Practice Exam Questions And Correct

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

• What is the primary purpose of the propeller governor on a constant-

speed propeller?

• Control fuel flow
• Maintain a set propeller RPM
• Adjust engine mixture
• Reduce vibration

Rationale: The propeller governor automatically adjusts blade pitch to

maintain the RPM selected by the pilot, regardless of changes in engine power or flight conditions.

• / 4

• Which type of bearing is commonly used in aircraft engines to support

radial loads?

• Thrust bearing
• Plain bearing
• Ball bearing
• Roller bearing

Rationale: Ball bearings are widely used to handle radial loads in aircraft

engines due to their ability to reduce friction and wear.

• What is the function of a turbocharger in a piston aircraft engine?
• Decrease engine temperature
• Increase engine power at high altitude
• Reduce fuel consumption
• Control exhaust emissions

Rationale: A turbocharger compresses intake air to compensate for lower

air density at altitude, maintaining sea-level power output.

• Which type of ignition system uses a magneto to generate high

voltage?

• Battery ignition
• Magneto ignition 2 / 4

• Capacitor discharge
• Electronic ignition

Rationale: A magneto produces its own voltage without relying on the

aircraft battery, providing a reliable ignition source independent of electrical power.

• What is the typical color of engine oil indicating extreme

contamination or oxidation?

• Amber
• Black
• Green
• Clear

Rationale: Engine oil that has turned black usually indicates contamination

from combustion products or excessive oxidation.

• What is the purpose of a crankcase breather?
• Increase oil pressure
• Reduce fuel consumption
• Prevent pressure buildup inside the engine
• Lubricate the crankshaft

Rationale: A crankcase breather allows excess pressure to escape,

preventing oil leaks and structural damage. 3 / 4

• During an engine run-up, what would cause a drop in RPM when the

magneto switch is set to "Left"?

• Faulty spark plug wires
• One magneto is malfunctioning
• Fuel starvation
• Low oil pressure

Rationale: When one magneto fails, the engine loses some of its spark,

causing a measurable drop in RPM during a magneto check.

• Which type of fuel is standard for most reciprocating aircraft engines?
• Jet-A
• 100LL avgas
• Jet-B
• Diesel

Rationale: 100LL (Low Lead) aviation gasoline is commonly used in general

aviation piston engines.

• What is the main advantage of a full-authority digital engine control

(FADEC) system?

• Reduces propeller drag
• Increases pilot workload
• / 4