All Practice Exams
100+ Free SAR-66 Module 15 Practice Questions
CAAS SAR-66 AML Module 15 — Gas Turbine Engine practice questions are available now; exam metadata is being verified.
✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately
100+ Questions
100% Free
Loading practice questions...
Same family resources
Explore More CAAS SAR-66 Aircraft Maintenance Modules
Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.
2026 Statistics
Key Facts: SAR-66 Module 15 Exam
92 Q / 115 min
Module 15 MCQ (Category B1.1)
CAAS AC 66-13 (Rev 1)
75%
Pass Mark per Module
SAR-66 Appendix 2
S$87.20
Fee per examination paper (from 1 Jan 2026)
ANO Twelfth Schedule para 11
10 years
Module Pass Validity
SAR-66
3 months
Wait after Two Fails in 3 Months
SAR-66
CAAS SAR-66 Module 15 (Gas Turbine Engine) tests Category B1.1 certifying staff on gas turbine engine theory, construction, and systems. The official exam comprises 92 three-option multiple-choice questions in 115 minutes (AC 66-13) with a 75% pass mark. Key topics include Brayton cycle thermodynamics, engine performance and thrust calculations, compressor and turbine aerodynamics, combustion section design, fuel/oil/bleed air systems, APU operations, fire detection/extinguishing, and engine monitoring/ground running procedures. Examination fee is S$87.20 per module paper under the ANO Twelfth Schedule (from 1 Jan 2026).
Sample SAR-66 Module 15 Practice Questions
Try these sample questions to test your SAR-66 Module 15 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1Which thermodynamic cycle describes the constant-pressure continuous combustion process in a gas turbine engine?
A.Brayton cycle
B.Otto cycle
C.Diesel cycle
D.Carnot cycle
Explanation: The open Brayton cycle models gas turbine operation, consisting of continuous adiabatic compression, constant-pressure heat addition in the combustor, adiabatic expansion in the turbine/nozzle, and constant-pressure heat rejection in the atmosphere.
2An aircraft turbojet engine ingests an airflow rate of 50 kg/s at a flight speed of 200 m/s. If the exhaust jet velocity is 500 m/s, what is the net unchoked thrust Fn generated (assuming fuel mass flow is negligible)?
A.15000 N
B.25000 N
C.10000 N
D.35000 N
Explanation: Net thrust F_n = ṁ · (V_j - V_a) = 50 kg/s · (500 m/s - 200 m/s) = 50 · 300 = 15,000 N (or 15 kN).
3How is Thrust Specific Fuel Consumption (TSFC) defined for a gas turbine engine?
A.The fuel mass flow rate per hour divided by the net thrust generated (kg / (N * h))
B.The total fuel consumed during a flight divided by distance traveled
C.The ratio of turbine inlet temperature to compressor pressure ratio
D.The electrical power output generated by the APU generator per liter of fuel
Explanation: TSFC measures engine fuel efficiency, defined as the mass of fuel burned per unit time per unit of thrust produced (e.g., kg/(N*h) or lb/(lbf*h)). Lower TSFC indicates better thermal and propulsive efficiency.
4What is the primary function of stator vanes in an axial flow compressor stage?
A.To convert kinetic energy imparted by the rotor into static pressure and direct airflow at the correct angle to the next rotor stage
B.To accelerate airflow to supersonic speeds before combustion
C.To ignite the compressed air-fuel mixture
D.To prevent turbine blade overspeed during acceleration
Explanation: In an axial compressor stage, rotor blades accelerate the air (increasing kinetic energy), and fixed stator vanes act as divergent passages that decelerate the air, converting kinetic energy into static pressure while turning the air onto the next rotor stage.
5What causes an axial compressor aerodynamic stall?
A.The local angle of attack of airflow over compressor rotor blades exceeds the critical stall angle
B.Fuel pressure delivered by the HMU exceeds combustion chamber pressure
C.Turbine inlet temperature drops below 200 °C
D.The compressor pressure ratio falls to zero
Explanation: Compressor stall occurs when the vector sum of axial airflow velocity and blade rotational speed results in an angle of attack exceeding the critical angle of the airfoil, causing airflow separation over the blade upper surface.
6Which design features are incorporated into modern dual-spool axial engines to prevent low-speed compressor stall and surge during acceleration?
A.Variable Stator Vanes (VSVs) and transient Compressor Bleed Valves (CBVs)
B.Fixed geometry stator vanes and constant fuel flow nozzles
C.Afterburner spray rings and adjustable tailpipe nozzles
D.Water-methanol injection nozzles in the turbine section
Explanation: To maintain stable airflow angles across a wide operating range, engines use Variable Stator Vanes (VSVs) on early stages and transient Compressor Bleed Valves (CBVs) on intermediate stages to dump excess air and prevent low-RPM front-stage stalling.
7What is a major advantage of a full annular combustion chamber compared to a multiple-can combustion chamber?
A.More uniform outlet temperature distribution, shorter overall length, and lighter weight for a given power output
B.Easier individual removal and replacement of worn burner cans during wing maintenance
C.Lower operating pressure requirement from the compressor
D.Elimination of the need for fuel atomizing nozzles
Explanation: Full annular combustors use a single continuous inner and outer liner housing. This design offers optimal space utilization, uniform circumferential thermal distribution at the turbine inlet, shorter shaft length, and lower engine weight.
8What proportion of total compressor discharge air enters the primary combustion zone to participate directly in fuel combustion?
A.20% to 25%
B.60% to 75%
C.90% to 95%
D.5% to 10%
Explanation: Only about 20% to 25% of compressor exit air (P3) is introduced as primary air around the fuel nozzle for near-stoichiometric combustion. The remaining 75% to 80% is used for liner film cooling and dilution to lower gas temperature before reaching the turbine.
9Which advanced cooling technique involves bleeding compressor air through internal microscopic passages inside a high-pressure turbine blade to form a protective boundary layer of cooler air over the outer airfoil surface?
A.Film cooling
B.Convection cooling
C.Transpiration cooling
D.Impingement cooling
Explanation: Film cooling discharges bleed air through small angled holes on the blade leading edge and surface, forming a continuous thin blanket of cooler air that isolates the blade alloy from direct contact with hot combustion gases.
10What metallurgical degradation phenomenon describes the slow, permanent elongation of high-pressure turbine blades under high centrifugal stress and elevated temperatures over time?
A.Creep
B.Thermal shock
C.Fretting corrosion
D.Galling
Explanation: Creep is the time-dependent plastic deformation of turbine blade superalloys under continuous high stress (centrifugal force) and high temperature. Left unchecked, creep causes blade tip rubbing against the outer turbine casing.
About the SAR-66 Module 15 Practice Questions
Verified exam format metadata for CAAS SAR-66 AML Module 15 — Gas Turbine Engine is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.