CPL (H) Aircraft Technical General & POF Question bank.

Last compiled on - Friday 27th November 2023.

Please note, this is not official HPTC study material, student compiled.

These questions have been compiled from multiple sources.

Some questions are from the study books and others are from students who have
recently written SACAA exams. Study hard and remember RTFQ! (Read the fucking question).

Straight Roller Bearings are used for?

A. Rotary Loads

Tapered (Thrust) Roller bearings are used for?

A. Thrust & Radial Loads

Centrifugal type pumps are used for?

A. Fuel systems (no relief valve is necessary)

Vane type pumps are used for?

A. Fuel & Vacuum Systems

Diaphragm type pumps are used for?

A. Fuel Systems

Gear type pumps are used for?

A. Oil Systems

In-line valves (check valves) do what?

A. Allow fluid in owner direction only.

The type of bearing most commonly used between the connecting rod and the crankshaft on low
powered aircraft engines is?
A. A plain bearing or plain split-bearing.

Ferrous Metals are what?

A. A group of metals using Iron as their main constituent.

Duraluminium is what?
A. An alloy of copper and aluminium.

What are the different airframe structures?

A. Monocoque – Single shell structure where all flight loads are carried by the outer skin.
B. Semi-monocoque – A stressed skin structure, flight loads are carried by the outer skin and
internally by formers and stringers.
C. Extruded – A longeron or spar is made from one piece of metal.

How do you determine load factor?

A. LOAD FACTOR – L/W
Where L=lift caused by manoeuvre. W=normal aircraft weight.

What are the types of rotor systems?

A. Semi-Rigid – Feathering and Flapping.
B. Rigid – Feathering.
C. Fully Articulated – Lead/Lag, Flapping & Feathering.

1
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Types of tail rotor systems?

A. Fenestron.
B. NOTAR.
C. Anti-torque system.

A decrease in cyclic pitch angle does what?

A. Causes an equal decrease in angle of attack.

Low Frequency Vibrations (100-500 cycles/pm)?

A. Out of track main rotor blades.
B. Worn bearings/parts.
C. Dampers out of adjustment.

Medium & High frequency vibrations (1,000-2,000 cycles/pm)

A. Tail rotor.
B. Engine.
C. Cooling fans.
D. Components of the drive train.

What are the types of Hydraulic Fluid?

A. Vegetable based – Castor oil & Alcohol based – Blue Coloured – Flammable and not
temperature tolerant, unsatisfactory for use in high pressure systems.
B. Mineral based – Kerosene/Petroleum based – Red Coloured – Flammable, good for use in
high pressure systems.
C. Synthetic Fluid – Phosphate Ester based – Purple colour – Good fire resistance and suitable
for use in high pressure systems.

Filters are located where?

A. Low pressure filter – Between the reservoir and the pump.
B. High pressure filter – On the output side of the pump, either immediately or at some point in
the system before the fluid returns to the reservoir.

With regard to hydraulic systems, what does a hydraulic fuse do?

A. Prevent a loss of fluid if there is a leak in the system.

What can cause a hydraulic lock?

A. Air in the system.

With regard to tyre inflation –

A. Under-inflated tyres – Outer treads are worn out faster & impose larger sideways forces on
the tyre walls.
B. Over-inflated tyres – Maximum tread wear of the centre of the tyre.

Low hydraulic fluid in an Oleo Pneumatic strut can cause?

A. Insufficient Shock absorption.

Lightest part of an aircraft tyre is shown by what?

A. A red dot.

2
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

For a tyre with markings 24X10.00-16 what is meant?

A. Outside diameter – 24
B. Tyre width – 10
C. Bead diameter – 16

Most common type of rotor de-icing?

A. Electrically heated elements or bleed air from a gas turbine engine.
Rectifiers do what?
A. Convert AC into DC.

Transformers do what?
A. Allows both current and voltage in AC to be changed, can’t be used with DC.

Inverters do what?
A. Convert DC into AC.

With reference to an alternator does the stator move?

A. The stator remains stationary.

What is the electrolyte in a Lead-Acid battery?

A. Sulphuric acid & pure water.

Diodes are used in an AC alternator to?

A. Convert AC output into DC.

A Nicad batteries electrolyte is?

A. Potassium Hydroxide.

Nicad batteries can?

A. Accept a very high charge rate.

Blue smoke from the exhaust is caused by?

A. Burning oil – piston rings may be worn.

Black smoke from the exhaust is caused by?

A. If immediately after start – too rich a mixture during priming.
B. An unlocked primer pump, allows additional fuel to be drawn into the combustion chamber
during start.

A crankshaft is balanced by?

A. Attaching small counterweights to the crank cheeks.

Excessive crankcase pressure is relieved by?

A. Using a scavenge pump.

During operation of a reciprocating engine, what does the camshaft rotate at?
A. Half the speed of the crankshaft.

In a piston engine, the spark occurs at?

A. Roughly 20* before TDC.

3
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

If Pre-ignition occurs in a piston engine, what is the corrective action?

A. Richen the mixture.

In a piston engine, if only one EGT probe is used, it is inserted in?

A. The exhaust pipe of the hottest running cyclinder.

Detonation in a piston engine is caused by?

A. Use of a lower octane fuel.

High cyclinder temps are an early indication of?

A. Detonation.

At what % throttle does the economizer open?

A. 60%-70%

What is the temperature range for carburettor icing?

A. +5*C to +27*C.

The capacitor in a magneto is?

A. Wired in parallel with the breaker points to prevent arcing.

A breakage or disconnection of the magneto earth wire will do what?

A. Make it impossible to stop the engine by switching off the ignition.

An impulse coupling in a magneto does what?

A. Accelerates the magneto’s rotation and retards ignition to compensate for the low RPM.

A transformer is used in a LT Magneto system to?

A. Step up the low voltage to a high voltage before transmission to the spark plugs.

Normal operation of a piston engine would be indicated on the spark plugs by?
A. A light grey coating.

An ignition switch in a magneto is incorporated to?

A. Isolate the magneto by grounding its primary circuit.

The flash point of oil is the temp at which?

A. Ignitable vapour is released.

Straight mineral oil is typically used when?

A. During the first 50hrs of use on new and overhauled engines.

In the case of a wet sump lubrication system, the oil filter is located where?
A. Between the pressure pump and oil cooler.

A scavenge pump is used in which system?

A. A dry sump engine lubrication system.

4
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Accelerator pumps are used in some carburettor systems to prevent?

A. A flat spot during when throttle is opened.

What do swirl chambers do?

A. They force any fuel vapour upwards for return to the fuel tank.

Indications of bootstrapping in a turbo-charged piston engine are?

A. Fluctuating manifold pressure indications.

Turbine hot start symptoms are?

A. Excessive EGT/TOT. – Too much fuel and not enough air.

Turbine cold start symptoms are?

A. Engine turns but fails to light – A defective ignition or igniter plug and low battery voltage.

The 2 main components of a centrifugal compressor are?

A. An impeller and a diffuser.

In the case of a gas turbine which has started but fails to reach idling RPM?
A. Indication of a hung start.

Compressor surge symptoms include?

A. Vibration and a large EGT rise.

If compressor stall occurs what should you do?

A. Decrease power setting and increase forward speed.

One early sign of compressor stall is?

A. Rapid turbine temperature increase or fluctuation.

EPR (Engine pressure ration) is what?

A. The ration of jet pipe pressure to compressor inlet pressure.

Fires originating in electrically powered equipment are what class?

A. Class C fires.

Flammable liquid fires are what class?

A. Class B fires.

To extinguish class A fires, what is used?

A. A mixture of water and glycol.

The most appropriate type of extinguisher for cockpit electrical fires is?
A. A CO2 extinguisher.

Class A fire in the passenger compartment is best extinguished by?

A. Water extinguisher.

Brake or wheel fires are normally extinguished by?

A. Dry chemical powder extinguishers.

5
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

To maintain stability in the hover?

A. 4 elements need to be constant.

Inflow roll or Transverse effect?

A. Induced flow is greater at the rear and less at the front.

What is Ohm’s law?

A. Current flowing in a circuit is directly proportional to the applied voltage.

When waveforms cross the zero axis at the same time, they are known to be?
A. In phase.

In an ammeter, if the generator fails, it will indicate what value?

A. -5

What do relief and bypass valves do?

A. Regulate pressure.

Law about noise abatement procedure can be found where?

A. ENR Appendix 4.

Turbochargers & superchargers do what?

A. Increase the critical altitude.

A typical oil lubrication system consists of?

A. An Oil tank, pump, filter, cooler and oil jets.

A gear type pump includes?

A. A pressure pump and scavenger pump.

What do stators do?

A. They are angled to pass air onto the next stage of the rotor at the correct angle of attack.

What do final row stators do?

A. They guide the gas flow onto the turbine blades at the correct angle.

Hydraulic systems are duplicated for what reason?

A. So if one pump is failing/fails, the remaining pump will supply hydraulic fluid under pressure.

Drag effect (Torque)

6
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. Travels in the direction opposite to that of blade travel.

B. Total reaction is perpendicular to rotor thrust.
C. In-line with the relative airflow.

Anti-rotational force is produced across which regions of the blade?

A. The stalled and driven regions.

How is fuel identified?

A. Identification is via the different dyes.

What is “Stroke”?
A. The distance between TDC & BDC.

What do skids do?

A. Provide resistance to movement when the helicopter is placed on a slope.

What are the types of helicopter undercarriage?

A. Skids, Wheels and Floats.

Oleo (Shock Struts) do what?

A. Prevent the plunger tube from rotating within the cyclinder.

In the flare, A.O.A and coning angles increase, causing RRPM and rotor thrust to increase, this
causes?
A. The helicopter to slow down.

If the shaded areas in the height velocity diagram are flown in what danger does this pose?
A. It may not be possible to perform a safe autorotation.

Pulling the collective up moves the swashplate up vertically, what does this do to the blades?
A. Causes the blades to obtain the same increase in angle of attack.

What approach height and power configuration applies to a stuck right pedal?
A. A low power setting.

What should you expect from a tail rotor failure?

A. An immediate yaw to the right.

What is lateral stability?

A. The rolling plane around the longitudinal axis.

What are the available rotor brake systems?

A. Disk or drum type.

Electrical work is measured in?

A. Joules

Electrical power is measured in?

A. Watts.

7
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Electrical load is measured in?

A. Amperes

The transmission system consists of?

A. The main rotor gearbox, drive shaft, free wheeling unit, rotor brake and tail rotor gearbox

The freewheeling unit is what?

A. A sprag clutch type or engine-to-gearbox centrifugal type.

What is required when the transmission shaft takes a different direction?

A. An intermediate gearbox or a follow-on drive shaft.
What is phase lag?
A. When the rotor blade is at its highest/lowest position 90* later than the point at which the
pitch control input was initiated.

Modern light aircraft employ what magneto system?

A. A high tension magneto system.

When is a single ignition check performed?

A. At 2,000 RPM

Where is the impulse coupling fitted?

A. To the left magneto.

In a flare, the increasing rotor RPM causes what to occur?

A. The airspeed slows and translational lift disappears.

Grade 100LL (low lead 100 octane)

A. Contains medium level lead content.

Equilibrium means what?

A. A state of zero acceleration.

In a non-symmetrical blade, what happens when A.O.A increases?

A. As A.O.A increases, the centre of pressure moves forward.

What is Wash-out?
A. Wash-out is the reduction of blade angle from root to tip.

On the total drag curve, which drag remains constant for some time with an increase in airspeed?
A. Profile drag (See diagram provided).

What is disc area?

A. Area of the tip path plane.

What is disc loading?

A. The gross helicopter weight divided by the disc area.

What is blade area?

8
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. The total area of all the helicopter blades.

What is blade loading?

A. The helicopter gross weight divided by the combined area of all rotor blades.

Centrifugal force is determined by RRPM, in what direction does it act?

A. In-line with the plane of rotation.

Define translational lift?

A. The gain in height for no increase in power.

Tail rotor thrust is accelerated in which direction (anti-clockwise rotor system)?

A. Air is drawn from the right and accelerated to the left.
Downwash over the tail rotor produces an effect called the?
A. Coandra Effect.

As the rotor blade flaps up/down, the CofG moves aft on the axis of rotation.
A. The blades accelerate with a flap up, this is due to the coriolis effect.

What is the Hookes Joint Effect?

A. The tendency of the rotor blades to realign themselves with the shaft axis.

To sustain a helicopter in flight at a constant height, what is required?

A. A net rotor thrust upward equaling the net rotor downwash.

When is over pitching most likely to occur?

A. When approaching a hover.

Where does reverse flow begin?

A. On the retreating side at the root of the blade.

Increasing RRPM in a flare is as a result of what?

A. Lowering the collective if avoiding height gain, reduced rotor drag and conservation of
momentum.

In a flare, what can occur?

A. Relative airflow can approach from below the plane of rotation, the orientation of all forces
are brought closer to the axis of rotation and there is a decrease in rotor drag.

Why is angle of attack less at the blade tips v.s. the blade root?
A. Due to wash-out.

In an autorotation, what does the driving force attempt to do?

A. Accelerate the blade.

In a vertical autorotation compared to forward flight, what should you expect?

A. A high rate of descent.

In an autorotation in forward flight due to the cyclic being manipulated, what happens to inflow
angles and the ROD?

9
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. Larger inflow angles occur and a reduced rate of descent.

In an autorotation, increased disc tilt leads to what?

A. Smaller inflow angles and an increased rate of descent.

Outward movement of the 3 regions cause?

A. The driving and driven regions of the blade to be pushed out towards the tips.

The pattern flow around the disc as vortex ring develops causes?
A. An upward flow around the stalled regions of the blade which tends to merge with the
induced flow over the centre area of each blade.

What is ground resonance?

A. The deliberate or unintentional oscillation of the helicopter when in contact with the ground.
What are the causes off blade sailing?
A. The slowly rotating blade moves into wind and experiences a relatively large increase in
velocity causing it to flap up with great force.

What is dynamic rollover?

A. A moment produced by the horizontal component of total rotor thrust about the point on
contact with the ground.

What is the recovery for dynamic rollover?

A. As the cyclic cannot prevent it, lower the collective smoothly.

What is the most dangerous situation for mast bumping?

A. A negative or low-G situation.

Exceeding RRPM limits will result in?

A. Blade attachment stress and exceeding blade tip velocities.

If the main rotor stalls it will?

A. Pitch nose down and align itself with the ROD flow.

What does advance angle do?

A. Fully compensates for phase lag.

What is trim control?

A. The helicopters autopilot.

High frequency vibrations are likely caused by?

A. The tail rotor.

What are the benefits of an offset flapping hinge?

A. There is less pendulum action.

What condition decreases helicopter performance?

A. Low pressure, high humidity, high temperature.

What is the lift coefficient of an aerofoil determined by?

10
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. The A.O.A and shape.

The tip vortices that increase induced drag are?

A. Only the downward component as it increases downwash behind the blade.

When flying into a headwind while maintaining appropriate airspeed, what happens?
A. The range reduces but the endurance is not affected.

In a vertical autorotation, Tortola rotor thrust should?

A. Equal gross weight.

What is the purpose of the offset flapping hinge?

A. To encourage the fuselage to remain more or less parallel with the main rotor disc.

If high RRPM is experience during a high altitude autorotation what should you do?
A. Raise the collective pitch lever to counteract the high RRPM.

Lowering the collective pitch lever will do what?

A. Simultaneously decrease the blade angle at the rotor blades by the same amount.

As the angle of bank during a level turn is increased, additional engine power must be applied in
order to?
A. Counteract the increased centrifugal force.

Wash-out is incorporated into lake designs to do what?

A. Reduce induced drag.

What is the correct method of recovery from retreating blade stall?

A. To lower the collective.

Lateral stability in a helicopter refers to stability in which plane of motion?

A. The rolling plane.

Directional stability in a helicopter refers to stability in which plane of motion?

A. The yawing plane.

What is the effect of flapback?

A. To reduce the helicopters forward speed.

An increase of humidity affects the helicopters performance how?

A. Higher humidity leads to a decrease in lift performance.

The coning angle is determined by what?

A. The combined effects of rotor thrust and centrifugal force.

The effect of the driven blade region during autorotation is to?

A. Provide good rotation force.

11
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

If ground resonance is suspected following a landing and RRPM is sufficient for flight,
the most appropriate action is?
A. To lift off immediately.

If ground resonance is suspected following a landing and RRPM is insufficient for flight, the most
appropriate action is?
A. To lower the collective completely, reduce the power and apply the rotor brake.

The measurement of a rotor blade to rotate about the spanwise (pitch change) axis is known as?
A. Feathering

Feathering is achieved by?

A. Use of the collective and cyclic.

Increasing the gross weight of the helicopter causes?

A. An increase in the amount of recirculation.

What are the symptoms of retreating blade stall in a helicopter with anti-clockwise rotating blades?
A. The nose pitches up, rotor vibration occurs and a roll to the left.

What creates induced drag?

A. The lift produced by an aerofoil.

When considering the maximum forward speed of the helicopter, what is a potential limiting factor?
A. Retreating blade stall.

During a balanced level turn, total rotor thrust must equal what factor?
A. Only the helicopters weight.

If the forward speed of the helicopter increases, what else increases?

A. Dissymmetry of lift will also increase.

What occurs in flight if rotor thrust increases while centrifugal force remains constant?
A. The rotor disc area will decrease.

A change in angle of attack will cause what changes?

A. It will cause a change only on lift and drag values.

For a helicopter in straight and level flight at a constant speed, the total rotor thrust component
includes which other components?
A. The powered thrust component required to counteract parasite drag.

During an autorotation, what occurs to the ROD if speed is added?

A. If forward speed is added, the ROD decreases.

The angle between the chord line of the blade and the plane of rotation is referred to as?
A. The blade pitch angle.

During an autorotation, a decrease in RRPM will have what effect?

A. It will decrease the coning angle of the rotor blades.

12
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

When moving from OGE hover to IGE hover, what action must be performed to
maintain the hover?
A. The collective must be lowered in order to maintain the hover.

A change in pitch will cause an aircraft to rotate around which axis?

A. The aircraft will rotate around its lateral axis and centre of gravity.

When climbing, the maximum height gain in the shortest distance will be achieved by?
A. Climbing at the best angle of climb speed (Vx)

During a straight climb at a constant speed?

A. Lift is greater than weight.

The lift force produced by the aerofoil always acts in which direction?
A. Lift force acts perpendicular to the relative airflow.

On an aerofoil, the point through which the total aerodynamic forces act is called?
A. The centre of pressure.
If aircraft gross weight is increased, what happens?
A. There will be a greater increase in induced drag and parasite drag.

If power is required during a descent, but speed is kept constant, what occurs?
A. The ROD will increase.

Maintaining level flight, decreasing speed results in an increase in?

A. Induced drag.

TAS is?
A. CAS/RAS corrected for temperature and altitude.

Induced drag is created by?

A. The pressure difference between the top and bottom surfaces of the aerofoil.

Engine bleed air used for air conditioning and autorotation in a turbo-jet aeroplane is usually taken
from which stage?
A. The compression stage.

A capacitor in parallel with breaker points prevents?

A. Arcing across the breaker points.

What is a relay?
A. An electromagnetically operated switch.

What is a busbar?
A. A distribution means for electrical power.

When an open circuit occurs in an electrical supply system, what happens?

A. The loss of continuity will prevent its working component from functioning.

13
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

The working cycle of a four stroke engine is?

A. Induction, compression, power, exhaust.

A typical hydraulic systems consists of?

A. An actuator, a pump, a reservoir and a
switch.

The crank assembly of a piston engine is comprised

of?
A. The crankshaft, connecting rod and the
camshaft.

At what speed does the camshaft rotate?

A. Half the speed of the crankshaft.

In the case of a non-gravity fuel pump, the electrical fuel pump would?
A. Provide the pressure required for the fuel injection nozzles.

Centrifugal force acts in-line with?

A. The plane of rotation.
Most light aircraft use which type of battery?
A. Lead acid battery.

How many volts and does a lead acid battery produce and how many cells are approx. inside?
A. 24 Volts with approx. 12 cells.

A turbine aircraft uses what type of battery?

A. Nickel cadmium battery.

How many volts does a Nickel cadmium battery produce and how many cells are approx. inside?
A. 24 Volts with approx. 19 cells.

The main aerodynamic difference between hovering and forward flight is?
A. Tail rotor effectiveness.

Control orbit is what?

A. To orbit and transfer pilot cyclic and collective input to the blade.

Drag dampers are used for what?

A. To equalise the angular difference between 3 or more blade rotors.

A typical fuel system will consist of?

A. The fuel tank, float type content transmitter, electric booster pump, fuel filter and bypass
valve.

Failure of the alternator or generator would cause the load meter to indicate what value?
A. Zero.

A transformer rectifier does what?

14
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. Generates an AC current at high or low voltages.

What is viscosity?
A. The resistance of a liquid to flow.

Take off power may only be set for 5 minutes because?

A. As speed increase power demand decreases.

Vertical descent is dangerous for what reason?

A. The aircraft begins to settle into its own downwash which generally enlarges tip vortices and
can lead to vortex ring state.

The pistons are usually made of what material?

A. High strength aluminium alloys.

Torque can be used to reduce what?

A. The camber toward the blade tips.

As the helicopter slows down to almost zero, what must happen?

A. The rotor disc must be levelled by decreasing translational effect.

What is the primary function of a compressor?

A. To increase the pressure of the air at the LP air inlet duct.

Where is the clutch located?

A. Between the engine and the driveshaft.

An electrical circuit usually consists of what?

A. A power source, a load, a switch and a conductor.

A typical sequence of a fuel system would be?

A. A fuel tank, shut-off valve, fuel filter then fuel nozzle.

Airflow reversal first occurs where?

A. On the retreating side at the root of the blade.

Induced drag is proportional to what?

A. To the induced flow.

What are the primary fixed wing flight controls?

A. The airlerons, elevator and rudder.

What are the primary rotary wing flight controls?

A. The cyclic, collective and pedals.

Which component transforms hydraulic pressure into linear motion?

A. An actuator or jack.

As induced for decreases, what increases?

15
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. Airspeed.

Hydraulic fluid is dangerous to a persons?

A. Eyes.

What is the purpose of a pressure relief valve in a high pressure system?

A. To relieve over pressure if the pressure reducing valve malfunctions.

An inverter does what?

A. Converts AC into DC.

Piston engine consumption is defined as what?

A. Fuel required to produce unit power for unit time.

An incorrectly set pressure relief valve in an oil system would result in?
A. Low oil pressure.

The compression ratio in a piston engine is the ratio of?

A. The total volume to the clearance volume.

What is the turbochargers purpose?

A. To maintain power with increasing altitude.

When you are climbing and air density decreases, no fuel adjustment will result in?
A. A rich mixture.

When you are descending from operations at high altitude, no fuel adjustment will result in?
A. A lean mixture.

Gear type pumps are used for?

A. The piston engine oil pressure system.

Diaphragm pumps are used for?

A. Piston engine fuel system.

Vane type pumps are used for?

A. Low pressure relief valves.

Centrifugal pumps are used for?

A. Fuel systems.

A cut-out valve is a?
A. Pressure regulator.

What is a fuse?
A. A deliberate weak point in an electrical circuit.

What is a circuit breakers use?

A. To restore a circuit when it is reset.

16
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

What does a commutator do?

A. Changes AC waveform to DC waveform.

What does a Voltage regulator do?

A. Regulates voltage.

The busbar in a centre reading ammeter is positioned where?

A. Between the alternator and the ammeter.

The busbar in a centre zero reading ammeter is placed where?

A. Between the ammeter and the battery.

What are quick drain vales used for?

A. The inspection of water and dirt that may be present in the fuel.

A centrifugal pump used in a fuel system doesn’t need what?

A. A relief valve.

The most widely used material in aircraft manufacture is what?

A. Aluminium alloys.

Composite materials normally include?

A. Aramid and Hybrid.

During a steady co-ordinated turn, what is required?

A. Additional lift.

Sandwich structure designs are often used for what reason?

A. Because it has a low mass and high stiffness.

An empennage is what?
A. Horizontal and vertical stabilisers.

The shape of a stressed skin fuselage is provided by what?

A. The formers, frames and stringers.

Torsion is the load on a structure caused by?

A. Twisting.

Hydraulic fluid’s main purpose is what?

A. The transmission and distribution of power.

What is the reservoir for?

A. The retain a reserve supply to compensate for any leakage in the system.

What is a baffle’s main function?

A. To prevent excessive movement regarding fluid.

An additional hydraulic pump is used for what purpose?

A. To supply fluid under pressure to the main hydraulic pump.

17
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Accumulators do what?
A. Store hydraulic fluid under pressure.

How would you notice nose wheel shimmy?

A. Noticed by vibration.

Static pressure enters the instrument from a static intake located where?
A. Somewhere on the aircraft where speed has no influence.

The primer pump does what?

A. Sprays fuel into the induction system close to the inlet valve.

Control of the rate of air discharged from a pressurised aircraft is a function of?
A. Cabin outflow valves.

The operation of a bi-metallic switch in a fire warning system is a result of what?

A. The distortion created by the differential expansion of two metals closing an electrical circuit.

In order to prevent a vacuum forming in the fuel tank as fuel is used, what is employed?
A. Vents within the aircraft tanks.

After 20 minutes of flying with full tanks, the engine stops but restarts immediately after selection of
another fuel tank. What was the issue?
A. A blocked fuel tank vent.
The main power source of an electrical system is provided by?
A. The battery.

Voltage is described as?

A. The electrical pressure required to force electrons through a circuit.

Frequency is expressed in?

A. Hertz.

A cut-out relay prevents what?

A. The battery discharging through the generator.

Battery capacity is expressed in?

A. Ampere-hours.

What does an impulse magneto do?

A. Retards ignition.

The priming of a piston engine by using the throttle causes?

A. The accelerator pump to squirt fuel into the venturi.

The breather pipe on an engine is used to?

A. Relieve excess sump pressure.

The basic requirement for any ignition system to?

18
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. Deliver a high tension spark to the spark plugs in each cylinder.

What is the primary function of oil?

A. The reduce the friction between moving parts.

Supercharging and turbocharging do what?

A. Increase the manifold pressure.

A typical turbine ignition system consists of?

A. A relay, two DC ignition units and two igniters.

High frequency vibration usually ones from?

A. The engine or tail rotor.

During a flight under normal conditions, a main rotor blade is seen to be running higher than the
other blades in the disc during cruise, this can be adjusted by?
A. Adjusting the trim tabs on the subject blade.

When using a strobe type tracking and balancing system, one blade is not equidistant from the other
blades in the lateral plane, the cause of this defect is?
A. The drag dampers on the subject blade are not functioning correctly.

Why is the drive shaft between the main rotor gearbox and the tail rotor made up of several parts?
A. To allow for flexing of the airframe in flight.

In case an autorotation is performed while the engines have stopped the main gearbox is still
provided with lubrication, how is this achieved?
A. The rotor maintains main gearbox rotation.

Flexible couplings in the tail rotor do what?

A. Absorb angular differences arising from the bending of the tail.

The purpose of the clutch in the helicopter lubrication system is to?

A. Permit the engine to be started without loading.

Main rotor droops do what?

A. Prevent blades from drooping too far during low RRPM ensuring they do not strike the
airframe.

The purpose of rotating scissors is?

A. To transmit the drive from the rotor hug to the rotating swashplate.

A fully articulated rotor can?

A. Flap, feather and drag.

In tail rotor a the blades range from a negative and a positive angle setting to ensure?
A. They are able to adjust the amount of thrust produced.

For a free power turbine, what is significant?

19
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

A. The turbine driving the main rotor transmission is mechanically independent

from the gas generator.

A pressure relief valve in an oil lubrication system that isn’t seated correctly could lead to?
A. Low oil pressure.

Compressor stall is due to?

A. An excessively high angle of attack on the rotor blades.

A gas turbine is run at idle on the ground for a period of time prior to shutdown for what reason?
A. To prevent/reduce thermal shock.

An axial compressor includes?

A. A low and high pressure.

The sand filter located on the air intakes of a gas turbine engine reduce?
A. The efficiency of the air intake.

What is found within the gas generators turbine stage?

A. Stators and rotors.

The use of igniters in a gas turbine are?

A. For in-flight relights.

Engine auxiliary gearboxes provide power for?

A. Hydraulics, electrical and pneumatic systems.

The primary reason for venting and engine oil tank is?
A. To prevent excessive pressure in the tank.

The function of swirl vanes around the fuel nozzle is to?

A. Decrease velocity and enhance mixing of fuel and air.

The greatest risk created by free turbine over speed is?

A. The bursting of the free turbine disk.

A DC current to a step-up transformer is used to generate?

A. A higher voltage to the igniters.

In a compressor stage, the sequence is what?

A. Rotor then stator.

The function of a drain valve in a gas turbine combustion chamber is to?

A. Remove unburned fuel from the combustion chamber.

In a turbo-jet aircraft the purpose of the turbine is to?

A. Drive the compressor, using part of the energy from the exhaust gases.

Thermal stress is caused by?

A. Overcooking and overheating.

20
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

In a Bell 206, when reverse flow is used, it is because of?

A. The short construction time?…

The highest gas flow in a turbine is found where?

A. On entry to the turbine.

What is momentum?
A. Uniform motion along a straight line.

The reason for a negative and positive pitch angle on a tail rotor is so?
A. Control can be maintained throughout an autorotation.

The point where the laminar boundary layer changes into the turbulent layer is called?
A. The transition point.

Where do tip vortices occur?

A. Behind the blade, towards the tip.

Lift and drag can be influenced by?

A. The blade’s aspect ratio, RRPM, airspeed, A.O.A and shape.

The axis of rotation is?

A. Acts perpendicular to the plane of rotation, blades rotate around this axis.

What is the shaft axis?

A. In-line with the mast. This axis only coincides with the axis of rotation when the plane of
rotation is perpendicular to the shaft axis.
Coning angle is the angular difference between the feathering axis and?
A. The plane of rotation/tip path plane.

Lead/lagging is?
A. Forward/aft movement in the plane of rotation.

The rotor system providing the most control with inputs from the flight controls is?
A. A rigid rotor system.

Blade angle/angle of attack is?

A. The angular difference between the chord-line and the plane of rotation in the absence of
airflow.

Rotational airflow is?

A. Always parallel to the plane of rotation.

What is the inflow angle?

A. The angle between the plane of rotation and the resultant airflow.

Total reaction is determined by which elements?

A. Lift and drag.

21
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Drag acts in line with?

A. The relative airflow.

The coning angle is determined by the?

A. Rotor thrust and centrifugal force.

Total rotor thrust always acts in line with?

A. The axis of rotation.

Incorporating sweepback allows for?

A. Higher blade tip speeds.

Rolling tendency occurs when?

A. Translating tendency has been corrected for.

Rolling tendency is reduced by?

A. Reducing the couple lever arm, offsetting the rotor mast to the left and with correct loading.

A tail rotor placed on a pylon can reduce?

A. Rolling tendency.

The cyclic changes the?

A. Angle of attack on each blade individually.

The swashplate’s tilt is altered by?

A. The cyclic control.

The vertical position of the swashplate is altered by?

A. The collective inputs.
The twist grip throttle is used for?
A. Fine tune engine control.

The mean blade lag position.

A. The blades move aft on their lead/lag hinge.

Movement about the lead/lag hinge can be caused by?

A. The coriolis effect, the hooke’s joint effect, drag changes and random changes.

The blade flaps up/down and the CofG moves aft, the flapping up of the blade will?
A. Accelerate as a result of the Coriolis effect.

Hooke’s joint effect demonstrates itself when?

A. The axis of rotation and the shaft axis are not in-line.

What are the factors determining recirculation?

A. Gross weight, hover height, type of obstructions and distance from obstructions.

Where is vortex ring state most likely to occur?

A. When operating within confined areas.

22
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

As the helicopter accelerates from the hover into forward flight, what happens?
A. Thrust and parasite drag produce a nose down couple.

The vertical component of total rotor thrust and weight produce?

A. A nose down couple.

A helicopter is in equilibrium when?

A. Flying straight and level at a constant airspeed.

When the airspeed reduces what happens?

A. The nose of the helicopter comes up and the tail comes down as a result of pendulum
action.

When raising the collective through precession, the?

A. Find answer…….

Designs reducing flapping amplitude?

A. Delta-3 hinges and offset pitch horns.

Reverse flow travels from?

A. The trailing edge to the leading edge.

The power required to drive the tail rotor becomes less when?
A. Translational lift is achieved, the horizontal and vertical stabiliser take over most of the work.

For a helicopter hovering in calm conditions a few inches off the ground?
A. Total rotor thrust is exactly equal and opposite to the gross weight.

The airflow resulting from the ROD, the rotor thrust increases because of?
A. The reduced induced flow, inflow angles decrease and angle of attack increases.
What is inertia?
A. The resistance to a change of speed and direction of travel of a mass.

In a flare the angle of attack increases and?

A. Induced flow decreases, total rotor thrust increases and rotor drag decreases.
Check this question…

Thrust reversal in a flare does what?

A. Slows the helicopter down, the fuselage pitches up and parasite drag reduces.

In a flare RRPM increase due to?

A. Lowering the collective to avoid height gain, the conservation of angular momentum and
reduced rotor drag.

As a result of the flare what occurs?

A. Airspeed decreases and translational lift is lost.

Flaring the helicopter downwind should be avoided as?

A. It could lead to vortex ring state.

23
CPL (H) Aircraft Technical General & POF Question bank.
Last compiled on - Friday 27th November 2023.
Please note, this is not official HPTC study material, student compiled.

Flaring the helicopter with a high airspeed while travelling downwind could lead to?
A. The tail boom striking the ground.

Describe the symptoms of retreating blade stall?

A. The nose pitches up and the aircraft rolls towards the retreating side.

Any recovery from retreating blade stall should include?

A. Reducing the blades angle of attack by lowering the collective.

Placarding of Vne information in helicopters normally assumes ?

A. maximum gross weight loading.

What is the initial reaction of the aircraft when the engine fails?
A. The disc flaps forward, the aircraft yaws and then rolls to the left.

The stalled and driven regions must be controlled carefully as they produce?
A. Anti-rotational force.

When the helicopter flares towards the end of an autorotation, the outward movement of the three
regions cause?
A. The RRPM to increase.

Tail rotor thrust is produced by (Anti-clockwise rotor system)?

A. Air being drawn in from the right and accelerated to the left.

The pilot control linkage (cyclic control) is always connected to the?

A. Stationary swashplate.

The construction used most in tail rotors is?

A. The semi-rigid rotor.

The main reason for high frequency vibrations from the tail rotor are?
A. The long lever arm where destabilising forces act with higher RRPM.

An advantage of the offset flapping hinge is?

A. There is less pendulum action.

24