Free Aviation Maintenance Technician Powerplant Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Aviation Maintenance Technician Powerplant practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1During a reciprocating-engine performance test, fuel flow is 90 lb/hr at 180 brake horsepower. What is the brake-specific fuel consumption?

   1. A. 0.50 lb/(hp·hr)
   2. B. 2.00 lb/(hp·hr)
   3. C. 1.50 lb/(hp·hr)
   4. D. 0.0083 lb/(hp·hr)

   Answer: A

   Explanation: The handbook defines reciprocating-engine specific fuel consumption as "the fuel flow (lb/hr) divided by brake horsepower." Thus 90/180 = 0.50 lb/(hp·hr). Reversing the division, adding the quantities before division, or unnecessarily dividing by 60 gives the distractors.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 1: Aircraft Engines — p. 1-2, Fuel Economy

2. 2A turbofan passes 240 lb/sec through its bypass duct and 40 lb/sec through its core. What is its bypass ratio?

   1. A. 7:1
   2. B. 6:1
   3. C. 1:6
   4. D. 5:1

   Answer: B

   Explanation: The handbook defines bypass ratio as "The amount of air flow in lb/sec from the fan bypass to the core flow of the engine". Thus 240/40 = 6:1. Adding core flow, reversing the ratio, or subtracting core flow produces the other results.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 1: Aircraft Engines — p. 1-36, Gas Turbine Engines—Types & Construction

3. 3A mechanic checks a conventional reciprocating-engine manifold pressure gauge. What pressure reference and units does this instrument use?

   1. A. Gauge pressure in pounds per square inch.
   2. B. Differential pressure in inches of water.
   3. C. Absolute pressure in inches of mercury.
   4. D. Ambient pressure in pounds per square inch.

   Answer: C

   Explanation: The handbook describes a gauge that "indicates absolute manifold pressure in inches of mercury". It is not a gauge-pressure or water-column instrument.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 10: Engine Maintenance & Operation — p. 10-23, Manifold Pressure Indicator

4. 4A conventional thermal-switch engine fire system has several temperature-sensitive switches controlling one warning light. How are the switches connected relative to each other?

   1. A. In parallel.
   2. B. In series.
   3. C. In a delta network.
   4. D. In a bridge network.

   Answer: A

   Explanation: The handbook states, "They are connected in parallel with each other, but in series with the indicator lights". Any one overheated switch can complete the warning circuit.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 9: Engine Fire Protection Systems — p. 9-2, Thermal Switch System

5. 5A mechanic increases resistance in the field circuit of a shunt-wound DC generator while other operating conditions remain unchanged. What happens to field current and generated voltage?

   1. A. Both increase.
   2. B. Field current increases; voltage decreases.
   3. C. Both decrease.
   4. D. Field current decreases; voltage increases.

   Answer: C

   Explanation: The handbook states, "As the resistance of the field circuit is increased, the field current is reduced; consequently, the generated voltage is also reduced." This is the field-control basis of voltage regulation.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 4: Engine Ignition & Electrical Systems — p. 4-12, Parallel (Shunt) Wound DC Generators

6. 6A mechanic traces the energy source of a conventional aircraft magneto during normal engine operation. What supplies its magnetic field?

   1. A. The aircraft battery.
   2. B. The main DC generator.
   3. C. The engine-driven permanent magnet.
   4. D. The starter-generator field winding.

   Answer: C

   Explanation: The handbook states that the magneto "uses a permanent magnet as a source of energy." Its engine-driven magnetic system supplies ignition energy independently of the aircraft battery or main generator.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 4: Engine Ignition & Electrical Systems — p. 4-1, Magneto-Ignition System Operating Principles

7. 7A fuel supply interruption results from premature fuel vaporization in lines and pumps. What is this condition called?

   1. A. Carburetor icing
   2. B. Hydraulic lock
   3. C. Vapor lock
   4. D. Compressor surge

   Answer: C

   Explanation: The handbook calls the resulting interruption "vapor lock." Vapor pockets obstruct equipment designed for liquid fuel.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 2: Engine Fuel & Fuel Metering Systems — p. 2-1, Vapor Lock

8. 8An opposed engine has a crossover connection between its two induction runners to reduce pressure imbalance. Which component is the mechanic inspecting?

   1. A. Induction air filter
   2. B. Turbocharger aftercooler
   3. C. Induction balance tube
   4. D. Turbocharger wastegate

   Answer: C

   Explanation: The handbook states, "The balance tube is used to reduce pressure imbalances between the two side induction runners." It supports consistent intake conditions across the engine.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 3: Induction & Exhaust Systems — p. 3-1, Reciprocating Engine Induction Systems

9. 9A mechanic traces the exhaust collector outlet on a turbosupercharged reciprocating engine. Which turbocharger component receives the collected exhaust to extract its energy?

   1. A. Compressor impeller
   2. B. Compressor diffuser
   3. C. Turbine wheel
   4. D. Bearing spacer

   Answer: C

   Explanation: The handbook states, "On turbosupercharged engines, the exhaust gases must be collected to drive the turbine compressor of the supercharger." The exhaust drives the turbine wheel, which powers the compressor; the compressor impeller and diffuser handle induction air.

   Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 3: Induction & Exhaust Systems — p. 3-21, Reciprocating Engine Exhaust Systems

10. 10A mechanic calculates that a propeller has a geometric pitch of 60 inches and an effective pitch of 48 inches. What is its slip per revolution?

    1. A. 12 inches
    2. B. 108 inches
    3. C. 48 inches
    4. D. 60 inches

    Answer: A

    Explanation: The FAA gives "Geometric pitch - Effective pitch = slip". Therefore, slip is 60 − 48 = 12 inches per revolution. Adding the pitches or reporting either pitch alone does not calculate slip.

    Reference: FAA-H-8083-32B, Aviation Maintenance Technician Handbook–Powerplant, Chapter 7: Propellers — p. 7-2, Propeller Aerodynamic Process