FAA Aviation Mechanic General
Knowledge Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
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1. An aircraft mechanic is troubleshooting an electrical circuit that
contains a circuit breaker protecting a conductor from excessive
current. The breaker opens repeatedly whenever the associated
equipment is operated, and inspection reveals no obvious short circuit
or damaged wiring. Which condition should the mechanic consider
most appropriate to investigate before simply replacing the circuit
breaker with one having a higher current rating?
A. The circuit breaker has been intentionally selected with a rating
substantially below the normal operating current of the equipment
B. The circuit contains an excessive electrical load, a short circuit, or another
condition causing current to exceed the breaker’s designed rating
C. The circuit breaker should always be replaced with a fuse of twice the
original amperage rating
,D. The circuit breaker is operating correctly only when the aircraft battery is
completely discharged
Answer: B
Rationale: A circuit breaker is designed to interrupt a circuit when
excessive current flows, protecting wiring and equipment from
overheating and possible fire. Repeated tripping requires troubleshooting
the underlying cause rather than installing a higher-rated protective
device, because increasing the rating can allow the wiring to carry unsafe
current.
2. When determining the resistance of a conductor using Ohm’s law, a
mechanic knows that voltage and current are measured under stable
circuit conditions. If a circuit has a measured voltage of 28 volts and a
current of 7 amperes, what is the calculated resistance of the circuit?
A. 0.25 ohm
B. 2 ohms
C. 4 ohms
D. 196 ohms
Answer: C
,Rationale: Ohm’s law states that resistance equals voltage divided by
current, or R = E/I. Dividing 28 volts by 7 amperes produces a resistance of
4 ohms.
3. During inspection of an aircraft electrical system, a mechanic finds
that two resistors are connected in series. One resistor has a
resistance of 10 ohms and the other has a resistance of 20 ohms.
What is the total resistance of the series circuit, assuming the
resistance values remain constant?
A. 0.5 ohm
B. 10 ohms
C. 20 ohms
D. 30 ohms
Answer: D
Rationale: In a series circuit, individual resistance values are added
directly. Therefore, 10 ohms plus 20 ohms equals a total resistance of 30
ohms.
4. A mechanic is examining a parallel electrical circuit containing two
equal-value resistors. Compared with a single resistor of the same
resistance value, how does connecting the two resistors in parallel
affect total circuit resistance?
, A. Total resistance increases to twice the value of either resistor
B. Total resistance remains exactly equal to the value of either resistor
C. Total resistance decreases to one-half the resistance of either resistor
D. Total resistance becomes zero regardless of the resistor values
Answer: C
Rationale: For two equal resistors connected in parallel, the equivalent
resistance is one-half the resistance of either resistor. Parallel circuits
provide additional current paths, which reduces total resistance.
5. An aircraft battery is rated at 24 volts and has a capacity of 40
ampere-hours. If a theoretical constant load of 4 amperes were
applied and battery efficiency and discharge characteristics were
ignored, approximately how long could the battery supply the load?
A. 4 hours
B. 10 hours
C. 16 hours
D. 160 hours
Answer: B
Rationale: Battery capacity in ampere-hours can be divided by the load
current to estimate theoretical operating time. Forty ampere-hours divided
Knowledge Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
Download Pdf
1. An aircraft mechanic is troubleshooting an electrical circuit that
contains a circuit breaker protecting a conductor from excessive
current. The breaker opens repeatedly whenever the associated
equipment is operated, and inspection reveals no obvious short circuit
or damaged wiring. Which condition should the mechanic consider
most appropriate to investigate before simply replacing the circuit
breaker with one having a higher current rating?
A. The circuit breaker has been intentionally selected with a rating
substantially below the normal operating current of the equipment
B. The circuit contains an excessive electrical load, a short circuit, or another
condition causing current to exceed the breaker’s designed rating
C. The circuit breaker should always be replaced with a fuse of twice the
original amperage rating
,D. The circuit breaker is operating correctly only when the aircraft battery is
completely discharged
Answer: B
Rationale: A circuit breaker is designed to interrupt a circuit when
excessive current flows, protecting wiring and equipment from
overheating and possible fire. Repeated tripping requires troubleshooting
the underlying cause rather than installing a higher-rated protective
device, because increasing the rating can allow the wiring to carry unsafe
current.
2. When determining the resistance of a conductor using Ohm’s law, a
mechanic knows that voltage and current are measured under stable
circuit conditions. If a circuit has a measured voltage of 28 volts and a
current of 7 amperes, what is the calculated resistance of the circuit?
A. 0.25 ohm
B. 2 ohms
C. 4 ohms
D. 196 ohms
Answer: C
,Rationale: Ohm’s law states that resistance equals voltage divided by
current, or R = E/I. Dividing 28 volts by 7 amperes produces a resistance of
4 ohms.
3. During inspection of an aircraft electrical system, a mechanic finds
that two resistors are connected in series. One resistor has a
resistance of 10 ohms and the other has a resistance of 20 ohms.
What is the total resistance of the series circuit, assuming the
resistance values remain constant?
A. 0.5 ohm
B. 10 ohms
C. 20 ohms
D. 30 ohms
Answer: D
Rationale: In a series circuit, individual resistance values are added
directly. Therefore, 10 ohms plus 20 ohms equals a total resistance of 30
ohms.
4. A mechanic is examining a parallel electrical circuit containing two
equal-value resistors. Compared with a single resistor of the same
resistance value, how does connecting the two resistors in parallel
affect total circuit resistance?
, A. Total resistance increases to twice the value of either resistor
B. Total resistance remains exactly equal to the value of either resistor
C. Total resistance decreases to one-half the resistance of either resistor
D. Total resistance becomes zero regardless of the resistor values
Answer: C
Rationale: For two equal resistors connected in parallel, the equivalent
resistance is one-half the resistance of either resistor. Parallel circuits
provide additional current paths, which reduces total resistance.
5. An aircraft battery is rated at 24 volts and has a capacity of 40
ampere-hours. If a theoretical constant load of 4 amperes were
applied and battery efficiency and discharge characteristics were
ignored, approximately how long could the battery supply the load?
A. 4 hours
B. 10 hours
C. 16 hours
D. 160 hours
Answer: B
Rationale: Battery capacity in ampere-hours can be divided by the load
current to estimate theoretical operating time. Forty ampere-hours divided
