EASA Part66
Module 15
Cats A1 · A3 · B1.1 · B1.3
Gas Turbine Engine EASA Part66 — Module 15 Practice Questions
Module 15 covers the gas turbine engine end-to-end — Brayton cycle theory, intake and compressor behaviour, combustion, the hot section, fuel and oil systems, indications, and ground operation. Below: what's examinable, exam format, and seven sample questions in the same style you'll meet on exam day.
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What Module 15 covers — in plain English
Module 15 is the dedicated gas-turbine paper sat by Category A1, A3, B1.1 and B1.3 candidates — the
aeroplane-turbine and helicopter-turbine licence streams. Candidates working towards a piston licence
(A2, A4, B1.2, B1.4) sit Module 16 instead, and B2 avionics candidates skip both. The syllabus walks
the engine from intake to tailpipe: Brayton-cycle fundamentals, inlet aerodynamics,
axial and centrifugal compressors, combustion, the hot section, bearings and seals, fuel and oil
systems, air and anti-ice systems, ignition and starting, indications, alternate constructions,
turboprop and turboshaft variants, APUs, the powerplant installation, fire protection, ground
operation and storage. B1 candidates also cover engine performance — gross and net thrust, EPR,
SFC, bypass ratio, flat rating — and the newer 15.15 section on geared turbofans, open-rotor and
hybrid-electric concepts introduced by EU 2023/989 in June 2024.
The exam is one of the larger Part66 papers — 92 questions in 115 minutes for B1.1/B1.3,
or 60 questions in 75 minutes for A1/A3. Time per question is roughly 75 seconds, so the paper rewards
candidates who can recognise a stem (e.g. "the working fluid of a gas turbine is …") and lock the
answer in without re-deriving it. The hot-section topics — combustion airflow split, NGV function,
turbine creep, EGT limits — and the FADEC/fuel-control questions are where most marks are lost. The
performance section also catches B1 candidates who memorise formulas but mix up which efficiency
applies (thermal, propulsive, or overall) for a given stem, or who confuse N1 and N2 spool
attribution on twin-spool engines.
Knowledge levels run mostly at level 2 for B1 across the syllabus, with level 3 on 15.21 —
Engine Monitoring and Ground Operation, reflecting that B1 engineers actually carry out
ground runs, borescope inspections and trend interpretation on the line. Cat A1/A3 candidates sit a
smaller subset, mostly at level 1, and skip 15.2 Performance, 15.8 Bearings and Seals, 15.15
Alternate Constructions and 15.22 Storage entirely. Section 15.6 Turbine and 15.3 Inlet are level 2
even at A-licence, because line maintenance on those sections is part of an A-engineer's scope. The
full per-section breakdown — including which paragraphs you can safely skim and which need full level-2
recall — is on our
Module 15 syllabus page.
These samples are drawn from our live Module 15 question bank of 1 377 questions. The full
timed practice quiz draws 92 questions per attempt (or 60 for Cat A), scored against the official EASA 75 % pass mark, with weak-area tracking across attempts.
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Ready for the full Module 15 timed practice quiz?
Sign up, pick Module 15 from the dashboard, and take a timed exam drawn from our
1 377-question bank — the number of questions follows your licence category (60 for Cat A,
92 for B1/B2/B2L/B3). Your score is tracked across attempts and we surface
your weakest sub-topics so revision time pays off.