ELECTRICAL

Question 1

What is the purpose of ELMS?

Answer 1

To provide load management and protection to ensure power is available to critical and essential equipment

Question 2

What loads does ELMS shed first?

Answer 2

Galleys first and then utilities

Question 3

What indication is there of ELMS load shedding?

Answer 3

LOAD SHED on EICAS

Question 4

List the main electrical sources?

Answer 4

L GEN
R GEN
APU GEN
Primary and secondary EXT power

Question 5

What will cause the EICAS message ELEC GEN DRIVE and what are your actions?
What will happen technically when the action is executed?

Answer 5

Low oil pressure being detected in an IDG
You should then immediately disconnect the IDG by pushing the respective DRIVE DISCONNECT switch. When you press that switch with the fuel control switches in the RUN position, the two-piece IDG input shaft moves apart.

Question 6

What causes automatic disconnection of an IDG?

Answer 6

The melting of a thermal plug at high drive temperature that causes a disconnect to happen

Question 7

When will the APU start automatically?

Answer 7

If both transfer busses are unpowered

Question 8

When does the EXT PWR AVAIL light illuminate?

Answer 8

When the external power source voltage and frequency are within limits

Question 9

What is the generator priority for main AC Busses?

Answer 9

In flight:

1. The respective IDG
2. APU
3. Opposite IDG

Question 10

What is normally the source for the ground service bus?

Answer 10

The right AC main bus

Question 11

How is the ground service bus powered without supply from the main bus?

Answer 11

With the APU or external power.

Question 12

What Equipment is powered by the Ground Service Bus?

Answer 12

Main battery charger
APU battery charger
Miscellaneous cabin systems and loads

Question 13

How can the Ground Handling Bus be powered?

Answer 13

From APU or EXT PWR source

Question 14

What Equipment is powered by the Ground Handling Bus?

Answer 14

Cargo handling
Fueling/de-fueling
The powered door opening system for the engine cowls.

Question 15

Which busses can be supplied by the Back up GENs?

Answer 15

R AC transfer Bus

L AC transfer Bus

Question 16

What unit converts the Back up GENs frequency?

Answer 16

A frequency converter

Question 17

How many back up generators can be used at a time?

Answer 17

Only one, as they both connect to the same frequency converter

Question 18

How many PMG are in each back up generator?

Answer 18

2

Question 19

What are the two PMGs in each back up generator used for?

Answer 19

Supplying DC Power to the flight control DC electrical system

Question 20

How are the TRUs supplied?

Answer 20

By the AC transfer busses

Question 21

What normally powers the HOT BAT BUS?

Answer 21

The main battery charger

Question 22

What is the purpose of the APU battery?

Answer 22

To provide dedicated Power to the APU Electric starter and APU control unit in case there is insufficient bleed air duct pressure for the APU air turbine starter (ATS)

Question 23

What is the secondary power source for the C FCDC PSA?

Answer 23

The captains flight instrument bus

Question 24

Which FCDC PSAs can be powered by the hot battery bus?

Answer 24

The left and Centre PSAs

Question 25

How long can the dedicated PSA battery provide Power for?

Answer 25

Max 10 minutes

Question 26

What is the purpose of the dedicated PSA battery?

Answer 26

To prevent interruptions to the related flight control DC bus

Question 27

What items does the standby electrical system supply power to?

Answer 27

Selected flight instruments, Communications and navigation systems and the flight control system AC: Center ILS, Radio alt, ENG igniters, VOR left DC: Captains and F/O s flight instument displays

Question 28

When does the static inverter supply the AC stanby bus?

Answer 28

If the left transfer bus is not powered

Question 29

What are the two sources of Power for the AC standby bus?

Answer 29

BAT BUS via an inverter and LEFT XFER BUS

Question 30

What does the RAT generator supply power to?

Answer 30

Stand-by power to the C1 and C2 TRUs

Question 31

What are the altitude and airspeed limitaitons on the RAT?

Answer 31

There are none, the RAT operates at all airspeeds and altitudes

Question 32

What supplies power until the RAT RPM is sufficient?

Answer 32

The main battery

Question 33

What will cause automatic deployment of the RAT?

Answer 33

Both AC transfer busses losing power in flight | All HYD systems are low

Question 34

What is DC Power used for?

Answer 34

Flight displays (PFD and ND) GPS ADIRU Flight control system

Question 35

``` What are the power ratings for: IDG APU EXT PWR RAT ```

Answer 35

IDG 120 kva APU 120 kva EXT PWR 90 kva RAT 7,5 kva

Question 36

What two components are the IDGs a combination of?

Answer 36

IDGs are a combination of a constant speed drive (CSD) and an AC generator.

Question 37

What drives the IDGs

Answer 37

The engine

Question 38

Can a disconnected IDG be re-connected in flight?

Answer 38

No, can only be done on the ground

Question 39

What kind of power and rating is provided to the Main AC BUS?

Answer 39

The IDGs and APU supplies 115 VAC, 400 Hz power to the left and right main AC buses.

Question 40

What is the power source order for the Main AC BUS?

Answer 40

The source order for powering the left and right main busses in flight are: - Respective IDG - APU generator - Opposite IDG

Question 41

What equipment does the utility buses power?

Answer 41

The utility busses powers galley heater, chiller boost fan, gasper fan, cockpit foot and shoulder heaters, door area heaters, lavatory water heaters and shavers

Question 42

If both transfer buses needs power, which back-up generator will supply the power?

Answer 42

The right back-up generator supplies power if it is available.

Question 43

List the power sources for the three PSAs?

Answer 43

- The R PSA gets power from the R PMG, R MAIN DC BUS and a short term battery supply - The C PSA gets power from the R PMG, HOT BAT BUS, CPT FLT INSTR BUS and a battery - The L PSA gets power from the L PMG, L MAIN DC BUS, HOT BAT BUS and a battery

Question 44

What is the purpose of the BAT and APU chargers?

Answer 44

- Change the AC power to DC power for the related DC buses, functions like a TRU. - Charge the batteries

Question 45

For how long can the Main battery supply power for?

Answer 45

It can supply standby system power for a minimum of 5 min

Question 46

What power sources are used for the stand-by power system

Answer 46

Hot BAT BUS RAT Left X-transfer bus

Question 47

Does the RAT supply AC or DC power?

Answer 47

AC that is converted to DC through the C1 and C2 TRUs

Question 48

What are the three power sources used for autoland?

Answer 48

The three power sources for an Autoland are: - Left IDG - Right Back-up generator - Right IDG

Question 49

Describe how the three autopilots gets power during an AUTOLAND. What feeds them and what are the respective power sources for the different feeds?

Answer 49

- The left set gets fed from the L X-TRANSFER BUS (AC) and L DC BUS (DC) with the L IDG as the power source - The center set gets fed from the STANDBY AC BUS (AC) and BAT BUS (DC) with the R IDG as the power source. - The right set get fed from the R X-TRANFER BUS (AC) and R DC BUS (DC) with the R BACK-UP generator as the power source.