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021 11 01 00 Basic principles
021 11 01 01 Basic generation of thrust and the thrust formula
(01) Describe how thrust is produced by a basic gas turbine engine.
(02) Describe the simple form of the thrust formula for a basic, straight jet engine and perform simple calculations (including pressure thrust).
(03) State that thrust can be considered to remain approximately
Syllabus reference BK Syllabus details and associated Learning Objectives
constant over the whole aeroplane subsonic speed range.
021 11 01 02 Design, types and components of turbine engines
(01) “List the main components of a basic gas turbine engine:
— inlet;
— compressor;
— combustion chamber;
— turbine;
— outlet.”
(02) Describe the variation of static pressure, temperature and axial velocity in a gas turbine engine under normal operating conditions and with the aid of a working cycle diagram.
(03) Describe the differences between absolute, circumferential (tangential) and axial velocity.
(04) “List the different types of gas turbine engines:
— straight jet;
— turbofan;
— turboprop.”
(05) State that a gas turbine engine can have one or more spools.
(06) Describe how thrust is produced by turbojet and turbofan engines.
(07) Describe how power is produced by turboprop engines.
(08) Describe the term ‘equivalent horsepower’ (= thrust horsepower + shaft horsepower).
(09) Explain the principle of a free turbine or free-power turbine.
(10) Define the term ‘bypass ratio’ and perform simple calculations to
Syllabus reference BK Syllabus details and associated Learning Objectives
determine it.
(11) Define the terms ‘propulsive power’, ‘propulsive efficiency’, ‘thermal efficiency’ and ‘total efficiency’.
(12) Describe the influence of compressor-pressure ratio on thermal efficiency.
(13) Explain the variations of propulsive efficiency with forward speed for turbojet, turbofan and turboprop engines.
(14) Define the term ‘specific fuel consumption’ for turbojets and turboprops.
021 11 01 03 Coupled turbine engine: design, operation, components and materials
(01) Name the main assembly parts of a coupled turbine engine and explain its operation.
(02) Explain the limitations of the materials used with regard to maximum turbine temperature, engine and drive train torque limits.
(03) Describe the possible effects on engine components when limits are exceeded.
(04) Explain that when engine limits are exceeded, this event must be reported.
021 11 01 04 Free-turbine engine: design, components and materials
(01) Describe the design methods to keep the engine’s size small for installation in helicopters.
(02) List the main components of a free-turbine engine.
(03) Describe how the power is developed by a turboshaft/free-turbine
Syllabus reference BK Syllabus details and associated Learning Objectives
engine.
(04) Explain how the exhaust gas temperature is used to monitor turbine stress.
021 11 02 00 Main-engine components
021 11 02 01 Aeroplane: air intake
(01) State the functions of the engine air inlet/air intake.
(02) Describe the geometry of a subsonic (pitot-type) air inlet.
(03) Explain the gas-parameter changes in a subsonic air inlet at different flight speeds.
(04) “Describe the reasons for, and the dangers of, the following operational problems concerning the engine air inlet:
— airflow separation;
— inlet icing;
— inlet damage;
— foreign object damage (FOD);
— heavy in-flight turbulence.”
021 11 02 02 Compressor and diffuser
(01) State the purpose of the compressor.
(02) Describe the working principle of a centrifugal and an axial flow compressor.
(03) “Name the following main components of a single stage and describe their function for a centrifugal compressor:
— impeller;
— diffuser.”
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(04) “Name the following main components of a single stage and describe their function for an axial compressor:
— rotor vanes;
— stator vanes.”
(05) Describe the gas-parameter changes in a compressor stage.
(06) Define the term ‘pressure ratio’ and state a typical value for one stage of a centrifugal and an axial flow compressor and for the complete compressor.
(07) State the advantages and disadvantages of increasing the number of stages in a centrifugal compressor.
(08) Explain the difference in sensitivity for FOD of a centrifugal compressor compared with an axial flow type.
(09) Explain the convergent air annulus through an axial flow compressor.
(10) Describe the reason for twisting the compressor blades.
(11) State the tasks of inlet guide vanes (IGVs).
(12) State the reason for the clicking noise whilst the compressor slowly rotates on the ground.
(13) State the advantages of increasing the number of spools.
(14) Explain the implications of tip losses and describe the design features to minimise the problem.
(15) Explain the problems of blade bending and flapping and describe the design features to minimise the problem.
(16) “Explain the following terms:
— compressor stall;”
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— engine surge.
(17) State the conditions that are possible causes of stall and surge.
(18) Describe the indications of stall and surge.
(19) Describe the design features used to minimise the occurrence of stall and surge.
(20) Describe a compressor map (surge envelope) with rpm lines, stall limit, steady state line and acceleration line.
(21) Describe the function of the diffuser.
021 11 02 03 Combustion chamber
(01) Define the purpose of the combustion chamber.
(02) List the requirements for combustion.
(03) Describe the working principle of a combustion chamber.
(04) Explain the reason for reducing the airflow axial velocity at the combustion chamber inlet (snout).
(05) State the function of the swirl vanes (swirler).
(06) State the function of the drain valves.
(07) Define the terms ‘primary airflow’ and ‘secondary airflow’, and explain their purpose.
(08) “Explain the following two mixture ratios:
— primary airflow to fuel;
— total airflow (within the combustion chamber) to fuel.”
(09) Describe the gas-parameter changes in the combustion chamber.
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(10) State a typical maximum value of the outlet temperature of the combustion chamber.
(11) “Describe the following types of combustion chambers and state the differences between them:
— can type;
— can-annular, cannular or turbo-annular;
— annular;
— reverse-flow annular.”
021 11 02 04 Turbine
(01) Explain the purpose of a turbine in different types of gas turbine engines.
(02) Describe the principles of operation of impulse, reaction and impulse-reaction axial flow turbines.
(03) Name the main components of a turbine stage and their function.
(04) Describe the working principle of a turbine.
(05) Describe the gas-parameter changes in a turbine stage.
(06) Describe the function and the working principle of active clearance control.
(07) Describe the implications of tip losses and the means to minimise them.
(08) Explain why the available engine thrust is limited by the turbine inlet temperature.
(09) Explain the divergent gas-flow annulus through an axial-flow turbine.
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(10) Explain the high mechanical thermal stress in the turbine blades and wheels/discs.
021 11 02 05 Aeroplane: exhaust
(01) “Name the following main components of the exhaust unit and their function:
— jet pipe;
— propelling nozzle;
— exhaust cone.”
(02) Describe the working principle of the exhaust unit.
(03) Describe the gas-parameter changes in the exhaust unit.
(04) Define the term ‘choked exhaust nozzle’ (not applicable to turboprops).
(05) Explain how jet exhaust noise can be reduced.
021 11 02 06 Helicopter: air intake
(01) Name and explain the main task of the engine air intake.
(02) Describe the use of a convergent air-intake ducting on helicopters.
(03) “Describe the reasons for and the dangers of the following operational problems concerning engine air intake:
— airflow separations;
— intake icing;
— intake damage;
— FOD;
— heavy in-flight turbulence.”
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(04) Describe the conditions and circumstances during ground operations when FOD is most likely to occur.
(05) Describe and explain the principles of air intake filter systems that can be fitted to some helicopters for operations in icing and sand conditions.
(06) Describe the function of the heated pads on some helicopter air intakes.
021 11 02 07 Helicopter: exhaust
(01) Describe the working principle of the exhaust unit.
(02) Describe the gas-parameter changes in the exhaust unit.
021 11 03 00 Additional components and systems
021 11 03 01 Engine fuel system
(01) “Name the main components of the engine fuel system and state their function:
— filters;
— low-pressure (LP) pump;
— high-pressure (HP) pump;
— fuel manifold;
— fuel nozzles;
— HP fuel cock;
— fuel control; or
— hydromechanical unit.”
(02) Name the two types of engine-driven high-pressure pumps, such as:
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“— gear-type;
— swash plate-type.”
(03) State the tasks of the fuel control unit.
(04) List the possible input parameters to a fuel control unit to achieve a given thrust/power setting.
021 11 03 02 Engine control system
(01) State the tasks of the engine control system.
(02) “List the following different types of engine control systems:
— hydromechanical;
— hydromechanical with a limited authority electronic supervisor;
— single-channel FADEC with hydromechanical backup;
— dual-channel FADEC with no backup or any other combination.”
(03) Describe a FADEC as a full-authority dual-channel system including functions such as an electronic engine control unit, wiring, sensors, variable vanes, active clearance control, bleed configuration, electrical signalling of thrust lever angle (TLA) (see also AMC to CS-E-50), and an EGT protection function and engine overspeed.
(04) Explain how redundancy is achieved by using more than one channel in a FADEC system.
(05) State the consequences of a FADEC single input data failure.
(06) State that all input and output data is checked by both channels in a FADEC system.
(07) State that a FADEC system uses its own sensors and that, in some
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cases, also data from aircraft systems is used.
(08) State that a FADEC must have its own source of electrical power.
021 11 03 03 Engine lubrication
(01) State the tasks of an engine lubrication system.
(02) “Name the following main components of a lubrication system and state their function:
— oil tank and centrifugal breather;
— oil pumps (pressure and scavenge pumps);
— oil filters (including the bypass);
— oil sumps;
— chip detectors;
— coolers.”
(03) Explain that each spool is fitted with at least one ball bearing and two or more roller bearings.
(04) Explain the use of compressor air in oil-sealing systems (e.g. labyrinth seals).
021 11 03 04 Engine auxiliary gearbox
(01) State the tasks of the auxiliary gearbox.
(02) Describe how the gearbox is driven and lubricated.
021 11 03 05 Engine ignition
(01) State the task of the ignition system.
(02) Name the following main components of the ignition system and state their function:
Syllabus reference BK Syllabus details and associated Learning Objectives
“— power sources;
— igniters.”
(03) State why jet turbine engines are equipped with two electrically independent ignition systems.
(04) Explain the different modes of operation of the ignition system.
021 11 03 06 Engine starter
(01) Name the main components of the starting system and state their function.
(02) Explain the principle of a turbine engine start.
(03) “Describe the following two types of starters:
— electric;
— pneumatic.”
(04) Describe a typical start sequence (on ground/in flight) for a turbofan.
(05) Define ‘self-sustaining rpm’.
021 11 03 07 Reverse thrust
(01) “Name the following main components of a reverse-thrust system and state their function:
— reverse-thrust select lever;
— power source (pneumatic or hydraulic);
— actuators;
— doors;
— annunciations.”
(02) Explain the principle of a reverse-thrust system.
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(03) Identify the advantages and disadvantages of using reverse thrust.
(04) “Describe and explain the following different types of thrust- reverser systems:
— hot-stream reverser;
— clamshell or bucket-door system;
— cold-stream reverser (only turbofan engines);
— blocker doors;
— cascade vanes.”
(05) Explain the implications of reversing the cold stream (fan reverser) only on a high bypass ratio engine.
(06) Describe the protection features against inadvertent thrust- reverse deployment in flight as present on most transport aeroplanes.
(07) Describe the controls and indications provided for the thrust- reverser system.
021 11 03 08 Helicopter specifics on design, operation and components for additional components and systems such as lubrication system, ignition circuit, starter, accessory gearbox
(01) State the task of the lubrication system.
(02) List and describe the common helicopter lubrication systems.
(03) “Name the following main components of a helicopter lubrication system:
— reservoir;
— pump assembly;
— external oil filter;”
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“— magnetic chip detectors, electronic chip detectors;
— thermostatic oil coolers;
— breather.”
(04) Identify and name the components of a helicopter lubrication system from a diagram.
(05) Identify the indications used to monitor a lubrication system including warning systems.
(06) Explain the differences and appropriate use of straight oil and compound oil, and describe the oil numbering system for aviation use.
(07) Explain and describe the ignition circuit for engine start and engine relight facility when the selection is set for both automatic and manual functions.
(08) Explain and describe the starter motor and the sequence of events when starting, and that for most helicopters the starter becomes the generator after the starting sequence is over.
(09) Explain and describe why the engine drives the accessory gearbox.
021 11 04 00 Engine operation and monitoring
021 11 04 01 General
(01) “Explain the following aeroplane engine ratings:
— take-off;
— go-around;
— maximum continuous thrust/power;
— maximum climb thrust/power.”
(02) Explain spool-up time.
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(03) Explain the reason for the difference between ground and approach flight idle values (rpm).
(04) State the parameters that can be used for setting and monitoring the thrust/power.
(05) Describe the terms ‘alpha range’, ‘beta range’ and ‘reverse thrust’ as applied to a turboprop power lever.
(06) Explain the dangers of inadvertent beta-range selection in flight for a turboprop.
(07) Explain the purpose of engine trending.
(08) Explain how the exhaust gas temperature is used to monitor turbine stress.
(09) Describe the effect of engine acceleration and deceleration on the EGT.
(10) Describe the possible effects on engine components when EGT limits are exceeded.
(11) Explain why engine-limit exceedances must be reported.
(12) Explain the limitations on the use of the thrust-reverser system at low forward speed.
(13) Explain the term ‘engine seizure’.
(14) State the possible causes of engine seizure and explain their preventative measures.
(15) “Describe the potential consequences of a leak in the following two designs of fuel and oil heat exchanger:
— oil pressure higher than fuel pressure with oil leaking into the fuel system, potentially affecting the combustion and running”
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“of the engine;
— fuel pressure higher than oil pressure with fuel leaking into the oil system, potentially increasing the risk of a fire due to fuel entering warm parts of the engine that should be free from fuel.”
(16) Explain oil-filter clogging (blockage) and the implications for the lubrication system.
(17) Give examples of monitoring instruments of an engine.
(18) Describe how to identify and assess engine damage based on instrument indications.
021 11 04 02 Starting malfunctions
(01) “Describe the indications and the possible causes of the following aeroplane starting malfunctions:
— false (dry or wet) start;
— tailpipe fire (torching);
— hot start;
— abortive (hung) start;
— no N1 rotation;
— no FADEC indications.”
(02) “Describe the indications and the possible causes of the following helicopter starting malfunctions:
— false (dry or wet) start;
— tailpipe fire (torching);
— hot start;
— abortive (hung) start;
— no N1 rotation;”
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“— freewheel failure;
— no FADEC indications.”
021 11 04 03 Relight envelope
(01) Explain the relight envelope.
021 11 05 00 Performance aspects
021 11 05 01 Thrust, performance aspects, and limitations
(01) Describe the variation of thrust and specific fuel consumption with altitude at constant TAS.
(02) Describe the variation of thrust and specific fuel consumption with TAS at constant altitude.
(03) Explain the term ‘flat-rated engine’ by describing the change of take-off thrust, turbine inlet temperature and engine rpm with outside air temperature (OAT).
(04) Define the term ‘engine pressure ratio’ (EPR).
(05) Explain the use of reduced (flexible) and derated thrust for take- off, and explain the advantages and disadvantages when compared with a full-rated take-off.
(06) Describe the effects of use of bleed air on rpm, EGT, thrust, and specific fuel consumption.
021 11 05 02 Helicopter engine ratings, engine performance and limitations, engine handling: torque, performance aspects and limitations
(01) Describe engine rating torque limits for take-off, transient and maximum continuous.
(02) Describe turbine outlet temperature (TOT) limits for take-off.
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(03) Explain why TOT is a limiting factor for helicopter performance.
(04) Describe and explain the relationship between maximum torque available and density altitude, which leads to decreasing torque available with the increase of density altitude.
(05) Explain that hovering downwind, on some helicopters, will noticeably increase the engine TOT.
(06) Explain the reason why the engine performance is less when aircraft accessories (i.e. anti-ice, heating, hoist, filters) are switched on.
(07) Describe the effects of use of bleed air on engine parameters.
(08) Explain that, on some helicopters, exceeding the TOT limit may cause the main rotor to droop (slow down).
(09) Describe overtorquing and explain the consequences.
021 11 06 00 Auxiliary power unit (APU)
021 11 06 01 Design, operation, functions, operational limitations
(01) State that an APU is a gas turbine engine and list its tasks.
(02) State the difference between the two types of APU inlets.
(03) Define ‘maximum operating and maximum starting altitude’.
(04) Name the typical APU control and monitoring instruments.
(05) Describe the APU’s automatic shutdown protection.