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IDAC Private Pilot Airplane (PPA) study materials
IDAC Private Pilot Airplane (PPA) study resources

IDAC Private Pilot Airplane (PPA) practice questions

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Question 1Air Law and ATC Procedures

Under ICAO Annex 2, an aircraft on the ground must give way to which of the following?

  1. Only other taxiing aircraft of heavier weight
  2. Only emergency vehicles displaying a flashing blue light
  3. Aircraft and vehicles towing aircraft Correct answer.
  4. All vehicles operating on the apron

Explanation

Annex 2 right-of-way rules state that an aircraft taxiing on the movement area must give way to aircraft and vehicles towing aircraft, and also to aircraft that are being towed. This protects the less manoeuvrable combination of tug and towed aircraft.

Question 2Air Law and ATC Procedures

In ICAO airspace classification, what service is provided to all flights in Class C airspace?

  1. Advisory service only, with no clearances required
  2. ATC service to IFR flights only, with VFR flights receiving traffic information
  3. No ATC service; position reporting on a common frequency
  4. ATC service to IFR and VFR flights, with separation provided between IFR and VFR Correct answer.

Explanation

Class C requires ATC service for both IFR and VFR flights, and separation is provided between IFR flights and between IFR and VFR flights. VFR flights are separated from each other only by traffic information.

Question 3Air Law and ATC Procedures

A pilot receives the clearance "HOLD SHORT OF RUNWAY 27". What does this authorise?

  1. Taxiing up to but not entering or crossing the runway Correct answer.
  2. Entering the runway and stopping before the centreline
  3. Line-up on the runway and wait for a take-off clearance
  4. Crossing the runway and continuing to the apron

Explanation

A hold-short instruction requires the aircraft to stop before the holding position marking and not to enter or cross the runway. It is not a clearance to line up or cross.

Question 4Air Law and ATC Procedures

What is the meaning of a flashing red light signal directed at an aircraft on the ground?

  1. Return to starting point on the aerodrome
  2. Stop Correct answer.
  3. Taxi clear of the runway in use
  4. Cleared to taxi

Explanation

For an aircraft on the ground, a flashing red light means stop. Steady red also means stop, while flashing white means return to the starting point and steady green means cleared to taxi.

Question 5Air Law and ATC Procedures

An aircraft is flying in the vicinity of an aerodrome and receives a steady red light signal from the tower. What must the pilot do?

  1. Continue flying but be alert for other traffic
  2. Return to the aerodrome and land
  3. Give way to other aircraft and continue circling Correct answer.
  4. Land and proceed to the apron

Explanation

For an aircraft in flight, a steady red light means give way to other aircraft and continue circling. It is a traffic-conflict signal, not an instruction to land.

Question 6Air Law and ATC Procedures

Unless otherwise stated in the AIP, what is the standard transition altitude in a State that has not set a fixed value?

  1. 5 000 ft Correct answer.
  2. 18 000 ft
  3. 3 000 ft
  4. 10 000 ft

Explanation

ICAO Annex 2 recommends a transition altitude of 5 000 ft unless a different value is published in the State's AIP. The transition level is then established so that the lowest usable flight level lies above the transition altitude.

Question 7Air Law and ATC Procedures

A pilot sets the altimeter to the standard pressure setting. Which value is used?

  1. 1 000 hPa (29.53 inHg)
  2. 1 225 g/cm² (1013 mb)
  3. QFE at the departure aerodrome
  4. 1 013.2 hPa (29.92 inHg) Correct answer.

Explanation

The standard pressure setting is 1 013.2 hectopascals, equivalent to 29.92 inches of mercury. Setting it makes the altimeter indicate flight levels rather than altitudes.

Question 8Air Law and ATC Procedures

When must a pilot change the altimeter from QNH to the standard pressure setting?

  1. When passing 10 000 ft in any airspace
  2. When climbing through the transition altitude Correct answer.
  3. When descending through the transition level
  4. When advised by the tower that QNH has changed

Explanation

Climbing through the transition altitude, the pilot changes from the local QNH to the standard pressure setting and reports the flight level. Descending through the transition level, the pilot changes back to QNH.

Question 9Air Law and ATC Procedures

What is the minimum horizontal distance a VFR flight must keep from cloud when flying at or above 3 050 m (10 000 ft) AMSL in most ICAO States?

  1. 600 m
  2. 5 km
  3. 1 500 m Correct answer.
  4. 300 m

Explanation

At and above 3 050 m AMSL, VFR flights normally require 1 500 m horizontal distance from cloud and 300 m vertical distance. Below that level the usual minimum is 1 500 m horizontally and 300 m vertically in controlled airspace, with reduced minima in some classes.

Question 10Air Law and ATC Procedures

In Class G airspace at and below 900 m AMSL, what is the minimum flight visibility for a VFR flight in most ICAO States?

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

Explanation

In Class G airspace at and below 900 m AMSL, the standard VFR minimum flight visibility is 5 km, with the aircraft clear of cloud and in sight of the surface. Reduced minima may apply in some States for slow aircraft.

Question 11Air Law and ATC Procedures

A VFR flight at 4 500 ft AMSL on a magnetic track of 090° should normally be flown at which altitude?

  1. 4 500 ft Correct answer.
  2. 5 500 ft
  3. 6 500 ft
  4. 7 500 ft

Explanation

The semicircular rule assigns magnetic tracks from 000° to 179° to odd thousands plus 500 ft, and tracks from 180° to 359° to even thousands plus 500 ft. A track of 090° therefore uses 4 500 ft or 6 500 ft.

Question 12Air Law and ATC Procedures

Which document contains the rules of the air that a pilot must follow when flying internationally?

  1. ICAO Annex 19
  2. ICAO Annex 14
  3. ICAO Annex 2 Correct answer.
  4. ICAO Annex 17

Explanation

Annex 2 to the Chicago Convention, titled Rules of the Air, sets out the general rules, right-of-way, light signals and VFR/IFR provisions. Annex 14 covers aerodromes, Annex 17 security and Annex 19 safety management.

Question 13Air Law and ATC Procedures

What is the purpose of a clearance delivery position at a controlled aerodrome?

  1. To relay weather observations to departing aircraft
  2. To provide apron surface guidance to parked aircraft
  3. To sequence aircraft on final approach
  4. To issue IFR and VFR route clearances before the aircraft requests taxi Correct answer.

Explanation

Clearance delivery issues the ATC clearance, including route, level and squawk, before the aircraft calls ground for taxi. This separates clearance issue from surface movement control and reduces frequency congestion.

Question 14Air Law and ATC Procedures

An aircraft is instructed to "squawk 4271". What does this mean?

  1. Set the altimeter to 4 271 ft
  2. Contact approach on 427.1 MHz
  3. Report position at 42°71' north
  4. Set the transponder code 4271 Correct answer.

Explanation

Squawk is the instruction to select a four-digit SSR code on the transponder. The code 4271 is then used by ATC to identify the aircraft on radar.

Question 15Air Law and ATC Procedures

What does the transponder code 7700 signify?

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

Explanation

7700 is the general emergency code and alerts ATC that the aircraft is in distress or urgency. 7600 denotes radio failure and 7500 denotes unlawful interference.

Question 16Air Law and ATC Procedures

An aircraft on approach experiences two-way radio failure in IMC. Under ICAO procedures, what should the pilot do?

  1. Continue on the last assigned route and level, then descend in accordance with the published lost-communication procedure Correct answer.
  2. Squawk 7600 and maintain the last level indefinitely
  3. Circle overhead the destination until fuel is low, then land
  4. Immediately descend below cloud and land at the nearest aerodrome

Explanation

In IMC, the pilot should continue along the last acknowledged route and level, then follow the published lost-communication procedure for the destination, which typically includes a specified descent and approach. Squawking 7600 is part of the procedure but maintaining the level indefinitely is not.

Question 17Air Law and ATC Procedures

In a controlled aerodrome, what does a flashing green light from the tower mean to an aircraft on the ground?

  1. Cleared for take-off
  2. Return to the apron
  3. Stop immediately
  4. Cleared to taxi Correct answer.

Explanation

A flashing green light directed at an aircraft on the ground means it is cleared to taxi. A steady green light in flight means cleared to land, and a flashing green in flight means return for landing.

Question 18Air Law and ATC Procedures

What does a red and white vertical striped marker board at the edge of a taxiway indicate?

  1. The taxiway is a one-way exit from the runway
  2. The taxiway leads to a holding position
  3. The taxiway is unusable and the aircraft must not proceed Correct answer.
  4. The taxiway is restricted to aircraft above a certain weight

Explanation

A red and white vertically striped board marks a closed or unusable taxiway or a road that must not be entered. It is a mandatory instruction sign, not an information sign.

Question 19Air Law and ATC Procedures

A yellow taxiway centreline leads to a runway holding position marked by two solid and two dashed yellow lines. From which side may the aircraft cross?

  1. From either side, provided the aircraft stops first
  2. From the solid-line side, after receiving a clearance Correct answer.
  3. From the dashed-line side, without a clearance
  4. Only from the side facing the runway threshold

Explanation

The solid lines face the side where the aircraft must hold, and the dashed lines face the runway. The aircraft approaches from the solid-line side, stops at the marking, and crosses only when cleared.

Question 20Air Law and ATC Procedures

Which of the following best describes the purpose of a Mandatory Instruction sign at an aerodrome?

  1. To warn of a bird hazard near the taxiway
  2. To identify a location beyond which an aircraft may not proceed without ATC clearance Correct answer.
  3. To provide directional information to the terminal apron
  4. To indicate the distance remaining to the runway end

Explanation

Mandatory instruction signs have white characters on a red background and mark a holding position or restricted area that requires an ATC clearance to enter. They are distinct from information and direction signs.

Question 21Air Law and ATC Procedures

What is the standard emergency frequency monitored by many ATC units and aircraft?

  1. 123.45 MHz
  2. 121.5 MHz Correct answer.
  3. 118.0 MHz
  4. 243.0 MHz

Explanation

121.5 MHz is the international aeronautical emergency frequency in the VHF band. 243.0 MHz is the corresponding military UHF emergency frequency.

Question 22Air Law and ATC Procedures

A pilot flying VFR at night in controlled airspace must normally meet which additional requirement?

  1. The flight must remain below 1 500 ft AGL at all times
  2. The flight must be conducted under IFR rules regardless of weather
  3. The flight must be conducted with the aircraft's position and altitude reported as required by ATC Correct answer.
  4. The pilot must carry a second pilot at all times

Explanation

Night VFR in controlled airspace is permitted in many States subject to ATC requirements, including position reporting and the carriage of appropriate equipment. It does not automatically require IFR or a second pilot.

Question 23Air Law and ATC Procedures

Under ICAO rules, when may an aircraft be flown at a level below the minimum safe altitude?

  1. When taking off or landing, or when specifically authorised by the competent authority Correct answer.
  2. Whenever the pilot considers it safe
  3. Only when the aircraft is above 5 700 kg MTOM
  4. Only when flying VFR in Class G airspace

Explanation

An aircraft may not be flown below the minimum safe altitude except during take-off or landing, or when specifically authorised by the competent authority. The minimum safe altitude is set to protect persons and property on the ground.

Question 24Air Law and ATC Procedures

What does an ATIS broadcast normally contain?

  1. Search and rescue coordination instructions
  2. Individual ATC clearances for departing aircraft
  3. Radar vectors for arriving aircraft
  4. Current aerodrome weather, runway in use and other operational information Correct answer.

Explanation

The Automatic Terminal Information Service provides current weather, runway in use, approach aids and other operational data on a continuous loop. Pilots acknowledge the information by its letter when contacting ATC.

Question 25Air Law and ATC Procedures

An aircraft is cleared to "descend to 4 000 ft, report leaving 6 000 ft". What must the pilot do?

  1. Maintain 6 000 ft until advised
  2. Report at 4 000 ft only
  3. Descend and report when passing 6 000 ft Correct answer.
  4. Descend to 6 000 ft and hold that level

Explanation

The clearance authorises descent to 4 000 ft and requires a report when the aircraft leaves 6 000 ft. The report is a position report, not a restriction on the descent.

Question 26Air Law and ATC Procedures

Under ICAO Annex 2, an aircraft operating on the ground at an aerodrome where a control tower is in operation must obtain which of the following before taxiing?

  1. An ATIS acknowledgement from the tower
  2. An advisory from the ground movement service
  3. A clearance from the aerodrome control tower Correct answer.
  4. A flight information service broadcast

Explanation

Annex 2 requires that an aircraft on the manoeuvring area of a controlled aerodrome be operated only with the permission of the aerodrome control tower, normally obtained as a taxi clearance. The ground movement service is a function of the tower, not a separate authority that issues clearances, and information services do not grant permission to move.

Question 27Air Law and ATC Procedures

An aircraft is flying in Class C airspace under VFR. What is the minimum separation the pilot must maintain from cloud when the flight is above 900 m (3 000 ft) AMSL but below 3 050 m (10 000 ft) AMSL?

  1. Clear of cloud with the surface in sight
  2. 5 km horizontally and 300 m (1 000 ft) vertically
  3. 1 500 m horizontally only, with no vertical requirement
  4. 1 500 m horizontally and 300 m (1 000 ft) vertically Correct answer.

Explanation

In Class C airspace, VFR flights must comply with the standard cloud separation of 1 500 m horizontally and 300 m (1 000 ft) vertically when above 900 m AMSL and below 3 050 m AMSL. The reduced 'clear of cloud' criterion applies only in Class D and E airspace below 900 m AMSL.

Question 28Air Law and ATC Procedures

Which of the following best describes the meaning of a 'clearance limit' in an IFR air traffic control clearance?

  1. The maximum altitude at which the aircraft may file a flight plan
  2. The time at which a clearance automatically expires
  3. The point to which an aircraft is granted air traffic control clearance Correct answer.
  4. The level at which an aircraft must cross the destination aerodrome

Explanation

ICAO Annex 2 defines the clearance limit as the point to which an aircraft is granted an ATC clearance. It is normally the destination aerodrome but may be an intermediate point, and further clearance is required beyond it. It is a geographical point, not a level, time, or filing limitation.

Question 29Air Law and ATC Procedures

A pilot wishing to enter a control zone at a controlled aerodrome with a tower in operation should normally do which of the following?

  1. Notify the tower after landing of the time of entry into the zone
  2. Request entry clearance from the appropriate ATC unit before entering the zone Correct answer.
  3. Rely on the ATIS broadcast as authority to enter the zone
  4. Enter the zone and then advise the tower once established inside

Explanation

A control zone is controlled airspace, so an aircraft must obtain an ATC clearance before entering it. The clearance is requested from the unit responsible for the zone, usually approach or the tower. Entering first and advising later, or treating ATIS as authority, is not a clearance.

Question 30Air Law and ATC Procedures

An aircraft is being vectored by radar in controlled airspace and the controller issues a heading that would take it outside controlled airspace. Which statement correctly reflects the pilot's responsibility under ICAO provisions?

  1. The pilot is obliged to descend immediately to remain below controlled airspace
  2. The pilot should ignore the heading and continue on the flight-planned route
  3. The pilot must advise ATC before deviating from the cleared heading and remains responsible for terrain clearance unless an assigned altitude is being maintained Correct answer.
  4. The pilot may follow the heading without comment because ATC accepts responsibility for separation from all traffic

Explanation

A pilot may not deviate from an ATC clearance without advising ATC and obtaining an amended clearance, and the pilot in command remains responsible for terrain clearance unless an assigned altitude is being maintained. ATC separation does not relieve the pilot of that responsibility. Ignoring the heading or descending without instruction is not an acceptable response.

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

In a normally aspirated piston engine, what is the primary function of the carburetor heat control?

  1. To lean the mixture at high altitude
  2. To cool the engine oil during descent
  3. To warm the fuel-air mixture to prevent or clear carburetor ice Correct answer.
  4. To increase manifold pressure for climb performance

Explanation

Carburetor heat routes heated air from around the exhaust or heat muff into the induction system, raising the temperature inside the carburetor so that ice cannot form or existing ice melts. It is an anti-ice and de-ice tool, not a performance or mixture control. Pilots must expect a slight loss of power when heat is applied because the heated air is less dense.

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

Which instrument in a light airplane is directly connected to the static pressure source only, without any pitot-pressure input?

  1. Airspeed indicator
  2. Attitude indicator
  3. Vertical speed indicator
  4. Altimeter Correct answer.

Explanation

The altimeter and the vertical speed indicator both operate from static pressure alone, while the airspeed indicator needs both pitot and static pressure. The altimeter is therefore purely a static-pressure instrument. The attitude indicator is a gyroscopic instrument and does not use the static system at all.

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

What is the purpose of the magneto in an aircraft ignition system?

  1. To generate the high-voltage spark that ignites the fuel-air mixture Correct answer.
  2. To charge the battery while the engine runs
  3. To regulate the alternator output voltage
  4. To drive the engine-driven fuel pump

Explanation

A magneto is a self-contained, engine-driven generator that produces high voltage for the spark plugs without relying on the aircraft battery. This independence is why the engine keeps running even if the electrical system fails. The magneto supplies ignition, not charging or fuel delivery.

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

During a preflight inspection, you notice the tire has a flat spot worn through the tread to the fabric. What is the correct action?

  1. Reduce tire pressure to spread the load over a larger area
  2. Deflate the tire and defer the flight until it is replaced Correct answer.
  3. Operate the aircraft normally because the tire still holds pressure
  4. Note it in the logbook and fly only short local flights

Explanation

A tire worn through the tread to the fabric or cord is unairworthy and must be replaced; the aircraft should not be flown. Deflating the tire and grounding the aircraft prevents further damage or a blowout during taxi or landing. Airworthiness requires that tires have adequate tread and no exposed fabric.

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

What does the green arc on an airspeed indicator represent?

  1. The stall speed with full flaps
  2. The never-exceed speed range
  3. The normal operating speed range Correct answer.
  4. The flap operating speed range

Explanation

The green arc on a color-coded airspeed indicator marks the normal operating range, from the flaps-up stall speed at the lower limit to the maximum structural cruising speed at the upper limit. The yellow arc beyond it indicates caution, and the red radial line marks never-exceed speed. Flap speeds are typically shown by the white arc.

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

What is the primary purpose of cowl flaps on an air-cooled engine?

  1. To increase ram air for the carburetor
  2. To reduce drag during cruise flight
  3. To regulate cabin heat output
  4. To control the flow of cooling air over the engine cylinders Correct answer.

Explanation

Cowl flaps are adjustable doors in the engine cowling that regulate how much air flows across the cylinders and oil cooler. Opening them increases cooling during high-power, low-airspeed phases such as climb. Closing them in cruise reduces cooling drag and helps maintain cylinder head temperature.

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

In a fixed-pitch propeller airplane, what happens to engine RPM when you push the throttle forward in level flight?

  1. RPM increases because manifold pressure rises Correct answer.
  2. RPM increases only if the mixture is leaned
  3. RPM decreases because the load increases
  4. RPM stays constant because the propeller is fixed

Explanation

With a fixed-pitch propeller, blade angle cannot change, so engine RPM is governed directly by throttle setting and airspeed. Opening the throttle increases manifold pressure and power, which raises RPM. The propeller load rises with RPM, which is why RPM stabilizes at a new higher value rather than climbing without limit.

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

What is the function of the master switch in a typical light airplane electrical system?

  1. To select which fuel tank is in use
  2. To start the engine directly
  3. To switch the magnetos on and off
  4. To connect and disconnect the battery and alternator from the electrical bus Correct answer.

Explanation

The master switch is typically a split rocker that controls the battery contactor and the alternator field, connecting or isolating the electrical bus from the power sources. It does not crank the engine or control ignition. Turning the master off removes electrical power from most systems except the magnetos.

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

An airplane is climbing at a constant indicated airspeed. What does the altimeter indicate as static pressure decreases?

  1. A decreasing altitude because pressure is lower
  2. A fluctuating altitude due to pitot pressure
  3. An increasing altitude as the pressure altitude rises Correct answer.
  4. A constant altitude because the setting is unchanged

Explanation

The altimeter is an aneroid barometer calibrated to show altitude, so as the aircraft climbs and static pressure falls, the indicated altitude increases. The Kollsman window setting adjusts for local pressure but does not change the direction of the response. Pitot pressure plays no role in the altimeter.

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

What is the most likely indication of carburetor ice in an airplane with a fixed-pitch propeller?

  1. A gradual decrease in RPM with the throttle unchanged Correct answer.
  2. A steady increase in RPM at cruise
  3. A sudden increase in oil temperature
  4. A rise in manifold pressure with no throttle change

Explanation

Carburetor ice restricts the venturi and reduces the fuel-air charge, so a fixed-pitch airplane typically shows a gradual RPM drop with the throttle fixed. Applying carburetor heat should produce a further RPM drop as the ice melts, then recovery. Rising RPM or manifold pressure would indicate more power, not icing.

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

During cruise, the ammeter shows a continuous discharge with the alternator on. What is the most appropriate initial response?

  1. Increase electrical load to test the alternator
  2. Turn off the master switch and continue the flight
  3. Reduce electrical load and land as soon as practical to investigate Correct answer.
  4. Ignore it because the battery will recharge itself

Explanation

A continuous discharge with the alternator on indicates the alternator is not supplying the bus, so the battery is being drained. The pilot should shed nonessential electrical loads and plan to land before the battery is depleted, since radios and flaps may be lost. Turning off the master would remove all electrical power and is not a fix.

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

Why is it important to avoid abrupt throttle movements on a turbocharged engine?

  1. The propeller may reverse pitch
  2. The turbocharger may overspeed and exceed manifold pressure limits Correct answer.
  3. The fuel tanks may vent overboard
  4. The magnetos may fail to fire

Explanation

Rapid throttle advancement on a turbocharged engine can cause the turbocharger to spool up quickly and produce an overboost, exceeding the manifold pressure limit and stressing the engine. Smooth, gradual throttle movements allow the wastegate and controller to regulate boost. Overboost can cause detonation and engine damage.

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

What causes the fuel-air mixture to become richer as altitude increases in a carbureted engine without mixture adjustment?

  1. The carburetor automatically adds fuel at altitude
  2. Fuel density decreases faster than air density
  3. The float bowl pressure increases with altitude
  4. Air density decreases while fuel metering stays roughly constant Correct answer.

Explanation

As altitude rises, air density decreases, so less air mass enters the carburetor, but the fuel metering jet delivers approximately the same fuel flow for a given throttle setting. The result is an increasingly rich mixture, which is why the mixture must be leaned as altitude increases. Excessive richness causes rough running and reduced power.

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

What is the function of the vacuum system in a light airplane with vacuum-driven gyroscopic instruments?

  1. To provide cabin pressurization
  2. To operate the flaps and landing gear
  3. To pressurize the fuel tanks
  4. To spin the gyros in the attitude and heading indicators Correct answer.

Explanation

The engine-driven vacuum pump draws air through the gyroscopic instruments, spinning the rotors that give the attitude indicator and heading indicator their rigidity in space. Loss of vacuum causes these instruments to become unreliable, so a vacuum gauge is provided. The airspeed indicator and altimeter do not depend on vacuum.

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

What does a lean mixture at high altitude cause if taken too far?

  1. Higher fuel consumption
  2. Increased engine temperature and possible detonation
  3. Increased oil pressure
  4. Rough engine operation and loss of power Correct answer.

Explanation

Over-leaning reduces the fuel available to burn, so the engine runs rough and loses power, and cylinder head temperatures may rise before the engine quits. The pilot should enrich the mixture to restore smooth operation. There is a narrow range between peak power and roughness that must be respected.

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

What is the purpose of the crankcase breather in a reciprocating engine?

  1. To vent fuel vapors from the tanks
  2. To supply air to the carburetor
  3. To prevent pressure buildup in the crankcase Correct answer.
  4. To allow oil to drain to the sump

Explanation

The crankcase breather vents blow-by gases and pressure that escape past the piston rings, preventing seals and gaskets from being forced out. It also helps carry moisture and fumes out of the crankcase. If the breather clogs, oil can be forced out through seals.

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

What does a high cylinder head temperature indication in climb most likely suggest?

  1. The fuel selector is on the wrong tank
  2. The mixture is too lean or cooling airflow is insufficient Correct answer.
  3. The oil level is too high
  4. The magnetos are timed too late

Explanation

High cylinder head temperature during climb usually indicates either an excessively lean mixture or inadequate cooling from low airspeed and closed cowl flaps. The pilot should enrich the mixture, increase airspeed, and open cowl flaps as appropriate. Ignoring high CHT can lead to detonation and cylinder damage.

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

What is the function of the constant-speed propeller governor?

  1. To feather the propeller automatically on engine failure
  2. To reverse propeller thrust during landing
  3. To synchronize the engine to the tachometer
  4. To change the blade angle to maintain a selected RPM Correct answer.

Explanation

The governor senses engine RPM and adjusts oil pressure to the propeller hub to change blade angle, holding the selected RPM as load and airspeed vary. Pushing the propeller control forward selects a higher RPM set point. Feathering and reversing are separate functions not performed automatically by the governor in light airplanes.

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

During a static run-up, the engine magneto check shows a drop of 150 RPM on the right magneto and 50 RPM on the left. What does this indicate?

  1. The right magneto circuit has a problem and should be investigated Correct answer.
  2. Both magnetos are operating normally
  3. The engine is running too lean
  4. The left magneto is misfiring

Explanation

A normal magneto drop is typically around 50 to 125 RPM on each magneto, and the two should be reasonably balanced. A 150 RPM drop on one magneto exceeds typical limits and suggests a faulty plug, harness, or magneto on that side, so maintenance should investigate before flight. The 50 RPM drop on the left is within normal range.

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

What is the purpose of the fuel selector valve in a light airplane with two tanks?

  1. To prime the engine before start
  2. To automatically balance fuel between tanks
  3. To allow the pilot to select which tank supplies the engine Correct answer.
  4. To shut off fuel flow to the engine only during maintenance

Explanation

The fuel selector lets the pilot choose the tank or tanks feeding the engine, and it also provides an OFF position. Pilots manage fuel balance by switching tanks in flight according to the airplane's limitations. It does not automatically equalize tanks or serve as a primer.