Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Boeing 747 > Electrical > Flashcards

Electrical Flashcards

1
Q

What does AVAIL light mean on APU GEN or EXT PWR switches

A

APU - generator power acceptable

EXT PWR - external power plugged in and power is acceptable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When would a generator DRIVE light illuminate?

A
  • IDG oil pressure low
  • IDG oil temperature high
  • Generator Control Breaker (GCB) open due to uncorrectable generator frequency fault
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Main AC electrical power sources

A
  • 4 Integrated Drive Generators (IDGs) (one mounted to each engines accessory gear box)
  • 2 APU generators
  • 2 external power sources
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens if electrical load exceeds power available (airplane or external)?

A

Electrical Load Control Units (ELCUs) shed AC loads in a programmed sequence until overload is relieved

  • Galley busses are shed first, followed by utility busses (galley busses only on passenger)
  • Utility Buses 1 and 2 and Galley Buses 1 and 2 (pax) are powered by ELCU logic (Utly Pwr Sw L)
  • Utility Buses 3 and 4 and Galley Buses 3 and 4 (pax) are powered by ELCU logic (Utly Pwr Sw R)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When will an IDG be automatically disconnected?

A

Excessively high IDG oil temperature without prior disconnection by flight crew

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When can APU generators be used?

A

APU auxiliary power can only be used on the ground

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Purpose of Split System Breaker (SSB)

A
  • divides the synchronous bus allowing each side of the AC electrical system to be powered by separate auxiliary or external power sources
  • Auxiliary and external power sources cannot be connected to the same side of the synchronous bus simultaneously.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the meaning of ELEC BUS ISLN on the EICAS display?

A

The related Bus Tie Breaker (BTB) is open

  • can be reset by pushing the Bus Tie Switch Off, and then AUTO, if fault is cleared
  • Bus is disconnected from the sync bus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is AC power distributed?

A
  • four main buses (AC BUS 1, AC BUS 2, AC BUS3, AC BUS 4)
  • two transfer buses (CA and FO)
  • ground service bus and ground handling bus
  • four utility buses
  • four galley buses (pax)
  • two standby buses (pax)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Purpose of transfer buses and how are they powered?

A
  • provide AC power to critical flight related equipment
  • CA transfer bus normally powered by AC Bus 3 (AC Bus 1 as back up)
  • FO transfer bus normally powered by AC Bus 2 (AC Bus 1 as back up)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When is the Main Deck Cargo Handling Bus powered?

A
  • powered on the ground when EXT PWR 2 or APU GEN 2 are AVAIL
  • pushing the AVAIL source deenergizes the main deck cargo handling bus
  • EXT PWR 2 is prioritized over APU GEN 2 if both AVAIL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Components of AC Standby Power System?

A
  • Main standby bus
  • APU Standby bus
  • Main Battery
  • APU Battery (24V)
  • Main standby inverter
  • APU standby inverter
  • Standby Power selector
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How long can main battery provide power to the main standby bus with the battery charger unpowered?

A

30 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Power source priority for Main Standby Bus

A

1) AC Bus 3
2) main standby inverter via main hot battery bus (with batt charger powered via AC 1)
3) mani standby inverter via main hot battery bus (without batt charger powered) - 30 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Power source priority of APU standby bus

A

1) CA transfer bus via AC Bus 3
2) CA transfer bus via AC Bus 1
3) APU standby inverter via APU Hot Batt Bus (charger not powered) - 30 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Components of DC electrical System

A
  • 4 Transformer Rectifier Units (TRUs) powered by respective AC bus and providing DC power to respective DC Bus
  • 4 DC Isolation Relays (DCIRs) connecting DC Buses to DC Tie Bus
  • Main Battery
  • APU Battery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Voltage of APU Battery

A

24V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Main Power Source of APU DC electric starter?

A

APU start transformer rectifier (TR) via:

Primary:

  • utility bus 4 (freight) via external or internal AC source
  • galley bus 2 (pax) vis external or internal AC source

Secondary:
- 24V APU Battery (disconnects battery charger during start)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Back up power for IRS

A
  • APU Hot Battery Bus
  • Center IRU operates for 5 mins and shutsdown
  • ON BATT Light on Maintenance Panel
20
Q

ELEC DRIVE EICAS Advisory message

A
  • IDG oil pressure low
  • IDG oil temp is high
  • Generator control open due to uncorrectable freq fault
21
Q

What does AVAIL light indicate?

A
  • power source is available

- power is acceptable

21
Q

When is Ground Service Bus Powered

A

1) AC Bus 1

2) EXT 1 or APU GEN 1 Avail via Ground Service Switch at Door L1

22
Q

Function of the Standby Power Switch in Auto or Batt

A

AUTO - allows main and APU standby busses to be powered from available sources
BATT - MX function for testing
- disables man and APU battery chargers

23
Q

Where is the Electrical Power-Up procedure located?

A

FCOM VOL 1; Supplemental Procedure 6.1

24
Q

What happens when you push Generator Drive Disconnect switch

A
  • disconnect IDG from engine
  • open related GCB
  • can only be reconnected on the ground by MX
25
Q

Equipment powered by Utility Busses

A
  • FWD Main Fuel Pumps 2 and 3
  • FWD Override/Jettison Pumps 2 and 3
  • Center Override/Jettison Pump (L)
  • Galley Equipment
  • APU TR
26
Q

Describe the electrical load shedding process?

A
  • 4 ELCUs (electrical load control units)
  • via logic sheds AC loads by priority until the loads are within the capacity of airplane or ground power generators
  • loads are restored when additional AC power becomes available
27
Q

What is the purpose of the electrical system overload protection?

A
  • provided by load management system

- configured to ensure power is available to critical and essential equipment

28
Q

Describe the sequence of events during engine start with SSB open (two external sources)

A
  • the IDG powers its side of the synchronous bus when voltage and frequency are acceptable
  • The previous power source is disconnected
  • When an engine on the opposite side of the airplane is started, the IDG powers its side of the synchronous bus
  • The previous power source is disconnected and the SSB closes
29
Q

What are some of the equipment items powered by the ground service bus?

A
  • main and APU battery chargers
  • fuel pumps for APU start
  • flight deck flood, navigation, and service lights
  • miscellaneous service outlets and equipment
30
Q

Equipment items powered by the ground handling bus?

A
  • lower cargo handling equipment
  • lower cargo compartment lights
  • lower cargo doors
  • fueling system
  • auxiliary hydraulic pump 4
31
Q

Electrical Configuration during Autoland

A
  • AC and DC buses 1, 2, and 3 are isolated from the sync bus
    • provides independent power sources for all 3 power autopilots
  • AC 4 powers the sync bus
  • BTB 1, 2, and 3 open
  • DCIR 1, 2, and 3 open
32
Q

Equipment powered by Main Standby Bus?

A
  • left EIU, left CDU, left ILS, left VOR
  • left ADC, left transponder, left EFIS control panel
  • various flight control components
  • standby ignition for all engines
  • primary EICAS display
  • standby instrument lights
  • RMI (if installed)
33
Q

Equipment on the APU standby bus

A
  • left FMC
  • left ND
  • left PFD
34
Q

Power Source of Main and APU battery busses

A

Normal: DC Bus 3 (powered by AC Bus 3 via TR)
Backup: respective Hot Battery Bus

35
Q

Equipment on Main battery bus

A
  • APU controller (alternate)
  • fuel valves (all engines)
  • all crossfeed valves
  • dome, storm, and selected indicator lights
  • IDG disconnect (all engines)
  • manual pressurization control
  • trailing edge flap control
  • CA interphone
  • left radio tuning panel
  • left VHF
36
Q

Normal power source of each hot battery bus

A
  • ground service bus via related battery charger (which acts as a TR)
  • AC Bus 1 powers ground service bus
37
Q

Equipment powered by Main Hot Battery Bus

A
  • APU fuel shutoff valve
  • spar valves (all engines)
  • APU and lower cargo fire extinguishers
  • engine fire extinguishers (all engines)
  • fire switch unlock (all engines)
38
Q

Equipment on APU Hot Battery Bus

A
  • IRU left, center, right DC power
  • left and right outflow valves
  • APU inlet door
  • APU controller (primary)
39
Q

Battery Locatoins

A

Main Battery - E and E Compartment

APU Battery - Tail

40
Q

MAIN DECK Handling Bus Priority Power Soure

A

Priority: EXT PWR 2 (AVAIL)

41
Q

What EICAS messages may appear during load shedding?

A 
FUEL PRESS CTR L
FUEL PUMP 2 FWD
FUEL PUMP 3 FWD
FUEL OVRD 3 FWD
FUEL OVRD 2 FWD
42
Q

Which busses power AP L, C, and R?

A

AP L - AC Bus 3
AP C - AC Bus 1
AP R - AC Bus 2

43
Q

What screens are powered with BATT on and STBY PWR switch Auto?

A
  • Left PFD
  • Left ND
  • Primary EICAS
  • Left CDU
44
Q

Main Power source of IRUs

A

3:1:2

Left IRU: AC Bus 3
Center IRU: AC Bus 1
Right IRU: AC Bus 2

Boeing 747 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions