NCATT AET & AEIT Endorsement Exam
Expert-Verified Questions with Detailed
Rationales 2026 Edition | Actual
Questions & Correct Answers | Instant
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Question 1:
A technician is troubleshooting an autopilot system that intermittently fails to
hold assigned altitude. The servos respond correctly during bench testing, but
the aircraft exhibits pitch oscillations during flight. What is the most likely
root cause and recommended diagnostic step?
A) Faulty autopilot computer requiring full replacement
B) Intermittent high resistance in the feedback loop or wiring harness
causing unstable response; perform continuity and insulation testing on
the encoder connectors
C) Low aircraft battery voltage
D) Software corruption in the flight management computer
Rationale: Autopilot systems rely on accurate feedback for stable control.
Intermittent connections create signal noise or loss, resulting in failure to hold
altitude. Systematic wiring checks per FAA AC 43.13-1B and manufacturer
manuals are the first step before component replacement to diagnose faults
efficiently and maintain airworthiness.
Question 2:
A technician is installing a new VHF communication transponder with a
ground strap to the aircraft. The installation must comply with FAA
environmental standards. What is the critical grounding requirement and the
potential consequence of improper bonding?
,A) Connect to any convenient airframe ground
B) Use a dedicated low-impedance ground strap to the airframe with less
than 0.5 milliohms resistance to prevent RF interference
C) Ground only the power return wire
D) No special grounding is required for modern transponders
Rationale: Proper bonding requires a dedicated low-impedance ground strap
to provide an effective RF return path. Poor bonding allows RF currents to
radiate inside the avionics bay, causing electromagnetic interference (EMI)
that can degrade communication and navigation system performance.
Question 3:
What is the allowable voltage drop in a 28-volt continuous aircraft circuit
according to industry standards?
A) 0.5 volts
B) 1.0 volt
C) 2.0 volts
D) 5.0 volts
Rationale: Voltage drop in aircraft wiring should not exceed 2% of the
regulated voltage when the generator is carrying rated current or the battery
is being discharged at the 5-minute rate. For a 28-volt system, 2% equals
approximately 0.56 volts; however, the commonly cited allowable drop is 1
volt. This ensures proper operation of connected avionics equipment.
Question 4:
Which conductor plating is most commonly used in aircraft wiring, and what
is its primary advantage?
A) Silver plating; highest conductivity
B) Nickel plating; high temperature resistance
C) Tin plating; slower oxidation rate than bare copper
D) Gold plating; corrosion resistance
Rationale: Copper wire is most commonly plated with tin, silver, or nickel.
Tin is the most common because it provides a slower oxidation rate than bare
,copper, maintaining good conductivity and solderability over time. Silver
plating offers the highest conductivity but is more expensive and susceptible
to corrosion.
Question 5:
A technician observes that a circuit breaker trips repeatedly immediately after
reset. What is the MOST appropriate troubleshooting step?
A) Replace the circuit breaker with a higher amperage rating
B) Identify and correct the short circuit or overload condition before
resetting again
C) Bypass the circuit breaker temporarily to restore system function
D) Reset the breaker with the master switch off
Rationale: A circuit breaker that trips immediately upon reset indicates a
short circuit or overload condition. The technician must identify and correct
the underlying fault before attempting another reset. Replacing with a higher-
rated breaker or bypassing creates a fire hazard and violates safety
regulations.
Question 6:
In aircraft electrical systems, what is the primary function of a current limiter?
A) To protect against voltage surges
B) To protect wiring and equipment from sustained overcurrent
conditions
C) To regulate system voltage
D) To provide emergency power
Rationale: Current limiters (fuses or circuit breakers) protect aircraft wiring
and equipment from sustained overcurrent conditions that could cause
overheating and fire. Unlike voltage regulators, they do not control voltage
levels but interrupt the circuit when current exceeds a safe threshold.
, Question 7:
Which of the following is the correct minimum bend radius requirement for
aircraft wiring installation?
A) 3 times the outside diameter of the wire bundle
B) 10 times the outside diameter of the wire bundle
C) 5 times the outside diameter of the wire bundle
D) 2 times the outside diameter of the individual wire
Rationale: Per AC 43.13-1B and industry standards, the minimum bend
radius for aircraft wiring is typically 10 times the outside diameter of the wire
bundle. This prevents damage to insulation and conductors, maintains
electrical integrity, and prevents stress fractures that could lead to
intermittent faults.
Question 8:
What is the purpose of a drip loop in aircraft wiring installation?
A) To provide strain relief for connectors
B) To allow moisture to drain away from connectors and equipment
C) To create service loops for future maintenance
D) To reduce EMI coupling between wire bundles
Rationale: A drip loop is a low point in a wire run that allows moisture to
drain away from connectors and electronic equipment. This prevents water
intrusion that could cause corrosion, short circuits, or degradation of
electrical connections. Proper drip loop installation is essential for
maintaining wiring integrity.
Question 9:
A technician measures the resistance of a bonding strap and finds it to be 2.5
milliohms. According to industry standards, this reading is:
A) Acceptable for all applications
B) Unacceptable; bonding resistance should be less than 0.5 milliohms
C) Acceptable for secondary bonding paths only
D) Within tolerance for aluminum airframes
Expert-Verified Questions with Detailed
Rationales 2026 Edition | Actual
Questions & Correct Answers | Instant
Download PDF
Question 1:
A technician is troubleshooting an autopilot system that intermittently fails to
hold assigned altitude. The servos respond correctly during bench testing, but
the aircraft exhibits pitch oscillations during flight. What is the most likely
root cause and recommended diagnostic step?
A) Faulty autopilot computer requiring full replacement
B) Intermittent high resistance in the feedback loop or wiring harness
causing unstable response; perform continuity and insulation testing on
the encoder connectors
C) Low aircraft battery voltage
D) Software corruption in the flight management computer
Rationale: Autopilot systems rely on accurate feedback for stable control.
Intermittent connections create signal noise or loss, resulting in failure to hold
altitude. Systematic wiring checks per FAA AC 43.13-1B and manufacturer
manuals are the first step before component replacement to diagnose faults
efficiently and maintain airworthiness.
Question 2:
A technician is installing a new VHF communication transponder with a
ground strap to the aircraft. The installation must comply with FAA
environmental standards. What is the critical grounding requirement and the
potential consequence of improper bonding?
,A) Connect to any convenient airframe ground
B) Use a dedicated low-impedance ground strap to the airframe with less
than 0.5 milliohms resistance to prevent RF interference
C) Ground only the power return wire
D) No special grounding is required for modern transponders
Rationale: Proper bonding requires a dedicated low-impedance ground strap
to provide an effective RF return path. Poor bonding allows RF currents to
radiate inside the avionics bay, causing electromagnetic interference (EMI)
that can degrade communication and navigation system performance.
Question 3:
What is the allowable voltage drop in a 28-volt continuous aircraft circuit
according to industry standards?
A) 0.5 volts
B) 1.0 volt
C) 2.0 volts
D) 5.0 volts
Rationale: Voltage drop in aircraft wiring should not exceed 2% of the
regulated voltage when the generator is carrying rated current or the battery
is being discharged at the 5-minute rate. For a 28-volt system, 2% equals
approximately 0.56 volts; however, the commonly cited allowable drop is 1
volt. This ensures proper operation of connected avionics equipment.
Question 4:
Which conductor plating is most commonly used in aircraft wiring, and what
is its primary advantage?
A) Silver plating; highest conductivity
B) Nickel plating; high temperature resistance
C) Tin plating; slower oxidation rate than bare copper
D) Gold plating; corrosion resistance
Rationale: Copper wire is most commonly plated with tin, silver, or nickel.
Tin is the most common because it provides a slower oxidation rate than bare
,copper, maintaining good conductivity and solderability over time. Silver
plating offers the highest conductivity but is more expensive and susceptible
to corrosion.
Question 5:
A technician observes that a circuit breaker trips repeatedly immediately after
reset. What is the MOST appropriate troubleshooting step?
A) Replace the circuit breaker with a higher amperage rating
B) Identify and correct the short circuit or overload condition before
resetting again
C) Bypass the circuit breaker temporarily to restore system function
D) Reset the breaker with the master switch off
Rationale: A circuit breaker that trips immediately upon reset indicates a
short circuit or overload condition. The technician must identify and correct
the underlying fault before attempting another reset. Replacing with a higher-
rated breaker or bypassing creates a fire hazard and violates safety
regulations.
Question 6:
In aircraft electrical systems, what is the primary function of a current limiter?
A) To protect against voltage surges
B) To protect wiring and equipment from sustained overcurrent
conditions
C) To regulate system voltage
D) To provide emergency power
Rationale: Current limiters (fuses or circuit breakers) protect aircraft wiring
and equipment from sustained overcurrent conditions that could cause
overheating and fire. Unlike voltage regulators, they do not control voltage
levels but interrupt the circuit when current exceeds a safe threshold.
, Question 7:
Which of the following is the correct minimum bend radius requirement for
aircraft wiring installation?
A) 3 times the outside diameter of the wire bundle
B) 10 times the outside diameter of the wire bundle
C) 5 times the outside diameter of the wire bundle
D) 2 times the outside diameter of the individual wire
Rationale: Per AC 43.13-1B and industry standards, the minimum bend
radius for aircraft wiring is typically 10 times the outside diameter of the wire
bundle. This prevents damage to insulation and conductors, maintains
electrical integrity, and prevents stress fractures that could lead to
intermittent faults.
Question 8:
What is the purpose of a drip loop in aircraft wiring installation?
A) To provide strain relief for connectors
B) To allow moisture to drain away from connectors and equipment
C) To create service loops for future maintenance
D) To reduce EMI coupling between wire bundles
Rationale: A drip loop is a low point in a wire run that allows moisture to
drain away from connectors and electronic equipment. This prevents water
intrusion that could cause corrosion, short circuits, or degradation of
electrical connections. Proper drip loop installation is essential for
maintaining wiring integrity.
Question 9:
A technician measures the resistance of a bonding strap and finds it to be 2.5
milliohms. According to industry standards, this reading is:
A) Acceptable for all applications
B) Unacceptable; bonding resistance should be less than 0.5 milliohms
C) Acceptable for secondary bonding paths only
D) Within tolerance for aluminum airframes
