ELECTRICAL SYSTEM

Question 1

What bus(es) are powered with a ‘DARK’ aircraft?

Answer 1

HOT BAT bus

Question 2

What is on the Hot Bat Bus?

Answer 2

-Clock
-Fire extinguisher bottles
-APU fuel valve
-Spar fuel valves
-Parking brake valve.

Question 3

With the EXT power AVAIL light illuminated, what bus(es) are powered?

Answer 3

HOT BAT and Ground Handling.

Question 4

With the BAT switch ON. What buses are powered?

Answer 4

HOT BAT bus and BAT bus (and Ground Handling)

Question 5

With the STBY Power switch AUTO:

Answer 5

HOT BAT, BAT, STBY DC and STBY AC (and Ground Handling)

Question 6

What if we place the STBY Power switch to BAT?

Answer 6

The aircraft main battery powers the STBY DC and STBY AC.

Question 7

In BAT position, on the ground, are battery chargers powered?

Answer 7

NO

Question 8

In BAT position, in flight?

Answer 8

Battery chargers ARE powered.

Question 9

What happens if we push the BAT switch OFF on the ground?

Answer 9

The APU will shut down.

Question 10

Is it a good idea to turn the batt switch off on the ground / Is this a good idea?

Answer 10

No. There WILL BE fire PROTECTION, but no DETECTION.

Question 11

What if we push the BAT switch OFF in flight?

Answer 11

No effect.

Question 12

How many batteries are there?

Answer 12

Two batteries: the main aircraft battery and the APU battery.

Question 13

Two batteries: the main aircraft battery and the APU battery.

Answer 13

The main aircraft battery and the APU battery are wired separately or in series.

Separately (207-342, 423, and 477) can power the STBY buses for 30 minutes.

In series (351, 378, 441 and 495) can power the STBY buses for 90 minutes.

Question 14

When does UTIL BUS shedding occur? BOSS

Answer 14

(BOSS)

Both thrust levers advanced to T/O range on the ground with engines shut down

Overload-electrical load exceeds power available

Starting engines

Single generator source (gen or eng failure)

Question 15

With a Left AC BUS Light fault, will the Captain’s flight instruments fail?

Answer 15

No. Automatically powered from right main AC BUS

Question 16

What is the purpose of the BUS TIE System?

Answer 16

(PPI- Prevent, Provide and Isolate)

Prevent paralleling of Left and Right main buses

Provide power to both main buses

Isolate faults

Question 17

What 3 actions does the BUS TIE System do?

Answer 17

1. Allows DC BUS Tie Breaker to close with loss of DC Power
2. Allows Capt’s Flt Instruments to remain powered with loss of LEFT MAIN AC BUS
3. (CONFIRM) THIRD… packet incorrect

Question 18

When can a disconnected IDG be reconnected?

Answer 18

ONLY on the ground

Question 19

How is the GROUND HANDLING BUS powered and what items are on it?

Answer 19

It is powered by EXT POWER or the APU generator

Cargo Handling and equipment

Question 20

After ENG start on GRND PWR or APU and the GEN CONT switches on, how is the ELEC System powered?

Answer 20

By the IDG powering their respected buses

Question 21

What is the Hyd Drive Gen?

How is it powered?

When does it activate automatically?

Answer 21

Hydraulic Drive Generator

Powered by the Center HYD SYS

Activates automatically when Left and Right buses are unpowered.

Question 22

What does the HDG provide power to?

Answer 22

1. BATT and HOT BATT Buses
2. Left and Right AC Transfer Buses
3. Standby AC and DC Buses
4. Captain’s FLT INSTR

Question 23

What Items are powered by the Ground Service Bus and how is it normally powered?

Answer 23

Main and APU battery chargers AND misc.

cabin lights / Right Main AC bus but can be powered alternatively by the APU Gen or EXT PWR

Question 24

Flying along, you get an EICAS message L IDG and look up to see the DRIVE light illuminated.
What happened and why?

Answer 24

The IDG has disconnected.

High Oil Temp or Low Oil Press

Question 25

What are the 5 times that pilot verification is required prior to pilot action?

Answer 25

1. Initial GPS Position
2. GEN DRIVE (IDG)
3. Thrust Levers
4. Fuel Control switches
5. Fires switches

Question 26

Can you do an ILS on with the HDG?

Answer 26

YES

Question 27

with the Hyd Drive Gen…
Will you have a Flight Director?

Answer 27

NO

Question 28

We momentary (master caution) or alternate switches (On Switch)

What type of switch is the External Power switch?

Answer 28

It is a momentary-action switch.

Question 29

What does the External Power light AVAIL mean?

Answer 29

External power is plugged in and quality is acceptable.

Question 30

What does the ON light (with regards to the EXT PWR) mean?

Answer 30

External power is powering the buses.

Question 31

What does the ISLN Light on the BUS TIE mean?

Answer 31

A FAULT has occurred, opening the AC Bus Tie breaker.

Question 32

What does the AC Bus OFF light mean?

Answer 32

AC Bus is unpowered.

Question 33

How are the galley buses powered?

Answer 33

Via the Utility bus

Question 34

Is it possible to shed the Galley Bus and not the Utility Bus?

Answer 34

YES

Question 35

How do you shed the Galley and Utility Buses on the ground from the cockpit?

Answer 35

Advance the Thrust Levers

Question 36

How do you reset the UTILITY Buses?

Answer 36

OFF, then ON.

Question 37

What is the Generator priority?

Answer 37

Respective Internal Drive Gen, APU generator, the opposite IDG.

(EXT AC will take priority if selected ON)

Question 38

What does a GEN DRIVE light mean?

Answer 38

HOT / LOP

Low oil pressure or high oil temperature