Aircraft Electrical Systems

Question 1

What two things must you take into consideration when selecting the wire size to use in an aircraft electrical system installation?

Answer 1

The current carrying capability of the wire and the voltage drop caused by the current flowing through the wire.

Question 2

What is the maximum number of wires that should be connected to any single stud in a terminal strip?

Answer 2

Four

Question 3

How is a wire bundle protected from chafing where the bundle goes through a hole in a fuselage frame or bulkhead?

Answer 3

The edges of the hole are covered with a flexible gourmet, and the bundle is secured to the structure with a cushioned clamp.

Question 4

What kind of clamp is used to secure a wire bundle to the aircraft structure?

Answer 4

A cushioned clamp

Question 5

Why are solderless splices usually better than soldered splices in the wiring of an aircraft electrical system?

Answer 5

Solder joints are usually stiff, and vibration can harden the wire and cause it to break. Solderless splices are designed to keep the joint flexible so vibration cannot cause a wire to break.

Question 6

What size generator must be used in an aircraft electrical system if the connected electrical load is 30 amps, and there is no way of monitoring the generator output?

Answer 6

The total continuously connected electrical load must be no more than 80% of the rated generator output. This would require a generator with a rating of 37.5 amps. Practically, a 40 amp generator would be installed.

Question 7

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

Answer 7

The lower resistance of the cold filaments cause high inrush current

Question 8

On which wing is the red navigation light?

Answer 8

On the left wing.

Question 9

What kind of fault can be found in a generator armature with a growler?

Answer 9

shorted coils

Question 10

Does an aircraft engine electric starter use a series or a parallel motor?

Answer 10

A series-wound motor.

Question 11

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

Answer 11

Aluminum wire is more brittle than copper. It is more subject to breakage when it is nicked or when it is subjected to vibration.

Question 12

What kind of rectifier is used in the small DC alternators installed in most light aircraft?

Answer 12

Six silicone diodes arranged in a three-phase, full wave rectifier.

Question 13

What kind of instrument would you use to measure very high resistance?

Answer 13

A megohmmeter.

Question 14

When is it important that aircraft electrical system wire bundles be enclosed in some type of conduit?

Answer 14

Any time a wire bundle is routed in an area where it is subject to abrasion or rough handling, it should be enclosed in a conduit.

Question 15

What size aluminum wire should be proper to replace a piece of 4 gage copper wire?

Answer 15

two-gage. When you substitute aluminum wire for copper wire, use a wire that is two gage numbers larger

Question 16

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

Answer 16

six-gage

Question 17

What three things must be synchronized before an aircraft AC generator is placed on the same bus with another AC generator?

Answer 17

The voltage, the frequency, and the phase rotation.

Question 18

How can the direction of rotation of the armature of a DC shunt-wound electric motor be reversed?

Answer 18

By reversing the connections to the shunt field coil with reference to the armature.

Question 19

What is meant by flashing the fields of a generator?

Answer 19

Restoring the residual magnetism to the frame of the generator. This is done by passing battery current through the field coils in the direction it normally flows when the generator is operating.