35
Q

What battery is used for the APU start?

A

BATT 2: powers the APU Start Bus

BATT 1: powers the FADEC and EICAS for monitoring

36
Q

IF RAT Does not deploy is there anything AC Powered?IF So what and how?

A

Yes STANDBY AC BUS via INVERTER from DC ESS 1

37
Q

What does selecting the IDG selector to OFF do?

A

De excites the field for the IDG and opens the Generator Line contactor

38
Q

When will the RAT deploy?

A

automatically deploys if AC BUSSES are not powered

manually by pilot

39
Q

TRU 1 OFF Selection does what?

A

Opens 2 contactors TRU 1 Contactor and ESS 1 Contactor

40
Q

Why would you turn BATT 1 Switch from “On” to “Off”?

A
  1. Performing the “Leaving the Airplane” checklist
  2. To close the BTC1 connector for issolation of the bus
41
Q

For how long on the ground if the Aircraft is left Powered by only the batteries will a horn sound?

42
Q

DC TIES OFF Selection does what?

A

Opens 3 Contactors

DCTC

ETC 1

ETC 2

43
Q

What is the RAT minimum speed to ensure it can supply AC ESS and DC ESS buses?

44
Q

Electrical Emergency

A

Loss of both IDGS and APU GEN INFLIGHT

45
Q

What will charge the batteries?

A

Any AC power source

46
Q

What is an ICC?

A

An electrical Control device which provides power distribution and protection for electrical loads

47
Q

What is the primary purpose of the AC generators?

A

To power the AC BUSSES and AC ESS BUS which…

Power the 3 Transformer Rectifier Units (TRU) 1 & 2 and ESS

48
Q

If an IDG is manually disconnected can it be reconnected by the flight crew?

A

No.

This is A maintenance function

49
Q

What is on the AC STANDBY BUS?

A

Engine exciters 1A and 2A

50
Q

WHAT KVA can RAT produce?

51
Q

If the airplane is using the AC GPU and the APU is started what should the pilot be sure to do?

A

Deselect the GPU button

52
Q

What takes priority in the system APU GEN or AC GPU?

53
Q

When is the RAT icon displayed on the electrical synoptic page?

A

when the RAT is deployed

54
Q

What components power the AC system?

A
  • 2 Integrated Drive Generators (IDG)
  • Auxiliary Power Unit (APU ) - Inverter
  • Ram Air Turbine (RAT)
  • AC GPU receptacle
55
Q

When do IDGs come on line?

56
Q

How does the IDG maintain a stable power output?

A

A Constant Speed Drive (CSD) attaches the IDG to the AGB (Accessory Gear Box)

57
Q

What causes an IDG to come off line Automatically?

A

When manual disconnection is not performed and IDG oil temperature reaches Very hot (336F)

58
Q

Can the APU GEN and AC GPU be on line simultaneously?

A

Momentary paralleling can occur to avoid transients.

NBPT no break power transfer

59
Q

What is the minimum battery voltage to close the battery busties?

60
Q

What is the purpose of the Inverter?

A

Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS when an AC source is not available

61
Q

Where can possible ground resets procedures be found?

A

Some possible in QRH and others in VOL 1 Ground reset procedures section

62
Q

What is the minimum airspeed for the RAT?

A

130 knots

Load shedding occurs below this speed

63
Q

What will cause the amber IDG light on the overhead panel to illuminate?

A

High oil temperature & Low oil pressure

HOTLOP

64
Q

At what Battery temperature will you receive a BATT 1(2) OVTEMP?

A

70C for 2 sec

65
Q

Can the APU replace a failed IDG?

A

Yes. Up to 33000

66
Q

What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?

A

Ground service Bus is in USE

Cockpit GPU button will display “AVAIL” even though the Ground service Bus is in USE

68
Q

What is on Hot Batt Bus 1

A
  • Engine 1A/2A Fire Extinguisher
  • Engine Fuel Shutof f Valve 1
  • Hydraulic Shutof f Valve 1
  • Engine 1 Oil Level Indication
  • Courtesy/Service Lights
  • DC Ceiling Lights
69
Q

What is on Hot Battery Bus 2

A
  • Engine 1B/2B Fire Extinguisher
  • Engine Fuel Shutof f Valve 2
  • Hydraulic Shutof f valve 2
  • Engine 2 Oil Level Indication
  • CMC
  • Panel Ref uel
  • Water and Waste System

Mesa ERJ E-JET 175 (27 decks)

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