NCATT AET & AEIT Endorsement Exam
Comprehensive Test Bank – 100+ Questions with Answers and
Rationales
National Center for Aerospace & Transportation Technologies
(NCATT) | 2025/2026 Edition | Graded A+
EXAM OVERVIEW
The NCATT AET (Aircraft Electronics Technician) certification exam has 90
questions with a passing score of 73%. The AEIT (Aircraft Electronics Installation
Technician) endorsement exam has 106 questions with a passing score of 70%.
Candidates must pass the AET before taking endorsements .
Exam References: Answers are based on AC 43.13-1B Chapter 11 and other
applicable FAA regulations and industry standards .
SECTION 1: ELECTROMAGNETIC INTERFERENCE (EMI) – FUNDAMENTALS
Questions 1-30
Q1. What does "EMI" stand for in aviation maintenance?
A) Engine Malfunction Indicator
B) Electromagnetic Interference
C) Electronic Maintenance Inspection
D) Emergency Mode Indicator
Answer: B) Electromagnetic Interference
Rationale: EMI is the standard acronym in avionics for electromagnetic
interference. It occurs when electromagnetic fields induce unwanted voltages in
electrical circuits .
,Q2. What is the primary mechanism by which EMI affects avionics systems?
A) Thermal heating of conductors
B) Unwanted coupling of electromagnetic energy into sensitive circuits
C) Galvanic corrosion of connectors
D) Electrostatic discharge from human touch
Answer: B) Unwanted coupling of electromagnetic energy into sensitive circuits
Rationale: EMI occurs when electromagnetic energy from a source couples (via
radiated or conducted paths) into a victim circuit, causing noise, false data, or
malfunction .
Q3. What is the definition of Electromagnetic Interference (EMI)?
A) Interference caused by mechanical vibration in aircraft components
B) Interference caused when electromagnetic fields (radio waves) induce high-
frequency voltages in a wire or component
C) Interference caused by corrosion in electrical connectors
D) Interference caused by improper soldering techniques
Answer: B) Interference caused when electromagnetic fields (radio waves)
induce high-frequency voltages in a wire or component
Rationale: EMI is specifically caused when electromagnetic fields induce high-
frequency voltages in a wire or component. This is defined in AC 43.13-1B 11-89 .
Q4. What is the typical frequency range of radiated EMI from aircraft
communication antennas?
A) 10 Hz – 1 kHz
B) 100 kHz – 30 MHz
C) 30 MHz – 1 GHz
D) Above 10 GHz
Answer: C) 30 MHz – 1 GHz
,Rationale: This frequency range covers most aviation communication and
navigation bands, including VHF comm, VOR, ILS, and DME, which are the most
susceptible to radiated EMI .
Q5. What is the dominant coupling mechanism for EMI between two parallel
wires in a bundle?
A) Radiated
B) Inductive and capacitive
C) Galvanic
D) Common impedance
Answer: B) Inductive and capacitive
Rationale: Proximity between parallel wires allows both magnetic (inductive) and
electric (capacitive) field coupling. This is why wire separation and twisting are
important EMI mitigation techniques .
Q6. What is the typical frequency range of conducted EMI in aircraft DC power
systems?
A) 0–150 kHz
B) 1–30 MHz
C) 30–100 MHz
D) >1 GHz
Answer: A) 0–150 kHz
Rationale: Conducted EMI on DC lines (ripple, switching noise, harmonics) usually
spans audio to low RF frequencies (kHz to ~150 kHz) .
Q7. Which frequency range is most susceptible to radiated EMI from aircraft
communication antennas?
A) 10 Hz – 1 kHz
B) 100 kHz – 30 MHz
, C) 30 MHz – 1 GHz
D) Above 10 GHz
Answer: C) 30 MHz – 1 GHz
Rationale: This frequency range covers most aviation communication and
navigation bands, which are the most susceptible to radiated EMI .
Q8. A ferrite core around a cable suppresses EMI by:
A) Reflecting energy back to source
B) Increasing the impedance for high-frequency currents
C) Reducing DC resistance
D) Shunting energy to ground
Answer: B) Increasing the impedance for high-frequency currents
Rationale: Ferrite cores act as common-mode chokes, increasing the impedance
for high-frequency currents and suppressing EMI .
Q9. Twisted pair wiring reduces EMI because:
A) It increases resistance
B) It creates magnetic field cancellation between twists
C) It lowers inductance
D) It increases capacitance
Answer: B) It creates magnetic field cancellation between twists
Rationale: Twisted pair wiring creates magnetic field cancellation because the
twists cause the magnetic fields from adjacent wires to oppose each other,
reducing both emissions and susceptibility .
Q10. What is the difference between radiated and conducted EMI?
A) Radiated travels through space; conducted travels via conductors
B) Conducted only occurs at power line frequencies
Comprehensive Test Bank – 100+ Questions with Answers and
Rationales
National Center for Aerospace & Transportation Technologies
(NCATT) | 2025/2026 Edition | Graded A+
EXAM OVERVIEW
The NCATT AET (Aircraft Electronics Technician) certification exam has 90
questions with a passing score of 73%. The AEIT (Aircraft Electronics Installation
Technician) endorsement exam has 106 questions with a passing score of 70%.
Candidates must pass the AET before taking endorsements .
Exam References: Answers are based on AC 43.13-1B Chapter 11 and other
applicable FAA regulations and industry standards .
SECTION 1: ELECTROMAGNETIC INTERFERENCE (EMI) – FUNDAMENTALS
Questions 1-30
Q1. What does "EMI" stand for in aviation maintenance?
A) Engine Malfunction Indicator
B) Electromagnetic Interference
C) Electronic Maintenance Inspection
D) Emergency Mode Indicator
Answer: B) Electromagnetic Interference
Rationale: EMI is the standard acronym in avionics for electromagnetic
interference. It occurs when electromagnetic fields induce unwanted voltages in
electrical circuits .
,Q2. What is the primary mechanism by which EMI affects avionics systems?
A) Thermal heating of conductors
B) Unwanted coupling of electromagnetic energy into sensitive circuits
C) Galvanic corrosion of connectors
D) Electrostatic discharge from human touch
Answer: B) Unwanted coupling of electromagnetic energy into sensitive circuits
Rationale: EMI occurs when electromagnetic energy from a source couples (via
radiated or conducted paths) into a victim circuit, causing noise, false data, or
malfunction .
Q3. What is the definition of Electromagnetic Interference (EMI)?
A) Interference caused by mechanical vibration in aircraft components
B) Interference caused when electromagnetic fields (radio waves) induce high-
frequency voltages in a wire or component
C) Interference caused by corrosion in electrical connectors
D) Interference caused by improper soldering techniques
Answer: B) Interference caused when electromagnetic fields (radio waves)
induce high-frequency voltages in a wire or component
Rationale: EMI is specifically caused when electromagnetic fields induce high-
frequency voltages in a wire or component. This is defined in AC 43.13-1B 11-89 .
Q4. What is the typical frequency range of radiated EMI from aircraft
communication antennas?
A) 10 Hz – 1 kHz
B) 100 kHz – 30 MHz
C) 30 MHz – 1 GHz
D) Above 10 GHz
Answer: C) 30 MHz – 1 GHz
,Rationale: This frequency range covers most aviation communication and
navigation bands, including VHF comm, VOR, ILS, and DME, which are the most
susceptible to radiated EMI .
Q5. What is the dominant coupling mechanism for EMI between two parallel
wires in a bundle?
A) Radiated
B) Inductive and capacitive
C) Galvanic
D) Common impedance
Answer: B) Inductive and capacitive
Rationale: Proximity between parallel wires allows both magnetic (inductive) and
electric (capacitive) field coupling. This is why wire separation and twisting are
important EMI mitigation techniques .
Q6. What is the typical frequency range of conducted EMI in aircraft DC power
systems?
A) 0–150 kHz
B) 1–30 MHz
C) 30–100 MHz
D) >1 GHz
Answer: A) 0–150 kHz
Rationale: Conducted EMI on DC lines (ripple, switching noise, harmonics) usually
spans audio to low RF frequencies (kHz to ~150 kHz) .
Q7. Which frequency range is most susceptible to radiated EMI from aircraft
communication antennas?
A) 10 Hz – 1 kHz
B) 100 kHz – 30 MHz
, C) 30 MHz – 1 GHz
D) Above 10 GHz
Answer: C) 30 MHz – 1 GHz
Rationale: This frequency range covers most aviation communication and
navigation bands, which are the most susceptible to radiated EMI .
Q8. A ferrite core around a cable suppresses EMI by:
A) Reflecting energy back to source
B) Increasing the impedance for high-frequency currents
C) Reducing DC resistance
D) Shunting energy to ground
Answer: B) Increasing the impedance for high-frequency currents
Rationale: Ferrite cores act as common-mode chokes, increasing the impedance
for high-frequency currents and suppressing EMI .
Q9. Twisted pair wiring reduces EMI because:
A) It increases resistance
B) It creates magnetic field cancellation between twists
C) It lowers inductance
D) It increases capacitance
Answer: B) It creates magnetic field cancellation between twists
Rationale: Twisted pair wiring creates magnetic field cancellation because the
twists cause the magnetic fields from adjacent wires to oppose each other,
reducing both emissions and susceptibility .
Q10. What is the difference between radiated and conducted EMI?
A) Radiated travels through space; conducted travels via conductors
B) Conducted only occurs at power line frequencies
