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Remark: For any reference to the direction of current flow, the conventional current flow shall be used, i.e. from positive to negative.
021 09 01 00 General, definitions, basic applications: circuit breakers, logic circuits
021 09 01 01 Static electricity
(01) Explain static electricity and describe the flying conditions where aircraft are most susceptible to build-up of static electricity.
(02) “Describe a static discharger and explain the following:
— its purpose;
— typical locations;
— pilot’s role of observing it during pre-flight inspection.”
(03) Explain why an aircraft must first be grounded before refuelling/defueling.
(04) Explain the reason for electrical bonding.
Syllabus reference BK Syllabus details and associated Learning Objectives
021 09 01 02 Direct current (DC)
(01) Explain the term ‘direct current’ (DC), and state that current can only flow in a closed circuit.
(02) X Explain the basic principles of conductivity and give examples of conductors, semiconductors and insulators.
(03) “Describe the difference in use of the following mechanical switches and explain the difference in observing their state (e.g. ON/OFF), and why some switches are guarded:
— toggle switch;
— rocker switch;
— pushbutton switch;
— rotary switch.
Explain the difference in observing their state (e.g. ON/OFF) and why some switches are guarded.”
(04) Define voltage and current, and state their unit of measurement.
(05) X Explain Ohm’s law in qualitative terms.
(06) X Explain the effect on total resistance when resistors are connected in series or in parallel.
(07) X State that resistances can have a positive or a negative temperature coefficient (PTC/NTC) and state their use.
(08) Define electrical power and state the unit of measurement.
021 09 01 03 Alternating current (AC)
(01) X Explain the term ‘alternating current’ (AC), and compare its use to DC with regard to complexity.
Syllabus reference BK Syllabus details and associated Learning Objectives
(02) Define the term ‘phase’, and explain the basic principle of single- phase and three-phase AC.
(03) State that aircraft can use single-phase or three-phase AC.
(04) Define frequency and state the unit of measurement.
(05) X Define ‘phase shift’ in qualitative terms.
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021 09 01 05 Intentionally left blank
021 09 01 06 Electromagnetism
(01) State that an electrical current produces a magnetic field.
(02) Describe how the strength of the magnetic field changes with the magnitude of the current.
(03) Explain the purpose and the working principle of a solenoid.
(04) Explain the purpose and the working principle of a relay.
(05) Explain the principle of electromagnetic induction and how two electrical components or systems may affect each other through this principle.
021 09 01 07 Circuit protection
(01) Explain the working principle of a fuse and a circuit breaker.
(02) Explain how a fuse is rated.
(03) Describe the principal difference between the following types of circuit breakers:
Syllabus reference BK Syllabus details and associated Learning Objectives
“— thermal circuit breaker sensing magnitude of current;
— magnetic circuit breaker sensing direction of current.”
(04) Describe how circuit breakers may be used to reset aircraft systems/computers in the event of system failure (when part of a described procedure).
(05) Explain a short circuit in practical terms using Ohm’s Law, power and energy expressions highlighting the risk of fire due to power transfer and extreme energy dissipation.
(06) Explain the risk of fire resulting from excessive heat in a circuit subjected to overcurrent.
(07) Explain that overcurrent situations may be transient.
(08) Explain the hazards of multiple resets of a circuit breaker or the use of incorrect fuse rating when replacing blown fuses.
021 09 01 08 Semiconductors and logic circuits
(01) Describe the effect of temperature on semiconductors with regard to function and longevity of the component.
(02) “Describe the following five basic logic functions, as used in aircraft FCOM documentation, and recognise their schematic symbols according to the ANSI/MIL standard:
— AND;
— OR;
— NOT;
— NOR;
— NAND.”
(03) Interpret a typical logic circuit schematic to the level of detail as found in an aircraft FCOM.
Syllabus reference BK Syllabus details and associated Learning Objectives
021 09 02 00 Batteries
021 09 02 01 Types, characteristics and limitations
(01) State the function of an aircraft battery.
(02) “Name the types of rechargeable batteries used in aircraft:
— lead-acid;
— nickel-cadmium;
— lithium-ion;
— lithium-polymer.”
(03) “Compare the different battery types with respect to:
— load behaviour;
— charging characteristics;
— risk of thermal runaway.”
(04) Explain the term ‘cell voltage’ and describe how a battery may consist of several cells that combined provide the desirable voltage and capacity.
(05) Explain the difference between battery voltage and charging voltage.
(06) Define the term ‘capacity of batteries’ and state the unit of measurement used.
(07) State the effect of temperature on battery capacity and performance.
(08) State that in the case of loss of all generated power (battery power only) the remaining electrical power is time-limited.
(09) Explain how lithium-type batteries pose a threat to aircraft safety and what affects this risk:
Syllabus reference BK Syllabus details and associated Learning Objectives
“— numbers of batteries on board an aircraft including those brought on board by passengers;
— temperature, of both battery and environment;
— physical condition of the battery;
— battery charging.”
(10) “Describe how to contain a battery thermal runaway highlighting the following:
— how one cell can affect the neighbouring cells;
— challenges if it happens in an aircraft during flight.”
021 09 03 00 Generation
“Remark: For standardisation purposes, the following standard expressions are used:
— DC generator: produces DC output;
— DC alternator: produces AC, rectified by integrated rectifying unit, the output is DC;
— DC alternator: producing a DC output by using a rectifier;
— AC generator: produces AC output;
— starter generator: integrated combination of a generator and a starter motor;
— permanent magnet alternator/ generator: self-exciting AC generator.”
021 09 03 01 DC generation
(01) Describe the basic working principle of a simple DC generator or DC alternator.
(02) Explain the principle of voltage control and why it is required.
Syllabus reference BK Syllabus details and associated Learning Objectives
(03) Explain the purpose of reverse current protection from the battery/busbar to the alternator.
(04) Describe the basic operating principle of a starter generator and state its purpose.
021 09 03 02 AC generation
(01) Describe the working principle of a brushless three-phase AC generator.
(02) State that the generator field current is used to control voltage.
(03) State the relationship between output frequency and the rpm of a three-phase AC generator.
(04) Explain the term ‘frequency wild generator’.
(05) “List the following different power sources that can be used for an aeroplane to drive an AC generator:
— engine;
— APU;
— RAT;
— hydraulic.”
(06) “List the following different power sources that can be used for a helicopter to drive an AC generator:
— engine;
— APU;
— gearbox.”
021 09 03 03 Constant speed drive (CSD) and integrated drive generator (IDG) systems
(01) Describe the function of a CSD.
Syllabus reference BK Syllabus details and associated Learning Objectives
(02) Explain the parameters of a CSD that are monitored.
(03) Describe the function of an IDG.
(04) Explain the consequences of a mechanical disconnection during flight for a CSD and an IDG.
(05) Explain that a CSD/IDG has its own, independent oil system and how a leak from this may appear as an engine oil leak.
021 09 03 04 Transformers, transformer rectifier units (TRUs), static inverters
(01) State the function of a transformer.
(02) State the function of a TRU and its purpose, including type of output.
(03) State the function of a static inverter and its purpose, including type of output.
021 09 04 00 Distribution
021 09 04 01 General
(01) Explain the function of a busbar.
(02) “Describe the function of the following buses:
— AC bus;
— DC bus;
— emergency AC or DC bus;
— essential AC or DC bus;
— battery bus;
— hot bus, ground servicing or maintenance bus.”
(03) State that the aircraft structure can be used as a part of the
Syllabus reference BK Syllabus details and associated Learning Objectives
electrical circuit (common earth) and explain the implications for electrical bonding.
(04) Explain the function of external power.
(05) State that a priority sequence exists between the different sources of electrical power on ground and in flight.
(06) Explain the term ‘load sharing’.
(07) Explain the term ‘load shedding’.
(08) Describe typical systems that can be shed in the event of a supply failure, such as passenger entertainment system and galley power.
(09) Interpret a typical electrical system schematic to the level of detail as found in an aircraft FCOM.
(10) Explain the difference between a supply (e.g. generator) failure and a bus failure, and the operating consequences of either.
021 09 04 02 DC distribution
(01) Describe a simple DC electrical system of a single-engine aircraft.
(02) Describe a DC electrical system of a multi-engine aircraft (CS-23/CS-27) including the distribution consequences of loss of generator(s) or bus failure.
(03) Describe the DC part of an electrical system of a transport aircraft (CS-25/CS-29) including the distribution consequences of loss of DC supply or bus failure.
(04) Give examples of DC consumers.
021 09 04 03 AC distribution
Syllabus reference BK Syllabus details and associated Learning Objectives
(01) Explain the difference in the principle of operation for a split AC electrical system and a parallel AC electrical system.
(02) “Describe the following distribution consequences:
— power transfer between different power supplies;
— power transfer in the event of a supply failure;
— loss of all normal AC supplies.”
(03) Give examples of AC consumers.
(04) Explain the conditions to be met for paralleling AC generators.
(05) State that volt-ampere (VA) is the unit for total power consumed in an AC system.
021 09 04 04 Electrical load management and monitoring systems: automatic generators and bus switching during normal and failure operation, indications and warnings
(01) “Give examples of system control, monitoring and annunciators using the following terms:
— generator control unit (GCU) for monitoring generator output and providing network protection;
— exciter contactor/breaker/relay for control of generator exciter field;
— generator contactor/breaker/relay for connecting the generator to the network;
— bus-tie contactor/breaker/relay for connecting busbars together;
— generator switch on the flight deck for manual control of exciter contactor;
— IDG/CSD disconnect switch on the flight deck for mechanical”
Syllabus reference BK Syllabus details and associated Learning Objectives
“disconnection of the generator;
— bus-tie switch on the flight deck with AUTO and OFF positions only.”
(02) “Describe, for normal and degraded modes of operation, the following functions of an electrical load management system on ground and in flight using the terms in 021 09 04 04 (01):
— distribution;
— monitoring;
— protection in the event of incorrect voltage;
— protection in the event of incorrect frequency;
— protection in the event of a differential fault.”
(03) Describe the requirement for monitoring the aircraft batteries.
(04) Explain the importance of monitoring the temperature of nickel- cadmium and lithium-type batteries.
(05) Interpret various different ammeter indications of an ammeter which monitors the charge current of the battery.
021 09 05 00 Electrical motors
021 09 05 01 General
(01) X State that the purpose of an electrical motor is to convert electrical energy into mechanical energy.
(02) State that because of the similarity in design, a generator and an electrical motor may be combined into a starter generator.
(03) “Explain that the size of the engine determines how much energy is required for starting, and state the following:
— small turbine engines may be able to use the battery for a”
Syllabus reference BK Syllabus details and associated Learning Objectives
“very limited number of start attempts;
— large turbine engines require one or more power sources, either external or on-board.”
021 09 05 02 Operating principle
(01) Describe how the torque of an electrical motor is determined by the supplied voltage and current, and the resulting magnetic fields within the engine.
(02) X State that electrical motors can be either AC or DC.
(03) “Explain the consequences of the following:
— rotor seizure;
— rotor runaway.”
021 09 05 03 Components
(01) X “Name the following components of an electrical motor:
— rotor (rotating part of an electrical motor);
— stator (stationary part of an electrical motor).”
021 10 00 00 PISTON ENGINES
Remark: This topic includes diesel and petrol engines.