electrical

Question 1

List the AC Power Components
A
List the AC Power Components

1. (2) IDGs (primary) 115 VAC, 400 Hz, 40 KVA, three phase
2. (1) APU115 VAC, 400 Hz, 40 KVA, three phase
3. (1) AC GPU Receptacle 115 VAC, 400 Hz, 40 KVA, three phase
4. (1) RAT - 115 VAC, 400 Hz, 15 KVA, three phase
5. ## (1) Inverter 250 VDC to 115 VAC direct to AC STBY BUS, one phase

2
Q
List AC Power Priority
A
List AC Power Priority

1. Onside (IDG)
2. Inside (APU)
3. Outside (AC GPU)
4. ## X-Side (Other IDG)

3
Q
What components power the DC system?
A
What components power the DC system?
3 TRUs (Transformer Rectifier Units) – 28VDC, 300A
2 Batteries – 22.8VDC, 27AH
1 DC GPU – 28VDC
–

4
Q
TRUs (Transformer Rectifier Units)
A
TRUs (Transformer Rectifier Units)

Primary DC power source
Converts 115VAC into 28VDC
Each works in isolation from the other
–

5
Q
Batteries
A
Secondary DC power source
2 NiCad batteries
Back-up for DC ESS
Charged via any AC power source thru the TRUs
18.0 volts minimum required to close the battery contactor
Will provide 10 minutes of power during an electrical emergency
–

6
Q
DC GPU
A
Hooks directly to the APU start bus and replaces BATT 2 during APU start.
Can only be turned on by a ground ramp button
Cannot charge BATT 2
–

7
Q
How many networks make up the electrical system on the airplane? Why?
n
A
How many networks make up the electrical system on the airplane? Why?
2 independent networks
Redundancy and fault isolation
–

8
Q
What happens if a power generating source fails?
A
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation.
–

9
Q
IDG in off means?
A
IDG in off means?

10
Q
IDG in disc means?
A
IDG in disc means?

11
Q
What happens if IDG stays on after disc light comes on?
A
It will shear if it is too much torque or melt if too hot.
–

12
Q
How does the IDG maintain a stable power output?
A
How does the IDG maintain a stable power output?

13
Q
What monitors and controls the IDG’s?
A
What monitors and controls the IDG’s?

14
Q
Can one IDG supply the entire electrical system?
A
Can one IDG supply the entire electrical system?
Yes
–

15
Q
What will cause the amber IDG light on the overhead panel to illuminate?
A
What will cause the amber IDG light on the overhead panel to illuminate?
High oil temperature 335F
Low oil pressure 140PSI
–

16
Q
Can the GPU power both buses?
A
Can the GPU power both buses?

17
Q
What does the DISC position on the IDG do?
A
What does the DISC position on the IDG do?

Disconnects IDG from CSD. If this fails it mechanically shears off
the CSD from the IDG
–

18
Q
If an IDG is manually disconnected can it be reconnected by the flight
crew?
A
If an IDG is manually disconnected can it be reconnected by the flight
crew?

19
Q
When do you know you need to DISC the IDG?
A
When do you know you need to DISC the IDG?

LOW Oil pressure low 140psi
HOT Oil temp high 335F
Amber light is on

20
Q
Flight crew can reconnect IDG after DISC has been engaged?
A
Flight crew can reconnect IDG after DISC has been engaged?
No, that is a MX function on the ground
–

21
Q
What is the primary purpose of the AC generators?
A
What is the primary purpose of the AC generators?

To power the AC BUSES and AC ESS BUS which…
Power the 3 Transformer Rectifier Units (TRU) 1, 2, and ESS
–

22
Q
What is the purpose of the Transformer Rectifier Units?
A
What is the purpose of the Transformer Rectifier Units?
To convert 115 VAC to 28 VDC
–

23
Q
Can the APU replace a failed IDG?
A
Can the APU replace a failed IDG?
Yes
–

24
Q
How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?
A
How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?

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.
–

25
Q
What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?
A
What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?

Ground service bus is in use
Cockpit GPU button will display AVAIL even though the ground service bus is in use
–

26
Q
If the airplane is using the AC GPU and the APU is started what should the pilot be sure to do?
A
If the airplane is using the AC GPU and the APU is started what should the pilot be sure to do?

27
Q
What (2) combinations provide power to accomplish APU
START?
A
What (2) combinations provide power to accomplish APU
START?
1. BATTs 1 & 2
2. BATTs 1 and DC GPU
–

28
Q
Which Battery controls the APU’s FADEC?
A
Which Battery controls the APU’s FADEC?

29
Q
Which battery is isolated from the network during APU
START to exclusively power the APU START BUS?
A
Which battery is isolated from the network during APU
START to exclusively power the APU START BUS?

30
Q
What is the minimum VDC required during the Safety &
Power On Checklist to consider APU Start?
A
What is the minimum VDC required during the Safety &
Power On Checklist to consider APU Start?

31
Q
What is the minimum battery voltage required to close the battery
contactor?
A
What is the minimum battery voltage required to close the battery
contactor?

32
Q
What is the min BATT 2 temp for APU start?
A
What is the min BATT 2 temp for APU start?

33
Q
The APU is a primary AC source (T/F)
A
The APU is a primary AC source (T/F)

34
Q
What is the purpose of the DC GPU receptacle?
A
What is the purpose of the DC GPU receptacle?

For APU start when batteries < 22.0 VDC, or
If battery temp is < -20°C
–

35
Q
How many ways can the AC GPU be turned on?
A
How many ways can the AC GPU be turned on?

1. AC GPU panel (AC/DC GS Panels & TRU 1)
2. (1) Opp. FWD Lav (AC/DC GS Panels & TRU 1)
3. ## (1) Switch Cockpit Overhead Panel (Powers whole aircraft network)

36
Q
What battery is used for the APU start?
A
What battery is used for the APU start?

BATT 2 powers the APU Start Bus
BATT 1 powers the FADEC & EICAS for monitoring
–

37
Q
What is the purpose of the Inverter?
A
What is the purpose of the Inverter?

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

38
Q
What is on the AC STANDBY BUS?
A
What is on the AC STANDBY BUS?
Engine exciters 1A and 2A
–

39
Q
What powers the Ram Air Turbine (RAT)?
Airflow turns the RAT propeller which spins the turbine inside
A
What powers the Ram Air Turbine (RAT)?

40
Q
When will the RAT deploy?
A
When will the RAT deploy?

Automatically deploys if AC BUSES are not powered or
Manually by pilot
–

41
Q
What’s powered by the rat?
A
What’s powered by the rat?

42
Q
What’s powered by AC ESS Bus?
A
What’s powered by AC ESS Bus?
Hydraulic3a
Right tank fuel AC pump
Flaps and Slats(only to 3 and half speed) *
Standby bus
–

43
Q
What does the RAT powers?
A
What does the RAT powers?

AC ESS bus which powers the AC Standby Bus,
the TRU ESS Bus directly powering DC ESS Bus 3 which powers DC ESS BUs 1&2
–

44
Q
Is there a total loss of power during the 8 second RAT deployment?
A
Is there a total loss of power during the 8 second RAT deployment?

45
Q
What is an example scenario you would manually deploy the
RAT?
A
What is an example scenario you would manually deploy the
RAT?

1. ## Auto RAT deployment doesn’t work

46
Q
What is the min RAT speed to avoid load shedding?
A
What is the min RAT speed to avoid load shedding?

47
Q
What happens under 130 kts for the RAT?
A
What happens under 130 kts for the RAT?

1. RAT only powers AC ESS
2. BATTs provide power only to DC ESS and AC STBY (thru static inverter)
3. ## Load shedding continues until AC ESS is no longer powered

48
Q
What does the BATTs backup?
A
What does the BATTs backup?

DC ESS Buses and AC STBY Bus through the inverter.
The static inverter (AC/DC inverter) converts 28 V DC power from batteries to 115 V AC power to supply the STANDBY AC BUS when an AC power source is not
available.
–

49
Q
What manages the electrical system?
A
What manages the electrical system?

4 Integrated Control Centers (ICC) they collect and confirm, distributes the power SPDA
2 Secondary Power Distribution Assemblies (SPDA)
–

50
Q
Can the DC GPU charge BATT 2?
A
Can the DC GPU charge BATT 2?

51
Q
Which battery does the DC GPU replace during an APU
Start?
A
Which battery does the DC GPU replace during an APU
Start?
Hooks directly to APU START Bus and replaces BATT 2
The ICCs, collect and confirm the power is safe and then send it to the SPDAs for distribution
–

52
Q
What is an SPDA?
A
What is an SPDA?
An electrical load-mgmt unit powered by the ICC’s that distributes
electrical loads to aircraft systems according to distribution logic.
–

53
Q
How many ICCs are there?
A
How many ICCs are there?

1. LICC (Mid E-Bay)
2. RICC (Mid E-Bay)
3. EICC (FWD E-Bay)
4. ## AICC (AFT E-Bay)

54
Q
How many SPDAs are there and where are they located?
A
How many SPDAs are there and where are they located?

1. SPDA 1 (FWD E-Bay)
2. ## SPDA 2 (Mid E-Bay)

55
Q
Thermal/Electronic CBs apply to what?
A
Thermal/Electronic CBs apply to what?

ICCs Thermal CBs (thermal 1st line of defense)
SPDAs Electronic CBs (elec. 2nd line of defen
–

56
Q
Thermal CBs are resettable in the MCDU?
A
Thermal CBs are resettable in the MCDU?

57
Q
Which part of the electrical system performs BITs?
A
Which part of the electrical system performs BITs?
SPDAs
–

58
Q
What is on DC HOT Bus 1?
A
What is on DC HOT Bus 1?
1. Eng 1A/2A Fire EXT
2. Eng FSOV 1
3. HYD SOV 1
4. Eng 1 Oil Level Indication
5. Courtesy/Service Lights
6. DC Ceiling Lights
–

59
Q
What is on DC HOT Bus 2?
A
What is on DC HOT Bus 2?
1. Eng 1B/2B Fire EXT
2. Eng FSOV 2
3. HYD SOV 2
4. Eng 2 Oil Level Indication
5. CMC
6. Panel Refuel
7. Water and Waste System
–

60
Q
Can the APU replace a failed IDG?
A
Can the APU replace a failed IDG?
Yes, start at 30,000 and max op ALT at 33,000
–

61
Q
What are the 3 types of BITs?
A
What are the 3 types of BITs?

1. Continuous Tests
2. Fault-Initiated Tests
3. ## Initiated Tests

62
Q
What 3 systems/components have BITs?
A
What 3 systems/components have BITs?

1. GCUs
2. AGCU (AUXILIARY GENERATOR CONTROL UNIT. The AGCU is a microprocessor-controlled assembly that provides control, protection, and distribution of power generated by the APU generator.)
3. ## SPDAs

63
Q
What is on the LICC?
A
What is on the LICC?

1. AC BUS 1 with BTC 1
2. AC/DC GND SVC
3. TRU 1
4. ## DC BUS 1 with DCTC 1

64
Q
What is on the RICC?
A
What is on the RICC?

1. AC BUS 2 with BTC 2
2. TRU 2
3. DC BUS 2
4. ## DC ESS BUS 2 with ETC 2

65
Q
What is located in the MID E-Bay?
A
What is located in the MID E-Bay?

1. SPDA 2
2. RICC & LICC
3. MAU 3
4. ## Modular Radio Cabinets MRCs (radios/TDRs)

66
Q
What EICAS message is displayed if RAT Fails to deploy?
A
What EICAS message is displayed if RAT Fails to deploy?

67
Q
Where is the static inverter located?
A
Where is the static inverter located?

68
Q
What kind of power does the inverter create?
A
What kind of power does the inverter create?

69
Q
Where are the batteries located?
A
Where are the batteries located?

BATT 1 = FWD E-BAY
BATT 2 = AFT E-BA
–

70
Q
What is located in the FWD E-Bay?
A
What is located in the FWD E-Bay?

1. BATT 1
2. SPDA 1
3. EICC
4. Static Inverter
5. MAUs 1 & 2
6. TCAS
   7.MRC1
   8.CMC
   –

71
Q
What is still powered when just the batteries are powering
the system (elec. emer)? When else are just these
instruments avail?
A
What is still powered when just the batteries are powering
the system (elec. emer)? When else are just these
instruments avail?

Compass backlight
1. DU 2 and 3
2. IESS
3. Clock
4. MCDU 2,
5. CCD 1
6. Audio Panels
7.Horizontal trim
–

72
Q
What is the EICAS message ELEC EMERGENCY indicate?
A
What is the EICAS message ELEC EMERGENCY indicate?

73
Q
Why is 3 phase power used over single phase?
A
Why is 3 phase power used over single phase?

3 phase power is constant at every instance nd the average
power is 1.5 times the maximum power of one phase.
2 phase average power is equal to max power of one phase
1 phase average power is equal to 0.5 the max power of one
phase
–

74
Q
When does BATT 1(2) OVERTEMP EICAS message come on?
A
When does BATT 1(2) OVERTEMP EICAS message come on?

75
Q
How many slots do MAUs 1, 2, and 3 contain?
A
How many slots do MAUs 1, 2, and 3 contain?

MAU 1 = 20 slots
MAU 2 & 3 = 16 slots
–

76
Q
What is the name of the electrical wiring that connects and
integrates the ICCs, SPDAs, and MCDUs together?
A
What is the name of the electrical wiring that connects and
integrates the ICCs, SPDAs, and MCDUs together?

77
Q
What kind of electronic CBs are located in the SPDAs?
A
What kind of electronic CBs are located in the SPDAs?

78
Q
The AC GPU button, located on the electrical system panel, controls the AC external power. Once the AC GPU is connected to the airplane and ________, an AVAIL light illuminates on the GPU button

Pushing the AC GPU button in connects external power to the ____, according to AC source priority. The AVAIL light extinguishes and an ____ light illuminates.
A
power quality requirements voltage/amperage/frequency) are within accepted limits,

AC BUS TIE

79
Q
RAT powers what big 3 electrical components
A
hydro 3A

right AC fuel pump

80
Q
electrical PBIT takes how many minutes and what not to do
A
3 minutes
don’t turn on the hydro pumps
–

81
Q
flap position if RAT deployed
A
flaps 3
–

82
Q
IDG oil system is air cooled
A
.
–

83
Q
Is there still cabin pressure while rat is deploying? What after deployment?
A
Is there still cabin pressure while rat is deploying? What after deployment?
Yes pressurized if packs still on.
If not, After deployment ,you have of follow QRH, if at appropriate
altitude, pressurization can start using APU or at appropriate altitude
–

84
Q
What is the PMA?
A
What PMA?

DC ESS Bus powered below 50% N2
Fadec is powered by PMA after 50% N2.
PMA is permanent magnet alternator separates FADEC from the electrical system to have its own.
–

85
Q
If using GPU then turned on APU, what happens?
A
If using GPU then turned on APU, what happens?
APU takes over
Turns from In-Use to AVAIL
–

86
Q
Gnd service bus powers?
A
Gnd service bus powers?

Fuelpanel
Courtesy/ceilinglights
–

87
Q
Why does it take 8 secs for the rat to deploy?
A
Why does it take 8 secs for the rat to deploy?

88
Q
When does the inverter comes on?
A
When does the inverter comes on?
same sequence as the rat when there is a complete loss of Ac power
Mainly to powers the ESS bus to power STBY bus. to keep the igniters on for the 8
secs.
–

89
Q
Why does it take 8 secs for the rat to deploy?

To adjust the blade angel for constant speed
A
Why does it take 8 secs for the rat to deploy?

To adjust the blade angel for constant speed