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WorksheetsWeek 4 Review(Updated)
Total questions: 27
Worksheet time: 14mins
During maintenance, a technician checks motor brushes. Which of the following details should be verified to ensure proper operation?
Alignment of brush terminals with the pole shoes
Brush length, free movement in holders, and correct spring pressure
Clearance between brush caps and the armature housing
While in flight, a generator shuts down immediately after a voltage spike. What does this indicate about the Generator Control Unit (GCU)?
It tripped the overvoltage protection circuit to disconnect the generator
It cut power to all buses to prevent further surges
It lowered alternator field current to stabilize output
A technician finds a failed capacitor in a radio filter circuit. To reduce unwanted low-frequency noise, which action would be most effective?
Install a capacitor designed for power factor correction
Replace it with a capacitor of slightly lower capacitance to better block low-frequency interference
Use a capacitor of the same capacitance but a higher voltage rating
After new brushes are installed in a DC motor, heavy sparking appears. What likely caused it?
Excess voltage applied to the motor terminals
Uneven contact between the brushes and the commutator
Loose connection on the field winding terminals
A technician installs a replacement alternator marked "60 Hz." What should be verified before returning the aircraft to service?
Confirm that the alternator frequency meets the manufacturer’s specifications
Adjust the alternator output to match bus voltage
Ensure that the current output matches the aircraft load requirement
Why should aviation technicians still be familiar with vacuum tube systems?
Certain older aircraft components still operate using vacuum tube technology
Modern avionics rely on tubes to test transistor performance
Tubes are required to power most analog instruments
If the secondary wiring on a single-pole, double-throw (SPDT) relay is reversed, what could occur?
The relay coil will short and overheat
The relay might switch circuits prematurely and cause malfunction
The contacts will remain open and prevent all current flow
A cockpit lamp appears dim even though voltage readings are normal. What is the most likely cause?
The current through the circuit is too low to supply full power to the lamp
The filament resistance dropped below the rated value
The circuit fuse is the wrong delay rating
If a DC power source were accidentally connected to an AC aircraft circuit, what could happen?
The system may not operate correctly and could suffer component damage
The circuit would automatically convert DC to AC
The system would continue to function at reduced efficiency
In a three-unit voltage regulator, which section prevents damage from excessive current flow?
Voltage regulator
Load relay
Current limiter
What is one major purpose of the Generator Control Unit (GCU) in an aircraft electrical system?
To protect the electrical network from overvoltage conditions
To control fuel flow between generator drive units
To monitor hydraulic pressure during power generation
What is the role of a Constant Speed Drive (CSD) in the electrical system?
To keep alternator speed constant for proper frequency output
To regulate oil flow through the alternator housing
To synchronize multiple generators for load sharing
During a generator test, the system automatically disconnects because voltage exceeds the limit. What should the technician inspect first?
The voltage regulator and field circuit for proper control
The alternator drive coupling for mechanical slip
The generator housing for overheating
Why must a rectifier produce clean, stable DC power in aircraft systems?
To ensure that downstream components receive consistent voltage and current
To regulate alternator field strength
To isolate inductive loads from AC surges
How does a GCU respond when an overvoltage condition occurs?
It isolates the generator from the main electrical bus
It reroutes current through the standby power unit
It maintains generator output by boosting field current
A DC motor receives voltage but does not rotate. The battery is known to be good. What should be checked next?
Condition and seating of the brushes on the commutator
Torque of the end-bell fasteners
Continuity of the external field resistor
Which internal parts of a Constant Speed Drive (CSD) maintain a steady alternator output speed?
Pressurized oil system and wobble plate mechanism
Magnetic clutch and rotor shaft
Differential gear assembly
What parameters does a Generator Control Unit (GCU) monitor to protect the electrical system?
Voltage levels and fault conditions
Circuit breaker timing intervals
Alternator lubrication cycles
A DC motor turns normally but produces weak torque. Tests reveal high resistance in the field circuit. What is the likely cause?
Reduced magnetism in the field coils due to excessive resistance
Over-energized armature causing current imbalance
Rotor drag from misaligned bearings
What is the main role of a transistor in an aircraft electrical circuit?
To amplify or switch electrical signals
To maintain constant AC voltage between buses
To act as a circuit breaker for overload protection
What does a three-phase AC generator produce?
Three alternating currents that are 120 degrees apart in phase
One sine wave with constant polarity
Two synchronized pulses per rotation
What does an inverter do in an aircraft power system?
Converts DC power into AC power
Converts AC voltage into magnetism
Steps down current to protect the main bus
During cruise, the instrument lights flicker and radios behave erratically. How could a bad voltage regulator cause this?
It failed to hold a constant voltage output
It opened the battery contactor under load
It drained current from the backup generator
Which material is most often used in aircraft semiconductors for its wide temperature range and reliability?
Silicon
Germanium
Copper
A pilot resets the field control relay after an overvoltage warning and system returns to normal. What does this suggest?
The voltage regulator or generator likely caused the overvoltage and needs inspection
The main alternator bearings are wearing out
The battery reached low capacity during flight
When inspecting a magnetic amplifier, the technician notes overheating and signal loss. What should be checked first?
Input AC signal and magnetic field control circuit
Cooling air flow through the amplifier housing
The transformer windings for continuity
What is the basic purpose of a diode in an aircraft electrical circuit?
To allow current to flow in only one direction
To regulate alternating current waveform
To store charge for later use
