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MCAA ATPL Theory Exam study materials
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MCAA ATPL Theory Exam practice questions

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Question 1Air Law and ATC Procedures

Under Article 1 of the Chicago Convention, each contracting State has which authority over its territory?

  1. Complete and exclusive sovereignty over the airspace above its territory Correct answer.
  2. Exclusive sovereignty only over airports designated as international
  3. Airspace authority delegated to ICAO for international flights
  4. Sovereignty only over the airspace above its territorial waters

Explanation

Article 1 of the Chicago Convention recognises that every State has complete and exclusive sovereignty over the airspace above its territory, including territorial waters. This sovereignty is not limited to airports and is not delegated to ICAO.

Question 2Air Law and ATC Procedures

Two aircraft of the same category are converging at approximately the same level. Which aircraft has the right of way?

  1. The aircraft on the right Correct answer.
  2. The aircraft that is flying lower
  3. The aircraft with the higher performance
  4. The aircraft on the left

Explanation

Under the Rules of the Air, when two aircraft of the same category converge at approximately the same level, the aircraft on the right has the right of way. The other aircraft must give way and avoid crossing ahead of it.

Question 3Air Law and ATC Procedures

What is the primary objective of an aircraft accident or incident investigation under ICAO Annex 13?

  1. To impose disciplinary sanctions on the personnel involved
  2. To determine who is legally liable for the occurrence
  3. To prevent accidents and incidents Correct answer.
  4. To settle insurance claims between the parties

Explanation

Annex 13 requires the investigation of accidents and incidents to be conducted for the prevention of future occurrences. It is not intended to apportion blame or determine liability.

Question 4Air Law and ATC Procedures

Which ICAO Annex contains the Rules of the Air that apply over the high seas?

  1. Annex 11
  2. Annex 2 Correct answer.
  3. Annex 10
  4. Annex 14

Explanation

Annex 2 contains the international Standards and Recommended Practices for Rules of the Air. It applies over the high seas so that aircraft of different States operate under common rules.

Question 5Air Law and ATC Procedures

Which SSR transponder code is used to indicate unlawful interference?

  1. 7700
  2. 7600
  3. 7500 Correct answer.
  4. 7000

Explanation

In SSR code assignments, 7500 is the special code for unlawful interference. Code 7600 indicates radio communication failure and code 7700 indicates an emergency.

Question 6Air Law and ATC Procedures

What is a runway strip at an aerodrome?

  1. A defined area around the runway intended to reduce damage if an aircraft runs off Correct answer.
  2. The obstacle-free volume above the runway approach path that must be kept clear of all objects
  3. The paved runway surface, including its shoulders and any stopway, used for the ground movement of aircraft
  4. The area between the runway edge and the taxiway centre line

Explanation

A runway strip is a defined area including the runway and, where provided, the stopway. It is intended to reduce the risk of damage to aircraft running off the runway and to protect aircraft during take-off and landing.

Question 7Air Law and ATC Procedures

Which publication contains information of a lasting character essential to air navigation within a State?

  1. AIC
  2. NOTAM
  3. AIRAC
  4. AIP Correct answer.

Explanation

The Aeronautical Information Publication, or AIP, contains information of a lasting character essential to air navigation. NOTAMs are used for temporary or short-notice information, while AICs provide notices and AIRAC is a regulated cycle for changes.

Question 8Air Law and ATC Procedures

Which air traffic service provides advice and information useful for the safe and efficient conduct of flights but does not provide separation?

  1. Air traffic advisory service
  2. Air traffic control service
  3. Alerting service
  4. Flight information service Correct answer.

Explanation

Flight information service provides advice and information useful for the safe and efficient conduct of flights. It does not include the separation of aircraft, which is a function of air traffic control service.

Question 9Air Law and ATC Procedures

An intercepting aircraft rocks its wings from a position slightly ahead and to the left of the intercepted aircraft. What does this signal mean?

  1. Follow me Correct answer.
  2. You may proceed on your present heading
  3. Land at the designated aerodrome
  4. Descend and proceed to your destination

Explanation

In ICAO interception signals, rocking the wings from a position slightly ahead and to the left of the intercepted aircraft means "Follow me". The signal to land is different and involves lowering the landing gear and circling the aerodrome.

Question 10Air Law and ATC Procedures

Under Article 7 of the Chicago Convention, cabotage is carriage of traffic between two points within the territory of another State for remuneration. How is cabotage normally treated?

  1. It is automatically permitted to every contracting State without any prior permission
  2. It is allowed only for non-scheduled flights
  3. It is prohibited in all circumstances
  4. It is subject to the permission of the State concerned Correct answer.

Explanation

Article 7 gives each contracting State the right to refuse permission to aircraft of other States to take on or discharge traffic for remuneration between points within its own territory. Cabotage is therefore not automatically granted and depends on the permission of the State concerned.

Question 11Air Law and ATC Procedures

Under Article 5 of the Chicago Convention, aircraft of other contracting States engaged in non-scheduled flights are permitted to:

  1. carry passengers or cargo for remuneration between two points in that State
  2. land at any aerodrome and take on traffic for hire or reward
  3. operate scheduled international air services without any prior authorisation
  4. fly into or transit the territory and make stops for non-traffic purposes Correct answer.

Explanation

Article 5 grants non-scheduled flights the right to fly into or transit a contracting State's territory and to make stops for non-traffic purposes without prior permission, subject to the State's right to require permission in specified areas. It does not grant cabotage or scheduled-service rights.

Question 12Air Law and ATC Procedures

Under ICAO Annex 2, a VFR flight at or above 3,050 m (10,000 ft) AMSL in controlled airspace must have a flight visibility of at least:

  1. 5 km
  2. 8 km Correct answer.
  3. 10 km
  4. 1.5 km

Explanation

Annex 2 sets the VFR flight visibility minimum at 8 km at or above 3,050 m (10,000 ft) AMSL, with distance from cloud of 1,500 m horizontally and 300 m vertically. Below that level the minimum is 5 km.

Question 13Air Law and ATC Procedures

Which ATC instruction must be read back in full by the pilot?

  1. Continue approach
  2. Runway vacated
  3. Wind 240 degrees, 12 knots
  4. Line up and wait Correct answer.

Explanation

Runway safety-related clearances and instructions, including line up and wait, take-off, land and hold short, require an explicit read-back. The read-back requirement also applies to route clearances, levels, headings, speeds, frequencies and transponder codes.

Question 14Air Law and ATC Procedures

At an aerodrome with a transition altitude of 5,000 ft, a departing aircraft climbs through 5,000 ft. Which altimeter setting should the pilot set when passing the transition altitude?

  1. The aerodrome QNH until the transition level is reached
  2. QFE, so that the altimeter indicates height above the aerodrome reference point
  3. Standard pressure 1013.2 hPa, to fly flight levels Correct answer.
  4. QNH, to continue indicating altitude above mean sea level

Explanation

When passing the transition altitude in the climb, the pilot changes from the aerodrome QNH to standard pressure 1013.2 hPa and flies flight levels. The reverse change is made when descending through the transition level.

Question 15Air Law and ATC Procedures

Under Annex 2, a special VFR flight may be authorised within a control zone only when the ground visibility is not less than:

  1. 8 km
  2. 1,500 m Correct answer.
  3. 5 km
  4. 800 m

Explanation

Special VFR may be authorised within a control zone when ground visibility is at least 1,500 m. The flight remains subject to an ATC clearance and must stay clear of cloud with the surface in sight.

Question 16Air Law and ATC Procedures

An accident occurs in the territory of a contracting State. Under Annex 13, which State is responsible for instituting the investigation?

  1. The State of Occurrence Correct answer.
  2. The State of the Operator
  3. The State of Manufacture of the aircraft
  4. The State of Registry of the aircraft

Explanation

Annex 13 assigns the responsibility for instituting an investigation to the State of Occurrence. That State may delegate the investigation, while other States may participate as accredited representatives.

Question 17Air Law and ATC Procedures

Under Annex 2, except when necessary for take-off or landing, an aircraft shall not be flown over a congested area at a height less than:

  1. 600 m (2,000 ft) above the highest obstacle within a radius of 1,500 m
  2. 300 m (1,000 ft) above the highest obstacle within a radius of 600 m Correct answer.
  3. 150 m (500 ft) above the highest obstacle within 300 m
  4. 300 m (1,000 ft) above the ground

Explanation

Annex 2 requires a minimum height of 300 m (1,000 ft) above the highest obstacle within 600 m of the aircraft when flying over congested areas, except for take-off and landing. This protects persons and property on the surface.

Question 18Air Law and ATC Procedures

A pilot sets the SSR transponder to code 7700. This indicates:

  1. Unlawful interference
  2. A communication check
  3. Radio failure
  4. A general emergency Correct answer.

Explanation

Code 7700 is the general emergency code. It alerts ATC that the aircraft is in an emergency, while 7600 indicates radio failure and 7500 indicates unlawful interference.

Question 19Air Law and ATC Procedures

An aircraft is destroyed in an accident over the high seas, outside the territory of any State. Under Annex 13, which State is responsible for instituting the investigation?

  1. The State of Occurrence
  2. The State of Registry Correct answer.
  3. The State of Manufacture
  4. The State of the Operator

Explanation

When an accident occurs outside the territory of any State, Annex 13 gives the State of Registry responsibility for instituting the investigation. There is no State of Occurrence in such a location.

Question 20Air Law and ATC Procedures

A controlled flight encounters a two-way radio failure while in VMC. Under Annex 2, the pilot should:

  1. climb to the last assigned level and maintain the current heading
  2. squawk 7600 and continue IFR to the destination aerodrome
  3. continue in VMC, land at the nearest suitable aerodrome and report arrival Correct answer.
  4. continue to the destination aerodrome and hold until radio contact is restored

Explanation

In VMC, the pilot should continue to fly in visual meteorological conditions, land at the nearest suitable aerodrome and report arrival to the appropriate ATS unit by the most rapid means. The procedural routing and level-keeping actions apply when the aircraft is in IMC.

Question 21Air Law and ATC Procedures

Which ICAO Annex contains the Standards and Recommended Practices for the licensing of flight crew and other aviation personnel?

  1. Annex 1 - Personnel Licensing Correct answer.
  2. Annex 11 - Air Traffic Services
  3. Annex 6 - Operation of Aircraft
  4. Annex 8 - Airworthiness of Aircraft

Explanation

Annex 1 to the Chicago Convention contains the international Standards and Recommended Practices for personnel licensing, including flight crew, air traffic controllers and other aviation personnel. Annex 6 deals with the operation of aircraft, Annex 8 with airworthiness and Annex 11 with air traffic services.

Question 22Air Law and ATC Procedures

During flight, a pilot transmits “MINIMUM FUEL” to ATC. Under ICAO air traffic procedures, what does this declaration mean?

  1. The aircraft has less fuel than final reserve and needs immediate priority handling.
  2. The aircraft can proceed to destination but can accept little or no delay. Correct answer.
  3. The aircraft must hold for 30 minutes before declaring an emergency.
  4. The aircraft is declaring an emergency and requires diversion to the nearest aerodrome.

Explanation

MINIMUM FUEL is an advisory declaration to ATC that the aircraft’s fuel supply has reached a state where it can accept little or no delay at its destination. It is not itself an emergency declaration; if the situation worsens, the pilot should declare MAYDAY FUEL. MAYDAY FUEL indicates that the aircraft is committed to landing at a specific aerodrome and requires priority.

Question 23Aircraft General Knowledge: Airframe, Systems and Powerplant

On a transport aeroplane, what is the purpose of the shimmy damper fitted to the nose landing gear?

  1. Prevent self-excited oscillation of the nosewheel Correct answer.
  2. Provide nosewheel steering during taxi
  3. Retract the landing gear into the bay
  4. Lock the landing gear in the down position

Explanation

A shimmy damper adds hydraulic or friction damping to the nosewheel steering axis. It prevents the nosewheel from oscillating rapidly about its vertical axis after touchdown or during taxi. It does not lock the gear or provide normal steering.

Question 24Aircraft General Knowledge: Airframe, Systems and Powerplant

In flight, which source normally supplies high-pressure air to the pneumatic system of a twin-engine transport aeroplane?

  1. Cabin recirculation fans
  2. Engine compressor bleed Correct answer.
  3. Hydraulic reservoir pressure
  4. Ram-air inlet flow

Explanation

Pneumatic system users such as anti-ice and pressurization are supplied with high-pressure air bled from engine compressor stages. The APU can also supply bleed air on the ground or in flight. Recirculation fans and ram air are not pressure sources.

Question 25Aircraft General Knowledge: Airframe, Systems and Powerplant

On most transport aeroplanes, how is thermal anti-icing of the wing leading edges achieved?

  1. Sprayed de-icing fluid
  2. Bleed air Correct answer.
  3. Inflatable rubber boots
  4. Electrical heater mats

Explanation

Transport aeroplanes use hot bleed air from the engines, routed through piccolo ducts in the wing leading edge, to prevent ice formation. Electrical mats are more typical of small aircraft or specific probes, and boots are de-icing, not anti-icing.

Question 26Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the primary function of a hydraulic accumulator in an aircraft hydraulic system?

  1. Cool fluid returning from the actuators
  2. Remove entrained air from the fluid
  3. Store energy and damp pressure surges Correct answer.
  4. Bypass excess fluid to the reservoir

Explanation

The accumulator contains gas behind a piston or bladder and stores hydraulic fluid under pressure. It supplies flow during transient peaks and absorbs pressure pulsations from pumps and actuators. It does not filter, cool, or bypass fluid.

Question 27Aircraft General Knowledge: Airframe, Systems and Powerplant

In a transport aeroplane fuel system, what is the primary purpose of the engine feed boost pumps in the wing tanks?

  1. Maintain fuel pressure and prevent vapour lock Correct answer.
  2. Transfer fuel between tanks for balance
  3. Provide cooling flow for the generator heat exchanger
  4. Pressurize the fuel quantity gauges

Explanation

Boost pumps raise fuel pressure before the engine-driven pump, which suppresses cavitation and vapour lock at high altitude. They also provide a positive feed for engine starting and crossfeed. They are not primarily for balance transfer, generator cooling, or quantity indication.

Question 28Aircraft General Knowledge: Airframe, Systems and Powerplant

In a parallel AC generation system, what controls the reactive load sharing between generators?

  1. Bus tie contactors
  2. Transformer rectifiers
  3. Frequency governors
  4. Voltage regulators Correct answer.

Explanation

In parallel AC operation, the voltage regulator controls generator excitation and therefore the reactive load share. The frequency governor controls real load share by adjusting drive speed. Bus ties connect buses but do not set load sharing.

Question 29Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the primary function of the cabin pressure outflow valve?

  1. Control the pack outlet temperature
  2. Regulate the bleed air entering the cabin
  3. Control cabin altitude by metering outflow Correct answer.
  4. Dump pressure only after landing

Explanation

The outflow valve is the controlled exit for cabin air. By opening or closing, it meters the air leaving the cabin and thus controls cabin pressure and cabin altitude. Inflow is set by the bleed and pack system, not by the outflow valve.

Question 30Aircraft General Knowledge: Airframe, Systems and Powerplant

Why is rudder travel limited as airspeed increases on many transport aeroplanes?

  1. Reduce pilot workload during taxiing
  2. Limit rudder deflection as dynamic pressure rises Correct answer.
  3. Balance thrust after an engine failure
  4. Improve yaw damping at low airspeed

Explanation

As airspeed and dynamic pressure increase, a given rudder deflection produces much greater hinge moment and structural load. The rudder travel limiter reduces maximum deflection to protect the fin and rudder. It is not a yaw damper or a thrust-balance system.

Question 31Aircraft General Knowledge: Airframe, Systems and Powerplant

How is the bypass ratio of a turbofan engine defined?

  1. Core temperature divided by bypass temperature
  2. Bypass mass flow divided by core mass flow Correct answer.
  3. Bypass pressure divided by core pressure
  4. Core mass flow divided by bypass mass flow

Explanation

Bypass ratio is the ratio of the mass airflow through the fan bypass duct to the mass airflow through the engine core. High-bypass engines move most of their air through the bypass duct. It is not a pressure or temperature ratio.

Question 32Aircraft General Knowledge: Airframe, Systems and Powerplant

In an engine fire-extinguishing system, what is the function of the squib?

  1. A valve that selects the protected engine
  2. A pressure gauge that shows bottle charge
  3. A heat-sensitive plug that melts in fire
  4. An electrically fired discharge cartridge Correct answer.

Explanation

A squib is an electrically initiated explosive cartridge fitted to the extinguisher bottle. When fired, it opens the bottle discharge valve and releases the agent into the selected engine line. It is not a gauge, sensing plug, or selector valve.

Question 33Aircraft General Knowledge: Airframe, Systems and Powerplant

In a semi-monocoque wing, which member carries the main bending loads along the span?

  1. The chordwise ribs
  2. The front and rear spars Correct answer.
  3. The upper and lower skin panels
  4. The spanwise stringers

Explanation

The spars are spanwise beams that carry the wing bending loads; the skin resists shear and torsion, ribs maintain the aerofoil shape, and stringers stiffen the skin between ribs. Semi-monocoque construction shares loads between these members, but the spars are the primary bending path.

Question 34Aircraft General Knowledge: Airframe, Systems and Powerplant

In an oleo-pneumatic shock absorber, what does the compressed nitrogen provide?

  1. Lubrication of the sliding piston surfaces
  2. Damping of the rebound by passing oil through an orifice
  3. A reserve of pressure for the wheel brakes
  4. The spring force that re-extends the strut Correct answer.

Explanation

In an oleo-pneumatic strut, nitrogen acts as the spring because it is compressed as the strut shortens and re-extends it when the load decreases. Oil forced through orifices provides the damping that dissipates the energy of the landing impact and prevents oscillation.

Question 35Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the normal role of the igniter plugs in a turbofan engine after a successful start?

  1. They are used only for motoring the high-pressure rotor
  2. They remain energised continuously to stabilise combustion
  3. They provide the spark for the main engine fuel control unit
  4. They are switched off and used only for relight Correct answer.

Explanation

Igniter plugs are energised for engine start and can be selected by the flight crew for relight after a flameout or for operation in heavy rain and turbulence. Once combustion is established and stable, they are normally switched off because the flame is self-sustaining.

Question 36Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the purpose of a hydraulic fuse in a transport aeroplane hydraulic system?

  1. To limit system pressure by bypassing fluid to the reservoir
  2. To filter particulate contamination from the return line
  3. To isolate a leaking branch and prevent loss of the system fluid Correct answer.
  4. To indicate a low fluid level in the associated reservoir

Explanation

A hydraulic fuse senses a sudden increase in flow, as occurs when a line downstream ruptures, and closes to isolate that branch. This limits the fluid lost and preserves enough pressure and fluid for the remaining services on that system.

Question 37Aircraft General Knowledge: Airframe, Systems and Powerplant

Why does a transport aeroplane equipped with a fuel jettison system use it before an overweight landing?

  1. To ensure that both wing tanks are balanced
  2. To lower the fuel temperature before landing
  3. To reduce mass to or below the maximum landing mass Correct answer.
  4. To purge the fuel lines of water contamination

Explanation

Maximum landing mass is lower than maximum take-off mass, so an aircraft that must land soon after take-off may be above the permitted landing mass. Jettisoning fuel reduces the mass to at or below the maximum landing mass, lowering the structural loads on landing.

Question 38Aircraft General Knowledge: Airframe, Systems and Powerplant

In a bootstrap air conditioning system, what is the main function of the air cycle machine?

  1. To add heat to the bleed air before it enters the cabin
  2. To cool the bleed air by expanding it through a turbine Correct answer.
  3. To remove water from the bleed air by centrifugal action
  4. To compress the bleed air to cabin pressure

Explanation

In the bootstrap cycle, bleed air is compressed, cooled in a heat exchanger, and then expanded through the ACM turbine. The expansion does work that drives the ACM compressor and leaves the air at a low temperature for cabin supply.

Question 39Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the purpose of the Mach trim system on a transport aeroplane?

  1. To limit the maximum rudder deflection at high Mach number
  2. To trim the aircraft for a constant Mach climb
  3. To schedule the horizontal stabiliser for flap extension
  4. To counter the nose-down trim change at high Mach number Correct answer.

Explanation

As Mach number increases, the centre of pressure moves aft and the aircraft develops a nose-down pitching moment, often called Mach tuck. The Mach trim system applies progressive nose-up trim to counteract this change and preserve stick-free handling characteristics.

Question 40Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the primary purpose of windshield heat on a transport aeroplane?

  1. To melt snow that has accumulated on the nose radome
  2. To prevent ice and keep the windshield clear Correct answer.
  3. To increase the strength of the windshield panels
  4. To prevent misting of the pilot's side windows only

Explanation

Windshield heat raises the transparency temperature to prevent ice accretion and to keep the glass clear, and it also helps demisting. The heat is normally supplied electrically or by hot air, with temperature control to avoid overheating the panel.

Question 41Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the function of bus tie breakers in a split-bus AC generation system?

  1. They automatically transfer the essential loads to the battery bus
  2. They protect the busbars against overvoltage by earthing the phase windings
  3. They disconnect a generator from its busbar when the generator frequency is too high
  4. They connect or isolate generator busbars for split or parallel operation Correct answer.

Explanation

Bus tie breakers link the individual generator busbars to each other or to the main bus, so the system can operate in parallel with all buses connected. Opening the BTBs splits the system into isolated channels, which prevents a fault on one generator from affecting the others.

Question 42Aircraft General Knowledge: Airframe, Systems and Powerplant

What is the purpose of variable stator vanes in the axial compressor of a turbofan engine?

  1. To improve the compressor stall margin at low rotational speeds Correct answer.
  2. To vary the bypass ratio with thrust setting
  3. To direct cooling air onto the turbine nozzle guide vanes
  4. To increase the pressure ratio at high rotational speeds

Explanation

At low rotational speeds the front stages of an axial compressor can stall because the airflow angles do not match the blade angles. Variable stator vanes change the inlet angle to the rotor blades, improving the stall margin and allowing stable operation across the speed range.

Question 43Aircraft General Knowledge: Airframe, Systems and Powerplant

On a transport aeroplane nose landing gear, what is the purpose of the torque link (scissors) fitted between the upper and lower parts of the shock strut?

  1. To absorb the vertical landing loads and dissipate them as heat before they reach the airframe
  2. To keep the wheel assembly aligned with the direction of travel by reacting torque about the strut axis Correct answer.
  3. To hold the gear securely in the down-and-locked position once extension is complete
  4. To steer the nose wheel during taxi by rotating the lower strut assembly

Explanation

The torque link connects the fixed upper cylinder to the rotating lower piston of the oleo strut and reacts torque about the strut axis. This keeps the wheels pointing in the direction of travel while still allowing the strut to compress and extend freely. Steering and down-locking are performed by separate systems, and vertical load absorption is the task of the oleo itself.

Question 44Aircraft General Knowledge: Airframe, Systems and Powerplant

If the cabin pressure of a pressurised transport aeroplane inadvertently becomes lower than the external ambient pressure, which component protects the fuselage structure?

  1. The positive pressure relief valve, which limits the maximum differential pressure reached
  2. The negative pressure relief valve, which opens inward and admits ambient air into the cabin Correct answer.
  3. The cabin altitude warning system, which alerts the crew so that oxygen masks can be used
  4. The cabin pressure controller, which drives the outflow valve to the fully open position

Explanation

The fuselage is designed to carry hoop and shear loads with the cabin pressure higher than ambient, that is, positive differential pressure. If ambient pressure exceeds cabin pressure the skin would be loaded in the reverse direction, so inward-opening negative relief valves admit outside air and equalise the pressure. Positive pressure relief valves and the outflow valve only govern the positive differential.

Question 45Aircraft General Knowledge: Electrics, Electronics and Instrumentation

The nominal open-circuit voltage of a fully charged lead-acid aircraft battery cell is approximately:

  1. 4.0 V
  2. 1.2 V
  3. 2.0 V Correct answer.
  4. 2.4 V

Explanation

A lead-acid cell has a nominal voltage of about 2 V, so a 12-cell battery gives the familiar 24 V aircraft bus. The 1.2 V value is typical of a nickel-cadmium cell, not lead-acid.

Question 46Aircraft General Knowledge: Electrics, Electronics and Instrumentation

A transformer rectifier unit (TRU) in an aircraft electrical power system converts:

  1. DC to DC at a higher voltage
  2. DC to AC at a constant frequency
  3. AC to AC at a different voltage
  4. AC to DC at a lower voltage Correct answer.

Explanation

The transformer steps the AC voltage down or up, and the rectifier converts the resulting AC into DC. A TRU therefore supplies DC equipment from an AC bus; it is not an inverter.

Question 47Aircraft General Knowledge: Electrics, Electronics and Instrumentation

A 24 V DC bus supplies a 48 W resistive load. The current in the circuit is:

  1. 4 A
  2. 2 A Correct answer.
  3. 1 A
  4. 0.5 A

Explanation

Using P = V × I, the current is I = P / V = 48 W / 24 V = 2 A. The other values would require a different load power or bus voltage.

Question 48Aircraft General Knowledge: Electrics, Electronics and Instrumentation

A four-pole AC generator rotates at 6000 RPM. The frequency of its output is:

  1. 400 Hz
  2. 600 Hz
  3. 100 Hz
  4. 200 Hz Correct answer.

Explanation

For an AC generator, f = (number of poles / 2) × (RPM / 60). With four poles and 6000 RPM, f = 2 × 100 = 200 Hz.

Question 49Aircraft General Knowledge: Electrics, Electronics and Instrumentation

Compared with a fuse of equivalent rating, a resettable aircraft circuit breaker has the advantage that it:

  1. can be reset after the fault has been cleared Correct answer.
  2. provides a visible indication of an open circuit only
  3. requires no thermal or magnetic sensing element
  4. opens more quickly under a short-circuit

Explanation

A circuit breaker can be reset after it trips once the fault is cleared, whereas a blown fuse must be replaced. This reset capability is its main operational advantage, not faster opening.

Question 50Aircraft General Knowledge: Electrics, Electronics and Instrumentation

A series-wound DC motor is well suited to engine starting because it produces:

  1. a very low current at standstill
  2. precise angular positioning without feedback
  3. a high torque at low rotational speed Correct answer.
  4. a nearly constant speed under all loads

Explanation

In a series-wound motor the field winding carries the same high current as the armature, producing strong torque at low speed. This high starting torque is ideal for turning a cold engine.