CPL Aircraft General Knowledge 2 — Questions and Answers
Question 1: What is the primary purpose of a magneto in a reciprocating aircraft engine?
- To provide electrical power to the aircraft's avionics
- To generate high-voltage current for ignition independent of the aircraft's electrical system (Correct answer)
- To regulate fuel flow to the engine cylinders
- To control the timing of valve opening and closing
Correct answer: To generate high-voltage current for ignition independent of the aircraft's electrical system
Magnetos are self-contained ignition systems that generate high-voltage current for spark plugs independently of the aircraft's main electrical system.
Question 2: Carburetor ice is MOST likely to form when outside air temperature and relative humidity are:
- High temperature, low humidity
- Temperature between 20°F and 70°F (-7°C to 21°C) with high humidity (Correct answer)
- Temperature below 0°F (-18°C) with any humidity level
- Temperature above 80°F (27°C) with high humidity
Correct answer: Temperature between 20°F and 70°F (-7°C to 21°C) with high humidity
Carburetor ice most commonly forms at temperatures between 20°F and 70°F with high relative humidity due to fuel vaporization cooling the carburetor throat.
Question 3: A constant-speed propeller governor controls propeller blade pitch to:
- Maximize thrust at all airspeeds regardless of RPM
- Maintain a selected RPM regardless of airspeed or power changes (Correct answer)
- Reduce propeller noise during cruise flight
- Prevent engine over-speeding only during descent
Correct answer: Maintain a selected RPM regardless of airspeed or power changes
The propeller governor automatically adjusts blade pitch to maintain the RPM selected by the pilot via the propeller control lever.
Question 4: Detonation in a reciprocating engine is best described as:
- Normal progressive combustion that produces maximum power
- Uncontrolled, explosive combustion causing excessively high cylinder pressures (Correct answer)
- Pre-ignition caused by hot carbon deposits in the cylinder
- Incomplete combustion resulting from an over-rich mixture
Correct answer: Uncontrolled, explosive combustion causing excessively high cylinder pressures
Detonation is the uncontrolled, near-instantaneous explosion of the fuel-air charge, generating abnormally high cylinder pressures that can damage pistons and valves.
Question 5: A turbocharger improves high-altitude performance primarily by:
- Cooling intake air to increase oxygen density
- Using exhaust gases to compress intake air and maintain manifold pressure (Correct answer)
- Increasing fuel flow proportionally with altitude gain
- Reducing exhaust back-pressure to improve engine efficiency
Correct answer: Using exhaust gases to compress intake air and maintain manifold pressure
A turbocharger uses exhaust gas energy to drive a compressor, maintaining near-sea-level manifold pressure at altitude and preserving engine power output.
Question 6: Which condition would MOST likely cause roughness and power loss in a fuel-injected engine (not a carbureted engine)?
- Carburetor ice forming in the fuel-air metering unit
- Induction system ice blocking the air intake (Correct answer)
- Vapor lock in the fuel injection lines
- Excessive fuel pressure from the engine-driven pump
Correct answer: Induction system ice blocking the air intake
Fuel-injected engines are not susceptible to carburetor ice but can suffer induction system ice in the air intake duct, reducing airflow and causing roughness.
Question 7: If oil pressure drops below the minimum limit in flight, the correct pilot action is to:
- Increase power to improve oil circulation and monitor the gauge
- Switch to the alternate oil pressure system and continue
- Reduce power and land at the nearest suitable airport as soon as practical (Correct answer)
- Ignore the indication if the oil temperature is normal
Correct answer: Reduce power and land at the nearest suitable airport as soon as practical
Low oil pressure indicates imminent risk of engine seizure; the pilot should reduce power and divert to the nearest suitable airport immediately.
CPL Aircraft General Knowledge 2
What is the primary purpose of a magneto in a reciprocating aircraft engine?