Airframe Mechanic Aircraft Electrical Systems Questions and Answers

Question 1

An aircraft's electrical schematic shows a device that uses a small current flowing through a coil to electromagnetically close a set of contacts, allowing a much larger current to flow to a high-power component like a starter motor.
Which device performs this function?

Accepted Answer

A relay

Answer

A circuit breaker

Answer

A diode

Answer

A resistor

Question 2

Which of the following is the primary purpose of a Transformer Rectifier Unit (TRU) in an aircraft electrical system?

Accepted Answer

To convert 115V AC power to 28V DC power

Answer

To step up DC voltage for long-distance transmission

Answer

To convert 28V DC power to 115V AC power for sensitive instruments

Answer

To regulate the frequency of the AC generator output

Question 3

A technician is performing maintenance on a nickel-cadmium (Ni-Cad) battery and observes a white, powdery residue on the battery case near the cell vents. This is most often caused by:

Accepted Answer

Electrolyte spewage due to overcharging or excessive heat.

Answer

Normal outgassing during a deep discharge cycle.

Answer

Electrolyte reacting with lead-acid fumes from a nearby battery.

Answer

The battery freezing in extremely low ambient temperatures.

Question 4

What is the primary function of a Constant Speed Drive (CSD) connected to an engine-driven AC generator?

Accepted Answer

To convert the variable engine RPM into a constant generator RPM.

Answer

To provide over-voltage protection for the electrical bus.

Answer

To act as a clutch, allowing the generator to be disengaged.

Answer

To cool the generator using a dedicated oil system.

Question 5

In a brushed DC generator, what is the combined function of the commutator and brushes?

Accepted Answer

To provide a sliding electrical connection and convert the internal AC to external DC.

Answer

To regulate the generator's output voltage.

Answer

To cool the armature windings by providing an air gap.

Answer

To vary the magnetic field strength of the stator.

Question 6

To verify the integrity of an electrical bond between an equipment rack and the aircraft structure, a technician should use a multimeter to measure for:

Accepted Answer

a very low resistance.

Answer

a specific AC voltage.

Answer

the absence of continuity.

Answer

the capacitance of the bonding strap.

An aircraft's electrical schematic shows a device that uses a small current flowing through a coil to electromagnetically close a set of contacts, allowing a much larger current to flow to a high-power component like a starter motor.Which device performs this function?

An aircraft's electrical schematic shows a device that uses a small current flowing through a coil to electromagnetically close a set of contacts, allowing a much larger current to flow to a high-power component like a starter motor.
Which device performs this function?