Electrical Systems

Question 1

How many electrical phases are in aircraft alternators?

Answer 1

Three

Question 2

What is the advantage of using AC power over DC power?

Answer 2

AC voltages can easily be stepped up or down.

Question 3

What is the frequency of AC voltage used in aircraft?

Answer 3

400 Hz

Question 4

How does a Constant Speed Drive (ISD) unit maintain a constant output frequency of the AC generator?

Answer 4

By maintaining a constant speed of the generator as the engine speed varies.

Question 5

What is an Integrated Drive Generator (IDG)?

Answer 5

When a Constant Speed Drive (CSD) is combined within the alternator housing.

Question 6

Where would you find a part number of a switch in an aircraft electrical system?

Answer 6

In the equipment table or bill of materials on the electrical circuit diagram for the aircraft.

Question 7

What is the main disadvantage of aluminum wire over copper wire for use in an aircraft electrical system?

Answer 7

Aluminum wire is more brittle, which makes it easier to break.

Question 8

What size aluminum wire would properly replace a #4 copper wire?

Answer 8

Two gauge, use two wire sizes larger for replacing copper wire with aluminum wire.

Question 9

What is the smallest sized aluminum wire that is approved for use in aircraft electrical systems?

Answer 9

Six gauge

Question 10

Can you substitute aluminum wire for copper wire?

Answer 10

Yes, but it must be two gauges larger to carry the same current.

Question 11

Can wire in free air carry the same current as wire in a bundle?

Answer 11

Wire in free air can be used to a higher current level than the same wire size in a bundle.

Question 12

What are common causes of wire failure in a crimped connector?

Answer 12

Wire wasnt inserted far enough or the connector was excessively crimped.

Question 13

What is one of the first things to check if an electrical component does not operate?

Answer 13

Always start with simple solutions and move to more complex.

Question 14

What may be provided by the manufacturer to assist in troubleshooting?

Answer 14

Manufacturers often provide a troubleshooting logic chart.

Question 15

What are four basic steps of troubleshooting?

Answer 15

1:Know how the system should operate
2:Observe how its operating
3:Divide the system into smaller sections to isolate trouble
4:Look for obvious problems first

Question 16

When routing a fluid line parallel to an electrical wire bundle, which should be on top?

Answer 16

Electrical wire should be on top.

Question 17

Why must a switch be derated if its used in a circuit that supplies incandescent lamps?

Answer 17

The high-inrush current

Question 18

What does the specific gravity of the electrolyte of a lead acid battery indicate?

Answer 18

The amount of acid relative to the water in the electrolyte, indicates the state of charge of the battery.

Question 19

What are the most likely causes of a battery with a distorted or swollen battery case?

Answer 19

The battery has been overcharged or over discharged.

Question 20

On nickel cadmium batteries, what is the minimum cell voltage at the end of the charge cycle?

Answer 20

1.55 Volts

Question 21

How is the state of charge determined on a nickel cadmium battery?

Answer 21

Measure the discharge following the manufacturers instructions