Knowledge Practice Exam Questions

FAA Mechanic Powerplant (AMP) Knowledge Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is a characteristic of a two-stroke cycle engine?
• It has separate intake and exhaust strokes.
• It requires a carburetor to operate.
• It completes a power cycle in one crankshaft revolution.
• It is more fuel efficient than a four-stroke engine.

Rationale: Two-stroke engines complete a power cycle (intake,

compression, power, exhaust) in one revolution of the crankshaft, unlike four-stroke engines which require two revolutions.

• What is the primary purpose of a turbocharger in an aircraft engine?
• To increase the fuel-air mixture. 1 / 4

• To increase the mass of air entering the cylinders.
• To reduce engine noise.
• To control engine temperature.

Rationale: A turbocharger compresses incoming air, allowing more oxygen

to enter the cylinder, which increases engine power output.

3. Detonation in a reciprocating engine is caused by:

• Lean fuel mixture.
• High oil temperature.
• Abnormal combustion where fuel-air mixture explodes rather than

burns smoothly.

• Spark plug fouling.

Rationale: Detonation occurs when the mixture explodes violently instead

of burning progressively, causing shock waves that can damage the engine.

• What is the purpose of an engine crankcase breather?
• To supply air to the carburetor
• To lubricate engine bearings
• To relieve excess pressure and prevent oil leaks
• To cool the engine

Rationale: A crankcase breather allows excess pressure and combustion

gases to escape, preventing oil leaks and damage to seals.

• Which component converts reciprocating motion into rotary motion in a

piston engine? 2 / 4

• Camshaft
• Valve lifter
• Crankshaft
• Connecting rod

Rationale: The crankshaft converts the linear motion of pistons into

rotational motion to drive the propeller or other components.

• What is the primary function of a magneto in an aircraft engine?
• To regulate fuel flow
• To generate electrical spark for ignition
• To monitor engine temperature
• To control propeller pitch

Rationale: A magneto produces a high-voltage spark independent of the

aircraft electrical system, which ignites the fuel-air mixture.

• What is a common symptom of valve overlap being excessive in a

reciprocating engine?

• Loss of oil pressure
• Rough running at low RPMs
• Excessive cylinder head temperature
• Pre-ignition

Rationale: Excessive valve overlap allows exhaust gases to mix with intake

charge, causing rough operation at low speeds.

• What is the purpose of a turbocharger wastegate?
• To increase engine oil flow 3 / 4

• To cool exhaust gases
• To regulate the maximum boost pressure
• To prevent detonation

Rationale: A wastegate limits boost by allowing excess exhaust gases to

bypass the turbine, preventing overboost conditions.

• What type of fuel is typically used in reciprocating aircraft engines?
• Jet A
• Aviation gasoline (100LL)
• Diesel
• Jet B

Rationale: Most small aircraft piston engines use 100LL aviation gasoline.

Jet fuels are used in turbine engines.

• What is the function of a propeller governor in a constant-speed

propeller system?

• To maintain engine RPM
• To adjust blade pitch for a selected RPM
• To control fuel flow
• To monitor oil pressure

Rationale: The governor adjusts propeller blade pitch automatically to

maintain the desired engine RPM under varying loads.

• Which lubrication system uses a pump to deliver oil under pressure to

critical engine components?

• Splash
• / 4