Airframe Systems & Components: Aircraft Electrical Systems 🔊

Question 1

What is the purpose of a circuit breaker?

Answer 1

To protect the circuits and wires from fire

Question 2

What are the two principles on which circuit breakers operate?

Answer 2

Thermal and magnetic

Question 3

What tool is used to measure the size of unmarked electrical wire?

Answer 3

A wire gauge

Question 4

What are the colors of aircraft position lights and where are they mounted?

Answer 4

Green on the right, red on the left, and white on the back

Question 5

What are the factors to be considered when selecting wire size for electrical power?

Answer 5

Allowable power loss in the line, permissible voltage drop in the line, and the current carrying ability of the conductor

Question 6

When is a circuit breaker or fuse designed to open the circuit?

Answer 6

Before the conductor emits smoke

Question 7

What type of breakers are not acceptable for use in aircraft?

Answer 7

Auto reset breakers

Question 8

What is a slow blow fuse?

Answer 8

A fuse that compensates for surges and high inrush current by not blowing for several milliseconds

Question 9

What are the three most common faults that occur in an electrical circuit?

Answer 9

Open circuits (wires are broken), shorted circuits (ground leads cause current to be returned by shortcuts to the power source), and low power (lights burn dimly and relays chatter)

Question 10

What size electrical conduit should be used for a specific cable bundle?

Answer 10

Allow for ease of maintenance and possible future circuit expansion, conduit should be 25% larger than the maximum diameter of the conductor bundle.

Question 11

What color insulator on a solderless connector is proper for a 10-gauge wire?

Answer 11

Yellow

Question 12

How should electrical switches typically be oriented in the on position?

Answer 12

Up or forward

Question 13

When should electrical switches be de-rated from their normal current rating?

Answer 13

High rush in circuits such as those containing incandescent lamps (landing lights), and inductive circuits that have magnetic energy stored in solenoid coils or relays, and for DC motor circuits, which draw several times their rated current during starting.

Question 14

When do DC electric motors draw several times their rated current?

Answer 14

During starting

Question 15

What would cause an AC electrical motor to run too fast?

Answer 15

An excessive supply of voltage or the motor field windings shorted

Question 16

What would cause an AC electrical motor to run too slow?

Answer 16

Low applied voltage, defective wiring, or no lubrication

Question 17

How is the output voltage of an alternator controlled?

Answer 17

By using a voltage regulator to control the exciter field current and thus regulate the exciter output voltage applied to the alternator field

Question 18

What should be checked before any aircraft electrical load is increased?

Answer 18

Check to determine the new load will not exceed the rated limits of the associated wires, conductors, and circuit protection

Question 19

What is the main advantage of using AC for aircraft electrical power systems?

Answer 19

The voltage is easily changed using transformers, thus reducing the size and weight of the wiring in the circuit

Question 20

In AC power systems, how is DC obtained for battery charging?

Answer 20

AC is changed to DC using rectifiers

Question 21

What warns pilots of overheating batteries?

Answer 21

A thermal sensor in the battery and a light in the cockpit

Question 22

How long should bonding jumper wires be made?

Answer 22

Large enough to handle all return current flow and as short as possible to prevent an increase in resistance

Question 23

What are two items that wear on a starter generator?

Answer 23

Commutator and the brushes

Question 24

What powers the ELT?

Answer 24

The ELT battery

Question 25

What is the purpose of a static wick?

Answer 25

It dissipates static energy to avoid damaging electrical components

Question 26

What are two types of AC generators?

Answer 26

Single phase and three phase

Question 27

When repairing aircraft electrical components what reference do you use?

Answer 27

The manufacturer’s maintenance manual