Airframe Electrical Systems

Question 1

What could cause an AC electric motor to run too fast?

Answer 1

Excessive applied voltage or shorted field windings

Question 2

What tool is used to check a motor or generator armature for shorts and opens under load conditions?

Answer 2

A Growler

Question 3

When using a Growler, what indication will occur when a short exists between an armature segment?

Answer 3

When a metal blade is held over the armature and a short exists in a segment, the blade will begin to vibrate and “chatter”.

Question 4

How is the output voltage of an alternator controlled?

Answer 4

By varying the field current that excites the alternator.

Question 5

What instruments are used to monitor electrical system loads?

Answer 5

Ammeters and voltmeters.

Question 6

How would you identify a specific wire in a wire bundle?

Answer 6

By the identification code marked on the wire.

Question 7

What tool would you use to determine the size of an unmarked wire?

Answer 7

A wire gauge

Question 8

What color are the navigation lights on the wingtips?

Answer 8

The left wingtip is red, the right is green.

Question 9

Name several types of electrical devices that would be considered intermittent loads on an electrical system.

Answer 9

Landing gear, cowl and wing flap motors, radio transmitters.

Question 10

Why would it be necessary to analyze an electrical system before increasing the load on the system?

Answer 10

To determine that the generator capacity, wire size, and protective device capacity will not be exceeded.

Question 11

What factors should be considered when determining the wire size for a particular application?

Answer 11

The system voltage, permissible voltage drop, current to be carried, wire length, and whether the load is continuous or intermittent.

Question 12

What is the relationship between the inside diameter of a conduit and the outside diameter of the wire bundle inside it?

Answer 12

The conduit must be 25% larger than the wire bundle.

Question 13

What is the maximum number of terminal lugs that can be placed on a single terminal strip stud?

Answer 13

Four

Question 14

What is the proper length for a bonding jumper?

Answer 14

As short as practical, but long enough to allow free movement of the component.

Question 15

Under what conditions must a switch be derated from its nominal rating?

Answer 15

When used with inductive circuits, circuits with high in-rush current.

Question 16

At what point do electric motors draw the most current?

Answer 16

When starting

Question 17

Circuit breakers are designed to open before what condition occurs?

Answer 17

Before the wire emits smoke.

Question 18

At what point in a circuit should the protective device be located?

Answer 18

As close to the power source as possible

Question 19

What type of circuit breaker may not be used in aircraft?

Answer 19

An automatic resetting type.

Question 20

What part of an aircraft is identified by a white navigation light?

Answer 20

The tail

Question 21

What could cause an AC electric motor to run too slowly?

Answer 21

Lack of lubrication, defective wiring, or low applied voltage.

Question 22

What should be done when making bonding or grounding connections between dissimilar materials?

Answer 22

Use a suitable washer so that any corrosion will occur on the washer.

Question 23

Prior to making a continuity check, what must be done to an electrical circuit?

Answer 23

The power must be turned off.