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Mauritius DCA ATPL Theory study materials
Mauritius DCA ATPL Theory study resources

Mauritius DCA ATPL Theory practice questions

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Question 1Air Law and ATC Procedures

Under the Mauritius Civil Aviation Regulations, an aircraft registered in Mauritius is primarily subject to which state's regulatory jurisdiction for airworthiness and crew licensing?

  1. The State of Manufacture of the aircraft
  2. The State of Registry, Mauritius Correct answer.
  3. The State of Design of the aircraft
  4. The State of the Operator only

Explanation

The Chicago Convention establishes that the State of Registry exercises primary jurisdiction over aircraft on its register, including airworthiness and personnel licensing. For a Mauritian-registered aircraft this is Mauritius, acting through the DCA.

Question 2Air Law and ATC Procedures

Which document must be carried on board every international flight and evidences that the aircraft conforms to its approved type design and is safe for flight?

  1. The Air Operator Certificate
  2. The Certificate of Registration
  3. The Noise Certificate
  4. The Certificate of Airworthiness Correct answer.

Explanation

The Certificate of Airworthiness is the document confirming the individual aircraft meets its approved type design and is maintained in a condition safe for flight. It must be carried on board for international operations.

Question 3Air Law and ATC Procedures

In the standard cruising level allocation table, an aircraft on a magnetic track of 000 to 179 degrees flying under IFR at FL 310 should be assigned which level?

  1. FL 320
  2. FL 300
  3. FL 310 Correct answer.
  4. FL 330

Explanation

For IFR flights on tracks 000 to 179 degrees, odd flight levels are used (FL 290, 310, 330). FL 310 therefore matches the semicircular rule for that track band.

Question 4Air Law and ATC Procedures

An aircraft is instructed to 'hold short of runway 14' at a controlled aerodrome. What does this instruction require the pilot to do?

  1. Continue taxiing but reduce speed near the runway
  2. Enter the runway and hold at the centreline
  3. Hold on the runway until take-off clearance is received
  4. Stop before the designated holding point and await further clearance Correct answer.

Explanation

A hold short instruction requires the aircraft to stop at the designated runway holding position and not enter the runway strip until explicitly cleared. It is a protective measure against runway incursion.

Question 5Air Law and ATC Procedures

A pilot receives the clearance 'cleared for take-off runway 32'. When may the aircraft begin the take-off roll?

  1. After reporting ready to the tower and receiving acknowledgement
  2. Once the aircraft has reached the holding point and the crew has completed checks Correct answer.
  3. Immediately upon receiving and reading back the clearance
  4. Only after the tower confirms the runway is clear of other traffic

Explanation

A take-off clearance authorises use of the runway, but the aircraft must still be at the holding point with take-off checks complete before beginning the roll. Reading back the clearance does not itself authorise movement onto or along the runway.

Question 6Air Law and ATC Procedures

Under ICAO rules, what is the minimum horizontal separation standard generally applied between two IFR aircraft at the same cruising level in a radar-controlled area using standard radar separation?

  1. 3 NM
  2. 5 NM Correct answer.
  3. 10 NM
  4. 15 NM

Explanation

The standard radar separation minimum in most terminal and en-route radar environments is 5 NM, unless a reduced or increased minimum is specifically prescribed. This is the baseline figure used in ATC separation planning.

Question 7Air Law and ATC Procedures

An aircraft on approach experiences a sudden loss of airspeed and a rapid increase in rate of descent while passing through low altitude on final. Which phenomenon should the pilot suspect?

  1. An altimeter setting error
  2. A pitot heater failure
  3. A static pressure blockage
  4. Wind shear, possibly a microburst Correct answer.

Explanation

Sudden airspeed loss combined with a rapid sink close to the ground is characteristic of wind shear, often from a microburst. The correct response is an immediate go-around with maximum performance.

Question 8Air Law and ATC Procedures

When must a pilot report a position to ATC on a flight operating under procedural control outside radar coverage?

  1. Only when the aircraft changes frequency
  2. Only at the top of descent
  3. Only when the aircraft deviates from track by more than 10 NM
  4. At compulsory reporting points and whenever instructed by ATC Correct answer.

Explanation

In procedural control, pilots must report at compulsory reporting points and at any other point or time ATC requires. These reports allow the controller to update the flight progress and maintain separation without radar.

Question 9Air Law and ATC Procedures

Which of the following best describes the purpose of a cleared level in an ATC clearance?

  1. The level the aircraft will maintain after reaching the destination
  2. The altitude at which the aircraft must begin descent
  3. The level the aircraft is authorised to occupy until a further clearance is issued Correct answer.
  4. The altitude to which the aircraft must climb after take-off only

Explanation

A cleared level is the altitude or flight level the aircraft is authorised to occupy and maintain until another clearance changes it. It is the basis on which the controller provides vertical separation.

Question 10Air Law and ATC Procedures

An aircraft on the ground receives the instruction 'line up and wait runway 09'. What is the correct action?

  1. Cross the runway and continue taxiing
  2. Enter the runway and position for take-off, then wait for take-off clearance Correct answer.
  3. Stop before the holding point and report ready
  4. Begin the take-off roll immediately

Explanation

Line up and wait authorises the aircraft to enter the runway and take up position for departure but not to begin the take-off roll. A separate take-off clearance is required before starting the roll.

Question 11Air Law and ATC Procedures

In the event of a radio communication failure on an IFR flight in VMC, what is the standard action under ICAO procedures?

  1. Squawk 7600 and continue to destination without further action
  2. Climb to the highest available level and hold until fuel is exhausted
  3. Descend immediately to the lowest safe altitude and orbit
  4. Continue under VFR, land at the nearest suitable aerodrome and report arrival Correct answer.

Explanation

When radio failure occurs in VMC, the aircraft should continue under VFR, land at the nearest suitable aerodrome and report its arrival to ATC. Squawking 7600 is correct but is not the whole procedure.

Question 12Air Law and ATC Procedures

What does the transponder code 7700 signify when set by a pilot?

  1. General emergency Correct answer.
  2. Loss of navigation capability
  3. Radio communication failure
  4. Unlawful interference

Explanation

Code 7700 is the general emergency code and alerts ATC that the aircraft is in distress or urgency. It should be set whenever the pilot considers the flight is in serious difficulty.

Question 13Air Law and ATC Procedures

An aircraft is cleared to descend to FL 100 from FL 200. During the descent the pilot is told to 'expect further clearance at 1420'. What does this mean?

  1. The aircraft must contact ATC at 1420
  2. The aircraft will receive a further clearance no later than 1420 Correct answer.
  3. The aircraft may descend below FL 100 after 1420
  4. The aircraft must be level at FL 100 by 1420

Explanation

An expect further clearance time informs the pilot when the next clearance is anticipated, so that fuel and contingency planning can be adjusted. It does not itself authorise any change of level.

Question 14Air Law and ATC Procedures

Which of the following is the correct read-back requirement for a clearance to cross an active runway?

  1. The pilot must read back only the runway designator
  2. The pilot must only acknowledge with the aircraft callsign
  3. No read-back is required for crossing clearances
  4. The pilot must read back the runway designator and the instruction to cross Correct answer.

Explanation

Runway crossing clearances must be read back in full, including the runway designator and the instruction to cross, so that the controller can verify the clearance was correctly understood. This is a key defence against runway incursion.

Question 15Air Law and ATC Procedures

An aircraft is flying at FL 350 in RVSM airspace. What is the required altimetry accuracy standard for RVSM operations?

  1. The aircraft must maintain the cleared level within 300 ft
  2. The aircraft must maintain the cleared level within 500 ft
  3. The aircraft must maintain the cleared level within 1000 ft
  4. The aircraft must maintain the cleared level within 200 ft Correct answer.

Explanation

RVSM operations require the aircraft to remain within 200 ft of the cleared level, supported by approved altimetry and autopilot systems. This allows 1000 ft vertical separation to be used between FL 290 and FL 410.

Question 16Air Law and ATC Procedures

Under ICAO Annex 2, when a pilot is in doubt about the position of the aircraft or the safety of the flight, what action is expected?

  1. Squawk 7600 and divert without notifying ATC
  2. Notify ATC immediately and request assistance Correct answer.
  3. Maintain the last cleared level regardless of terrain
  4. Continue on the cleared route and wait for ATC to intervene

Explanation

If in doubt about position or safety, the pilot must notify ATC immediately and request assistance, so that separation can be adjusted. Silence or assumption is not acceptable when safety is in question.

Question 17Air Law and ATC Procedures

What is the purpose of a Minimum Safe Altitude Warning (MSAW) provided by ATC?

  1. To alert the controller when a tracked aircraft descends below a defined minimum safe altitude Correct answer.
  2. To replace the pilot's responsibility for terrain avoidance
  3. To provide terrain clearance guarantees for all aircraft
  4. To warn pilots of wake turbulence encounters

Explanation

MSAW is a controller aid that generates an alert when a radar-tracked aircraft descends below a defined minimum safe altitude. It supplements, but never replaces, the pilot's responsibility for terrain clearance.

Question 18Air Law and ATC Procedures

An aircraft is on a magnetic heading of 270 degrees and is instructed to 'turn right onto 090'. What is the shortest turn direction and the resulting heading?

  1. Turn right through north to 090 Correct answer.
  2. Turn left through north to 090
  3. Turn right through south to 090
  4. Turn left through south to 090

Explanation

From 270 degrees, turning right passes through 360/000 and reaches 090 after 180 degrees. This is the same angular distance as turning left, but the instruction specifies right.

Question 19Air Law and ATC Procedures

Which condition must be met before a pilot may operate an aircraft under Special VFR at a controlled aerodrome?

  1. The flight must be conducted only at night
  2. The pilot must hold an instrument rating and the aircraft must be IFR equipped
  3. The aircraft must be above 2000 ft AGL at all times
  4. Clearance must be obtained from ATC and the aircraft must remain clear of cloud and in sight of the surface Correct answer.

Explanation

Special VFR allows flight in controlled airspace below VMC minima only with an ATC clearance and while remaining clear of cloud and in sight of the surface. It is a clearance-based procedure, not an automatic entitlement.

Question 20Air Law and ATC Procedures

What is the standard aerodrome traffic pattern direction unless otherwise published or instructed?

  1. Determined by wind direction only
  2. Alternating by runway
  3. Right-hand
  4. Left-hand Correct answer.

Explanation

Unless the aerodrome chart or ATC specifies otherwise, the traffic pattern is flown left-hand. Pilots must check published information because specific runways may have right-hand patterns.

Question 21Air Law and ATC Procedures

An aircraft is instructed to 'squawk ident'. What action should the pilot take?

  1. Set code 7700 and transmit on guard
  2. Change to the emergency frequency
  3. Turn the transponder to standby
  4. Set the assigned code and press the ident button on the transponder Correct answer.

Explanation

Squawk ident means the pilot should press the identification feature on the transponder, which causes the special position identification pulse to be displayed to the controller. The assigned code remains unchanged.

Question 22Air Law and ATC Procedures

Which of the following describes the correct action when an aircraft is unable to comply with a clearance issued by ATC?

  1. Ignore the clearance and continue on the previous route
  2. Advise ATC immediately that the clearance is unable to be accepted Correct answer.
  3. Comply as far as possible and advise ATC at the next reporting point
  4. Comply silently and note the deviation in the technical log

Explanation

If a clearance cannot be accepted, the pilot must advise ATC immediately so that alternative instructions can be issued. Delaying the notification may compromise separation.

Question 23Air Law and ATC Procedures

In the event of an unlawful interference (hijack), which transponder code should be selected if the pilot is able to do so discreetly?

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

Explanation

Code 7500 is the designated code for unlawful interference. Selecting it alerts ATC that the aircraft is subject to hijacking without the need for voice communication.

Question 24Air Law and ATC Procedures

An aircraft on an IFR flight is given a clearance to descend 'when ready' to FL 120. What does 'when ready' authorise?

  1. Descent after the next position report
  2. Descent at the pilot's discretion, subject to the cleared level Correct answer.
  3. Immediate descent at maximum rate
  4. Descent only after ATC gives a further call

Explanation

'When ready' authorises the pilot to begin the descent at a time of the pilot's choosing, while respecting the cleared level and any published restrictions. It transfers timing discretion to the pilot.

Question 25Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

On a typical transport-category aeroplane, the primary structural function of the wing spar caps is to carry which type of load?

  1. Local skin buckling pressure
  2. Bending moments along the span Correct answer.
  3. Engine thrust into the fuselage
  4. Torsional shear between ribs

Explanation

Spar caps are the thick longitudinal members located at the top and bottom of the spar web, positioned far from the neutral axis, and therefore carry the spanwise bending loads in tension and compression. The web resists shear, while the skin and ribs handle torsion and local buckling.

Question 26Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

In a hydraulically powered flight control system, what is the purpose of the accumulator installed in the pressure line?

  1. To cool the hydraulic fluid by increasing its residence time in the system
  2. To convert hydraulic pressure into electrical signals for the cockpit indicators
  3. To filter particulate contamination from the return line before it reaches the reservoir
  4. To store pressurised fluid so that transient high demands can be met and pressure surges damped Correct answer.

Explanation

A hydraulic accumulator contains a gas-charged chamber separated from the fluid, so it stores energy and releases fluid during peak demand, smoothing pump load and damping pressure fluctuations. It also provides a limited emergency supply in some systems.

Question 27Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

Which statement correctly describes the operation of a constant-speed propeller driven by a governor?

  1. The governor varies engine fuel flow so that propeller speed stays constant
  2. The governor adjusts blade angle so that engine speed remains at the selected value as power or airspeed changes Correct answer.
  3. The governor changes the propeller reduction gear ratio to maintain constant rpm
  4. The governor limits manifold pressure by opening the wastegate at high altitude

Explanation

A propeller governor senses engine/propeller rpm and ports oil to or from the propeller hub to change blade angle, thereby varying blade load and holding rpm at the selected setting. Fuel flow and gear ratio are not controlled by the propeller governor.

Question 28Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

A lead-acid aircraft battery is being charged. Which condition indicates that gassing is occurring?

  1. Electrolyte bubbles freely and the cell voltage has risen to its fully charged value Correct answer.
  2. The specific gravity of the electrolyte falls below the discharged value
  3. The electrolyte level falls while the cell voltage drops sharply
  4. The battery case becomes cold while current rises steadily

Explanation

Near full charge the charging current electrolyses water, releasing hydrogen and oxygen, which appears as vigorous bubbling (gassing) while terminal voltage reaches its maximum. Continued charging at high rate then only heats the battery and consumes water.

Question 29Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

What is the primary purpose of the firewall in an engine compartment?

  1. To reduce noise transmission from the engine into the fuselage
  2. To support the engine mounts and carry engine thrust loads
  3. To provide cooling airflow around the exhaust manifold
  4. To contain a fire and prevent it spreading into the adjacent structure and cabin Correct answer.

Explanation

The firewall is a fire-resistant bulkhead that separates the engine compartment from the rest of the aeroplane so that a fire is contained and delayed from reaching the cabin or fuel and control runs. It is normally made of stainless steel or a fire-resistant composite.

Question 30Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

In a gas turbine engine, what is the function of the compressor bleed valves (handling bleed valves) during low-speed operation?

  1. To release excess air from the compressor to prevent surge and stall at low rotational speed Correct answer.
  2. To pressurise the cabin during descent
  3. To supply cooling air to the turbine discs at all power settings
  4. To increase the fuel flow to the combustor during acceleration

Explanation

At low rpm the rear compressor stages cannot accept the airflow delivered by the front stages, so bleed valves open to spill surplus air overboard and keep the compressor operating away from the surge line. They close progressively as engine speed and power increase.

Question 31Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

During a normal pressurised flight, the cabin pressure controller is set to the landing field elevation. What determines the cabin altitude at cruise?

  1. The cabin differential pressure limit and the selected cabin rate of climb Correct answer.
  2. The aircraft's actual altitude above the tropopause
  3. The position of the outflow valve in the fully closed position
  4. The engine bleed air temperature at the compressor outlet

Explanation

In the automatic mode the controller schedules cabin altitude so that the maximum differential pressure is not exceeded, while keeping the cabin rate of change within comfortable limits. The cabin therefore climbs at a controlled rate until it reaches the value permitted by the differential limit.

Question 32Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

An aircraft is equipped with a DC generator rated at 200 A and a battery of 40 Ah. Following a complete generator failure in flight, which statement best describes the effect on the electrical system?

  1. The generator will continue to supply the essential bus through the reverse current relay
  2. The battery will supply all loads indefinitely because generators are only needed for starting
  3. The battery voltage will remain constant until it is completely discharged
  4. The battery will supply essential loads for a limited time only, so non-essential loads must be shed Correct answer.

Explanation

A 40 Ah battery can only deliver its rated capacity for a short period, and at high discharge rates the available capacity is reduced further. Load shedding to essential services is therefore required to preserve battery power for the time needed to reach an alternate or complete the approach.

Question 33Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

A transport aeroplane suffers a complete loss of normal hydraulic pressure. Which design feature most commonly allows the crew to retain control of the primary flight controls?

  1. Reliance on the autopilot servos powered by the standby battery
  2. Use of the engine bleed air to drive the flight control surfaces directly
  3. Back-up systems such as an air-driven pump, an electric pump on another bus, or manual reversion Correct answer.
  4. Automatic switching of the flight controls to the pressurisation system

Explanation

Certification requires that a hydraulic failure does not leave the aeroplane uncontrollable, so designs provide redundancy such as engine-driven pumps on separate systems, electric or air-driven standby pumps, accumulators, or manual reversion for some surfaces. The exact combination depends on the type.

Question 34Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

Why is a turbine engine's exhaust gas temperature (EGT) a more critical limitation than rpm during take-off?

  1. EGT is used to set the propeller blade angle
  2. EGT determines the fuel freeze point in the tanks
  3. EGT reflects the turbine entry temperature, which limits the life of turbine blades and nozzles Correct answer.
  4. EGT directly indicates the compressor surge margin

Explanation

EGT is used as an indirect indication of turbine entry temperature because the hot section cannot be measured directly in service. Excessive EGT accelerates creep and oxidation of turbine blades and nozzle guide vanes, so it is the limiting parameter for take-off thrust and engine life.

Question 35Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

On an aeroplane with a DC electrical system, what is the purpose of the reverse current relay in the generator circuit?

  1. To reverse the polarity of the generator output for the standby bus
  2. To limit the generator output current to the rated value
  3. To disconnect the generator from the bus when current flows from the battery into the generator Correct answer.
  4. To change the generator from series to shunt field excitation

Explanation

If a generator's output voltage falls below the bus voltage, the battery would discharge through the generator and could damage it. The reverse current relay senses the direction of current and opens the generator contactor when reverse current is detected.

Question 36Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

A fire in an engine compartment is detected by a continuous-loop system. What is the principal advantage of this type of detector over spot detectors?

  1. It can distinguish between an engine fire and a bleed air leak automatically
  2. It resets itself automatically after the fire is extinguished
  3. It senses overheating over the whole protected area rather than at discrete points Correct answer.
  4. It requires no electrical power to operate

Explanation

A continuous-loop detector runs around the engine compartment and responds to a temperature rise anywhere along its length, giving coverage of the whole zone. Spot detectors only sense at their installed locations and can miss a fire between them.

Question 37Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

What is the function of the anti-icing system on a turbojet engine inlet?

  1. To heat the fuel before it enters the fuel control unit
  2. To prevent ice formation on the inlet lip and guide vanes that could be ingested and damage the engine Correct answer.
  3. To cool the compressor inlet air for increased mass flow
  4. To supply pressurised air to the cabin during icing conditions

Explanation

Ice forming on the inlet lip or on the inlet guide vanes can break away and cause foreign object damage or distort the airflow into the compressor. Hot bleed air or electrical heating is used to keep these surfaces above freezing.

Question 38Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

An aircraft's electrical system uses a split-bus arrangement with a bus tie contactor. What is the main operational benefit of this arrangement?

  1. The buses can be operated at different voltages for different equipment
  2. A failed generator can be isolated while the remaining generator supplies both buses through the tie Correct answer.
  3. The battery can be charged at a higher rate from both generators simultaneously
  4. The tie contactor prevents any load from being supplied by the battery

Explanation

With a bus tie, each generator normally feeds its own bus, and if one generator fails the tie closes so the serviceable generator can supply the whole system, subject to load limits. This gives redundancy without duplicating every load.

Question 39Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

During a landing gear retraction, the gear doors remain open after the gear has locked up. Which component is most likely to be the cause?

  1. The brake accumulator precharge is too high
  2. The gear downlock springs are over-tensioned
  3. The hydraulic reservoir is over-serviced with fluid
  4. The door sequence valve or its associated linkage is out of adjustment Correct answer.

Explanation

Gear and door sequencing is controlled by sequence valves or mechanical linkages that ensure doors open before the gear moves and close after it locks. If the sequence is misadjusted, the door-close signal may not be given even though the gear has locked up.

Question 40Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

What is the primary reason that transport aeroplane fuel tanks are vented to the atmosphere?

  1. To supply air to the combustion chamber for starting
  2. To allow fuel vapour to escape so that the fuel's octane rating is preserved
  3. To prevent excessive positive or negative pressure in the tanks as fuel is used or the aircraft climbs and descends Correct answer.
  4. To provide a path for refuelling under pressure

Explanation

Vent systems equalise tank pressure with ambient pressure so that the structure is not overstressed during climb and descent and so that fuel can be drawn without creating a vacuum. They also allow fuel to transfer between tanks and prevent siphoning.

Question 41Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

In a pressurised aeroplane, what is the function of the negative pressure relief valve?

  1. To open if cabin pressure exceeds external pressure by more than a small amount, preventing structural damage Correct answer.
  2. To maintain cabin altitude at the selected value during climb
  3. To supply fresh air to the cabin when the packs fail
  4. To dump cabin pressure rapidly after a decompression

Explanation

If the cabin pressure were allowed to exceed ambient pressure in the negative sense, the fuselage would be loaded in the reverse direction it was designed for. The negative pressure relief valve opens automatically to limit this differential.

Question 42Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

A turbofan engine is fitted with a hydraulically operated thrust reverser. Which statement best describes the purpose of the reverser interlock system?

  1. It prevents reverse thrust from being selected unless the thrust levers are at idle and the aircraft is on the ground Correct answer.
  2. It prevents the reverser from being stowed until reverse thrust has been fully deployed
  3. It automatically deploys the reverser on landing when the weight-on-wheels signal is present
  4. It limits the maximum reverse thrust to 50 percent of forward thrust

Explanation

Interlocks ensure reverse thrust can only be selected when the engine is at idle and the aircraft is on the ground, preventing inadvertent deployment in flight. Additional interlocks prevent thrust lever movement until the reverser is fully deployed.

Question 43Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

An aircraft's air data computer supplies altitude, airspeed and Mach to the autopilot. If the static source becomes blocked, which combination of indications would most likely be observed during a climb?

  1. Altitude increasing, airspeed decreasing and Mach decreasing
  2. Altitude increasing, airspeed increasing and Mach frozen
  3. Altitude frozen, airspeed increasing and Mach increasing Correct answer.
  4. Altitude frozen, airspeed decreasing and Mach decreasing

Explanation

With a blocked static source, the static pressure remains at the value trapped at the time of blockage, so indicated altitude stays constant. As the aircraft climbs, total pressure falls while static pressure stays trapped, so the difference grows and both airspeed and Mach indications increase.

Question 44Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment

In a multi-engine aeroplane with constant-speed propellers, what is the purpose of the propeller feathering system?

  1. To reduce blade pitch to zero so that the propeller stops rotating in flight
  2. To increase blade pitch to the take-off setting for maximum thrust
  3. To synchronise the rpm of all propellers on the aircraft
  4. To rotate the blades to a high pitch angle that minimises drag and windmilling on a failed engine Correct answer.

Explanation

Feathering turns the blades edge-on to the relative airflow so that a failed engine's propeller produces minimum drag and stops windmilling, reducing asymmetric drag and protecting the engine. It is normally actuated by oil pressure or by a dedicated feathering pump.

Question 45Aircraft General Knowledge – Instruments

In a light aircraft pitot-static system, which component is connected to the static port only?

  1. The airspeed indicator
  2. The stall warning vane
  3. The vertical speed indicator Correct answer.
  4. The pitot pressure line to the airspeed indicator capsule

Explanation

The vertical speed indicator responds to changes in static pressure as the aircraft climbs or descends, so it is fed from the static source alone. The airspeed indicator needs both pitot (dynamic) and static pressure to compute the pressure difference that represents speed. The stall warning vane is a mechanical device and is not part of the pitot-static plumbing.

Question 46Aircraft General Knowledge – Instruments

An aircraft climbs at a constant indicated airspeed while the static pressure falls. What happens to the true airspeed?

  1. It decreases in proportion to the static pressure.
  2. It increases as altitude increases. Correct answer.
  3. It oscillates around the indicated airspeed.
  4. It remains equal to the indicated airspeed.

Explanation

Indicated airspeed depends on dynamic pressure, which falls with air density for a given true speed. As altitude rises, density decreases, so a constant indicated airspeed corresponds to a higher true airspeed. The relationship is roughly that true airspeed increases by about 2 percent per 1000 ft at constant IAS.

Question 47Aircraft General Knowledge – Instruments

Which statement correctly describes the sensing principle of a rate gyro used in a turn indicator?

  1. It senses angular acceleration about its spin axis.
  2. It senses linear acceleration along the aircraft lateral axis.
  3. It senses the earth's magnetic field to determine heading rate.
  4. It senses the rate of rotation about an axis perpendicular to its spin axis. Correct answer.

Explanation

A rate gyro has one gimbal and its spin axis is restrained by a calibrated spring. When the instrument is rotated about the input axis perpendicular to the spin axis, gyroscopic precession deflects the gimbal against the spring by an amount proportional to the rate of turn. It therefore indicates rate of rotation, not attitude or acceleration.

Question 48Aircraft General Knowledge – Instruments

During a coordinated level turn, the turn coordinator shows a standard rate turn. What is the approximate rate of turn?

  1. 6 degrees per second
  2. 1.5 degrees per second
  3. 12 degrees per second
  4. 3 degrees per second Correct answer.

Explanation

A standard rate turn is defined as 3 degrees per second, which completes a full 360-degree turn in two minutes. The turn coordinator is marked at this rate so pilots can maintain a standard rate for timed procedures. Twice that rate would be a steep turn requiring much more bank.

Question 49Aircraft General Knowledge – Instruments

An artificial horizon shows a steady 5-degree bank to the left while the aircraft is actually wings level in straight flight. Which error is most likely?

  1. Real gravity is being replaced by the apparent vertical during a prolonged acceleration.
  2. The turn indicator has jammed.
  3. The erection mechanism has failed and the gyro has toppled. Correct answer.
  4. The static port is blocked.

Explanation

A steady false bank indication with no corresponding turn is typical of a gyro that has toppled or whose erection system has failed, so the horizon bar is no longer referenced to the true vertical. During acceleration errors the indication is transient and settles once acceleration stops. Blocked static ports affect pressure instruments, not the attitude gyro.

Question 50Aircraft General Knowledge – Instruments

What is the purpose of the erection mechanism in a vertical gyro used for an artificial horizon?

  1. To keep the gyro spin axis aligned with the local vertical. Correct answer.
  2. To spin the rotor up to operating speed.
  3. To align the gyro with magnetic north.
  4. To damp out precession caused by the turn indicator.

Explanation

The erection system applies small correcting torques so the gyro spin axis remains aligned with the local vertical despite the earth's rotation and minor disturbances. Without it the gyro would slowly drift and the horizon indication would become progressively wrong. It does not spin the rotor or reference magnetic north.