Bus
Common point where electrical components are attached
Remote Controlled Circuit Breaker
not readily accessible to the crew
Do not reset these
Examples of switch type Circuit Breakers
Non-essential Bus
Radio Masters
AOA/Pitot Heat
Bus Feeder
feeds power between the main bus and load bus
Relay
Switch that opens and closes based on system inputs
Ground Fault
Short which allows power to flow to the ground
Sources of DC power
Starter Generator x2
GPU
Battery
Battery
24v 40 amp/hr
lead-acid
located in the aft compartment
Standby Battery
24V
30 minutes
located in the nose compartment
only will power the standby bus
Min volts for a battery start
22V
What happens when you place the bat switch in the EMER position?
Battery Relay and Battery Tie In relay open and the Emer bus power relay will stay closed (battery disconnects from all EXCEPT Emergency Bus)
Where does the GPU plug into?
Aft left behind & below #1 engine and aft compartment door
Does the battery need to be on for a GPU start?
Yes
GPU
28 - 28.5V
1000-1500 amps
Generators
28V
400 amps
In the accessory compartment on each engine
What is the purpose of the GCU
1) Equalize the load between the two generators
2) Monitor gen output and disconnect them if required
3) Tells the generators when to be a starter
Load Limit
Airborne
Single Generator
Below 32,500'
400 amps
Load Limit
Airborne
Single Generator
Above 32,500'
280 amps
Load Limit
Ground
Single or Dual Generator
280 amps
Gen Reset Switch
Controls the GCU
RESET -
OFF - cuts the generator off from the system through the gen relay
NORM -
Master Gen Switch
Controls the Gen relay
Also is attached to the 3 battery relays and opens them as well
Inverters
Converts DC power to AC power
26 VAC
115 VAC
What powers the NO1 Inverter
The left load bus
What powers the NO2 Inverter
The right load bus and the emergency bus (if the right load bus fails)
Inverter Selector Switch
#1 - Allows the NO1 inverter to power the primary AC and NO2 power the secondary
AUTO - #2 will power the primary ac bus IN THE EVENT OF A #1 FAILURE
#2 - reverse of the #1 position
What is the normal position of the Inverter Selector Switch
AUTO (guarded position)
What is the normal setting for the AC volt selector switch
115V primary (12 o clock position)
What is the normal position of the standby battery switch? Where is it located
ARM and it is located on the co pilots side
What works with just standby power?
C - Co Pilot Instrument Lights
R - RTU 1
U - UHF Radio
I - ITT (Left)
S - Standby Attitude
S - Standby Altimeter
E - EFC for engine start
What items are on the Emergency Bus
S - Standby Bus
L - Landing Gear Lights
E - Engine Ignition and Control
E - Emergency Pitch Trim
V - VHF Nav 1
E - Engine Fire Detect / Smoke Detect
S - Selected LH Inst
Indication of a single generator fail
GEN FAIL Light (Amber)
Popped CB or zero Amps/volts
What buses do you lose with a single generator fail?
None
For single generator ops, what is the min N2 on the engine with the good generator?
58%
What are the indications for a dual generator fail?
GEN FAIL Lights
Popped CB and zero Amps/Volts
What buses do you lose with a dual generator fail?
None, as long as the battery is still operating
What happens when you select EMER on the battery switch?
It will open the battery relay and the battery tie in relay. It will close the bat feeder relay. This will power the Emergency Bus and Standby Bus
What will you lose for landing with just the Emergency and Standby bus working?
Normal Gear Extension
Flaps
Speed Brake
Anti-Skid
Inverter Fail Indications
INV Fail light (Amber)
Popped CB and zero volts
When does the AC BUS SHED annunciator come on? What would have caused this
When the secondary buses are depowered and the primary shed buses are no longer receiving power.
This happens when you are on the standby/emergency buses and an inverter fails. The system senses you are min power and it will turn off the secondary buses a
What do you lose if you lose the secondary buses? (AC System)
Ground Recording Unit
If an inverter fails, where should you put the AC volt selector?
115V for the good inverter
Battery Feeder Fail Light only
The feeder protection unit has failed and the battery is not being monitored.
Turn off the battery
Battery Feeder Fail and Emergency Bus Feeder Light
Emergency bus relay has opened
In the event of a LH load bus fail you will also lose the emergency bus
Battery Feeder Fail, Emergency Bus Feeder Light, and BAT CUTOFF
Battery Feeder protection unit disconnected the battery from the system
Bus Feeder Fail
Power is flowing through the third feeder on the main bus. Indicates that one of the other feeders has failed
How many feeders are on the main bus to the load bus? How many are normally powered?
3
2
How many times can you reset a remote controlled circuit breaker?
None
What causes a BATT CUTOFF light?
Battery relay is open
Indications of an electrical fire
Smell, sight, erratic avionics, or smoke alarm
Where is the smoke detector?
In the back by the avionics rack
Why do you turn off XFeed for an electrical fire?
Boost pumps will be turned off; therefore, a single jet pump can not operate two engines at full throttle.
Could cause a flameout
Master Gen Switch in EMER
BAT Switch is OFF
What Buses are powered?
Just the standby bus
Master Gen Switch in EMER
BAT Switch is in EMER
What buses are powered?
The standby and the emergency
Where are the anti-collision lights?
Flashing strobes on the wingtips and aft point of the fuselage
Where are the NAV lights?
wingtips and trailing edge of the vert stab. The right wing is green and the left wing is red. The vert stab is a white light
Max speed for the landing lights
200KTs
Max altitude for the landing lights
20,000'
How do you know that the landing/taxi lights are extended and illuminated?
LDG LT EXT light will illuminate on the glare shield
With the INTEG switch on, when do the instrument panel flood lights automatically illuminate?
When power is lost to the LH load bus
What lights illuminate during the emergency light test?
2 flood lights
2 emergency exit lights
all powered by 4 independent batteries