What means "split bus" system?

The left and right electrical buses

are isolated from each other.

What does a GCU does?

a) protects (generators)

b) Regulate (at 28.5V)

How long will the batteries provide power under normal load?

20 minutes

How long will the batteries provide power on load shedding?

60 minutes

What output in Volts must the GPU

have to illuminate the switchlight to AVAIL?

26.5V to 32V

What does a bus tie relay do?

Allow one generator to be connected through this relay to power the entire electrical system

What should you check before to disconnect a GPU?

a) ensure the AVAIL light illuminated, then extinguish

b) Confirm visually GPU disconnected before taxiing

What does the interior

switchlight means?

Depressing the switch shuts off

all electrical in the cabin

What is on the right

circuit breaker panel?

Main DC

Emer bus

Avionic bus

What is on the left circuit breaker panel and not found on the right side?

Standby instruments bus

Where does the cabin

entry light receive power from?

Right battery bus

When does the emergency lights illuminates?

a) Emergency lights switch ON

b) With loss of DC when in arm position

c) 5G's impact

d) Pax safety ON

When does the battery overtemp

first appear?

64C

Message and master warning reoccurs at 71C

Can you dispatch if a battery overtemp message clears itself?

 Prohibited until maintenance is accomplished

What powers the

emergency lighting?

4 emergency nicad battery pack

located in lavatory and cabin walkway

How long is emergency lighting powered?

a) Indefinitely using main DC

b) 60 minutes using emer bus

c) 10 minutes using the packs

What does pressing the exterior power switch do when the GPU is available?

Connect the GPU to right emergency bus

What happens when turning on the APU generator?

Closes the relay and

connects to left emergency bus

When will a bus tie automatically open in flight?

Over current condition if already selected close

(600 amps+)

What bus connects when

turning on the batteries?

Connect battery bus to emer bus

What bus do you connect

when you press the L or R elec

norm/emer switch?

Emer bus to main DC bus

How much electrical load are provided by each generator

with the bus tie closed?

Half of the total electrical load

How many amps should

a GPU be set at for engine start?

1000-1500 amps

What is on the left battery bus?

a) aft baggage

b) tail cone lights

c) APU test panel in tailcone

d) NWS accumulator bleed

e) L battery voltage

What is on the right battery bus?

a) cabin entry lights

b) under pylon lights

c) lav service

d) ELT panel

e) right battery voltage

What bus does the bus tie relay connects to?

L and R EMER buses

What happens to the APU generator when the left engine generator is online and why?

APU generator will trip off line.

APU generator is connected to the L EMER bus, and you can only have one power source at a time

What monitors the electrical system?

MAU's

(Modular Avionics Unit)

What does a DC-DC convertor do?

keep voltage at 24 V

minimum during engine start

What powers the EICAS?

R EMER bus

When does the bus tie closes automatically?

On the ground only

a) when a start switch is pressed (Engine or APU)

b) Whenever a single primary source of power is selected

What should the battery voltage register with a GPU connected and EXT PWR on?

28.5 V (28 V displayed)

Why is the APU amps

restricted to 275 amps?

Cooling issues.

Otherwise, same generator as the engines.

Are the current limiters monitored?

No, they don't feed safety of flight systems

When does a bus tie must be manually selected?

In flight.

What means AVAIL?

Voltage of GPU within range.

Has nothing to do with amps.

True or false:

 The batteries affect bus tie operation

False

What are the 4 primary

source of DC power?

2 engine generators

1 APU

1 GPU

How many primary source of DC power can be active on the emer bus?

 Only one at a time

How is each power source prioritized?

Engine generators have priority over

APU, which has priority over

GPU

What means a amber bus tie closed message on the ground with both engine running?

Malfunction

The tie should have opened as soon as a primary source is active on each side

When should you close a

bus tie in flight?

To start an engine or the APU

When is the DC gen o'current

cas message inhibited?

Engine start + 2 minutes

What flight controls are on the

EMER bus?

Aileron and rudder trim

Secondary pitch trim

Rudder bias override

What knobs can the right seat pilot still be able to select

on EMER in the cockpit?

Emer press (if needed)

Manual temperature

Does the ignition system works

on EMER?

Yes

On what bus are the

 pylon precoolers?

EMER bus

On what bus is the fire detection system?

EMER bus

On what bus is the fuel

and hydraulic SOV?

EMER bus

On what bus is the

anti-skid system?

EMER bus

What must be achieved 90 seconds after engine start?

Idle

What amps should the battery be at prior to T/O and why?

20 amps

To ensure the batteries are fully charged

in case of an emergency return

What amps should the battery

be at prior to second engine start?

100 amps

What lights are ON during

emergency lighting?

Exit signs

5 seat lights

partial aisle lighting

3 lights over the right wing

1 first step light on the left fuselage

Does the bus tie work manually on the ground?

Does not, even if the switch does illuminate when pressed

What does "remote CB tripped" means?

Circuit breaker in the aft J-box has tripped.

Not all systems are monitored by this message

Are the circuit breakers in the aft closet monitored?

No, they are non essential to flight ( DVD, lav motor, coffee heat, etc...)

What does it mean when the entry light switch by the door turns red instead of cyan when pressed?

It indicates  a short.

To find where, refer to the individual switch panel wiring found in the maintenance manual

The lav motor is stuck.

What can you do?

Press the interior switch

What lights in the cabin

will still be ON,

even when the interior

switch is pressed off?

Entry lights

Emergency lights

What is the memory item

for a dual generator failure?

Not a memory item

What source of power is

always used for start?

Batteries

Are the engine generators used for start in flight?

Never

When will you see 2 start switch illuminate?

Cross generator start only

What happens if you close the

bus tie in flight, and forget

to re-open it?

The cyan "bus tie closed" message will turn amber, and remind crew to open it after 5 minutes

When does the

bus tie closed appears?

a) The bus tie relay is closed

b) A single primary power source powers both systems

What is the memory item for a battery overtemp L or R?

Affected battery switch OFF

On what bus are the thrust reversers?

Main DC

Why does the "cabin door light" message displays when closing the door without power?

Require main DC to reset switches monitored

by the printed circuit boards (PCB)

What type are the batteries?

Nicad 25 Volts

44 amps/hr

What are some benefits to Nicad batteries?

a) holds 24 V until nearly dead, then drops rapidly

b) Last longer, in terms of number of charge/discharge cycle

c) Faster charge and discharge rate than acid batteries

You just started the right engine

with a GPU. Engine generator is now selected on. What happens to

the GPU?

Drops offline

Avail light will illuminate

Why must the batteries be installed for the APU to be operating?

Batteries are required for fire protection

Why is the battery voltage

on the hot battery bus?

Need to display voltage during a battery overheat,

as the procedure requires to turn off the battery

What happens to the stick shaker while landing on EMER?

May be inoperative

Do not slow below Vref

As you turn off the emergency lights, you notice that the cabin door step outside and the left forward table light remains on.What could be the reason?

The 5 G switch on one battery pack

has tripped.

Each pack has a 5 G's switch,

and its associated row of lights

Why can it be a good idea to start the right engine first with an APU running?

You will be charging the batteries quicker, using the right engine generator AND the APU generator on the left bus

Why can it be a good idea

to start the left engine first

while using a GPU?

You will be charging the batteries quicker by using the left engine generator AND the GPU relay

How do you know if

the battery is really off,

after completing a bat o'temp procedure?

a) Battery off L-R message appears

b) No amps are showing

How can you "fix"

bus tie closed on the ground?

Turn one generator off.

Message will becomes cyan

Turn the generator back on.

Forces the bus tie to open

How quickly must you react during a dual generator failure to get a full 60 minutes on the batteries?

EMER must be selected within 5 minutes

Why do we turn off the X-feed knob

during a dual generator failure?

To turn off the supplying fuel pump,

which is a big draw of power

Why are we asked to leave icing environment in EMER?

a) No windshield heat

b) No EICAS, and therefore no CAS messages to inform us on the anti-ice system

What powers the flaps?

Main DC

What powers NWS?

 Main DC

Do the speedbrakes still

 work in emer?

No electricity involved

to use the speedbrakes

What is the engine start primary assist sequence during start?

a) GPU

b) APU generator

c) Engine generator

You know that when switched to EMER,

the batteries will supply power

for 60 minutes.

What is the condition for this to happen?

Provided EMER was selected within

5 minutes after failure of the second generator.

You just switched to EMER.

What happens to the exterior lights?

They are inop. Advise ATC

You just switched to EMER.

What happens to the X-feed valve?

The valve failed in last position.

If a change is nessecary, select the change

prior to move the ELEC switch to EMER

You just switched to EMER.

What happens to the windshields?

They are no longer heated.

Exit icing conditions.

You just switched to EMER.

What happens to the autopilot?

No longer works

What are the main uses

for the batteries?

Engine or APU start

AND

Emergency sources

True or false: Bus tie closure

is automatic on the ground

and manual in flight

True

What source of power the FADEC's use

during engine start if a fault

occurs with the PMA's?

FADEC can revert to start bus power

What volts and amps must a GPU

regulated to for engine start?

28.5 V and 1500 Amps

What are the Stby annunciators for?

(fuel low,stab, gen off, oil press)

Provide warnings while using EMER bus

You have a dual gen failure and unable to get them back. Why are you asked to turn off the Eicas?

Too much bogus information. Better to have it off.