Electrical

Question 1

What are the four primary power sources? How many primary power sources can power one side at a time?

Answer 1

Left gen, right gen, APU, GPU

Only one primary power source can power one side at a time.

Question 2

What are the two secondary power sources? Describe them.

Answer 2

Left and right batteries. 25v 44 amp hour NiCAD’s

Question 3

Is there a standby battery? Describe it:

Answer 3

Yes, one standby battery, 24v lead acid, good for 180 minutes, located in the nose.

Question 4

Describe the electrical system

Answer 4

DC powered, split bus system with two 300 amp starter/generators (1/side) and 1-275 amp APU starter generator.

Question 5

What are the specifications for the GPU/EPU?

Answer 5

Max 1500 amps, 28 volts

Question 6

Is there any form of AC power on the airplane?

Answer 6

Yes, two AC powered alternators power the windshield anti-ice.

Question 7

How does the bus tie system operate on the ground versus in the air?

Answer 7

Auto on the ground.

Manual in the air.

Question 8

How will a bus tie open in flight?

Answer 8

Massive over current (600 amps)

Question 9

How many batteries participate in every engine start? What about windmilling?

Answer 9

Both batteries. No, hence “windmill”

Question 10

What does a cyan bus tie closed cas message indicate?

Answer 10

Bus tie is closed and one primary power source is powering both sides.

Question 11

What does AVAIL mean with a GPU plugged in?

Answer 11

GPU has been connected and voltage is acceptable

Question 12

What does an amber bus tie closed cas message indicate?

Answer 12

Bus tie is closed with one primary power source powering each side.

Question 13

When should the starter disengage?

Answer 13

44% N2

Question 14

1st engine start uses what?
2nd engine start?
What are the batteries never used for?

Answer 14

1. 1st engine start: both batteries
2. 2nd engine start: cross gen start
3. Batteries are for start assisted starts only. NEVER cross gen starts.