Aircraft Engine: Key Terms and Definitions

Aircraft Engine: Key Terms and Definitions

Below is a concise dictionary featuring essential terms and definitions related to aircraft engines, also known as aero engines. These entries are drawn from authoritative aviation glossaries and technical references.

Aircraft Engine (Aero Engine)
The power component of an aircraft propulsion system, converting fuel into mechanical work to propel the aircraft. Main types include piston engines, gas turbines (turboprop, turbofan, turbojet), and, less commonly, rocket and electric engines.

Air Start
The act or instance of starting an aircraft's engine while in flight, especially a jet engine after flameout.

Bleed Air
Compressed air tapped from the compressor stages of a turbine engine, used for deicing, anti-ice, cabin pressurization, heating, and cooling.

Bleed Valve
A device in turbine engines to bleed off a portion of compressor air, maintaining blade angle of attack and ensuring stall-free engine acceleration and deceleration.

Boost Pump
An electrically driven fuel pump, usually centrifugal, located in a fuel tank to provide fuel under pressure to the engine.

Compressor
The section of a gas turbine engine that acts as an air pump, increasing the energy of incoming air for combustion.

Compressor Surge
A severe compressor stall across the entire compressor, potentially causing severe damage if not quickly corrected.

Condition Lever
A control in turbine engines that regulates fuel flow to set desired engine RPM for ground and flight operations.

Constant Speed Propeller
A propeller whose blade pitch is automatically varied by a governor to maintain constant RPM despite changing air loads.

Controllable-Pitch Propeller
A propeller with blades that can be adjusted in pitch during flight from the cockpit.

Core Airflow
Air drawn into the engine for the gas generator section, crucial for combustion and power generation.

Cowl Flaps
Devices around air-cooled engine cowlings that regulate airflow for engine cooling.

Crankshaft
The main shaft of the engine, converting the linear motion of pistons into rotary motion to drive the propeller or rotor.

Exhaust Gas Temperature (EGT)
The temperature of exhaust gases as they exit the turbine section, an important parameter for engine monitoring.

Fuel Injection
A fuel metering system that delivers fuel directly to the cylinders or combustion chamber under pressure for efficient combustion.

Gas Generator
The core power-producing portion of a gas turbine engine, typically including the compressor, diffuser, combustor, and turbine.

Gas Turbine Engine
A heat engine in which burning fuel adds energy to compressed air, producing thrust or torque to drive a propeller or rotor.

Governor
A device that automatically controls the propeller blade angle to maintain selected RPM.

Ignition System
The system responsible for igniting the fuel-air mixture in the engine's combustion chamber.

Propeller
A rotating blade assembly driven by the engine, producing thrust by accelerating air rearward.

Reciprocating Engine (Piston Engine)
An engine that uses pistons moving back and forth within cylinders to convert fuel into mechanical work.

Turbofan
A type of gas turbine engine where a fan driven by the turbine accelerates a large mass of air, providing most of the thrust.

Turbojet
A gas turbine engine producing thrust solely by expelling jet exhaust at high speed.

Turboprop
A gas turbine engine that drives a propeller via a reduction gearbox, with most thrust provided by the propeller.

Turboshaft
A gas turbine engine optimized to produce shaft power rather than jet thrust, commonly used in helicopters.

For more in-depth coverage, comprehensive glossaries are available in aviation handbooks and technical manuals, such as the FAA's Airplane Flying Handbook and McGraw-Hill's Aircraft Powerplants textbook.