Electrical System

Question 1

What’s the main sources of power

Answer 1

4:
IDG #1&2
APU Gen
External power

Question 2

What are the 5 DC buses

Answer 2

DC bus #1&2
Battery bus
Hot battery bus
Switched hot battery bus

Question 3

What bus is powered with all switches off, and what does it power

Answer 3

Hot battery bus.

Fire protection and fuel valves

Question 4

When does the TR Unit light come on

1. On the ground
2. In the air

Answer 4

1. If any have failed

2. If #1 failed or 2&3

Question 5

What systems are you left with on batteries only

Answer 5

• Dome and flood lights
• manual pressurization
• VHF1
• PA system
• intercom
• Capt inboard outboard and upper DU
• Right igniters
• Left FMC and CDU
• Left Nav, ILS, IRS, GPS
• transponder 1, DME1

Question 6

How long will the right IRS operate on battery power

Answer 6

5 minutes

Question 7

What important things have changed when operating on battery power

Answer 7

• flap indication is inoperable
• no auto speed brake on landing
• no anti ice or window heat
• only suction feeding
• no electric trim
• manual pressurization

Question 8

When does the elec light illuminate

Answer 8

Only on the ground when:

- a fault exist in the DC or standby power system (like the battery charger, static Inverter etc

Question 9

When does the DC bus relay open during normal ops

Answer 9

At GS intercept

Question 10

Where do the TRs draw their power

Answer 10

TR1: TB1
TR2: TB2
TR3: TB2 (normal) TB1 (alternate)

Question 11

What does TR3 normally power

Answer 11

The battery bus