ASTM NCATT AET – Aircraft Electronics Technician — Questions and Answers

Question 1: Which approach is most effective for problem-solving in Avionics Systems?

Ignoring the problem until it resolves itself
Random trial and error
Always asking someone else
Systematic analysis followed by evidence-based decision making (Correct answer)

Correct answer: Systematic analysis followed by evidence-based decision making

Systematic, evidence-based approaches lead to more reliable solutions than ad hoc methods.

Question 2: What quality metrics are most important in Navigation Equipment?

Measurable outcomes, process compliance, and stakeholder satisfaction (Correct answer)
Only financial metrics
Only speed of completion
No metrics are needed

Correct answer: Measurable outcomes, process compliance, and stakeholder satisfaction

Quality in Navigation Equipment is measured through multiple dimensions including outcomes, processes, and satisfaction.

Question 3: A TCAS II system issues a Resolution Advisory (RA). What must the flight crew do?

Advise ATC and request vectors
Follow the RA maneuver immediately regardless of ATC instructions (Correct answer)
Confirm the RA with ATC before maneuvering
Disconnect autopilot and maintain current flight path

Correct answer: Follow the RA maneuver immediately regardless of ATC instructions

FAA regulations and ICAO standards require crews to follow TCAS II Resolution Advisories immediately, as the system coordinates escape maneuvers between conflicting aircraft.

Question 4: After completing avionics maintenance, a technician notices the aircraft skin has several small scratches near the avionics bay access panel. The CORRECT action is to:

Polish the scratches with abrasive compound and return to service
Document the damage in the maintenance record and defer to sheet metal inspection (Correct answer)
Apply touch-up paint immediately to prevent corrosion
Ignore scratches smaller than 1/8 inch

Correct answer: Document the damage in the maintenance record and defer to sheet metal inspection

Any new airframe damage found during maintenance must be documented and assessed by qualified personnel before return to service.

Question 5: A technician performing a functional test notices an avionics unit fails its self-test only when the aircraft is at operating temperature. The best diagnostic strategy is to:

Use a thermal camera or temperature-sensitive spray to identify heat-sensitive components while monitoring with a digital multimeter (Correct answer)
Increase the cooling airflow and retest without further investigation
Replace the unit immediately since intermittent faults are not repairable
Test the unit only at room temperature and clear the fault code

Correct answer: Use a thermal camera or temperature-sensitive spray to identify heat-sensitive components while monitoring with a digital multimeter

Thermal imaging or temperature spray helps isolate components whose electrical characteristics shift with temperature, causing the intermittent failure.

Question 6: Which FAA regulation requires that all avionics work performed on air carrier aircraft be inspected by a qualified inspector before return to service?

14 CFR Part 91.409
14 CFR Part 65.81
14 CFR Part 121.369 (Correct answer)
14 CFR Part 43.9

Correct answer: 14 CFR Part 121.369

14 CFR Part 121.369 requires air carriers to have an approved inspection program ensuring all maintenance, including avionics, is inspected before return to service.

Question 7: On an aircraft wiring diagram, a wire labeled '20AWG' indicates what about the conductor?

The wire insulation is 0.020 inches thick
The wire was installed during revision 20 of the aircraft wiring document
The conductor size is American Wire Gauge 20, indicating its cross-sectional diameter (Correct answer)
The wire is rated for a maximum of 20 volts DC

Correct answer: The conductor size is American Wire Gauge 20, indicating its cross-sectional diameter

AWG (American Wire Gauge) is a standardized system for wire conductor sizing. A higher AWG number means a smaller conductor diameter. 20AWG is a common gauge for aircraft signal and low-current power wiring.

Question 8: What is the standard AC power frequency used by most transport-category aircraft electrical systems?

400 Hz (Correct answer)
50 Hz
60 Hz
800 Hz

Correct answer: 400 Hz

Aircraft AC electrical systems operate at 400 Hz, which allows lighter and smaller transformers and motors compared to the 50/60 Hz used in ground power systems.

Question 9: Which type of data transmission sends bits one at a time sequentially over a single channel?

Parallel transmission
Synchronous burst transmission
Multiplex transmission
Serial transmission (Correct answer)

Correct answer: Serial transmission

Serial transmission sends data bit-by-bit over a single wire, as used in avionics buses like ARINC 429 and RS-232.

Question 10: When routing new avionics wiring near aircraft control cables, the minimum separation distance specified in AC 43.13-1B is:

1/4 inch
6 inches
1/2 inch
3 inches (Correct answer)

Correct answer: 3 inches

AC 43.13-1B specifies a minimum 3-inch separation between electrical wiring and aircraft control cables to prevent chafing interference with flight control systems.

Question 11: What is the importance of communication skills in Navigation Equipment?

Clear communication prevents errors, builds relationships, and ensures understanding among all parties (Correct answer)
Technical skills are sufficient without communication
Communication is only important for managers
Communication skills cannot be learned

Correct answer: Clear communication prevents errors, builds relationships, and ensures understanding among all parties

Effective communication is essential for coordination, error prevention, and stakeholder relationships.

Question 12: What does the term 'paralleling' mean when applied to aircraft AC generators?

Isolating a failed generator from the bus
Synchronizing and connecting multiple generators to share load equally (Correct answer)
Connecting generators in series to increase voltage
Switching between generator and APU power

Correct answer: Synchronizing and connecting multiple generators to share load equally

Paralleling AC generators means synchronizing their frequency, phase, and voltage so they can be connected together and share the electrical load equally.

Question 13: Which set of flight instruments receives input directly from the pitot-static system?

Altimeter, airspeed indicator, and vertical speed indicator (VSI) (Correct answer)
GPS, altimeter, and airspeed indicator
Attitude indicator, heading indicator, and turn coordinator
Magnetic compass, altimeter, and attitude indicator

Correct answer: Altimeter, airspeed indicator, and vertical speed indicator (VSI)

The pitot-static system supplies air pressure data to three instruments: the altimeter (static pressure), the airspeed indicator (pitot minus static pressure), and the vertical speed indicator (rate of static pressure change). Gyroscopic instruments use vacuum or electrical power, not pitot-static pressure.

Question 14: Under 14 CFR Part 39, an Airworthiness Directive (AD) is legally classified as:

A Federal Regulation with the force of law (Correct answer)
An advisory from the manufacturer only
A recommendation that operators should follow
An optional upgrade program

Correct answer: A Federal Regulation with the force of law

Airworthiness Directives issued under 14 CFR Part 39 are Federal Regulations and must be complied with; non-compliance renders the aircraft unairworthy.

Question 15: What does the term 'CDI sensitivity' refer to in area navigation (RNAV) operations?

The crosstrack distance represented by full-scale needle deflection (Correct answer)
The rate at which the CDI updates its position display
The gain setting of the VOR receiver RF amplifier
The minimum signal strength required to lock onto a course

Correct answer: The crosstrack distance represented by full-scale needle deflection

CDI sensitivity refers to the crosstrack distance (in nautical miles) that represents full-scale deflection; it scales from ±5 NM en route to ±0.3 NM during approach.

Question 16: When an avionics technician discovers a discrepancy during an inspection that cannot be corrected before flight, what document must be used to record it?

Work order only
Verbal notification to the pilot
Discrepancy log in the aircraft maintenance record (Correct answer)
FAA Form 8130-3

Correct answer: Discrepancy log in the aircraft maintenance record

Discrepancies that cannot be immediately corrected must be entered in the aircraft maintenance record so the crew and subsequent technicians are aware.

Question 17: An aircraft pitot heat circuit draws 8 amps normally but now draws only 2 amps with full voltage applied. This most likely indicates:

A short circuit in the heater element
A failed circuit breaker
An open or partial open in the heater element increasing resistance (Correct answer)
Low bus voltage from the generator

Correct answer: An open or partial open in the heater element increasing resistance

Lower-than-normal current with correct voltage indicates increased resistance, such as a partially open or deteriorated heating element.

Question 18: HF radio communication in aviation typically operates in which frequency range?

960–1215 MHz
108–118 MHz
118–137 MHz
2–30 MHz (Correct answer)

Correct answer: 2–30 MHz

HF (High Frequency) communication systems operate between 2 and 30 MHz, providing long-range voice and data communication via ionospheric skip propagation.

Question 19: Which wire specification is the current standard for most aircraft applications due to its lightweight PTFE insulation?

MIL-W-5086 (PVC-insulated)
SAE AS22759 / MIL-W-22759 (PTFE-insulated) (Correct answer)
AWM Style 1007 (appliance wire)
MIL-W-16878 (general purpose)

Correct answer: SAE AS22759 / MIL-W-22759 (PTFE-insulated)

SAE AS22759 (formerly MIL-W-22759) uses PTFE (Teflon/Tefzel) insulation, which provides excellent heat resistance, low weight, and durability — making it the current standard for most aircraft wiring applications.

Question 20: An avionics technician is assigned to work near aircraft fuel tanks. Which of the following is the MOST critical safety precaution?

Keep a fire extinguisher within 10 feet at all times
Bond and ground the aircraft, eliminate all ignition sources, and ensure adequate ventilation (Correct answer)
Wear fire-resistant clothing only
Work only during daylight hours for better visibility

Correct answer: Bond and ground the aircraft, eliminate all ignition sources, and ensure adequate ventilation

Fuel vapor ignition prevention requires grounding to prevent static sparks, eliminating all ignition sources, and ventilation to disperse accumulated fuel vapors.

Question 21: Which frequency band does a typical radio altimeter operate in?

C-band (4.2–4.4 GHz) (Correct answer)
UHF (329–335 MHz)
Ka-band (35 GHz)
VHF (108–118 MHz)

Correct answer: C-band (4.2–4.4 GHz)

Radio altimeters operate in the C-band at 4.2–4.4 GHz, transmitting FM continuous-wave signals toward the ground to measure altitude above terrain.

Question 22: Which component in an aircraft’s electronic system converts electrical energy into mechanical movement?

Capacitor
Diode
Transformer
Relay (Correct answer)

Correct answer: Relay

A relay is an electrically operated switch that uses an electromagnet to open or close contacts. When an electrical current flows through its coil, it creates a magnetic field that moves a lever, converting electrical energy into a mechanical switching action to control other circuits.

Question 23: In an aircraft bus tie system, what is the function of a Bus Tie Breaker (BTB)?

Regulate voltage between two AC buses
Convert AC bus power to DC for avionics
Protect the bus against overvoltage conditions
Connect or isolate AC buses to allow power transfer between sources (Correct answer)

Correct answer: Connect or isolate AC buses to allow power transfer between sources

A Bus Tie Breaker connects two AC buses together, allowing one generator to power both buses if one generator fails.

Question 24: During an ILS approach, a glideslope pointer above center on the ADI/flight director indicates the aircraft is:

Above the glideslope — fly down
Below the glideslope — fly up (Correct answer)
On the glideslope — maintain current rate
Glideslope signal unreliable — go around

Correct answer: Below the glideslope — fly up

A glideslope deviation pointer above center means the glideslope beam is above the aircraft, so the aircraft is below the glideslope and must climb (fly up) to intercept it.

Question 25: During troubleshooting, a technician finds that an aircraft navigation light works normally on the ground but fails in flight. The MOST likely cause is:

Reduced generator output at cruise RPM
An intermittent open caused by vibration or thermal expansion (Correct answer)
Antenna interference with the lighting circuit
A faulty circuit breaker that only trips in flight

Correct answer: An intermittent open caused by vibration or thermal expansion

Vibration, thermal cycling, or connector movement in flight can cause intermittent opens that are not present under static ground conditions.

Question 26: During a resistance check of an aircraft wiring harness connector, a technician finds 0.8 ohms on a pin that should measure below 0.1 ohms. The BEST corrective action is to:

Accept the reading as it is below 1 ohm
Apply additional voltage to burn through the resistance
Clean or replace the connector to restore proper contact resistance (Correct answer)
Install a heavier gauge wire to compensate

Correct answer: Clean or replace the connector to restore proper contact resistance

Connector contact resistance above specification indicates contamination, corrosion, or wear that requires cleaning or connector replacement to prevent voltage drop and heat buildup.

Question 27: An HF antenna coupler (ATU) is required because:

The HF transceiver output is balanced and the antenna is unbalanced
HF frequencies require circular polarization
HF signals cannot propagate without impedance transformation to 600 ohms
Antenna impedance varies widely across HF frequencies and must be matched to the transmitter (Correct answer)

Correct answer: Antenna impedance varies widely across HF frequencies and must be matched to the transmitter

HF antennas are electrically short relative to the wavelength at many HF frequencies, so the ATU performs impedance matching to maximize power transfer.

Question 28: When troubleshooting an aircraft electrical system and the ammeter shows a discharge indication with the engine running, what is the most likely cause?

An open circuit in a non-essential bus
The avionics master switch is OFF
Battery is fully charged
The alternator is not producing output or is off-line (Correct answer)

Correct answer: The alternator is not producing output or is off-line

A discharge reading on the ammeter with the engine running indicates the battery is supplying the electrical load, which means the alternator has failed or been disconnected.

Question 29: According to 14 CFR Part 65, what minimum age is required for an FAA Airframe and Powerplant (A&P) certificate?

16 years
17 years
18 years (Correct answer)
21 years

Correct answer: 18 years

14 CFR Part 65.71 requires an applicant for an A&P certificate to be at least 18 years of age.

Question 30: What is the correct procedure when a technician accidentally drops a tool inside an aircraft during avionics maintenance?

Notify the pilot but continue maintenance
Complete the maintenance task first, then retrieve the tool
Immediately stop work and retrieve the tool, documenting the event (Correct answer)
Note the tool's location and retrieve it during next access

Correct answer: Immediately stop work and retrieve the tool, documenting the event

A dropped tool must be immediately retrieved and the event documented, as a loose tool can jam flight controls or cause electrical hazards.

Question 31: What resistance value should a properly functioning ESD wrist strap measure when tested with a wrist strap checker?

Less than 10 ohms
Approximately 1 megohm (1 MΩ) (Correct answer)
0 ohms (dead short to ground)
Greater than 100 megohms (open circuit)

Correct answer: Approximately 1 megohm (1 MΩ)

A correctly functioning ESD wrist strap contains a 1 MΩ resistor in series. This provides enough resistance to protect the technician from electrical shock while still allowing static charge to drain safely to ground. A dead short (0 Ω) would create a shock hazard.

Question 32: Which of the following correctly describes a Cockpit Voice Recorder (CVR) recording duration requirement under current FAA regulations for newly certified transport aircraft?

30 minutes
4 hours
2 hours (Correct answer)
1 hour

Correct answer: 2 hours

Current FAA regulations require CVRs on newly certified transport category aircraft to retain the last 2 hours of audio.

Question 33: What does a high VSWR reading on an antenna analyzer indicate about an aircraft antenna installation?

There is a significant impedance mismatch causing reflected power (Correct answer)
The antenna gain is above specification
The coaxial feedline has excessive capacitance
The antenna is properly matched to the transmission line

Correct answer: There is a significant impedance mismatch causing reflected power

A high Voltage Standing Wave Ratio means reflected power is returning to the transmitter, indicating an impedance mismatch in the antenna system.

Question 34: How should an ESD-sensitive avionics LRU be transported between the aircraft and the avionics shop?

Placed in a standard cardboard box padded with foam rubber
Carried directly in both hands to maintain physical control of the unit
Wrapped tightly in plastic bubble wrap to prevent physical damage
Transported in approved ESD-protective (conductive or dissipative) packaging (Correct answer)

Correct answer: Transported in approved ESD-protective (conductive or dissipative) packaging

ESDS assemblies must be transported in approved ESD-protective packaging — conductive bags, dissipative foam, or other approved containers. Standard cardboard and plastic bubble wrap are insulators that can generate and hold static charge, increasing the risk of ESD damage.

Question 35: A technician uses an oscilloscope to observe a 400 Hz aircraft power bus waveform and notices the top of the sine wave is flattened. This condition is called:

Frequency modulation
Phase shift
Hysteresis
Clipping or waveform clipping (Correct answer)

Correct answer: Clipping or waveform clipping

Clipping occurs when a signal exceeds the linear range of a component or supply, causing the peaks to be cut flat.

Question 36: An avionics technician installs a replacement VHF comm radio. Which document provides the approved data confirming the replacement is authorized?

The shop's internal work order
The Pilot's Operating Handbook only
FAA-approved data such as STC, AML, or aircraft manufacturer data (Correct answer)
The technician's logbook entry

Correct answer: FAA-approved data such as STC, AML, or aircraft manufacturer data

Approved data such as an STC, AML listing, or aircraft manufacturer's maintenance manual must authorize avionics installations.

Question 37: A passenger address (PA) amplifier on a transport category aircraft fails silently — no audio in cabin, no fault indication. The BEST initial test is:

Verify ACARS datalink is not jamming PA frequencies
Inject a known audio signal at the amplifier input and measure output at speaker tap points (Correct answer)
Replace the amplifier module immediately
Check all CVR inputs for signal

Correct answer: Inject a known audio signal at the amplifier input and measure output at speaker tap points

Signal injection at the amplifier input and probing the output isolates whether the fault is in the amplifier itself or in upstream audio sources and wiring.

Question 38: Which fastener material used in aluminum aircraft skin would create the greatest risk of galvanic corrosion?

Titanium fasteners
2024 aluminum alloy rivets
Stainless steel (300-series) fasteners
Uncoated carbon steel fasteners (Correct answer)

Correct answer: Uncoated carbon steel fasteners

Uncoated carbon steel and aluminum are far apart in the galvanic series, creating a large electrochemical potential difference that drives aggressive galvanic corrosion. Aluminum and titanium are much closer in the galvanic series, making titanium an acceptable fastener in aluminum structure.

Question 39: DME (Distance Measuring Equipment) operates on the principle of measuring:

Doppler shift of a carrier frequency
Signal strength attenuation over distance
The phase difference between two RF signals
Round-trip pulse propagation time between aircraft and ground station (Correct answer)

Correct answer: Round-trip pulse propagation time between aircraft and ground station

DME measures the slant-range distance by timing the round-trip delay between an interrogation pulse sent by the aircraft and the reply pulse from the ground transponder.

Question 40: How many bits are contained in each ARINC 429 data word?

16 bits
8 bits
64 bits
32 bits (Correct answer)

Correct answer: 32 bits

Each ARINC 429 transmission consists of a 32-bit word, divided into a label field (bits 1–8), a source/destination identifier (bits 9–10), data field (bits 11–28), sign/status matrix (bits 29–30), and a parity bit (bit 32).

Question 41: What navigation system uses the time difference of arrival (TDOA) of signals from multiple ground stations?

LORAN-C (Correct answer)
VOR
ILS
ADF

Correct answer: LORAN-C

LORAN-C determines position by measuring the time difference of arrival of pulsed signals from a chain of synchronized ground transmitters.

Question 42: Which of the following test equipment is specifically designed to verify the accuracy of an aircraft's transponder Mode C altitude encoding?

VOR test set
TCAS test unit only
ILS ramp tester
Pitot-static test set used in conjunction with an encoding altimeter check (Correct answer)

Correct answer: Pitot-static test set used in conjunction with an encoding altimeter check

Mode C altitude encoding is verified by applying known simulated altitudes via a pitot-static test set while monitoring the transponder's Gillham code output.

Question 43: Which bus architecture is commonly used in modern commercial aircraft for avionics data communication?

USB 3.0
CAN bus
RS-232
ARINC 429 (Correct answer)

Correct answer: ARINC 429

ARINC 429 is the standard data bus used in commercial aviation for unidirectional communication between avionics systems.

Question 44: Which component in an aircraft AC power system is responsible for detecting a generator fault and removing it from the bus?

Constant Speed Drive (CSD)
Generator Control Unit (GCU) (Correct answer)
Current Transformer (CT)
Transformer Rectifier Unit (TRU)

Correct answer: Generator Control Unit (GCU)

The Generator Control Unit monitors generator output parameters and trips the Generator Control Breaker (GCB) to disconnect a faulty generator from the bus.

Question 45: What is the standard word length for data transmitted on an ARINC 429 data bus?

16 bits
24 bits
64 bits
32 bits (Correct answer)

Correct answer: 32 bits

ARINC 429 uses a 32-bit word format that includes label, source/destination identifier, data, sign/status matrix, and parity bit fields.

Question 46: Which type of aircraft battery is most commonly used in modern general aviation aircraft due to its maintenance advantages?

Nickel-cadmium (NiCd)
Sealed absorbed glass mat (AGM) lead-acid (Correct answer)
Lithium-ion
Lead-acid (flooded cell)

Correct answer: Sealed absorbed glass mat (AGM) lead-acid

Sealed AGM lead-acid batteries are widely used in general aviation because they are maintenance-free, spill-proof, and do not require water additions like flooded-cell batteries.

Question 47: A technician finds that an avionics connector pin is recessed (pushed back) in its housing. The CORRECT repair procedure is to:

Apply epoxy to secure the pin in position
Use the approved extraction and insertion tool for that connector series (Correct answer)
Replace the entire connector assembly immediately
Re-insert the pin using needle-nose pliers

Correct answer: Use the approved extraction and insertion tool for that connector series

Approved extraction and insertion tools must be used to prevent damage to the connector housing, pin contacts, and adjacent pins during repair.

Question 48: When working on aircraft avionics in a confined space, what is the FIRST action a technician should take before beginning work?

File a maintenance log entry
Begin the repair immediately to save time
Verify adequate ventilation and identify all exit routes (Correct answer)
Request a second technician to observe

Correct answer: Verify adequate ventilation and identify all exit routes

Before entering any confined space, technicians must confirm adequate ventilation and identify all exit routes as a primary safety measure.

Question 49: Why is it essential for an Aircraft Electronics Technician to maintain detailed records of all maintenance activities?

To ensure compliance with aviation regulations and provide a history of work performed (Correct answer)
To avoid the need for further inspections
To meet personal job performance goals
To improve personal time management

Correct answer: To ensure compliance with aviation regulations and provide a history of work performed

Maintaining detailed records of all maintenance activities is crucial for an Aircraft Electronics Technician to ensure compliance with stringent aviation regulations and provide a comprehensive history of work performed. These records serve as vital documentation for airworthiness, traceability, and accountability, supporting future troubleshooting, inspections, and regulatory audits. Accurate documentation is fundamental to aircraft safety and operational integrity.

Question 50: What is the typical voltage output of an aircraft's 28V DC bus system when fully regulated?

24 volts
26 volts
27.5–28.5 volts (Correct answer)
32 volts

Correct answer: 27.5–28.5 volts

A regulated 28V system operates between approximately 27.5 and 28.5 volts to properly charge 24V batteries while powering the aircraft's electrical loads.

Question 51: How should risk be managed in Avionics Systems?

Through identification, assessment, mitigation strategies, and ongoing monitoring of potential risks (Correct answer)
By ignoring potential problems
By avoiding all risk entirely
Risk management is not necessary

Correct answer: Through identification, assessment, mitigation strategies, and ongoing monitoring of potential risks

Effective risk management involves a systematic process of identifying, evaluating, and addressing potential threats.

Question 52: A current transformer (CT) in an aircraft AC power system is primarily used for:

Filtering harmonic distortion from the bus
Converting single-phase to three-phase power
Measuring load current without breaking the circuit (Correct answer)
Stepping up voltage for high-power equipment

Correct answer: Measuring load current without breaking the circuit

Current transformers allow current monitoring by inducing a proportional secondary current, enabling measurement without interrupting the high-current circuit.

Question 53: What is the primary purpose of standardized procedures in Navigation Equipment?

To create unnecessary bureaucracy
To benefit only management
To ensure consistency, safety, and quality across all practitioners (Correct answer)
To slow down work processes

Correct answer: To ensure consistency, safety, and quality across all practitioners

Standardized procedures ensure that all practitioners deliver consistent, safe, and high-quality outcomes.

Question 54: A logic analyzer shows that a data bus has valid framing and clock, but all data bits read as logic '1'. The most likely cause is:

The clock frequency is too high
The power supply is 10% over nominal
An open circuit on the data line causing it to float to the pull-up rail (Correct answer)
The analyzer probe impedance is loading the bus

Correct answer: An open circuit on the data line causing it to float to the pull-up rail

An open data line with a pull-up resistor will float to the positive supply (logic '1'), causing all bits to read as '1' regardless of what the driver is transmitting.

Question 55: An aircraft Transformer Rectifier Unit (TRU) converts:

115V AC three-phase to 28V DC (Correct answer)
400 Hz AC to 60 Hz AC for ground equipment
DC battery power to AC for avionics
28V DC to 115V AC for large loads

Correct answer: 115V AC three-phase to 28V DC

A TRU uses a transformer to step down voltage and a rectifier bridge to convert three-phase 115V AC aircraft power into 28V DC for DC-powered systems.

Question 56: When reading an aircraft’s technical manual, what is the most critical aspect to focus on?

The publication date of the manual
The section that describes maintenance procedures and safety instructions (Correct answer)
The length of the manual
The color illustrations used in the manual

Correct answer: The section that describes maintenance procedures and safety instructions

When reading an aircraft’s technical manual, the most critical aspect for an Aircraft Electronics Technician is to focus on the sections detailing maintenance procedures and safety instructions. These sections provide the precise, approved steps for performing tasks correctly and safely, ensuring compliance with manufacturer guidelines and preventing accidents or further damage. Adhering strictly to these instructions is paramount for maintaining airworthiness and ensuring technician safety.

Question 57: A ground return circuit fault in aircraft wiring most commonly causes:

Reversed polarity at the equipment terminals
Tripped circuit breakers on multiple buses
Reduced voltage at the load and erratic equipment operation (Correct answer)
Overcurrent in the affected circuit

Correct answer: Reduced voltage at the load and erratic equipment operation

A poor ground return adds resistance in series with the load, causing a voltage drop that results in reduced voltage at the equipment and erratic operation.

Question 58: What does the term 'load shedding' mean in the context of aircraft electrical power management?

Increasing generator output during peak demand
Disconnecting non-essential electrical loads to reduce demand on a degraded power source (Correct answer)
Balancing load between two generators
Testing circuit breakers sequentially

Correct answer: Disconnecting non-essential electrical loads to reduce demand on a degraded power source

Load shedding involves selectively disconnecting non-essential electrical consumers to reduce the demand on a power system operating in a degraded or emergency condition.

Question 59: What non-destructive testing (NDT) method is most effective for detecting corrosion beneath the outer skin of an aluminum aircraft panel that shows no exterior symptoms?

Magnetic particle inspection
Eddy current or ultrasonic testing (Correct answer)
Visual inspection with a bright flashlight and mirror
Dye penetrant inspection

Correct answer: Eddy current or ultrasonic testing

Eddy current and ultrasonic testing can detect material loss or density changes beneath the surface of aluminum panels without removing the skin. Dye penetrant requires a surface-breaking defect to be visible; magnetic particle inspection only works on ferromagnetic metals.

Question 60: What is a multimeter primarily used for in aircraft electronic maintenance?

Providing audio feedback for signal analysis
Displaying circuit schematics
Measuring electrical parameters such as voltage, current, and resistance (Correct answer)
Generating test signals

Correct answer: Measuring electrical parameters such as voltage, current, and resistance

A multimeter is a versatile handheld instrument that combines several measurement functions into one unit, making it indispensable in aircraft electronic maintenance. Its primary use is to measure fundamental electrical parameters such as voltage (volts), current (amps), and resistance (ohms). This allows technicians to perform basic troubleshooting, check continuity, verify power supply levels, and identify simple circuit faults efficiently.

Question 61: In a CMOS logic circuit used in avionics, what is the most critical handling precaution?

Avoid exposure to fluorescent lighting
Never power the device above 3.3V
Store in a magnetic-shielded container
Use ESD wrist straps and grounded work surfaces to prevent electrostatic discharge (Correct answer)

Correct answer: Use ESD wrist straps and grounded work surfaces to prevent electrostatic discharge

CMOS devices have very high input impedance and can be permanently damaged by electrostatic discharge (ESD), requiring grounded wrist straps and ESD-safe work surfaces during handling.

Question 62: When measuring resistance in an installed aircraft circuit with a digital multimeter, the technician must first:

Switch the meter to DC voltage mode
De-energize the circuit and discharge any capacitors (Correct answer)
Set the meter to the highest resistance range
Short the test leads and zero the meter as in an analog meter

Correct answer: De-energize the circuit and discharge any capacitors

Measuring resistance in a live circuit will give inaccurate readings and can damage the meter; the circuit must be de-energized first.

Question 63: PWM (Pulse Width Modulation) is used in avionics primarily to:

Modulate radio carrier frequencies
Provide power line communication between LRUs
Control motors and actuators by varying the duty cycle (Correct answer)
Synchronize multiple ARINC data buses

Correct answer: Control motors and actuators by varying the duty cycle

PWM controls the average power delivered to motors and actuators by varying the on-time (duty cycle) of a fixed-frequency digital pulse.

Question 64: What quality metrics are most important in Avionics Systems?

No metrics are needed
Measurable outcomes, process compliance, and stakeholder satisfaction (Correct answer)
Only speed of completion
Only financial metrics

Correct answer: Measurable outcomes, process compliance, and stakeholder satisfaction

Quality in Avionics Systems is measured through multiple dimensions including outcomes, processes, and satisfaction.

Question 65: What is the primary purpose of standardized procedures in Electrical Troubleshooting?

To create unnecessary bureaucracy
To slow down work processes
To ensure consistency, safety, and quality across all practitioners (Correct answer)
To benefit only management

Correct answer: To ensure consistency, safety, and quality across all practitioners

Standardized procedures ensure that all practitioners deliver consistent, safe, and high-quality outcomes.

Question 66: A technician connects a data bus analyzer to an ARINC 429 bus. The analyzer shows no valid words being decoded. Which condition is least likely to cause this?

A short circuit between the A and B bus lines
The transmitting LRU is in normal operational mode (Correct answer)
Reversed A and B differential pair connections
Incorrect bit rate selected on the analyzer (12.5 kbps vs. 100 kbps)

Correct answer: The transmitting LRU is in normal operational mode

A transmitting LRU in normal operational mode should be producing valid data; the other options would all prevent proper decoding.

Question 67: A SATCOM system on an aircraft provides communication primarily via:

HF sky-wave propagation
Ground-based VHF repeaters
Geostationary or LEO satellites (Correct answer)
UHF line-of-sight links

Correct answer: Geostationary or LEO satellites

SATCOM uses geostationary (e.g., Inmarsat) or low Earth orbit satellites to relay voice and data communications globally, including over oceans.

Question 68: What is the most important foundational concept in Electrical Troubleshooting?

Ignoring established guidelines
Only following instructions from supervisors
Understanding core principles and their practical application in Electrical Troubleshooting (Correct answer)
Memorizing all rules without understanding

Correct answer: Understanding core principles and their practical application in Electrical Troubleshooting

Core principles provide the foundation for all decision-making and practice in Electrical Troubleshooting.

Question 69: What does a Weather Radar system use to detect precipitation intensity?

Reflected radio wave energy (return power) (Correct answer)
Infrared thermal signatures
Static charge accumulation
Doppler frequency shift only

Correct answer: Reflected radio wave energy (return power)

Weather radar measures the power of reflected radio waves; heavier precipitation returns stronger signals, color-coded on the display.

Question 70: What is the maximum data transfer rate of the MIL-STD-1553B data bus commonly used in military aircraft?

1 Mbps (Correct answer)
10 Mbps
100 Mbps
100 kbps

Correct answer: 1 Mbps

MIL-STD-1553B operates at a fixed 1 Megabit per second (1 Mbps). It uses a time-division multiplexing scheme and a command/response protocol managed by the Bus Controller.

Question 71: What is the purpose of IRS (Inertial Reference System) alignment and why must it be performed stationary?

To synchronize the IRS clock with GPS time signals
To zero out accumulated drift errors from the previous flight
To calibrate barometric sensors against a known field elevation
To establish a precise north reference and initial position before computing navigation (Correct answer)

Correct answer: To establish a precise north reference and initial position before computing navigation

IRS alignment uses Earth's rotation sensed by the gyros to determine true north and must be done stationary because any movement during alignment introduces position and heading errors.

Question 72: What role does continuing education play in Navigation Equipment?

Only required for new practitioners
Keeping practitioners current with evolving best practices and new developments (Correct answer)
Only beneficial for management
It is optional and rarely helpful

Correct answer: Keeping practitioners current with evolving best practices and new developments

Continuing education ensures practitioners stay current with advances in their field.

Question 73: What fundamental gyroscopic property allows an attitude indicator (artificial horizon) to maintain a reference to the earth's horizon?

Resonance — the gyro vibrates at the earth's natural frequency
Precession — the gyro tilts 90° from an applied force
Rigidity in space — a spinning gyro resists any change to its orientation (Correct answer)
Pendulosity — the gyro is weighted to seek the gravitational vertical

Correct answer: Rigidity in space — a spinning gyro resists any change to its orientation

Gyroscopic rigidity in space (also called gyroscopic inertia) means that a rapidly spinning mass tends to maintain its plane of rotation in a fixed orientation relative to inertial space. The attitude indicator exploits this to keep the gyro aligned with the true horizon as the aircraft maneuvers around it.

Question 74: A technician signs off on an annual inspection. Where must the inspection sign-off entry appear?

On the aircraft's instrument panel placard
Only in the shop's work order file
In the FAA registry database directly
In the aircraft's maintenance records (logbooks) (Correct answer)

Correct answer: In the aircraft's maintenance records (logbooks)

Annual inspection results must be entered in the aircraft maintenance records (logbooks) per 14 CFR 43.11.

Question 75: FAA Order 8300.10 (Airworthiness Inspector's Handbook) is primarily used by whom?

Aircraft manufacturers only
Air traffic controllers
Airline passengers
FAA Aviation Safety Inspectors (Correct answer)

Correct answer: FAA Aviation Safety Inspectors

FAA Order 8300.10 provides guidance and standardized procedures for FAA Aviation Safety Inspectors performing airworthiness functions, including oversight of maintenance and avionics.

Question 76: What type of modulation is used by HF aviation voice transceivers?

Pulse amplitude modulation
FM
Single Sideband (SSB) (Correct answer)
AM double sideband

Correct answer: Single Sideband (SSB)

HF aviation radios use Single Sideband (SSB) modulation because it is more power-efficient and occupies less bandwidth than double-sideband AM.

Question 77: When performing a continuity check on an aircraft wiring harness, the technician should FIRST:

Apply 28 VDC to the circuit and measure with a voltmeter
Remove the harness from the aircraft for bench testing
Disconnect power and verify the circuit is de-energized before testing (Correct answer)
Use an RF signal injector for better accuracy

Correct answer: Disconnect power and verify the circuit is de-energized before testing

Before any continuity test, the circuit must be completely de-energized to protect equipment and prevent inaccurate readings from back-EMF sources.

Question 78: An ADC (Analog-to-Digital Converter) performs which conversion in avionics systems?

Converts digital signals to analog signals
Converts analog signals to digital signals (Correct answer)
Converts AC voltage to DC voltage
Converts binary to hexadecimal notation

Correct answer: Converts analog signals to digital signals

An ADC samples continuous analog sensor data and converts it to discrete digital values for processing by a microprocessor.

Question 79: A CVR (Cockpit Voice Recorder) is required to retain audio from the last:

30 minutes of flight
4 hours of operation
2 hours of flight (Correct answer)
6 hours from wheels-off

Correct answer: 2 hours of flight

Current regulations (14 CFR 91.609) require CVRs to retain at least 2 hours of the most recent audio to capture enough data for accident investigation.

Question 80: Which FAA Advisory Circular provides guidance on the installation of electronic flight display systems in certificated aircraft?

AC 20-165 (Correct answer)
AC 91-21
AC 25.1309
AC 43.13-1B

Correct answer: AC 20-165

AC 20-165 addresses airworthiness approval of automatic dependent surveillance-broadcast (ADS-B) out systems, including electronic flight display installations.

Question 81: What is the function of a Flight Data Recorder (FDR) mandatory parameter — 'pitch attitude'?

Record bank angle about the longitudinal axis
Record nose-up or nose-down aircraft rotation about the lateral axis (Correct answer)
Record heading changes about the vertical axis
Record engine torque values

Correct answer: Record nose-up or nose-down aircraft rotation about the lateral axis

Pitch attitude records rotation about the lateral (wing-to-wing) axis, indicating nose-up or nose-down orientation during flight.

Question 82: In ARINC 629 multi-transmitter data bus used on the Boeing 777, how is bus access controlled?

Priority levels are hard-wired into each LRU at manufacture
Each terminal uses a decentralized CSMA/CA protocol with periodic and aperiodic transmission (Correct answer)
A central bus controller grants access tokens to each LRU
Time-division multiplexing assigns fixed slots to each transmitter

Correct answer: Each terminal uses a decentralized CSMA/CA protocol with periodic and aperiodic transmission

ARINC 629 uses a decentralized protocol where each terminal autonomously manages periodic and aperiodic data transmission without a central bus controller.

Question 83: When troubleshooting an ARINC 429 bus fault, a technician finds all labels on that bus are missing. The most likely cause is:

Incorrect baud rate on a single receiver
Transmitter output failure in the source LRU or open wire on the bus pair (Correct answer)
Receiver card failure in one LRU
Software version mismatch on one listener

Correct answer: Transmitter output failure in the source LRU or open wire on the bus pair

Since ARINC 429 is unidirectional with one transmitter feeding multiple receivers, a transmitter failure or open bus wire eliminates all labels for every listener on that bus.

Question 84: What is the primary purpose of the FAA's Safety Management System (SMS) as applied to repair stations?

To track mechanic licensing only
To proactively identify and mitigate safety risks (Correct answer)
To replace all existing maintenance regulations
To certify new avionics equipment

Correct answer: To proactively identify and mitigate safety risks

SMS provides a systematic, proactive approach to identifying hazards and managing safety risks before they result in accidents or incidents in the maintenance environment.

Question 85: How should ethical dilemmas be handled in Navigation Equipment?

Make decisions based solely on personal preference
Follow established ethical guidelines, consult with supervisors, and prioritize stakeholder welfare (Correct answer)
Ignore ethical concerns
Always choose the cheapest option

Correct answer: Follow established ethical guidelines, consult with supervisors, and prioritize stakeholder welfare

Ethical decision-making requires following professional guidelines and prioritizing the welfare of all stakeholders.

Question 86: A VOR receiver measures the phase difference between which two signals?

9960 Hz subcarrier and 30 Hz variable signals
30 Hz reference and 30 Hz variable signals (Correct answer)
AM reference and FM variable signals
UHF pulse and VHF carrier signals

Correct answer: 30 Hz reference and 30 Hz variable signals

VOR bearing is determined by comparing the phase of the 30 Hz omnidirectional reference signal against the 30 Hz variable phase signal.

Question 87: What is the nominal voltage of a standard 14-volt aircraft electrical system when measured at the bus with the alternator online?

12 volts
13.8–14.5 volts (Correct answer)
28 volts
24 volts

Correct answer: 13.8–14.5 volts

A 14V system typically operates at 13.8–14.5 volts at the bus when the alternator is charging, slightly above the 12V battery nominal voltage to maintain a charging state.

Question 88: What makes a professional competent in Navigation Equipment?

Only experience matters
A combination of education, practical experience, ongoing learning, and adherence to professional standards (Correct answer)
Only formal education matters
Only certifications matter

Correct answer: A combination of education, practical experience, ongoing learning, and adherence to professional standards

Competence requires the integration of knowledge, skills, experience, and professional conduct.

Question 89: A pilot reports the radio altimeter reads zero while airborne over water at 500 feet. The most likely cause is:

Antenna connector failure or water intrusion in the antenna (Correct answer)
GPS satellite outage
ADC barometric sensor blockage
Static discharge from precipitation

Correct answer: Antenna connector failure or water intrusion in the antenna

Radio altimeter antenna failures or connector corrosion cause false zero or invalid readings because the RF signal path is broken.

Question 90: A ramp tester for an ILS localizer system provides test signals to the aircraft's nav receiver. After tuning the receiver, the CDI needle deflects fully left and does not center. This most likely indicates:

The autopilot is commanding a left turn override
The glideslope antenna is misaligned
A fault in the receiver's deviation output circuit or a course deviation signal is being injected (Correct answer)
The ramp tester is outputting a valid on-course signal and the receiver is working normally

Correct answer: A fault in the receiver's deviation output circuit or a course deviation signal is being injected

A ramp tester injecting an on-course signal should produce a centered CDI; full deflection suggests the receiver or its deviation output is faulty.

Question 91: In aircraft wiring, what is the minimum voltage drop allowed across a wire under full load current according to MIL-W-5088 / FAA AC 43.13-1B guidelines?

The voltage drop should be as low as possible, typically not to exceed 1 volt for essential circuits (Correct answer)
Exactly 0 volts
No more than 10% of supply voltage for all circuits
Up to 5 volts for any circuit

Correct answer: The voltage drop should be as low as possible, typically not to exceed 1 volt for essential circuits

FAA AC 43.13-1B guidance recommends limiting voltage drop to no more than 1 volt for essential avionics circuits to ensure proper equipment operation.

ASTM NCATT AET – Aircraft Electronics Technician

The ASTM NCATT AET certification exam validates the knowledge and skills of aircraft electronics technicians in areas including AC/DC fundamentals, digital techniques, RF energy, test equipment, avionics systems, and aviation safety regulations.

Questions

120 min

Time Limit

73%

To Pass

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