PNG CASA Basic Gas Turbine key terms

The thermodynamic cycle describing the operation of a gas turbine engine, consisting of compression, constant-pressure combustion, expansion, and heat rejection. It is an open cycle in practice, where air is drawn in and exhaust gases are expelled.

The ratio of useful work output to the heat energy supplied by fuel. In gas turbines, it increases with compression ratio and turbine inlet temperature, but is limited by material and cooling constraints.

The ratio of the total pressure at the compressor outlet to the total pressure at the compressor inlet. Higher compression ratios generally improve thermal efficiency but require more compressor stages and stronger materials.

The temperature of the gas entering the turbine, a critical limit that determines engine power and efficiency. It is constrained by the high-temperature strength of turbine blades and the effectiveness of cooling systems.

The mass of fuel consumed per unit of thrust or power produced per unit time, often expressed as kg/(kN·h) or kg/(kW·h). It is a key indicator of engine efficiency and is affected by operating conditions.

A severe instability in the compressor where airflow reverses momentarily, causing loud bangs, vibration, and potential damage. It can be triggered by abrupt throttle changes, inlet distortion, or compressor fouling.

A condition where the smooth airflow over compressor blades breaks down, reducing pressure rise and causing vibration and possible surge. It is often caused by excessive angle of attack of the blades or inlet distortion.

The temperature of the exhaust gases leaving the turbine, measured by thermocouples. It is a key indicator of engine health and is used to monitor performance and detect faults such as hot section deterioration.

The forward force produced by a gas turbine engine, resulting from the acceleration of air and exhaust gases. It is typically measured in kilonewtons (kN) or pounds-force (lbf) and varies with altitude, temperature, and throttle setting.

A method of rating an engine so that its maximum thrust or power remains constant up to a certain altitude or temperature, beyond which it decreases. This ensures consistent performance under varying ambient conditions.

The slow, permanent deformation of a material under sustained load at high temperature, particularly relevant to turbine blades and discs. It is a life-limiting factor and is managed through material selection and cooling.

The weakening and eventual failure of a material due to repeated cyclic loading, such as vibration or rotation. It can lead to cracks in compressor and turbine blades and requires regular inspection.

A high-performance alloy containing nickel, chromium, and other elements, used for turbine blades and discs due to its excellent strength and resistance to creep and oxidation at high temperatures.

A ceramic layer applied to hot section components, such as turbine blades, to insulate them from high gas temperatures, reducing metal temperature and extending component life.

Techniques such as internal air passages and film cooling that keep turbine blades below their melting point in the hot gas stream. Cooling air is typically bled from the compressor, which slightly reduces engine efficiency.

The design feature of the engine casing that ensures a failed fan or compressor blade is contained within the engine and does not penetrate the aircraft structure or endanger personnel.

The large rotating blades at the front of a turbofan engine that accelerate air to produce the majority of thrust. They are susceptible to foreign object damage and are designed for high strength and fatigue resistance.

The ratio of the mass flow of air bypassing the engine core to the mass flow entering the core. A high bypass ratio improves propulsive efficiency and reduces noise, typical of modern turbofan engines.

The system that supplies oil to bearings and gears to reduce friction, remove heat, and prevent corrosion. It typically includes a tank, pumps, filters, coolers, and monitoring devices.

The pressure of the oil supplied to the engine bearings and gears, critical for proper lubrication. Low oil pressure can indicate a pump failure, leak, or blockage and requires immediate attention.

The laboratory examination of oil samples for metal particles, contamination, and oil condition. It helps detect early wear of engine components and is part of a condition monitoring program.

A magnetic plug installed in the oil system that attracts ferrous metal particles, providing an early warning of internal wear or damage. It is inspected during maintenance and can trigger a warning in the cockpit.

The component that meters fuel to the engine based on throttle position, compressor speed, and ambient conditions. It ensures the correct fuel-air ratio for safe and efficient operation.

A device that atomizes fuel into a fine spray for mixing with air in the combustion chamber. Proper atomization is essential for efficient combustion and low emissions.

The system that provides the electrical spark to ignite the fuel-air mixture during starting and, in some engines, for continuous relight. It typically includes igniter plugs, exciter units, and wiring.

The section of the engine where fuel is mixed with compressed air and burned. It must efficiently burn fuel, distribute the hot gases evenly to the turbine, and minimize pressure loss.

The precise control of fuel flow to the engine to match power requirements and operating conditions. It is managed by the fuel control unit and is critical for engine response and efficiency.

The system that rotates the engine to a speed where it can sustain operation, typically using an electric starter, air turbine starter, or hydraulic starter. It includes controls and indicators for monitoring the start sequence.

A start condition where the engine fails to accelerate to idle speed, often due to insufficient starter power, fuel, or ignition. It requires immediate action to prevent damage and is typically aborted.

A start condition where the exhaust gas temperature exceeds limits due to excess fuel or insufficient airflow. It can cause damage to the hot section and requires immediate shut down and investigation.

The sensors, gauges, and displays that provide information on engine parameters such as speed, temperature, pressure, and fuel flow. It is essential for safe operation and fault diagnosis.

The systematic recording and analysis of engine parameters over time to detect deterioration or faults. It helps predict maintenance needs and improve reliability.

The approved performance limits for an engine, such as maximum takeoff thrust, maximum continuous thrust, and idle. They are established by the manufacturer and approved by the airworthiness authority.

A takeoff performed at less than maximum rated thrust to reduce engine wear and extend life. It is permitted under specific conditions and is calculated based on aircraft weight, runway, and ambient conditions.

A mandatory instruction issued by an airworthiness authority to correct an unsafe condition on an aircraft or engine. Compliance is required within a specified time and is part of continuing airworthiness.

The records and manuals that specify maintenance procedures, intervals, and approvals. It includes the aircraft maintenance manual, component maintenance manual, and maintenance records, ensuring traceability and compliance.

The process of identifying the cause of a malfunction using symptoms, test results, and troubleshooting procedures. It often involves using fault codes, performance data, and physical inspections.

A systematic approach to locating and rectifying faults, typically following manufacturer's instructions. It includes verifying the problem, isolating the cause, and confirming the repair.

The study of how people interact with systems and environments, aiming to reduce human error and improve safety. In aviation maintenance, it includes factors like fatigue, communication, and workload.

A formal framework for managing safety risks, including policies, procedures, and reporting systems. It is required by aviation authorities and promotes a proactive safety culture.