Electrical Flashcards
(41 cards)
What does the AVAIL light indicate on the external and APU PWR switches?
The related power source is plugged in and the power quality is acceptable
FCOM 2 ELEC 6.10.5
The APU generator power quality is acceptable
FCOM 2 ELEC 6.10.4
What bus is powered on the ground when APU GEN 1 or EXT PWR 1 is available?
The ground handling bus is automatically powered on the ground when APU GEN 1 or EXT PWR 1 is available (not power hungry).
The ground service bus must be manually connected with the p/b whenever AC bus 1 is not powered***
FCOM 2 ELEC 6.20.5
When is the main deck cargo handling bus powered?
The main deck cargo handling bus is powered on the ground when external power 2 or APU generator 2 is available.
An interlock prevents either source from powering main electrical busses and the main deck cargo handling bus simultaneously.
Engaging the relevant avail source to ON will de-energise the main deck cargo handling bus.
If both EXT PWR 2 & APU GEN 2 are available, putting EXT PWR 2 to ON will transfer main deck cargo bus power to APU GEN 2.
FCOM 2 ELEC 6.20.8
What electrical power source would you select if cargo handling is required?
A number two source must be available so use external power 1 or APU gen 1
FCOM 2 ELEC 6.20.8
When is the ground service bus powered?
Whenever AC bus 1 is powered on the ground or in flight. If AC BUS 1 is not powered the ground service bus can be connected to the same source powering the ground handling bus by pushing the ground service switch on the 1L door.
FCOM 2 ELEC 6.20.5
What is the function of the standby power switch in the auto position?
It allows the main and APU standby busses to be powered from available sources
FCOM 2 ELEC 6.10.2
Batt position is for maintenance purposes**
Where would you find the electrical power up procedure?
FCOM 1 NP 6.1 ELEC POWER UP
What does a BUS isolation ISLN light illuminated indicate?
That the bus tie breaker (BTB) is open.
FCOM 2 ELEC 6.30.1
What happens when you push a generator drive disconnect (DRIVE DISC) switch?
It will disconnect the IDG from the engine when above idle speed; and
It will open the generator control breaker (GCB)
FCOM 2 ELEC 6.10.6
What condition would automatically disconnect the IDG if not manually disconnected by the flight crew?
Excessively high drive oil temperature. The relevant GCB opens.
An ELEC GEN OFF EICAS message will appear.
Manually pushing the drive disconnect switch after an auto disconnect will replace the ELEC DRIVE with DRIVE DISC EICAS message.***
How do you reconnect an IDG that has been disconnected?
An IDG cannot be reconnected by flight crew action
FCOM 2 ELEC 6.20.3
What does a generator DRIVE light indicate?
IDG oil pressure low
IDG oil temperature high
GCB open due to an uncorrectable generator frequency fault
FCOM 2 ELEC 610.7
What are some equipment items powered by the utility busses?
Forward main fuel pumps 2 & 3
Forward override/jettison pumps 2 & 3
Center override/jettison pump
Recirculating fans
**galley busses 1-4 are powered directly from the relevant AC bus.
FCOM 2 ELEC 6.20.6
Describe the electrical load shedding process
If load > capacity the Electrical Load Control Units (ELCU) will load shed in priority order.
If capacity later > demand the loads are restored in reverse order.
FCOM 2 ELEC 6.20.1
The following EICAS messages may appear:
- FUEL PUMP 3 FWD
- FUEL OVRD 2 FWD
- FUEL OVRD 3 FWD
- FUEL PRESS CTR L
- FUEL PUMP 2 FWD
What is the purpose of the electrical system overload protection?
To ensure power is available to critical and essential equipment first
FCOM 2 ELEC 6.20.1
During load shedding, would you expect to see and EICAS. Advisory message ELEC UTIL BUS L, R?
No because while auto shedding the EICAS message ELEC UTIL BUS L, R is inhibited.
FCOM 2 ELEC 6.20.1
What are the main AC electrical power sources?
4 IDG’s
2 APU GEN’s
2 EXT PWR sources
FCOM 2 ELEC 6.20.2
Describe the function of the split system breaker SSB
The SSB divides the synchronous bus allowing each side of the AC electrical system to be powered by a separate aux or external source.
FCOM 2 ELEC 6.20.2
Describe the electrical system sequence of events during engine start with the SSB open
When an engine is started that IDG powers it’s side of the SSB and will trip off an APU or external source on its side.
When another engine is started, its IDG synchronises and causes the opposite side external or APU source to trip off, the SSB then closes to power all AC busses.
CPAT AC Power distribution 36/41
Describe the electrical system sequence of events with a single power source power in the synchronous bus, when an engine is starting, SSB closed…
With a single APU or external source an engine start causes that IDG to trip off the external or APU source, the SSB remains closed and all AC busses are powered by one IDG until more engines are started.
CPAT AC power distribution 36/41
Which bus powers the captains transfer bus and the main standby bus?
CAPT TXFR:
AC Bus 3 but will revert to AC Bus 1 if that is unpowered.
Main Standby:
AC3; or
With Batt ON, STBY PWR in AUTO & AC 3 not powered the Main standby bus gets power from the main standby inverter drawing power from main battery charger through the main hot battery bus.
FCOM 2 ELEC 6.20.9
Which bus powers the first officers transfer bus?
AC bus 2 backed up by AC Bus 1
FCOM 2 ELEC 6.20.4
Which bus provides backup power for both transfer busses?
AC Bus 1
FCOM 2 ELEC 6.20.4
What are some of the equipment items powered by the ground service bus?
Main and APU battery chargers
Fuel pumps for APU start
Flight deck flood, navigation and service lights
Miscellaneous service outlets and equipment
FCOM 2 ELEC 6.20.5
