Powerplant Operations & Maintenance Flashcards

What is the function of a turbine in a jet engine?

Answer: Drive the compressor

In a jet engine, the primary function of the turbine is to drive the compressor. Located downstream of the combustor, the turbine extracts energy from the hot, high-pressure exhaust gases. This energy is then used to turn a shaft that powers the compressor at the front of the engine, sustaining the continuous flow of air necessary for combustion.

Which part mixes air and fuel in a piston engine?

Answer: Carburetor

In a piston engine, the carburetor is the part responsible for mixing air and fuel. It atomizes the fuel and blends it with incoming air in the correct proportions before the mixture enters the engine cylinders for combustion. This ensures an optimal air-fuel ratio for efficient engine operation and power generation.

Why is engine oil important in aircraft engines?

Answer: Lubricates and cools parts

Engine oil is critically important in aircraft engines because it lubricates and cools parts. It reduces friction between moving components, preventing wear and tear, and also carries away excess heat generated during operation. Additionally, engine oil helps to clean the engine by suspending contaminants, ensuring smooth, efficient, and reliable performance.

What does the magneto system do?

Answer: Generate spark for ignition

The magneto system is a self-contained, engine-driven electrical generator that produces high-voltage electrical pulses. These pulses are sent to the spark plugs, creating the necessary spark to ignite the fuel-air mixture in the engine cylinders. This process initiates and sustains combustion, allowing the engine to run independently.

Which type of engine powers most modern commercial jets?

Answer: Turbofan

Turbofan engines are the most common type of engine used in modern commercial jets due to their exceptional efficiency and high thrust output. They operate by drawing in a large volume of air, with a significant portion bypassing the core engine. This bypass air provides substantial thrust and reduces fuel consumption compared to pure turbojets, making them ideal for long-range commercial flights.

What is checked during a borescope inspection?

Answer: Internal engine components

A borescope inspection is a non-destructive testing (NDT) method that uses a flexible or rigid optical instrument to visually inspect internal areas of an engine that are otherwise inaccessible. This allows mechanics to detect cracks, corrosion, foreign object damage, and other anomalies without the need for costly and time-consuming engine disassembly. It's a key tool for preventative maintenance.

What causes detonation in a piston engine?

Answer: Overheating and wrong fuel

Detonation in a piston engine occurs when the fuel-air mixture ignites spontaneously and uncontrollably in multiple places within the cylinder, rather than a smooth, controlled burn. This damaging phenomenon is often caused by excessive engine temperatures (overheating) or using fuel with an octane rating too low for the engine's compression ratio (wrong fuel), leading to severe engine stress and potential damage.

What is the purpose of an engine cowling?

Answer: Reduce drag and aid cooling

An engine cowling is an aerodynamic covering that encloses an aircraft engine. Its primary purposes are to streamline the engine to reduce aerodynamic drag, thereby improving efficiency, and to manage airflow around the engine components. This controlled airflow facilitates proper cooling and prevents overheating, ensuring optimal engine performance and longevity.

What tool measures cylinder compression in piston engines?

Answer: Compression tester

A compression tester is a specialized tool used to measure the pressure within an engine cylinder when the piston is at the top of its compression stroke. This test helps diagnose engine health by identifying issues like worn piston rings, faulty valves, or head gasket leaks. Low compression readings indicate a problem that needs attention to restore engine performance.