Free UK Part-66 Module 14 Propulsion (B2) Practice Questions

Sample Practice Questions

Try these 10 sample questions from the UK Part-66 Module 14 Propulsion (B2) practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1Which feature distinguishes the operating cycle of a gas turbine from that of a reciprocating engine?

   1. A.Its main cycle functions occur simultaneously in separate sections.Correct answer: A
   2. B.Its main cycle functions occur successively in one cylinder.
   3. C.Its compression occurs only after combustion has finished.
   4. D.Its exhaust phase interrupts airflow through the compressor.

   Explanation: The handbook states: "A significant feature of the gas turbine engine is that separate sections are devoted to each function, and all functions are performed simultaneously without interruption.". Separate continuously operating sections distinguish this cycle from the sequential cylinder cycle.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Gas Turbine Engines—Types & Construction, p. 1-36

2. 2What does engine pressure ratio indicate on an EPR-equipped turbofan?

   1. A.The thrust being developedCorrect answer: A
   2. B.The amount of oil in the tank
   3. C.The compressor bearing temperature
   4. D.The propeller reduction-gear torque

   Explanation: The handbook states: "Engine pressure ratio (EPR) is an indication of the thrust being developed by a turbofan engine". EPR is a thrust-setting indication, rather than a fluid-quantity, temperature or propeller-torque indication.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Engine Pressure Ratio Indicator, p. 10-54

3. 3Why must the starter establish sufficient compressor airflow before turbine light-off?

   1. A.The airflow eliminates the need for an ignition source.
   2. B.The airflow is needed to support combustion.Correct answer: B
   3. C.The airflow prevents fuel from reaching the nozzles.
   4. D.The airflow keeps the combustor at atmospheric pressure.

   Explanation: The handbook states: "there must be sufficient airflow through the engine to support combustion before the air-fuel mixture is ignited.". Fuel and ignition need an adequate combustion-air supply.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Gas Turbine Engine Starters, p. 5-8

4. 4What is a spool in a gas turbine engine?

   1. A.A compressor, its shaft, and the turbines that drive itCorrect answer: A
   2. B.A combustion liner and the casing surrounding it
   3. C.An exhaust nozzle and its thrust reverser mechanism
   4. D.An inlet duct and the guide vanes mounted within it

   Explanation: The handbook states: "a spool is a compressor and a shaft and turbines that drive that compressor". The spool is a rotating compressor–shaft–turbine assembly; the other assemblies do not define a spool.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Types & Construction, p. 1-36

5. 5Which sensing locations provide pressures for the EPR system described in the handbook?

   1. A.The oil-pump inlet and oil-pump discharge
   2. B.The fuel-pump inlet and fuel-pump discharge
   3. C.The combustion liner and engine oil tank
   4. D.The engine inlet and turbine exhaustCorrect answer: D

   Explanation: The handbook states: "It is instrumented by total pressure pickups in the engine inlet (Pt2) and in the turbine exhaust (Pt7).". The ratio uses total pressures at the inlet and turbine exhaust.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Engine Pressure Ratio Indicator, p. 10-54

6. 6Why does a turbine starter continue assisting after light-off?

   1. A.The engine has not yet reached self-sustaining speed.Correct answer: A
   2. B.The engine must be held below any accelerating speed.
   3. C.The ignition system cannot operate while the starter stops.
   4. D.The starter supplies all normal engine shaft power in flight.

   Explanation: The handbook states: "Once ignition and fuel have been introduced and the lite-off has occurred, the starter must continue to assist the engine until the engine reaches a self-sustaining speed.". Initial combustion alone does not establish self-sustaining engine operation.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Gas Turbine Engine Starters, p. 5-8

7. 7Which components normally belong to the high-pressure spool of a two-spool turbofan?

   1. A.The high-pressure compressor, shaft, and driving turbinesCorrect answer: A
   2. B.The fan, reduction gearbox, and propeller shaft
   3. C.The exhaust nozzle, tail cone, and thrust reverser
   4. D.The low-pressure compressor, fan, and driving turbines

   Explanation: The handbook states: "The high-pressure spool is the high-pressure compressor, shaft, and turbines.". The high-pressure spool contains the high-pressure compressor and its driving assembly, distinct from the low-pressure fan spool.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Types & Construction, p. 1-36

8. 8Which instrument is normally used to set turboprop shaft power?

   1. A.A manifold vacuum gauge
   2. B.A fuel-quantity indicator
   3. C.A torquemeterCorrect answer: C
   4. D.An EPR indicator

   Explanation: The handbook states: "Turboprops are usually fitted with a torquemeter that measures torque applied to a shaft". The torquemeter measures the shaft loading used for turboprop power settings.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Torquemeter (Turboprop Engines), p. 10-55

9. 9What does a rise in EGT after fuel introduction normally indicate during turbine starting?

   1. A.The starter clutch has mechanically disengaged.
   2. B.The engine has necessarily reached stabilized idle.
   3. C.The fuel supply has been completely shut off.
   4. D.Light-off has occurred.Correct answer: D

   Explanation: The handbook states: "EGT rise indicates light up". EGT rise is evidence of combustion, not by itself proof of idle or starter disengagement.

   Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Figure 5-14, p. 5-9

10. 10Which airflow ratio defines bypass ratio in a turbofan engine?

    1. A.Fan bypass airflow divided by engine core airflowCorrect answer: A
    2. B.Engine core airflow divided by fan bypass airflow
    3. C.Total engine airflow divided by engine core airflow
    4. D.Fan bypass airflow divided by total engine airflow

    Explanation: The handbook states: "The amount of air flow in lb/sec from the fan bypass to the core flow of the engine is the bypass ratio.". The numerator is bypass flow and the denominator core flow; reversing the ratio or using total flow changes the quantity.

    Reference: FAA Aviation Maintenance Technician Handbook—Powerplant — Types & Construction, p. 1-36