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GCAA Ghana ATPL Theory study materials
GCAA Ghana ATPL Theory study resources

GCAA Ghana ATPL Theory practice questions

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Question 1Air Law and ATC Procedures

Under the ICAO Convention on International Civil Aviation (Chicago Convention), which body is responsible for adopting and amending the International Standards and Recommended Practices contained in the Annexes?

  1. The Air Navigation Commission acting alone
  2. The ICAO Council Correct answer.
  3. The Assembly of Contracting States
  4. The Secretary General of ICAO

Explanation

Article 37 of the Convention obliges ICAO to adopt standards and recommended practices, and Article 90 gives the Council the power to adopt and amend the Annexes. The Council acts on proposals from the Air Navigation Commission but the adoption authority rests with the Council. The Assembly sets broad policy and budgets but does not itself amend Annexes.

Question 2Air Law and ATC Procedures

A Ghanaian-registered aircraft is flying over the high seas. Which law governs the conduct of the flight and the licensing of its crew?

  1. The law of the State of the operator's principal place of business
  2. The law of the State of registry, Ghana Correct answer.
  3. The law of the nearest coastal State
  4. International law administered by ICAO directly

Explanation

Article 12 and Article 32 of the Chicago Convention place responsibility for rules of the air and crew licensing on the State of registry when the aircraft is outside the territory of any State. Over the high seas no State's national law applies, so the registry State's regulations and licences govern. Coastal States have no jurisdiction over foreign aircraft in flight over the high seas.

Question 3Air Law and ATC Procedures

In the ICAO classification of aircraft, an aircraft with maximum certificated take-off mass of 5 700 kg or less and certified for a maximum of 19 passenger seats is classified as:

  1. Aeroplane
  2. Commuter category aeroplane Correct answer.
  3. Rotorcraft
  4. Large aeroplane

Explanation

ICAO Annex 6 Part II and related definitions distinguish commuter category aeroplanes by the 5 700 kg and 19-seat thresholds. An aeroplane above these limits is treated as a large aeroplane under the applicable Part. The term 'aeroplane' alone is a broad category and does not capture the mass and seat limits.

Question 4Air Law and ATC Procedures

An aircraft is on a flight from Accra to Lagos. Which State is responsible for ensuring that the aircraft's Certificate of Airworthiness remains valid for the flight?

  1. The State of departure
  2. The State of destination
  3. The State of registry Correct answer.
  4. The State of the operator

Explanation

Article 31 of the Chicago Convention requires every aircraft engaged in international navigation to be provided with a certificate of airworthiness issued or rendered valid by the State in which it is registered. Continuing airworthiness oversight therefore rests with the State of registry. Other States may inspect the certificate but do not issue or renew it.

Question 5Air Law and ATC Procedures

For a flight under the instrument flight rules in controlled airspace, which of the following is a required element of the flight plan that must be filed before departure?

  1. The aircraft's insurance policy number
  2. The cruising speed and cruising level Correct answer.
  3. The number of cabin crew carried
  4. The name of the pilot's employer

Explanation

ICAO Annex 2 requires the flight plan to contain specified particulars including aircraft identification, type, wake turbulence category, departure aerodrome, time, route, cruising speed and cruising level, and destination. Cruising speed and level are essential for ATC to plan separation. Items such as employer name or insurance details are not flight plan items.

Question 6Air Law and ATC Procedures

A flight plan has been filed for a controlled flight. In which circumstances may ATC require the pilot to change the flight plan before departure?

  1. When the proposed plan conflicts with traffic or airspace requirements Correct answer.
  2. Only when the aircraft is overloaded
  3. Only when weather is below the pilot's minima
  4. Never, because the filed plan is binding on ATC

Explanation

ATC may require changes to a filed flight plan where the proposed route, level or time cannot be accommodated because of traffic, airspace restrictions or similar operational reasons. A flight plan is a request for clearance and ATC retains the authority to amend it. Weather minima and loading are pilot responsibilities and are not the basis for ATC amendment.

Question 7Air Law and ATC Procedures

In the standard ICAO phonetic alphabet used in radiotelephony, the word used to represent the letter 'Q' is:

  1. Quebec Correct answer.
  2. Quartz
  3. Quito
  4. Queen

Explanation

ICAO Annex 10 Volume II prescribes the international radiotelephony spelling alphabet, in which Q is represented by 'Quebec'. The alphabet is standardized so that letters are understood regardless of language background or radio quality. The other words are not part of the prescribed alphabet.

Question 8Air Law and ATC Procedures

When transmitting a call sign for a Ghanaian-registered aircraft on an international flight, which form is normally used?

  1. The pilot's surname followed by the departure aerodrome
  2. The registration prefix and registration letters, or the approved company call sign with flight number Correct answer.
  3. The operator's AOC number
  4. The aircraft type followed by the flight number

Explanation

ICAO Annex 10 specifies that aircraft call signs are formed either from the registration marking or from the approved telephony designator of the operator followed by the flight identification. Both forms allow ATC to identify the aircraft unambiguously. Personal names or certificate numbers are not valid call signs.

Question 9Air Law and ATC Procedures

What is the standard phraseology used by ATC to authorize an aircraft to proceed under specified traffic conditions within controlled airspace?

  1. 'Stand by'
  2. 'Line up'
  3. 'Cleared' Correct answer.
  4. 'Proceed as requested'

Explanation

In ICAO standard phraseology 'cleared' is used to authorize an aircraft to proceed under conditions specified by ATC, such as 'cleared to land' or 'cleared for take-off'. It conveys a positive authorization. Phrases such as 'proceed as requested' or 'stand by' do not constitute a clearance.

Question 10Air Law and ATC Procedures

A pilot reads back a clearance and the controller notices an error in the read-back. What action must the controller take?

  1. Cancel the flight plan
  2. Record the error for later investigation only
  3. Immediately issue a correction and ensure it is read back correctly Correct answer.
  4. Assume the pilot will notice the error in flight

Explanation

ICAO Annex 10 and PANS-ATM require the controller to listen to the read-back and promptly correct any discrepancy, with the corrected clearance again read back. This read-back and hear-back loop is the principal defence against communication errors. Deferring correction to later or recording only is not acceptable.

Question 11Air Law and ATC Procedures

In which class of airspace are both IFR and VFR flights permitted, with all flights provided with air traffic control service and separated from each other?

  1. Class G
  2. Class F
  3. Class E
  4. Class C Correct answer.

Explanation

Class C airspace permits IFR and VFR flights, provides ATC service to all, separates IFR from IFR and IFR from VFR, and separates VFR from VFR with traffic information. In Class E, VFR flights are not separated from each other or from IFR. Class F is advisory and Class G is uncontrolled.

Question 12Air Law and ATC Procedures

An aircraft is flying VFR in Class D airspace. Which statement correctly describes the ATC service provided?

  1. ATC provides separation between all VFR and IFR flights
  2. ATC provides no service to VFR flights
  3. ATC provides traffic information to VFR flights and separation between IFR flights Correct answer.
  4. ATC provides separation only between VFR flights

Explanation

In Class D airspace both IFR and VFR flights are permitted and ATC provides separation between IFR flights. VFR flights receive traffic information about other flights but are not separated from them. This distinction is a common source of confusion between Class C and Class D.

Question 13Air Law and ATC Procedures

Under the Convention on International Civil Aviation, what is the status of an aircraft's nationality?

  1. An aircraft has the nationality of the State of the operator
  2. An aircraft has the nationality of the State whose flag it flies, which is the State of registry Correct answer.
  3. An aircraft has the nationality of the State of departure
  4. An aircraft has no nationality in international law

Explanation

Article 17 of the Chicago Convention states that aircraft have the nationality of the State in which they are registered. Article 18 further provides that an aircraft cannot be validly registered in more than one State. The flag flown corresponds to the State of registry, and this nationality determines which State exercises regulatory oversight.

Question 14Air Law and ATC Procedures

An aircraft registered in Ghana is operated under a dry lease by an operator established in another State. Which State is primarily responsible for the operational control and flight operations safety oversight of the aircraft?

  1. The State of registry unless a transfer of oversight functions has been agreed and recorded Correct answer.
  2. The State of the lessor's nationality
  3. Always the State where the aircraft is physically located
  4. The State of the aircraft manufacturer

Explanation

Under Annex 6 and the Article 83 bis framework, the State of registry remains responsible for operational oversight unless functions have been transferred to the State of the operator by agreement and notified to ICAO. Without such a transfer, registry responsibility continues. Physical location, manufacturer and lessor nationality are irrelevant.

Question 15Air Law and ATC Procedures

Which of the following best describes the function of a Notice to Airmen (NOTAM)?

  1. A notice containing information on the establishment, condition or change of a facility, service or hazard that is essential to operational personnel Correct answer.
  2. A commercial advertisement issued by an aerodrome operator
  3. A publication of permanent changes to aeronautical charts
  4. A record of aircraft maintenance release

Explanation

A NOTAM is issued to give timely information about temporary or permanent changes to facilities, services or procedures, or about hazards, that are essential to personnel concerned with flight operations. Permanent changes are normally incorporated into AIP amendments, but a NOTAM may precede this. NOTAMs are operational notices, not commercial or maintenance documents.

Question 16Air Law and ATC Procedures

An aircraft on final approach receives a clearance to land, but the pilot observes that the runway is occupied by a vehicle. What is the correct action?

  1. Land regardless because the clearance has been issued
  2. Execute a go-around and inform ATC Correct answer.
  3. Continue the approach and rely on the controller to move the vehicle
  4. Turn off the landing lights and continue

Explanation

The pilot in command retains final responsibility for the safety of the flight and must not land on an obstructed runway. Executing a go-around and informing ATC is the correct response, after which ATC can resolve the conflict. A clearance does not relieve the pilot of the duty to see and avoid.

Question 17Air Law and ATC Procedures

What is the purpose of the minimum safe altitude warning (MSAW) function in an ATC system?

  1. To alert the controller when an aircraft's tracked altitude is below a prescribed minimum Correct answer.
  2. To provide terrain data to the aircraft's navigation system
  3. To calculate the aircraft's fuel consumption
  4. To automatically adjust the aircraft's altimeter setting

Explanation

MSAW is a ground-based safety net that alerts controllers when a tracked aircraft's altitude and position indicate a risk of collision with terrain or an obstacle relative to prescribed minimum altitudes. The controller then warns the pilot. It does not set altimeters, feed navigation systems or compute fuel.

Question 18Air Law and ATC Procedures

Under Annex 2 rules of the air, what is the minimum vertical separation normally required when an aircraft is flying above cloud and below cloud in VFR at high altitude, where the prescribed VMC minima apply?

  1. 1 000 ft above and 1 000 ft below cloud Correct answer.
  2. 2 000 ft above and 2 000 ft below cloud
  3. No vertical cloud clearance is required
  4. 500 ft above and 500 ft below cloud

Explanation

ICAO Annex 2 prescribes VMC minima that vary with altitude and airspace, and at higher altitudes the vertical cloud clearance is generally 1 000 ft above and 1 000 ft below cloud with specified horizontal distance. The lower 500 ft clearance applies only at lower levels in certain airspace. Candidates must apply the minima relevant to the altitude and airspace in use.

Question 19Air Law and ATC Procedures

An aircraft is intercepted by a military aircraft. According to ICAO Annex 2, what should the intercepted aircraft do first?

  1. Ignore the intercepting aircraft and continue the flight plan
  2. Follow the intercepting aircraft and attempt to establish radio communication Correct answer.
  3. Descend to the lowest safe altitude and leave the area
  4. Immediately change frequency and squawk 7700

Explanation

Annex 2 and its attachment on interception require the intercepted aircraft to follow the intercepting aircraft's instructions, attempt to establish radio communication and, if able, notify ATC. The intercepting aircraft may use visual signals if radio contact fails. Immediate evasive action or ignoring the intercept is unsafe and contrary to the prescribed procedure.

Question 20Air Law and ATC Procedures

Which of the following is the correct action for a pilot who experiences a two-way radio communication failure in IMC while in controlled airspace?

  1. Squawk 7600 and climb to the highest available level
  2. Continue according to the last acknowledged clearance or the filed flight plan and comply with the prescribed procedures Correct answer.
  3. Turn back to the departure aerodrome without notifying anyone
  4. Land immediately at the nearest aerodrome regardless of conditions

Explanation

Annex 2 and PANS-ATM prescribe communication failure procedures: the pilot should continue in accordance with the last received and acknowledged clearance, or the flight plan, and follow the specified actions such as squawking 7600 and maintaining the assigned level for a period. The objective is predictable behaviour so ATC can protect the airspace. Immediate diversion or arbitrary climbs are not prescribed.

Question 21Aircraft General Knowledge: Airframe, Systems, Electrics, Powerplant and Emergency Equipment

In a gas turbine engine, what is the primary function of the diffuser section of the compressor outlet?

  1. To decrease air velocity and increase static pressure before combustion Correct answer.
  2. To increase air velocity to maximise ram effect at the combustor inlet
  3. To mix fuel with air and initiate the combustion process
  4. To drive the accessory gearbox through a bevel gear train

Explanation

The diffuser converts high-velocity compressor delivery air into higher static pressure by slowing the airflow, which is required for stable combustion and efficient pressure rise. It performs no fuel-metering or mechanical drive function.

Question 22Aircraft General Knowledge: Airframe, Systems, Electrics, Powerplant and Emergency Equipment

Why is a constant-speed propeller able to absorb nearly full engine power across a wide range of airspeeds?

  1. Its diameter changes with RPM to alter the disc area
  2. Its blades are fixed at the angle giving maximum thrust at take-off
  3. Its blade angle is varied so the blade element angle of attack stays near optimum Correct answer.
  4. Its RPM is allowed to rise and fall freely with airspeed

Explanation

A constant-speed unit changes blade pitch as airspeed and power vary, keeping each blade element at an efficient angle of attack and thereby maintaining an efficient power absorption. This is why manifold pressure and RPM can be controlled independently.

Question 23Aircraft General Knowledge: Airframe, Systems, Electrics, Powerplant and Emergency Equipment

On an aircraft electrical system, what is the purpose of the reverse-current cut-out associated with a DC generator?

  1. It protects the generator field winding against over-excitation
  2. It limits generator output voltage to the busbar nominal value
  3. It reverses the polarity of the generator to assist engine starting
  4. It disconnects the generator when current flows from the battery into the generator Correct answer.

Explanation

The reverse-current cut-out opens the generator contactor when the generator voltage falls below busbar voltage, preventing the battery from discharging through the generator and motoring it. Voltage regulation and field protection are separate functions.

Question 24Aircraft General Knowledge: Airframe, Systems, Electrics, Powerplant and Emergency Equipment

Which property makes a fire-detection loop of the continuous-element type suitable for engine nacelles?

  1. It triggers only when a single point exceeds a fixed temperature
  2. It detects smoke by optical scattering within the nacelle
  3. It requires no electrical supply and works purely by pressure change
  4. It responds to an average temperature rise along its whole length and resists localised hot spots Correct answer.

Explanation

Continuous-element loops use a material whose resistance changes with temperature along the entire sensing length, giving coverage of large areas and reducing false alarms from small local hot spots. Point detectors and optical smoke detectors behave differently.

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

What is the function of a bleed-air anti-ice system on a turbojet engine intake?

  1. It reduces intake airflow to prevent ice crystal formation
  2. It sprays anti-icing fluid onto the intake lip when icing is detected
  3. It supplies hot compressor air to the intake lip to keep surface temperature above freezing Correct answer.
  4. It electrically heats the intake lip through embedded resistance mats

Explanation

Bleed-air anti-ice systems duct hot high-pressure compressor air to the intake lip and, on some types, to the front frame, keeping metal temperature above the freezing point so ice cannot accrete. Fluid and electrical heating are alternative methods.

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

In a hydraulic system, what is the role of the accumulator?

  1. It converts hydraulic pressure into mechanical actuation
  2. It stores pressurised fluid to damp pressure surges and supply transient demand Correct answer.
  3. It filters particulate contamination from the return line
  4. It limits system pressure by bypassing fluid to the reservoir

Explanation

An accumulator contains a gas-charged chamber that absorbs pressure pulses and stores energy to meet short-term high demand, such as during rapid gear or flap operation. Filtration, actuation and pressure limiting are performed by other components.

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

During a climb at constant indicated airspeed, an aircraft with a turbocharged piston engine maintains rated manifold pressure. What determines the maximum altitude at which this can be sustained?

  1. The altitude at which the oil temperature falls below the gauge range
  2. The altitude at which the fuel/air mixture becomes too rich to burn
  3. The altitude at which the propeller reaches its RPM limit
  4. The critical altitude, where the turbocharger reaches its maximum permissible speed Correct answer.

Explanation

The critical altitude is reached when the turbocharger is operating at its limiting speed and can no longer maintain sea-level manifold pressure; above it, manifold pressure falls with further climb. Mixture, propeller and oil temperature limits are separate considerations.

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

A twin-engine aircraft has both generators feeding a common busbar through reverse-current cut-outs. One generator fails in flight. What is the expected system response?

  1. The failed generator's cut-out opens and the remaining generator supplies the busbar Correct answer.
  2. The failed generator continues to supply the busbar through the other generator's regulator
  3. The busbar trips and all electrical loads are shed permanently
  4. Both cut-outs open and the battery supplies the whole busbar until reset

Explanation

When a generator loses output, its terminal voltage falls below busbar voltage, so its reverse-current cut-out opens and isolates it while the healthy generator continues to carry the busbar load. The battery is not the primary source while a generator is available.

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

Why must the fuel/air mixture be leaned as altitude increases in a normally aspirated piston engine?

  1. Cylinder temperature rises, requiring extra fuel for cooling
  2. Fuel density falls with altitude, so more fuel must be added
  3. Air density falls faster than fuel flow, so the mixture would otherwise become too rich Correct answer.
  4. The compressor delivers less air, so the mixture becomes too lean

Explanation

As altitude increases, air density decreases while the carburettor meters fuel largely by volume, so the mixture becomes progressively richer. Leaning restores the correct fuel/air ratio for efficient combustion and prevents fouling.

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

An aircraft's landing gear is held up by hydraulic pressure and lowered by system pressure, with no mechanical downlock. What happens if hydraulic pressure is lost in flight?

  1. The gear remains locked in the up position until pressure is restored
  2. The gear extends under gravity and air loads, and may not lock down Correct answer.
  3. The gear extends and automatically locks in the down position
  4. The gear retracts further as the actuators bleed down

Explanation

Where the gear is held up by hydraulic pressure with no mechanical uplock, loss of pressure allows the gear to free-fall, but without a downlock or emergency extension system it may not lock. This is why such designs incorporate emergency gravity extension and downlock springs.

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

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

  1. It limits the maximum positive differential pressure across the fuselage
  2. It admits cabin air if cabin pressure falls below ambient, preventing inward structural loads Correct answer.
  3. It regulates the cabin rate of climb during descent
  4. It dumps cabin pressure if the outflow valve fails closed

Explanation

The negative pressure relief valve opens when outside pressure exceeds cabin pressure, preventing the fuselage from being loaded inwards. Positive pressure relief and outflow valve control are handled by separate components.

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

Which statement correctly describes the operation of a fire-extinguishing system using a halon agent in an engine nacelle?

  1. The agent cools the fire by absorbing heat into a water spray
  2. The agent is discharged only after the engine has been restarted
  3. The agent displaces oxygen by forming a foam blanket over the engine
  4. The agent is discharged into the nacelle as a gas that interrupts the combustion chain reaction Correct answer.

Explanation

Halon extinguishes fire chemically by breaking the combustion chain reaction, and it is stored as a liquefied gas discharged into the protected zone. Foam and water are used in different applications, and discharge occurs with the engine shut down.

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

What is the purpose of the torque meter on a turboprop engine?

  1. To indicate the power being delivered to the propeller so the crew can set power within limits Correct answer.
  2. To measure propeller RPM so the governor can be adjusted
  3. To monitor the oil pressure in the reduction gearbox
  4. To indicate compressor delivery pressure for the EPR gauge

Explanation

Torque is proportional to the power delivered through the reduction gearbox to the propeller, so the torque meter is the primary power indication for a turboprop. RPM, EPR and oil pressure are measured by other instruments.

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

An aircraft with a 28 V DC system has a battery rated at 40 Ah. The battery is used to supply a 20 A load with the generators offline. Ignoring inefficiencies and derating, approximately how long can the battery sustain the load?

  1. 0.5 hours
  2. 4 hours
  3. 2 hours Correct answer.
  4. 20 hours

Explanation

Battery endurance is the ampere-hour capacity divided by the load current, so 40 Ah divided by 20 A gives approximately 2 hours. Real endurance is shorter because of derating and voltage fall-off.

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

How does an anti-lock braking system improve braking performance on a contaminated runway?

  1. It modulates brake pressure to keep the wheel near the slip ratio giving maximum friction Correct answer.
  2. It disables braking on the wheels with the least load
  3. It increases hydraulic pressure to the brakes beyond the normal maximum
  4. It applies continuous full braking to all wheels simultaneously

Explanation

Anti-lock systems sense wheel deceleration and release brake pressure before the wheel locks, keeping tyre slip near the value that produces maximum available friction. This preserves directional control and shortens stopping distance on slippery surfaces.

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

What is the effect of a leak in the static pressure line of a pitot-static system on the indicated airspeed during a climb?

  1. Airspeed indication remains correct but the altimeter over-reads
  2. Airspeed indication is unaffected because the pitot line provides the reference
  3. Airspeed indication reads higher than actual because cabin static pressure is used Correct answer.
  4. Airspeed indication reads lower than actual because cabin static pressure is used

Explanation

A static leak allows cabin (higher) pressure to reach the instrument instead of ambient static pressure, increasing the apparent pressure difference across the capsule and causing an over-read of airspeed. The altimeter would also under-read in the climb.

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

In a high-bypass turbofan, why does a fan blade failure require careful design of the containment casing?

  1. Released blade fragments carry high energy and must not penetrate the nacelle or fuselage Correct answer.
  2. Containment reduces the noise produced by the fan
  3. Containment prevents the fan from overspeeding after blade loss
  4. The fan blades are the only components that can fail in the engine

Explanation

A released fan blade carries very high kinetic energy, and the casing must contain it to protect the aircraft structure. This is a certification requirement for fan-blade-off events.

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

What is the purpose of the fuel-oil heat exchanger in a turbofan engine?

  1. To separate water from the fuel before combustion
  2. To cool the fuel using ram air before it reaches the fuel control unit
  3. To heat the oil to reduce its viscosity during cold starts
  4. To cool the engine oil using fuel while warming the fuel to prevent ice blockage Correct answer.

Explanation

The fuel-oil heat exchanger transfers heat from the hot engine oil to the cold fuel, cooling the oil and warming the fuel so that dissolved or free water does not freeze in the fuel system. Ram-air and electrical heating are alternative arrangements.

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

An aircraft has a 115 V AC system with a constant-frequency generator driven through a constant-speed drive. What is the primary function of the constant-speed drive?

  1. To increase generator voltage to 115 V
  2. To convert AC output to DC for the battery bus
  3. To keep the generator rotor speed constant despite engine speed changes Correct answer.
  4. To disconnect the generator in the event of a fault

Explanation

The constant-speed drive maintains a constant output speed to the generator so that the AC frequency remains at 400 Hz regardless of engine RPM. Voltage regulation, rectification and fault disconnection are separate functions.

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

Why is a wet-sump lubrication system generally limited to engines of modest power output and limited aerobatic capability?

  1. The system cannot provide oil cooling through a heat exchanger
  2. Oil is stored in a separate tank that cannot be pressurised
  3. Oil is stored in the crankcase, so oil can collect at the wrong end under sustained unusual attitudes Correct answer.
  4. The system relies on a scavenge pump with no pressure pump

Explanation

In a wet-sump system the oil supply sits in the engine crankcase, so sustained negative or unusual attitudes can uncover the pick-up and interrupt supply. Dry-sump systems use a separate tank and are preferred where aerobatics or high power are involved.

Question 41Aircraft General Knowledge: Instrumentation

In a light aircraft, the turn coordinator differs from a standard rate turn-and-slip indicator mainly because its gyro is mounted so that it senses which quantity?

  1. Rate of yaw only, with the gyro spin axis horizontal and parallel to the longitudinal axis
  2. Rate of roll as well as rate of yaw, with the gyro spin axis tilted about 30 degrees from horizontal Correct answer.
  3. Rate of pitch, with the gyro spin axis lateral
  4. Rate of yaw only, with the gyro spin axis vertical

Explanation

The turn coordinator uses a gyro whose spin axis is canted so that the gimbal responds to rolling motion as well as yaw, allowing it to indicate rate of turn during bank entry and in a coordinated turn. The older turn-and-slip indicator responds essentially to yaw rate alone. This canted mounting is why the miniature aircraft in a turn coordinator banks and shows turn quality.

Question 42Aircraft General Knowledge: Instrumentation

An aircraft is climbing at a constant indicated airspeed with the pitot heat off. The static source becomes partially blocked while the pitot tube remains clear. What happens to the airspeed indication?

  1. It reads progressively higher than the true value as altitude increases Correct answer.
  2. It freezes at the value at the moment of blockage
  3. It reads progressively lower than the true value as altitude increases
  4. It drops to zero immediately

Explanation

With the pitot tube clear, total pressure is still correct, but the trapped static pressure stays at the value at blockage while the true static pressure falls with climb. The measured pressure difference therefore grows, so the instrument over-reads, and the error increases with height. The indication climbs steadily even at constant speed.

Question 43Aircraft General Knowledge: Instrumentation

What is the primary purpose of the gyromagnetic compass (slaved gyro) system in an aircraft?

  1. To measure rate of turn for the autopilot
  2. To combine a directional gyro's stability with a magnetic detector unit's long-term heading accuracy Correct answer.
  3. To provide attitude information in place of the artificial horizon
  4. To replace the magnetic compass as a completely independent heading source

Explanation

A flux valve or magnetometer senses the earth's magnetic field and supplies a slow correction signal to the directional gyro, so the gyro provides short-term rigidity while the magnetic reference removes drift. The result is a stable heading display free of most turning and acceleration errors of a direct-reading compass. The system is not independent of magnetism, since it relies on the detector unit.

Question 44Aircraft General Knowledge: Instrumentation

On a three-pointer altimeter set to 1013 hPa, the long thin pointer indicates hundreds of feet, the short thick pointer thousands and the triangle ten thousands. If the indication shows 2 on the triangle, 4 on the short pointer and 5 on the long pointer, what altitude is displayed?

  1. 2 450 ft
  2. 24 050 ft
  3. 20 450 ft
  4. 24 500 ft Correct answer.

Explanation

Each pointer is read in its own scale: the triangle gives 20 000 ft, the short pointer gives 4 000 ft and the long pointer gives 500 ft. Adding them gives 24 500 ft. Reading each pointer on its own dial prevents the classic misreading of a three-pointer altimeter.

Question 45Aircraft General Knowledge: Instrumentation

Which statement correctly describes the sensing mechanism of a rate-of-climb indicator?

  1. It uses a gyroscope to integrate vertical acceleration
  2. It measures the pressure difference between a calibrated leak and the static pressure inside a case Correct answer.
  3. It measures total pressure changes with a Bourdon tube
  4. It compares pitot pressure with static pressure through a capsule

Explanation

The vertical speed indicator has a capsule connected to static pressure and a case connected to static pressure through a calibrated leak. When altitude changes, the capsule pressure changes immediately while the case pressure lags, and the resulting differential drives the pointer. In steady flight the leak equalises the pressures and the needle returns to zero.

Question 46Aircraft General Knowledge: Instrumentation

An aircraft with a Machmeter is cruising at high altitude. The Machmeter indicates the ratio of true airspeed to local speed of sound. Which combination of inputs does it use to derive this value?

  1. Pitot pressure, static pressure and the calibrated relationship between pressure ratio and Mach number Correct answer.
  2. Static pressure and total temperature
  3. Pitot pressure and static pressure only
  4. Total temperature and angle of attack

Explanation

The Machmeter is fed pitot and static pressure, and its mechanism is shaped so that the pressure ratio produces a display of M, using the standard adiabatic relationship between pressure ratio and Mach number. No direct temperature input is needed because the pressure ratio uniquely defines Mach number in the standard atmosphere assumptions. At altitude the same pressure ratio corresponds to a higher true airspeed.

Question 47Aircraft General Knowledge: Instrumentation

Why must the gyro of an artificial horizon be erected and monitored, and what happens if the erection mechanism is faulty during a prolonged turn?

  1. The gyro is air-driven and is unaffected by acceleration
  2. The gyro uses a magnetic reference and follows the earth's field
  3. The gyro is gravity-erected and will precess to a false vertical, causing a persistent attitude error Correct answer.
  4. The gyro is electrically driven and needs no erection at all

Explanation

The vertical gyro is kept aligned with the true vertical by an erection system using pendulous vanes or torque motors. During sustained acceleration, apparent gravity is displaced, so a faulty or slow erection mechanism can tilt the gyro and leave a lasting attitude error. This is why the horizon may need to be checked and caged after unusual manoeuvres.

Question 48Aircraft General Knowledge: Instrumentation

In a remote-reading compass system, what is the function of the flux valve (flux gate)?

  1. It senses the horizontal component of the earth's magnetic field and provides a heading reference signal Correct answer.
  2. It measures aircraft acceleration to feed the autopilot
  3. It provides the vertical reference for the attitude indicator
  4. It converts AC to DC for the gyro motor

Explanation

The flux valve is mounted where it is least disturbed by aircraft magnetism and detects the direction of the horizontal component of the earth's field. Its signal is used to slave the directional gyro to magnetic north. Because it responds to the horizontal component, it is sensitive to turning and acceleration errors that the slaving loop averages out.

Question 49Aircraft General Knowledge: Instrumentation

A pilot notices that the airspeed indicator shows a higher-than-expected value during a climb at high altitude and lower than expected during a descent, while the static system is clear. Which error best explains this behaviour?

  1. Position or installation error caused by airflow around the static ports Correct answer.
  2. Instrument friction in the capsule
  3. Lag in the pitot line
  4. Density error in the airspeed indicator

Explanation

Position error arises because the static pressure at the sensing ports differs from the true ambient static pressure due to airflow around the airframe. The error varies with angle of attack, configuration and speed, so it changes between climb and descent. Calibration data is used to correct indicated airspeed to calibrated airspeed.

Question 50Aircraft General Knowledge: Instrumentation

Which instrument uses a sealed case containing a diaphragm connected to static pressure to display altitude, and what happens to its indication if the static line becomes blocked at altitude?

  1. The airspeed indicator; it will read zero
  2. The altimeter; it will continue to indicate the altitude at which the blockage occurred Correct answer.
  3. The vertical speed indicator; it will show a continuous climb
  4. The altimeter; it will read the cabin altitude

Explanation

The altimeter capsule responds to static pressure inside a sealed case, so if the static source is blocked the trapped pressure remains constant and the pointer freezes at the altitude of blockage. Changes in aircraft altitude no longer reach the capsule. This is why an alternate static source is provided.