Module 15 Gas Turbine Engine study guide
Module 15 Gas Turbine Engine · Work through your exam, one topic at a time.
Module 15, Gas Turbine Engine, is one of the knowledge modules in the EASA Part-66 aircraft maintenance licence syllabus. It is aimed at candidates working toward a turbine-engine rating or a Category B1/B2/B3 licence, and at certifying staff who need to show they understand how a gas turbine engine and its systems actually function before they sign anything off. The Module 15 Gas Turbine Engine study guide has 11 sections and about 3,248 words.
01Fundamentals (thermodynamics, thrust, engine layouts, station numbering)
The Fundamentals domain checks whether you can reason from the Brayton cycle to real engine behavior: how pressure ratio and turbine inlet temperature set efficiency and specific work, how thrust is produced, how engine layouts differ, and how stations are labeled. Expect numeric thrust questions and layout comparisons rather than pure definitions.
319 words, about 2 min02Engine Performance (thrust, specific fuel consumption, ratings, derating)
Engine Performance tests your ability to compute thrust and specific fuel consumption, interpret ratings, and explain how altitude, temperature, bleed, and derating change available thrust. Questions often give a short scenario and ask for the effect, not just the formula.
297 words, about 1 min03Inlet and Compressor (construction, operation, stall and surge)
This domain covers how the inlet delivers uniform, high-pressure air to the compressor and how the compressor raises pressure without stalling. The exam tests inlet pressure recovery and distortion, axial versus centrifugal construction, stage matching, and the difference between rotating stall and surge.
316 words, about 2 min04Combustion Section (combustion process, chamber types, fuel nozzles)
The combustion section domain tests the chain from diffuser to turbine inlet: how fuel is atomized and mixed, how the flame is stabilized, why the liner has primary, intermediate, and dilution zones, and how chamber type affects maintenance and emissions. The diffuser slows air and raises static pressure before the liner; the pressure loss is a deliberate trade for flame stability.
301 words, about 2 min05Turbine Section (blades, nozzles, cooling, clearances)
Turbine Section questions focus on extracting work from hot gas without exceeding metal limits: nozzle guide vanes versus rotor blades, impulse and reaction staging, cooling schemes, tip clearance, and creep. Nozzle guide vanes accelerate and turn the gas; rotor blades extract work.
303 words, about 2 min06Exhaust and Thrust Reversers
This domain tests exhaust nozzle function, exhaust cone and strut hardware, and thrust-reverser types and logic. Expect questions on nozzle pressure ratio, reverser deployment, and the effect of exhaust blockage or leaks.
284 words, about 1 min07Bearings, Seals and Lubrication
This domain covers how the rotor is supported, sealed, and lubricated. The exam tests bearing types and load paths, seal selection, oil-system architecture, and the meaning of oil pressure, temperature, and debris indications.
291 words, about 1 min08Fuel Systems (metering, control, FADEC)
Fuel Systems questions cover metering, control, and the hand-off between hydro-mechanical and FADEC control. Expect fuel scheduling, fuel-oil heat exchange, nozzle supply, and FADEC redundancy.
289 words, about 1 min09Air Systems (bleed, cooling, anti-ice, starting)
Air Systems covers bleed extraction, cooling, anti-ice, and starting air. The exam tests bleed sources, the penalties of bleed, valve logic, and how cooling air protects the turbine.
300 words, about 2 min10Starting and Ignition Systems
Starting and Ignition tests the sequence from motoring to idle, ignition sources, and abnormal starts. Expect light-off, hung start, hot start, wet start, and EGT limits.
266 words, about 1 min11Engine Indication and Monitoring (vibration, EGT, trend monitoring)
Engine Indication and Monitoring covers EGT, N1/N2, vibration, and trend monitoring. The exam tests how parameters are interpreted, what exceedances mean, and how trends detect deterioration.
282 words, about 1 min