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KCAA ATPL Theory study materials
KCAA ATPL Theory study resources

KCAA ATPL Theory practice questions

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Question 1Air Law

Under the Convention on International Civil Aviation (Chicago Convention), each Contracting State has complete and exclusive sovereignty over:

  1. airspace allocated to it by the ICAO Council
  2. only the airspace above its territorial sea
  3. the airspace above its territory up to 60,000 feet
  4. the airspace above its territory Correct answer.

Explanation

Article 1 of the Chicago Convention provides that every State has complete and exclusive sovereignty over the airspace above its territory, which includes its land areas and territorial waters. The Convention does not state a vertical height limit for that sovereignty.

Question 2Air Law

To exercise the privileges of a Kenya Airline Transport Pilot License, the holder must maintain a valid:

  1. Class 1 medical certificate Correct answer.
  2. Class 2 medical certificate
  3. Class 1 or Class 2 certificate, at the holder's choice
  4. Class 3 medical certificate

Explanation

ICAO Annex 1 and the Kenyan personnel licensing requirements require an ATPL holder to hold a current Class 1 medical certificate. The Class 1 standard is stricter than Class 2 because of the higher safety risk associated with commercial air transport.

Question 3Air Law

The Kenya Civil Aviation Authority is established and empowered to regulate civil aviation in Kenya by:

  1. the Kenya Airports Authority Act, 1991
  2. the Civil Aviation Act, 2013 Correct answer.
  3. the Air Navigation Act, 1968
  4. the Chicago Convention, Article 1

Explanation

The Kenya Civil Aviation Authority was established by the Civil Aviation Act, 2013 (No. 21 of 2013). The Act gives KCAA responsibility for the safety and economic regulation of civil aviation, including licensing, oversight and enforcement.

Question 4Air Law

Two aircraft of the same category are converging at approximately the same level. According to ICAO Annex 2, the aircraft that has the right of way is the one:

  1. that is faster
  2. on the right Correct answer.
  3. that is lower
  4. on the left

Explanation

Annex 2 provides that when two aircraft of the same category are converging at approximately the same level, the aircraft on the right has the right of way. The aircraft on the left must give way and avoid passing over, under or in front of the other unless well clear.

Question 5Air Law

For a VFR flight at or above 10,000 ft AMSL in controlled airspace, ICAO Annex 2 requires a minimum flight visibility of:

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

Explanation

Annex 2 requires a VFR flight at or above 10,000 ft AMSL in controlled airspace to have flight visibility of at least 8 km, with distance from cloud of 1,500 m horizontally and 1,000 ft vertically. Below 10,000 ft the flight visibility requirement is 5 km.

Question 6Air Law

An aircraft accident occurs in State A involving an aircraft registered in State B and operated by a company in State C. Under ICAO Annex 13, the State responsible for instituting the investigation is:

  1. State C, the State of the Operator
  2. the State of Manufacture of the aircraft
  3. State A, the State of Occurrence Correct answer.
  4. State B, the State of Registry

Explanation

Under Annex 13, the State of Occurrence is responsible for instituting the investigation and for notifying the State of Registry, State of Operator, State of Design and State of Manufacture. The State of Registry may participate and appoint an accredited representative.

Question 7Air Law

The objective of the alerting service provided by an ATS unit is to:

  1. broadcast current meteorological reports and forecasts to aircraft in flight
  2. provide standard separation between all IFR and VFR flights in controlled airspace
  3. notify and assist organizations concerned with aircraft needing search and rescue aid Correct answer.
  4. issue traffic information to every aircraft operating within the area control service

Explanation

Alerting service is defined in Annex 11 as a service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid and to assist such organizations as required. It is distinct from air traffic control and from the flight information service.

Question 8Air Law

The primary objective of ICAO Annex 17 is to:

  1. standardize the investigation of aircraft accidents and incidents
  2. facilitate the clearance of aircraft and passengers through customs
  3. ensure the airworthiness of aircraft used in international operations
  4. safeguard international civil aviation against acts of unlawful interference Correct answer.

Explanation

Annex 17 contains Standards and Recommended Practices for safeguarding international civil aviation against acts of unlawful interference. Its objectives include the security of passengers, crew, ground personnel and the public.

Question 9Air Law

In an ICAO Annex, a Standard differs from a Recommended Practice in that a Standard is:

  1. applicable only to scheduled international operations
  2. mandatory for States unless a difference is notified Correct answer.
  3. binding only after national parliamentary ratification
  4. advisory and optional for all Contracting States

Explanation

A Standard is a specification whose uniform application is recognized as necessary for the safety or regularity of international air navigation, and Contracting States must comply or notify ICAO of any difference. A Recommended Practice is desirable but not mandatory.

Question 10Air Law

Under Article 5 of the Chicago Convention, aircraft of one Contracting State not engaged in scheduled international air services may fly into or over the territory of another Contracting State:

  1. without prior permission, subject to designated-airport landing rules Correct answer.
  2. only when carrying a certificate of airworthiness issued by the destination State
  3. only after obtaining prior diplomatic clearance
  4. only if the flight is made for humanitarian purposes

Explanation

Article 5 gives non-scheduled flights of Contracting States the right to fly into or transit another State's territory without prior permission, subject to the right of the State flown over to require landing at a designated airport and to make regulations. This provision is often called the non-scheduled flight or transit provision.

Question 11Air Law

An aircraft registered in Kenya carries the nationality mark '5Y' painted on its fuselage. Under ICAO Annex 7, this mark indicates the...

  1. State that manufactured the aircraft
  2. Category of airworthiness certificate issued
  3. Commercial operator responsible for the flight
  4. State in which the aircraft is registered Correct answer.

Explanation

Annex 7 requires the nationality or common mark to identify the State of registry; Kenya's assigned mark is 5Y. The registration mark, which follows the hyphen, identifies the individual aircraft within that State.

Question 12Air Law

A foreign airline intends to operate a scheduled international air service into Nairobi. Under Article 6 of the Chicago Convention, that service may be operated only if...

  1. the aircraft holds a valid ICAO noise certificate
  2. the airline has joined a multilateral pooling agreement
  3. the service is operated at least twice weekly
  4. Kenya has granted special permission or authorization Correct answer.

Explanation

Article 6 provides that no scheduled international air service may be operated over or into the territory of a Contracting State except with the special permission or other authorization of that State. Kenya therefore must grant permission before the foreign airline may serve Nairobi.

Question 13Air Law

Under ICAO Annex 1, the minimum age for first issue of an Airline Transport Pilot Licence is...

  1. 20 years
  2. 18 years
  3. 21 years Correct answer.
  4. 23 years

Explanation

Annex 1 sets the minimum age for first issue of an ATPL at 21 years. The corresponding minima for a CPL and a PPL are 18 and 17 years respectively.

Question 14Air Law

Two aeroplanes are approaching to land at the same aerodrome. One is at a higher altitude than the other. According to ICAO Annex 2, which aircraft shall give way?

  1. The lower aircraft, because it is closer to the threshold
  2. The higher aircraft, because the lower one can land Correct answer.
  3. The aircraft that is faster, to maintain separation
  4. Neither, because both are established on final approach

Explanation

Annex 2 requires the aircraft at the higher altitude to give way to the lower aircraft approaching to land. The lower aircraft must not, however, cut in front of or overtake the higher aircraft.

Question 15Air Law

A VFR flight is conducted in controlled airspace at 6,000 ft AMSL. Under ICAO Annex 2, the minimum flight visibility required is...

  1. 5 km Correct answer.
  2. 8 km
  3. 10 km
  4. 1,500 m

Explanation

For VFR flight below 10,000 ft AMSL, Annex 2 prescribes a minimum flight visibility of 5 km. At or above 10,000 ft the minimum is 8 km.

Question 16Air Law

A pilot receives an ATC clearance that includes a runway for departure and an initial altitude. Under ICAO Annex 2, the pilot shall...

  1. read back only the aircraft call sign and 'roger'
  2. request a written copy of the clearance before taxiing
  3. read back the runway and altitude instructions in full Correct answer.
  4. acknowledge only by activating the transponder ident function

Explanation

Annex 2 requires pilots to read back clearances concerning runway-in-use, altitude, heading and speed. A simple ident or 'roger' does not satisfy the read-back requirement for these instructions.

Question 17Air Law

Under Article 29 of the Chicago Convention, which document must be carried on board an aircraft engaged in international navigation?

  1. The certificate of registration Correct answer.
  2. The current aerodrome landing chart
  3. The operator's safety management manual
  4. The aircraft maintenance programme

Explanation

Article 29 lists the documents that must be carried on board, including the certificate of registration, certificate of airworthiness, crew licences, journey log book, passenger manifest and cargo declaration. The maintenance programme and safety management manual are not among the listed documents.

Question 18Air Law

Under ICAO Annex 18, dangerous goods may be carried on an aircraft only when...

  1. the aircraft is a freighter with no passengers
  2. a dangerous goods transport document accompanies the consignment Correct answer.
  3. the goods are packed by the shipper in unmarked containers
  4. the captain has completed a dangerous goods course

Explanation

Annex 18 requires dangerous goods to be accompanied by a dangerous goods transport document containing the information specified in the Technical Instructions. The operator must also ensure acceptance checks are completed before loading.

Question 19Air Law

A foreign operator proposes to carry passengers from Nairobi to Mombasa for remuneration. Under Article 7 of the Chicago Convention, Kenya is entitled to...

  1. reserve cabotage traffic to its own national aircraft Correct answer.
  2. deny the flight unless the aircraft is ICAO type-certified
  3. require the operator to use a Kenyan-registered aircraft only
  4. levy a cabotage fee equal to the air navigation charge

Explanation

Article 7 permits each Contracting State to reserve cabotage, meaning the carriage of traffic between two points within its territory for remuneration, to its own national aircraft. Kenya may therefore refuse the foreign operator's proposed domestic sector.

Question 20Air Law

A Kenyan-issued certificate of airworthiness is presented to another Contracting State. Under Article 33 of the Chicago Convention, that State shall recognize the certificate provided...

  1. the certificate is written in English
  2. the aircraft is operated by a Kenyan national
  3. the issuing State meets or exceeds ICAO minimum standards Correct answer.
  4. the certificate was validated by the State of Registry before use

Explanation

Under Article 33, a Contracting State must recognize certificates of airworthiness and licences issued by another Contracting State if the issuing State's requirements meet or exceed the ICAO minimum standards. The recognition is not conditional on language, operator nationality or prior validation.

Question 21Air Law

Under ICAO Annex 10, the aeronautical emergency frequency that must be available for use by aircraft in distress is:

  1. 136.975 MHz
  2. 122.800 MHz
  3. 118.100 MHz
  4. 121.500 MHz Correct answer.

Explanation

ICAO Annex 10 designates 121.500 MHz as the aeronautical emergency frequency for civil aircraft. It is used for distress and urgency communications and for emergency locator transmitter homing. Pilots should be able to select this frequency promptly when an emergency arises.

Question 22Air Law

Under ICAO Annex 11, the air traffic services unit responsible for providing air traffic control service to aerodrome traffic and for control of aircraft on the manoeuvring area is the:

  1. aerodrome control tower Correct answer.
  2. area control centre
  3. flight information centre
  4. approach control office

Explanation

Annex 11 assigns aerodrome control service to the aerodrome control tower, which issues clearances and information to aircraft on the manoeuvring area and to aerodrome traffic. Area control centres and approach control offices provide control services to en-route and arriving/departing traffic respectively, while a flight information centre provides flight information service and alerting service rather than aerodrome control.

Question 23Air Law

Under ICAO Annex 6, Part I, an operator must retain the recorded data from a flight data recorder for at least:

  1. 30 days
  2. 60 days Correct answer.
  3. 90 days
  4. 12 months

Explanation

Annex 6, Part I requires the operator to retain flight recorder recordings for at least 60 days, unless a longer period is requested by the investigating authority. The recordings must be preserved so that they remain available for accident or incident investigation. This retention period applies to flight data recorder data and cockpit voice recorder recordings.

Question 24Air Law

An aircraft registered in State A is involved in an accident on the high seas, outside the territory of any State. Under ICAO Annex 13, the State responsible for instituting the investigation is:

  1. the State from which the aircraft last departed
  2. the State of Manufacture
  3. the State of the Operator
  4. the State of Registry Correct answer.

Explanation

Annex 13 provides that when an accident occurs in territory not belonging to any State, such as the high seas, the State of Registry institutes the investigation. Other States with a substantial interest, such as the State of the Operator, State of Design and State of Manufacture, may be entitled to participate. The State of Registry therefore bears the primary responsibility for instituting the investigation in this situation.

Question 25Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In a semi-monocoque aircraft fuselage, the stringers primarily:

  1. provide mounting points for the engine bearers
  2. carry bending loads and stiffen the skin Correct answer.
  3. react torsional loads only at the wing attachment
  4. form the pressure-tight boundary of the cabin

Explanation

Stringers run longitudinally and, together with the skin, carry axial and bending loads while stiffening the skin against buckling. The skin carries much of the shear and torsional load, and frames maintain the cross-section. This division of load is the basis of semi-monocoque construction.

Question 26Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

Cowl flaps on an air-cooled reciprocating engine installation are used to:

  1. prevent detonation by cooling the induction air
  2. maintain a constant cylinder-head temperature automatically
  3. increase the engine oil supply during high-power operation
  4. regulate cooling airflow through the cylinder fins Correct answer.

Explanation

Cowl flaps vary the exit area for cooling air, so they control how much air flows past the cylinder fins and oil cooler. Opening them in climb or high-power, low-speed flight increases cooling; closing them reduces drag and prevents over-cooling in cruise or descent.

Question 27Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

If the static pressure source to the instruments becomes completely blocked, the vertical speed indicator will, after the initial transient:

  1. indicate a steady climb
  2. indicate a steady descent
  3. indicate the true vertical speed
  4. indicate zero Correct answer.

Explanation

The VSI measures the rate of change of static pressure. With the static source blocked, the pressure inside the instrument cannot follow aircraft altitude changes, so after the initial transient the pointer returns to zero and remains there.

Question 28Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

A pressure relief valve in an aircraft hydraulic system protects the system by:

  1. returning excess fluid to the reservoir at the set pressure Correct answer.
  2. preventing cavitation by pressurising the reservoir
  3. directing fluid to the actuator only during retraction
  4. closing the pump outlet when pressure falls below the set value

Explanation

A pressure relief valve opens at a preset pressure and returns excess fluid to the reservoir, limiting system pressure. It is a safety device and does not normally control pump displacement or flow to the actuators.

Question 29Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

The cabin outflow valve in a pressurisation system controls:

  1. the compressor delivery temperature at the bleed port
  2. cabin pressure and its rate of change Correct answer.
  3. the opening of the engine bleed valves
  4. the cabin altitude warning threshold setting

Explanation

The outflow valve is the controlled exit for cabin air. By opening or closing it, the pressure controller regulates cabin pressure and the rate of cabin altitude change while bleed air enters the cabin.

Question 30Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

A propeller governor maintains constant engine speed by:

  1. adjusting the ignition timing with engine speed
  2. varying the throttle position through a linkage to the carburettor
  3. changing blade angle with oil pressure Correct answer.
  4. bleeding air from the manifold to the propeller dome

Explanation

The governor senses engine speed and ports oil to or from the propeller hub. Changing oil pressure moves the blades toward fine or coarse pitch, which changes the load on the engine and holds the selected RPM.

Question 31Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

During a pre-flight engine run, a magneto check shows an excessive RPM drop when selecting the left magneto. This most likely indicates:

  1. the mixture is too lean for the run-up
  2. the propeller is out of balance
  3. a fault in the left magneto circuit Correct answer.
  4. the right magneto is incorrectly timed

Explanation

The magneto check compares the RPM drop on each magneto with the manufacturer's limit. An excessive drop on one magneto indicates a fault in that magneto, its harness, or a spark plug in that circuit, and the engine should not be flown until rectified.

Question 32Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

An aircraft anti-skid brake system releases brake pressure when:

  1. the pilot selects reverse thrust
  2. the wheel speed exceeds the aircraft ground speed
  3. the brake pedal force exceeds a fixed maximum
  4. wheel deceleration indicates an incipient skid Correct answer.

Explanation

An anti-skid system compares wheel speed or deceleration with a reference. If a wheel decelerates too rapidly, the system interprets an incipient skid and reduces brake pressure to allow the wheel to spin up again.

Question 33Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

A variable-displacement hydraulic pump fitted with a pressure compensator will:

  1. maintain constant displacement and rely on the relief valve for pressure control
  2. bypass all pump output to the reservoir whenever pressure is below the set value
  3. reduce displacement as system pressure approaches the set value Correct answer.
  4. increase displacement when system pressure rises above the set value

Explanation

A pressure-compensated variable-displacement pump reduces its displacement as system pressure reaches the compensator setting. This matches flow to demand and holds pressure without routing full pump output continuously over the relief valve.

Question 34Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

If the pitot tube is completely blocked but the static ports remain clear, the airspeed indicator during a climb will:

  1. remain at zero until the pitot drain becomes unblocked
  2. read correctly, because the static pressure is still sensed normally
  3. overread, as trapped pitot pressure exceeds static pressure Correct answer.
  4. underread, because trapped pitot pressure falls with increasing altitude

Explanation

With the pitot tube blocked, the pressure trapped in the pitot line stays constant. In a climb the static pressure falls, so the capsule senses a larger pressure difference and the ASI overreads; the error increases with altitude.

Question 35Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

A shimmy damper is installed on the nose landing gear of a light twin-engine aircraft. Its function is to:

  1. prevent the nosewheel from casting through 360 degrees during ground handling
  2. reduce the steering angle available to the pilot at high taxi speeds
  3. damp torsional oscillation of the nosewheel assembly about its steering axis Correct answer.
  4. assist the centring cams in returning the nosewheel to the straight-ahead position after a turn

Explanation

The shimmy damper is a small hydraulic or friction unit fitted between the fixed gear leg and the steering collar; it absorbs the energy of rapid castoring oscillations before they can build into shimmy. It exerts no restoring force, so it plays no part in centring the wheel. Steering limits and castoring stops are provided by separate mechanical stops or the steering mechanism.

Question 36Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

On most jet transport aircraft, the wing leading edge is protected against ice accretion by:

  1. cyclically inflated pneumatic boots on the leading-edge panels
  2. electrically heated resistance mats bonded to the leading-edge skin
  3. a glycol-based fluid weeping through porous leading-edge panels
  4. hot air bled from the engine compressors and ducted along the leading edge Correct answer.

Explanation

Transport jets use thermal anti-icing: bleed air from the engine compressor is fed through piccolo tubes inside the leading-edge slats or the wing D-nose, keeping the skin above freezing so ice cannot form. Electrical heating is normally reserved for propellers and small protected areas. Pneumatic boots and weeping-fluid systems are used on other aircraft categories and have insufficient capacity for a transport wing.

Question 37Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In an aircraft hydraulic system, an accumulator stores energy by:

  1. cooling the fluid and thereby reducing its volume
  2. compressing nitrogen against a bladder or piston that separates it from the hydraulic fluid Correct answer.
  3. holding a reservoir of fluid at a pressure below ambient
  4. driving a variable-displacement pump at a constant rotational speed

Explanation

The accumulator contains a gas charge, normally nitrogen, separated from the hydraulic fluid by a bladder, diaphragm or piston. Fluid pumped into the fluid side compresses the gas and stores energy, which is released to smooth pump pressure pulses, meet peak demands and maintain pressure when the pumps are not running. The stored energy is therefore held in the compressed gas, not in the fluid itself.

Question 38Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In a capacitance-type fuel quantity indicating system, the quantity of fuel in a tank is derived from:

  1. a float-operated rheostat that varies resistance with fuel level
  2. the hydrostatic pressure at the bottom of the tank sensed by a transducer
  3. the change in capacitance of a probe as fuel, which has a higher dielectric constant than air, replaces air between its plates Correct answer.
  4. the fuel mass flow measured at the engine and integrated over elapsed time

Explanation

The tank unit is a capacitor whose dielectric is the fuel/air mixture inside the tank. Fuel has a relative permittivity of about 2 against about 1 for air, so the capacitance rises as fuel fills the probe; the indicator converts this into a quantity, corrected by fuel density to display mass. This gives far greater accuracy in irregular tank shapes than a simple float system.

Question 39Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In an air-cycle air conditioning pack, the bleed air is cooled mainly by:

  1. passing it through a fuel-cooled heat exchanger in the wing
  2. mixing it directly with cold ram air before it enters the cabin
  3. expanding it through a turbine that extracts work, after it has passed through heat exchangers Correct answer.
  4. passing it through a Freon evaporator located in the mixing manifold

Explanation

Bleed air is first cooled in the primary and secondary heat exchangers by ram air or fan air, and the remaining heat is then removed by expanding the air across the turbine of the air cycle machine. Extracting work in the turbine drops both the pressure and the temperature sharply. The turbine work is used to drive the machine's compressor or cooling fan, making the cycle regenerative.

Question 40Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

A constant-speed drive (CSD) is fitted between the engine gearbox and an AC generator because:

  1. it keeps the generator rotor speed, and hence the output frequency, constant while engine speed varies Correct answer.
  2. it provides the torque required to start the engine from the APU generator
  3. it converts the generator's AC output into a constant DC voltage
  4. it limits the generator output to a value set by the current transformer in the GCU

Explanation

Generator frequency is proportional to rotor speed, so a generator driven directly from an engine would produce a frequency that varies over a wide range as engine rpm changes. The CSD is a hydraulic unit that accepts a variable input speed and delivers a constant output speed, typically 6000 rpm to give 400 Hz. It therefore decouples electrical frequency from engine speed.

Question 41Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

An aircraft has fully powered, irreversible flight controls. Artificial feel is required because:

  1. the pilot must be prevented from making any input that exceeds the design manoeuvre loads
  2. with irreversible controls the pilot receives no aerodynamic feedback, so control forces would not increase with speed and g-load Correct answer.
  3. the hydraulic actuators must be given a reference pressure in order to operate
  4. the control surfaces would otherwise flutter at high speed

Explanation

In an irreversible system the surface cannot back-drive the control column, so the natural link between airspeed, surface deflection and stick force is lost. Artificial feel, using springs, bob weights and Q-feel units, restores a force that rises with airspeed and with normal acceleration. This gives the pilot a tactile cue to the aerodynamic load on the structure.

Question 42Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

During a long acceleration on the take-off roll, an electrically driven artificial horizon shows a climbing indication although the aircraft is still on the ground. The reason is:

  1. the horizon bar has been locked by the fast-erection circuit
  2. the erection system responds to the apparent vertical, so forward acceleration tilts the indicated horizon upwards Correct answer.
  3. the gyro has not reached full speed and therefore lacks sufficient rigidity
  4. the synchronising knob has been left in the pulled position

Explanation

Pendulous erection devices align the gyro with the resultant of gravity and acceleration rather than with the true vertical. During forward acceleration the apparent vertical tilts rearwards, and the erection system slowly drives the gyro to match it, so the horizon bar rises and a false climb is shown. The error reverses during deceleration and disappears once the acceleration ceases.

Question 43Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

Which set of indications is most consistent with a compressor stall in a running turbojet engine?

  1. A gradual increase in thrust with a slowly falling EGT
  2. A steady, smooth rise in EGT with rpm and fuel flow remaining stable
  3. Rumbling or banging noises, fluctuating rpm and fuel flow, and a rapid rise in EGT Correct answer.
  4. A sudden drop in EGT together with a simultaneous rise in oil pressure

Explanation

A compressor stall is an aerodynamic breakdown of the flow over the compressor blades, so the affected stages cannot pass air smoothly and combustion becomes unstable. The classic signs are a deep rumble or bang, unstable rpm and fuel flow, a rapid rise in EGT and a loss of thrust. Severe stalls may cause a flame-out or mechanical damage, so power must be reduced and the engine handled in accordance with the flight manual.

Question 44Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In a transport aircraft engine fire-detection system with two detector loops and 'AND' logic:

  1. the second loop only confirms the warning after the extinguisher has been discharged
  2. a fire warning is given only when both loops detect a fire, and the loss of one loop is annunciated as a system fault Correct answer.
  3. both loops must fail before the fire extinguishing system can be armed
  4. a fire warning is given when either loop detects a fire, the second loop providing redundancy

Explanation

With AND logic the fire warning is triggered only when both loops sense a fire at the same time, which greatly reduces the chance of a false warning from a single faulty detector. If one loop fails, an AND warning can no longer be generated, so the failure is flagged on the fire panel and the crew applies the relevant procedure, which in many designs involves reverting to single-loop operation with the fault displayed.

Question 45Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

Transport aircraft tyres are normally inflated with dry nitrogen rather than compressed air mainly because nitrogen:

  1. eliminates the need for a pressure gauge during servicing
  2. is inert and reduces internal fire risk and wheel corrosion Correct answer.
  3. has a lower density, which reduces landing-gear weight
  4. increases the tyre's load-carrying capacity for a given inflation pressure

Explanation

Dry nitrogen is inert and contains no oxygen or moisture, so it does not support combustion inside the tyre and avoids corrosion of the wheel assembly. This is valuable when brake heat raises tyre temperature, because an oxygen-rich mixture under pressure can ignite if the tyre is damaged. Nitrogen does not change the tyre's structural load rating, remove the need for pressure checks, or produce a useful reduction in gear weight.

Question 46Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In an aircraft DC electrical system, a circuit breaker is preferred to a fuse for many services because a circuit breaker:

  1. provides a visual indication of busbar voltage
  2. can be reset in flight after an overload Correct answer.
  3. automatically restores power without crew action
  4. limits fault current more quickly than a fuse

Explanation

A circuit breaker trips on overcurrent and can be reset by the crew once the fault or overload has been removed, which improves dispatch reliability. A fuse performs the same protective function but must be replaced after operation. Neither device is a voltmeter, and a breaker does not restore power automatically without crew action.

Question 47Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

On a transport aeroplane, the Mach trim system becomes active at high Mach number in order to:

  1. apply nose-up trim to oppose the nose-down Mach tuck Correct answer.
  2. schedule the horizontal stabiliser for landing configuration
  3. limit the maximum cruise Mach number by reducing thrust
  4. increase rudder authority for engine-out control

Explanation

At high subsonic Mach numbers, shock-induced flow changes move the aerodynamic centre and produce a nose-down pitching tendency known as Mach tuck. The Mach trim system applies nose-up elevator trim to preserve longitudinal handling characteristics. It does not limit thrust, boost rudder authority, or configure the stabiliser for landing.

Question 48Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

The dorsal fin fitted ahead of the vertical stabiliser on many transport aeroplanes primarily improves:

  1. roll control during asymmetric flight
  2. longitudinal stability at forward centre of gravity
  3. directional stability at high angles of attack Correct answer.
  4. the effectiveness of the elevator at low speed

Explanation

A dorsal fin extends the effective vertical surface forward and smooths the airflow into the fin. At high angles of attack it delays blanking of the fin by the fuselage and wake, thereby improving directional stability. It does not primarily affect longitudinal stability, roll control, or elevator effectiveness.

Question 49Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

On a multi-stage axial compressor, variable inlet guide vanes are moved to:

  1. bypass excess air directly into the combustion chamber
  2. control the turbine outlet temperature during start
  3. prevent front-stage stall at low corrected engine speeds Correct answer.
  4. increase the compression ratio at all engine speeds

Explanation

At low corrected engine speeds the front compressor stages see excessive angle of attack and tend to stall or surge. Variable inlet guide vanes modulate the airflow direction so that the incidence remains acceptable across the operating range. They do not bypass air into the combustor or directly schedule turbine outlet temperature.

Question 50Aircraft General Knowledge (Airframe, Systems, Powerplant, Instruments)

In a modern transport aeroplane, the air data computer provides outputs to the flight deck and other systems by:

  1. controlling cabin pressure according to the selected flight level
  2. measuring aircraft attitude directly from the inertial reference system
  3. detecting ice accretion and automatically selecting wing anti-ice
  4. computing airspeed, altitude and Mach from pitot-static and probe inputs Correct answer.

Explanation

The air data computer combines pitot and static pressures with total air temperature and probe corrections to compute airspeed, altitude, Mach number and related parameters. These outputs feed displays, flight guidance and other aircraft systems. Attitude comes from inertial or gyroscopic sources, ice detection is a separate function, and cabin pressure is controlled by the pressurisation system.