New Zealand CPL Aircraft technical knowledge and loading
Describe the common methods of cross feeding fuel.
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Describe the general rules for refueling an aircraft, and the correct use of fuel tank dipsticks and magna-sticks.
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Describe the normal handling of the power control for a single lever control system: (a) when the aircraft is on the ground; (b) for 'exercising' the CSU; (c) prior to take-off and landing; (d) when increasing or decreasing power in the air.
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Describe the typical vertical and lateral operational modes.
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specific gravity and the weight of fuel.
0.72kg/L
Horsepower conversions
1 HP=550ft lbs =3/4 KW
In a typical aircraft engine, explain the function of: (a) cowling ducts and baffles; (b) cooling fins; (c) pilot-operated cowl flaps; (d) oil cooler; (e) radiator; (f) intercooler
(a) cowling ducts and baffles; are carefully placed to direct a smooth flow of air through the fins around each cylinder (b) cooling fins; Increase the surface area of the cylinder head for greater cooling (c) pilot-operated cowl flaps; gives pilot more control over the cooling of the engine. (d) oil cooler; (e) radiator; (f) intercooler
(n) gross weight;
Gross weight , the total weight of the aircraft
Explain and define the speed limitations for landing gear operation.
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Explain the meaning of : (a) battery capacity; (b) thermal runaway.
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Explain the normal symptoms of intake ice formation, and the correct use of alternate air sources.
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For a constant speed propeller, differentiate between the functions of the propeller (pitch) control and the throttle control, when the propeller is: (a) in the constant-speed range; (b) below the constant-speed rpm range.
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Outline the service limits and tolerances for a direct-reading compass.
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Solve the following loading problems: (a) loading or offloading weight and find new CG position; (b) loading or offloading weight to place the CG at a given station; (c) loading or offloading weight at a given station without exceeding CG limits; (d) moving weight from one station to another and finding new CG position; (e) establishing payload available given a maximum zero fuel weight.
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With respect to carburettor air intakes, explain the correct use of ram air, filtered air, carburettor heat.
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Max amount of drift for DI
16 degrees
Describe the distinguishing features of aviation turbine fuel (AVTUR) and state the difference between the decals used on AVTUR and AVGAS fuelling equipment.
AVTUR is a kerosine type fuel. It has a distinct smell and is straw coloured or clear. AVTUR DECALS are black and white. AVGAS decals are read and white.
Describe the features of undercarriage construction; explain the operation of an oleo-pneumatic shock strut.
Can have a leaf spring or bungee construction, oleo-pneumatic landing gear consists of two tubes which telescope together using compressed air to help absorb the shock .
Define the terms: Engine Torque and Engine Power.
Engine Torque is the turning effect or the amount of effort that the engine can produce on the crankshaft. The engine torque is the force the engine exerts on the propeller. Brake Engine Horse Power: is the actual power output from the crankshaft. Indicated Horse Power: the power developed inside the engine cylinders for the combustion process. The indicated power is always larger than the Break power BHP=IP-Friction power friction Power: the power lost in driving engine accessories and oil pumps Rated Power= break power under standard running conditions at the stated RPM
Distinguish between a turn indicator (TI) and a turn coordinator (TC).
Exactly the same indication, except the needle is replaced by that of a small aircraft. TC show roll as well as rate of turn.
With the aid of diagrams, explain the method of operation of typical pitch changing mechanisms.
For hydrolic types, engine oil is often used. The simplest type is the movable piston cylinder type.Uses a hydrolic cylinder to coarsen pitch with a mechanical link. Fixed position movable dome type, high pressure oil moves dome forward and coarsens the pitch. The Pitch will then move back towards fine under the influence of the CTM. Can use counter weights to make the prop system reverse. Reversible electric motors can also be used by a system of gears
Explain the following errors which the DI is subject to: (a) gimbal error; (b) real drift (or real wander); (c) apparent drift (or apparent wander); (d) low rotor speed.
Gimbal error results from unwanted precession when the orientation of the rotor axis and longitudinal axis is not a required. Not a problem except in steep turns. real Error- caused by frictional forces within the rotor and gimbal system causing unwanted precession. Apperant drift- due to the earth's rotation in new zealand the error is about 11 degrees/hour this can be corrected for by the use of a precession nut. If there is to much suction the rate of precession increases and vice versa
Valve overlap
then both valves are open
Distinguish between suction pump, venturi, and positive pressure systems.
vacuum pumps suck air out of instruments, can be engine driven. Venturi Tubes can be mounted on the outside of the aircraft which provides suction for the plane.
blow down
valve leads assist scavenging of the exhaust gasses by giving theme more time to escape, and by utilizing the pressure in the cylinder to blow out the exhaust gasses
Explain fuel octane ratings and performance numbers.
Iso-octane is a hydrocarbon with good anti-knock possibilities. It can be used to create A performance Number, A fuel which is 100 Octane has the same performance as Iso-octane
maximum certificated landing weight (MCLW)
Maximum certivied gross weight for landing
(g) index units;
Moment/10000
With the aid of a diagram, explain the principle of operation of a turn indicator.
The turn indicator indicates the rate of a particular turn. Precesional force of an aircraft's turn is balanced against the restraining spring. If the aircraft is being exposed to a force greater than 1 g, the Ti will over read.
(m) ramp weight;
The weight of the aircraft prior to the start of the taxi,
With the aid of diagrams, describe simple 'two-wire' and 'single wire' grounded electrical circuits.
Two wire use a wire for return, single wire systems use the aircraft body.
State the fundamental operating principle of the reciprocating (piston) engine.
A gas will expand if it is heated, if, however, the gas is confined and unable to expand freely, then the pressure of the gas will increase when heat is applied. pv=RT which applies to perfect gasses
Explain the general conditions for the most efficient engine operation.
A low RPM Reduces friction Losses and improves volumetric efficiency The Higher MAp (manifold pressure) The higher map means that to obtain the required power the throttle is wider open, Improving Volumetric efficiency Leaning the mixture Having the aircraft at altitude Works best if the aircraft is at full throttle height, engine breaths better and the colder air increases performance. Carborator heat on cold
Explain 'electromagnetism' and with the aid of diagrams, show the lines of magnetic force around a straight conductor and a coil.
A magnetic field is present whenever there is an electric current present See diagram 9-11
Describe the function of the: (a) air data computer; (b) signal generator; (c) input data sources to a basic glass flight display system.
A signal must be generated in digital format, and transmitted to the computer. The air data computer, takes analog data sources and converts then into digital data. Raw data are: static pressure, pitote pressure, total temperature, angle of attack, These are transpitted to the data transmitter os altitude, vertical speed, CAS, TAS, Mach, Vmo, Angle of Attack, TAT, SAT.
Explain the operation of anti-skid brake systems.
AC generator gives an output for each wheel in proportion to the speed of the wheel. Whenever a certain amount of negative acceleration is exceeded, it activates an anti-skid valve
(k) payload;
AKA Commercial load includes passengers, their baggage, freight, cargo etc.
(j) basic operating weight (aircraft prepared for service weight);
AKA aircraft prepaired for service weight this includes Basic Empty Weight, pilot and crew, crews baggage, food, water etc. The total Minus Payload and Fuel
Centrifugal Twisting moment, (CTM)
Acts through the centres of mass on either side of the pitch-change axis, they therefore have an effect of the pitch-blade angle, acting towards pulling the blades into fine pitch
Explain the term ignition timing and the need for spark advance.
After The spark there is a small delay in which the flame begins to grow and the compression stroke slows down therefore the initiation of charge must be 15-40 degrees before the spark advance Usually set at an optimal 25 degrees
Describe the general operating limitations of air-driven and electrically-driven AH.
Air driven limits are typically 5 pitch and 90 role modern instruments have 60 pitch and 110 role. In electrical the movement freedom is greater, unlimited in some instruments
Briefly explain the advantages and disadvantages of pneumatic systems versus hydraulic systems.
Air is Universally available and inexhaustible, Air is lightweight Simplicity-very simple construction no fire hazard Not suitable for the operation of large or heavy units Can be a delay and lack of precision in control operations. Difficult to provide air-tight seals and to replace leaks.
Describe the performance reductions associated with: (a) ice accumulation; (b) operation of anti-ice and de-icing equipment
All reduce performance
Explain the need for the following in an aero-engine carburettor: (a) atomization and diffusion; (b) accelerating system; (c) idling system; (d) power enrichment (economizer) system; (e) mixture control and cut-off system.
An atomonization and Diffusion system: at the main jet outlet to improve the vaporization of fuel. an Idling system to provide sufficient fuel for engine operation when the butterfly is closed or nearly closed. and the fuel flow form the main jet becomes unreliable. An acceleration system to increase and match the rate of fuel flow to the increase in the rate of air flow when the throttle is opened. An enrichment which provides extra fuel when the throttle approaches and reaches its wide open system this excess fuel does not burn, but provides cooling through evaporation at high power settings which helps to prevent detonation and overheating mixture control, and idle cut-off systems
Explain the consequences of operating with over-rich and over-lean mixture settings.
An over-rich mixture can cause loss of power, rough running, fouling of the spark plugs and possibly formation of lead deposits on the piston heads and valves. Extra Fuel in the cylinders cools them through evaporation. An Over-lean mixture at high power settings will cause excessively high cylinder head temperatures, possibly leading to detonation. This can cause a loss of power or complete engine failure.
Aerodynamic Twisting Moment (ATM)
Arises whenever the centre of pressure of the propeller blade does not act on a line through the pitch change axis. Acts to coarsen the blade angle, negligible in comparison to CTM.
Explain the differences between aviation gasoline (AVGAS) and motor gasoline (MOGAS).
Avgas is formulated to meet different requirements under stricter quality standards then MOGAS. Avgas Has a higher octane (its more leaded)
Bore
Bore: the internal diameter of the cylender.
Bottom dead centre (BDC)
Bottom dead centre (BDC): the position of the piston when it is the minimum distance from the crankshaft.
Explain the following in broad terms: thermal efficiency, mechanical efficiency, and volumetric efficiency.
Break Thermal Efficiency =Break power/ Fuel Consumption The inverse is the break specific fuel consumption = FF/BP Mechanical efficiency is part of the overall thermal efficiency =BP/IP The efficiency of the Induction charge is Volumetric efficiency. =Volume of charge/piston displacement
Describe the function and operation of a typical TCAS system.
Can avoid collisions with any Transponder equipped aircraft (mode C or mode S) Can issue warnings, or instructions depending on the type installed.
outside air temperature gauges;
Can be bi-mattalic strip type -uses a bi-mattalic helix usually brass and iron strips are used. Can also use the mechanical bulb system.
Explain the reasons why excessively high engine temperatures and rapid cooling must be avoided.
Can cause the cylinder heads to crack.
Clearance Volume
Clearance Volume : the space or volume above the piston when it is at TDC.
Detail the actions recommended in the case of loss of power through faulty fuel selection.
Close the throttle, Check the fuel tank selection, Tun on Electric Fuel Pump, set mixture Full rich.
Compression Ratio
Compression Ratio: The ration of the piston at BDC to the space above the piston at TDC, therefore: compression ratio = (Swept Volume + clearance volume) / clearance volume
Describe the function and principle of operation of a cockpit fitted or portable oxygen system.
Constant flow system: Provide the same amount of flow regardless of altitude Altitude Adjustable System: has a knob to set the regulator for the right amount of oxygen Altitude Compensation Systems: Automatic Adjustment for altitude
With the aid of a diagram, explain the principle of operation and limitations of: (a) a vertical speed indicator (VSI);
Contains a flexible capsule which is vented to the outside world via an outside vent. A metering unit which acts as a restricting element on the passage of air through it. Correct rate of climb and decent is given regardless of altitude.
Explain the principal differences between continuous flow fuel injection, and direct fuel injection systems.
Continuous flow is when fuel is injected directly into the intake manifold air at the inlet port of each cylinder. In direct acting systems, the fuel is injected into the cylinder head.
cycle
Cycle: the order of events while an engine is running, for a piston engine: -the introduction of fresh fuel-air mixture into the cylinder -compression and ignition of the mixture - expansion of the ignited charge and absorption of the energy -expulsion of the combustion products
Distinguish between the way in which fuses, circuit breakers and overload switches operate.
If a fuse wire shorts the circuit, the circuit breaker will pop out and stop the current before it causes a problem. Overload switches will switch themselves off if the voltage goes over a set limit.
Explain the diagnosis and dangers in the handling of electrical malfunctions including: (a) an excessive charge rate; (b) alternator/generator failure; (c) resetting of blown fuse/popped circuit breakers; (d) use of fuses as a switch; (e) issues related specifically to "technically enhanced aircraft" (TEA).
Insufficient current to charge the battery- indicates a constant negative charge. Too much current, in this case the current will indicate an abnormally high positive rate. You can normally reset a circuit breaker once only, provided there is no smell. Do not replace a fuse with one of a higher rating. It is normal to wait a couple of minutes to allow the circuit to cool down.
Describe the components and operation of a Attitude Heading Reference System (AHRS) system.
It is an integrated gyroscope system that provides attitude heading yaw and role information, Might also incorporate electro mechanical gyroscopes.
Explain the following errors affecting a VSI; (a) lag; (b) position error.
Lag is that it takes the VSI a couple of seconds to adjust to this. So a IVSI has be developed using a g-force induced suction to help offset the lag of the VSI. Position error- caused through fluctuations of the static vent.
Left-zero Ammeter Center-Zero ammeter
Left Zero ammeter indicates only the load which is placed on a ammeter, nothing to do with battery centre-zero ammeter measures current flow into and out of the battery
Explain the advantages of using hydraulics to operate aircraft services.
Lightweight, provide for ease of installation, have minimum maintenance requirements. Efficient, only small losses in fluid friction.
Pascal's Principle
Liquids are Virtually incompressible
Explain the main functions of the engine oil system.
Lubrication Cooling Cleaning
Explain The gasoline fuel colours in New Zealand
MOGAS 91-purple MOGAS 96-yellow 100LL-Blue 100/130-green 115/145-purple Kerosine-Straw
Explain the caution against using automobile fuel (MOGAS) in an aircraft engine, unless specifically authorized.
MOGAS is more Volatile than AVGAS and Vaporizes More Readily . Do not use MOGAS unless it is specificity authorized in the aircraft.
With the aid of a diagram, describe the principle of operation of a simple alternator (a magnet rotating inside a loop conductor).
Magnetic field induces EMF
Manifold Pressure
Manifold Pressure: the pressure of the fuel-air mixture exiting at any one time in the induction manifold Crank angle: the number of degrees of crankshaft rotation
Manifolds
Manifolds: the system of pipes and ducts which leads the fuel-air mixture from the carborator into individual cylinders.
With respect to a four-stroke piston engine, state the meaning of the following terms: cycle, stroke, top dead centre (TDC) and bottom dead centre (BDC), bore, clearance and swept volumes, compression ratio, firing interval, firing order, manifolds, manifold pressure and crank angle.
Manifolds: the system of pipes and ducts which leads the fuel-air mixture from the carborator into individual cylinders. Manifold Pressure: the pressure of the fuel-air mixture exiting at any one time in the induction manifold Crank angle: the number of degrees of crankshaft rotation
Explain the operation and the proper handling of, mechanical, fluid and thermal ice protection systems.
Mechanical Systems use a rubber boot fitted to the critical surface which has tubes which can be inflated pnumaticly and then rapidly deflated to knock all of the ice off. The ice has to be the right thickness or the boot may become ineffective Fluid systems- utilize a de-icing fluid which can be excreted by the aircraft wing Thermal systems- use the introduction of heat either by bleeding air from the engine or electrically.
With the aid of diagrams: (a) describe mechanical advantage; (b) show how this can be gained hydraulically; (c) describe the principle of operation of typical aircraft hydraulic services
Mechanical advantage is when a small force is used to gain a larger force elsewhere. If a smaller piston has a greater pressure than the larger piston, the smaller piston will have the mechanical advantage, but it will have to move further.
oil temperature gauges
Mechanical bulb type- puts a volatile chemical in a temperature probe, as the temperature increases more of it turns to gas and the pressure increases in a sensitive bourdone tube. The electrical radiometer thermometer (resistance thermometer) Consists of a coil in the oil which changes its resistance when heated. Carbourater air temperature gauges operate using the same principles.
Explain the correct use of the mixture control.
Mixture is usually at full rich for take off, unless field elevation is exceptionally high. To lean the mixture the mixture control should be slowly moved towards the lean position. The RPM will increase slightly and then the mixture will become more theoretically correct, afterwords the RPM will decrease and the engine will be rough running, the correct position is slightly rich of max rpm. Mixture is then put at full rich at top of decent during flight. Some aircraft will have an EGT gauge which temp will peek at the Chemically correct ratio
Describe the construction of aircraft wheel assemblies and tyres.
More wheels are used in larger aircraft to provide that there is a sufficiently large enough footprint to spread the load and provide sufficient traction for breaking. To facilitate easier stowage in the wheel bays after take off
fuel quantity, fuel flow gauges and fuel flow gauges.
Most common is the flote type which has a flote which varies the resistance of the gauges depending on the height of the flote in the tank. Another uses a series of capacitance probes which use the difference in electrical conductivity of the water when making the capacitance. Fuel flow will be indicated on supercharged engines, usually by a vane type fuel flow meter.
Describe the essential features of a retractable undercarriage system.
Most gear is retractable, but can be mechanical, also can include doors to cover the gear in flight
Describe common fire extinguishing systems and the limitations with their use
Normally held in a pressurized bottle which can be released electrically. Can also Be automatically discharged in the event of a crash by inertia switches.
With respect to oil grades, differentiate between the commercial aviation numbers and SAE ratings and the significance of the oil grade.
Oils are graded by their Viscosity,Commercial aviation oil has a commercial aviation number which = twice the oil grade given by the society of automotive engines.
Explain the function and operation of static discharge wicks and bonding strips.
On the trailing edge of wing and tail components, Static wicks are installed to dissipate any charges which might build up Bonding strips ground the aircraft components, keeping them at the same electrical charge.
Explain operational principles for the handling of the electrical DC system, including: (a) avoiding overheating electrical services if operated during pre-flight; (b) not starting or stopping the engine with unnecessary electrical equipment switched on; (c) checking satisfactory operation of the alternator/generator after start, and periodically during flight; (d) use of a ground power unit.
Only operate landing lights briefly for systems as well as pitote heat. large voltage fluctuations when the alternator turns on or off may destroy circuits. After start up the ammeter should show a positive flow and then go to zero once battery is charged. ensure the electrical switches are switched off after flight.
Indicated Power= PLANK
P=Net Indicated Mean Effective Pressure L=length of stroke A=area on top of Piston N=speed of engine K=#of cylinders
With the aid of schematic diagrams, describe the operation of a typical hydraulic system.
Pg 16-10 can be Temporary or Pressurized
Distinguish between primary and secondary cells, wet-cells and dry cells, leadacid and nickel-cadmium (and similar) types.
Primary Cells Cannot be recharged, Secondary cells can be recharged,lead acid which is the wet cell type nickel cadmium is als a wet cell type
Describe the types of failure which can affect the CSU, including the conditions which can lead to a 'runaway propeller' and the required remedial action.
Prop normally becomes a fixed pitch propeller. If it is at full course, it will not be able to deliver power for a baulked approach. if a negative angle of attack is achieved on the prop this could cause a runaway propeller. If this happens, retard the throttle, reduce the airspeed by raising he nose of the aircraft, place the pitch control to full course.
Explain the function and operation of the alternate static system.
Provides an alternate static source usually in the cockpit if the exterior one becomes blocked
Torsion links
Put in an oleo to prevent rotation
Distinguish between the basic types of piston aircraft engine.
Radial- pistons in a circle around crankshaft, Common aircraft are the Stearman, Dakota, Harvard, Beaver, and Grumman Ag Cat. In-line-cylenderes all in the same configuration, prop on bottom Inverted in-line, prop on top providing better ground clearance and better positioning of the thrust line, Tigermoth Chipmunk Horizontally opposed- cylinders in two lines on opposite sides of the crank shaft.
With respect to carburettor ice, explain the process and the atmospheric conditions for the formation of: (a) refrigeration (or fuel) ice; (b) throttle ice; (c) impact ice.
Refrigeration Ice can occure in ambient temperatures well above freezing (up to 25 degrees) when RH exceeds about 50% . Throttle ice is more common at lower throttle settings. Both are common when the temperature in the carburettor is between -10 to 0. Impact ice is likely to occur, when ambient air temperature is near or below 0 degrees when the aircraft is flying through visible moisture with the ambient air temperature at or below 0 degrees.
Describe the pre-flight and in-flight serviceability checks for an ASI.
Remove pitote cover, ensure pitote tube is not damaged check the pitote and static air intakes for impurities. Have one person put their hand on the pitote and another person flip the switch in the cockpit. Check that the asi is not damaged and the needle is at zero check that the needle comes off the zero stop shortly after the start of the take off role and indicates the appropriate speed lift-off.
manifold pressure and boost gauges
Require on aircraft with constant speed props or supercharged engines to set power. It is the inlet pressure on the engine side of the cabourrator or supercharger. Uses Aneroid casual sensing equipment smiler to a barometer.
Explain the term RNP and the significance of the RNP value.
Required navigational performance Normally accurate to 18-10 metered of position
(i) empty weight CG position;
The C of G if no weight is added to the plane it is found in aircraft loading manual
Describe the basic characteristics of an electrical flow using the terms [amps, volts, electromagnetic force (emf) and ohms].
The Current (amps) is the amount of electrons flowing from positive to negative, the volt measures the pressure of this flow which is also the EMF, the ohm is the amount of resistance but up to the electrons when flowing.
Describe the basic features of a typical aircraft direct-reading magnetic compass, and explain the reason(s) for: (a) pendulous suspension of the magnet system; (b) immersing the magnet system in fluid.
The Z component causes the compass card to dip down, the C of G is offset to help keep the compass level. The fluid provides damping to help remove oscillations (aperiodic). Buoyancy so that the amount of weight suspended by the pivot is reduced. Lubrication of the pivot.
Describe the effects of a straight-line acceleration and a turn, on the pendulous unit of an air-driven AH, and state the errors in indication arising from these effects
The air forces of the exit air are used in conjunction with a pendulum to balance the AI. If you turn or accelerate linearly, the pendulum will swing too.
Explain the reasons for a reduction in power when carburettor heat is operated.
The air is heated this results in a lower density air which can reduce engine performance.
Explain: (a) the principles of aeroplane balance, and the function of the tailplane in providing the final longitudinal balancing force; (b) the significance of lateral fuel imbalance and the limitations typically applied.
The aircraft is rarely perfectly balanced, so the tail elevator is used to provide the final balancing force.
Define rated power and explain the terms 'rated altitude' or 'critical altitude'.
The altitude or critical altitude is the altitude at which rated power is developed at full throttle.
Explain the main disadvantages of the fixed-pitch propeller, which the constant-speed (variable-pitch) propeller was designed to overcome.
The propeller cannot change the pitch which is effectively a gear, and so the power must be reduced. Airspeed Directly Effects Propeller RPM. The operate at a relativity narrow range of airspeeds and rpm/angle of attack.
(f) station;
The same as Arm
Explain the likely result of using a higher grade, or a lower grade, of fuel than that recommended for a given aircraft.
The use Of a higher grade of fuel than recommended increases the chance of plug fouling, and can cause corrosion in older aircraft The use of a higher grade of fuel than recommended Increases the risk of detonation and is prohibited
Describe the likely results of operating an engine with: (a) incorrect oil type; (b) incorrect oil quantity
The wrong type of oil could result in poor lubrication, overheating, the wrong oil pressure and possible engine damage. If the oil level dipstick is below the minimum level, the engine will begin to overheat, there would be a smaller reserve should a leak develop in flight. If it is over full, excess oil might be forced out a various parts of the engine such as the front shaft seal.
Describe typical gear warning and indicating systems.
There are both electrical and back-up mechanical indicators There will also be a cockpit warning system to tell the pilot if the aircraft is in the landing configuration but gear is still up
Explain the basic principle of operation of an exhaust-driven turbocharger.
There is a waste gate which runs the amount of exhaust gas going to the turbine, this can be fixed or it can be operated by: A second throttle lever which can be adjusted for different altitudes. It can be directly connected to the throttle, so as to give maximum power, however operators must be careful because the throttle becomes sensitive. An automatic gate control where the pilot sets the required manifold pressure and the throttle. The waste gate is then set to maintain the desired manifold pressure
Describe the ways in which heat from the combustion process is dispersed from a typical aero-engine.
They are typically air cooled
Top dead centre (TDC)
Top dead centre (TDC): the position of the piston when it is farthest from the crankshaft.
Briefly describe the various construction styles of a fuselage
Truss-boxed longerons with struts to support them monocoque-Pure monocoque uses only stressed skin as a structure, Stressed Skin (semimonocoque) - used extensively involves a combination of frame and skin loading.
Explain the principle of operation of a battery.
Two dissimilar electrodes are placed in an electrolyte solution, if the electrodes are connected in a circuit, they will produce a current.
Outline the operation of a typical fire detection system.
Unit-type fire detectors, usually a thermocouple or bimetallic switch positioned where fire is likely to occur. Contunuilus loop detectors are used in engine bays or nacelles to indicate overheating, the wire is covered with a wire which is covered in a substance that becomes a conductor when heated.
Describe the correct procedures to be used for carrying out a fuel check.
Use a clear, clean Plastic Container Water will appear as globules in the bottom of the container. If the check is negative, Empty the contents into the receptical provided If the check is positive, carry out another check, if this is still positive, seek guidance of a flight instructor or maintenance engineer.
Describe the function, principle of operation and limitations of a Global Navigation Satellite System (GNSS).
Uses a system of 24 satellites to give position on earth. Each satellite in ranges is distance measured by radio. Needs 3 satellites to pick location, and 4 to know altitude.
Detail the systems which typically require DC power in an aircraft.
Usually most of the electronics in the aircraft, although some airplanes have systems what can use AC. Some or all of the gyroscopic instruments. Usually its just t/c. Usually fuel quality indicators or oil temperature or carbourator air temperature. the starting system, Light, radios.
State Ohm's law.
V=IR
vacuum gauges.
Vacuum gauges is a bourdon tube, since it is a vacuum it will increase in curvature as suction increases,
Differentiate between the three types of hydraulic oil. State any limitations and appropriate use of each type.
Vegetable Base - castor oil and alcohol, prone to forming sludge and causing corrosion. Used in older aircraft with natural seals. Coloured Blue. Mineral base- Kerosene type petrochemical product-widely used. Combustible, good lubricator. Dyed Red Synthetic- Hydroscopic, attracts water out of the air, must be kept sealed. Not flammable, attacks plastics. Dyed purple, green, or amber
Explain the limitations and cautions for the operation of a FD-AFCS system.
Very system specific, there will be specific checks of the autopilot before take off and a requirement to have the system disconnected during take off and landing. Maximum and minimum speeds will apply to different modes of operation. As well as system and aircraft limitations.
Describe typical emergency gear operation systems and procedures.
Will have a manual release gear to allow gear to become extended should the aircraft fail. Overcentering cams ensure the gear is locked even if hydraulic pressure is not maintained. They will also have an emergancey hand pump or a supply of compressed air to lock the gear into place.
Describe ice detection, windscreen heating and rain clearance systems.
Wings of aircraft have lights which allow for detection of ice at night Windscreen heating protects against bird impact, fogging of the glass, and ice formation. Rain Clearance Systems can be wipers, air blasters, or a chemical spray
With the aid of a diagram, explain the power available curve.
With a fixed pitch propeller, the amount of power available is dependent on the TAS
With the aid of diagrams, describe the principle of operation of an electromagnetic switch (or relay) and a solenoid switch. Describe typical examples of their use in aircraft electrical circuits.
Work Similarly to remotely flip a switch, see diagram 9-12, 9-13
Explain the relationship between a fluctuating or low oil pressure reading accompanied by a rise in oil temperature, and the actions which the pilot should take.
You should plan to land as soon as possible. You should judge the situation and plan a landing before the engine fails.
Describe the components and operation of a typical light twin EFIS cockpit display system.
a PFD and a MFD or NAV display, stand-by instruments,
Show the features of a practical generator, and explain how the output is passed through a commutator to provide DC.
a simple copper rings which are contacted by carbon brushes. this allows the brush to switch the current at the appropriate time.
Explain the basic features and operation of: (a) a lead-acid battery; (b) a nickel-cadmium (nicad) battery.
a. a container full of acid electrolyte, a number of thin flat lead acid plates which form the electrodes. NiCad are simmaler
Explain the general engine handling techniques for maintaining engine temperatures within the proper range, for aircraft: (a) without CHT gauge or cowl flaps; (b) fitted with CHT gauge and cowl flaps.
a. avoid running the engine on the ground with the throttle totally closed. Avoid climbing the aircraft for long periods at a high power setting and low airspeed. descending with the throttle closed for extended periods b. open cowl flaps while taxing open for take-off, partially closed for climb and cruise, closed for decent. open on final approach, ready for a go-around.
Describe the likely causes of: (a) low oil pressure; (b) high oil pressure; (c) high oil temperature.
a. low oil quantity, loss of oil pressure, faulty oil pressure gauge. b. likely from a faulty pressure relief valve. c. might just be a general overheating, could also indicate a failure of the lubrication system
With the aid of schematic diagrams, outline the operation of a typical pneumatic system.
back up systems when the air is stored in bottles for later use Low pressure systems, can be operated by an engine driven pump, or from a bleed-off from the engine compressor. Full Pneumatic high pressure systems-uses 3000 psi, air stored in bottles.
cylinder head and exhaust gas temperature (thermocouples);
because of the high temperature difference, a thermocouple is normally used. When two dissimilar metals are heated the produce a small voltage which is measured on the temperature gauge. Normally a copper-constantian or Iron constantian types are used. Can measure temperatures up to 400 degrees. the chrome-alumel type is normally used in jet engines and can go up to 1100 degrees. Exhaust gas temperature gauges use the same principle and are used to help pilots lean the mixture.
Explain the effects of the application of a load to an airframe structure (stress and strain) and differentiate between bending, tensile, compression, torsional and shear loads.
bending loads- bends a structure most notably the wings, they bend downwards on the ground and upwards in flight. A Tensile load is one which tends to stretch a structural member, and a compression load is one which tends to compress a structural member. torsional load- one that tends to twist a structure Shear load- is one which tends to cause the sliding of one part over another, can be parallel to junctions between parts.
Briefly describe the construction of tailplane and fin, and control surfaces.
usually a similar construction to the wings. These controls have less torsion and are usually of a stiffer design.
With the aid of a diagram, explain the principle of operation of an attitude indicator (AI) or artificial horizon (AH).
utilizes a horizontally spinning earth gyro. Instrument indications are provided by an aircraft image which remains fixed, and a horizon bar which remains horizontal and represents the actual aircraft.
(b) datum;
datum is the point at which all of the measurements of the arm are taken
Crank angle:
degrees of crank shaft rotation
detonation
detonation: the spontaneous combustion (or exploding) of a charge before ignition is timed to occur.
Describe the typical source of carburettor heat hot air.
engine compartment and then around exhaust.
Ribs
formers to which skin is attached to provide structural shape.
List the advantages and disadvantages of using fuel injection systems in aeroengines.
freedom from Refrigeration ice more uniform delivery of the fuel air mixture to each cylinder Improved Control of the fuel-air ratio fewer maintenance Problems Better throttle response Increased Engine efficiency Disadvantages: Vapour locking in the lines may make restarting a hot engine difficult narrow fuel lines means susceptibility to fuel blockage Return System may cause uneven fuel loading.
Distinguish between gravity-feed and pump-feed fuel systems.
gravity fed fuel Systems are on High-wing aircraft and are used to provide fuel to the engine using only gravity.
Stringers.
help to take some of the bending load and stiffen the skin
(a) arm;
horizontal distance from a reference datum to a centre of gravity.
Explain the power management requirements as the propeller blades are traveling from the normal thrust to the reverse thrust angle.
if power is applied when the prop is in the wind-milling arc, the prop will over-speed.
With the aid of a diagram, explain the operation of a typical CSU governor.
incorporates flyweights which are rotated by the engine and are sensitive to engine speed. They are prevented from flying out by a speeder spring which is positioned by the pilot, tension of this spring is operated in the cockpit by the pitch control lever.
Inlet and exhaust valves Valve lead and valve lag:
inlet valves admit the fuel-air mixture into the valve and exhaust valves allow exhaust gasses to escape Valve lead is early opening of the exhaust valve valve lag is late opening of the exhaust valve
Explain the fuel-air ratios for achieving maximum power output and best economy.
it has been found that for maximum power output, the engine is best run at 1:12 and for best fuel economy at 1:16
Describe the inherent properties of a spinning gyroscope rotor.
it is basically a wheel that spins very quickly. This causes it to posses two inherit properties strongly. Rigidity: is gyroscopic inertia, which makes the gyroscope maintain their alignment in space. Precession: Causes a force applied at a rim of the giro to act at a 90 degree angle to it
Explain the function of pitot heat.
it is good practice to switch the heater on when flying in icing conditions or in heavy precipitation.
Describe the properties of magnetism, including polarity, attraction and repulsion.
like magnets repel,opposite magnets attract. A solid can though of having a number of random magnetic (polar) sections. these can be moulded in some substances to become magnets
Describe the terms magnetic field, magnetic flux, and permeability.
magnetic field is the space around a magnet in which its influence can be detected. The amount of electric field passing through a given area is the flux Permeability is the preference a magnetic field has for a particular substance.
Spars
main load bearing structural component of the wing.
Explain different types of loading which an airframe must be designed to accept.
manoeuvring loads-loads generated by excessive manoeuvring G forces. Gust Loads- caused by changes in direction and velocity of air mass Control Surface loads- loads exerted by the deflection of the control surfaces. Can be in the form of Aero-static Distortion. Pressurization loads- arise in aircraft with a pressurized cabin where the pressurization makes the aircraft cabin go through a expansion and contraction during flight. Landing and Take-off loads- the loads experienced at touchdown, during the landing role-out, and to a lesser extent during the take off run.
Briefly describe the common types of wing construction.
most light aircraft have straight wings, while many faster aircraft employ a use of a sweped wing stricture which brings the C of g closer and gives the wing more strength. they are usually of the stressed skin type of aircraft. Biplane Wings, low weight/ strength but high drag. Braced Monoplane- wing is externally braced between the fuselage. Only good for lower speed aircraft. Unbraced monoplane (or cantilever)- Wind connected to the fuselage only at the wing roots .
Explain the need for voltage regulation for both alternators and generators, and how a generator also requires a current regulator and a reverse current relay.
need a regulator so there is not excessive voltage output. Alternators can be constructed so that the amperage of the current always remains within limits. Generators Require a current regulator to prevent the voltage from coming in at a dangerous RPM, They also require reverse current relay to prevent current from the battery flowing back into the generator when it is not running or producing a lower voltage than the battery.
Describe the normal handling of the propeller pitch and power controls for a two lever control system: (a) when the aircraft is on the ground; (b) for 'exercising' the CSU; (c) prior to take-off and landing; (d) when increasing or decreasing power in the air.
operate Control Smoothly, On the ground the prop is normally full fine. The Exercise is when during run up the prop is cycled from fine to course and back a few times to free up any cold oil in the system. In pre-take-off and pre landing checks, ensure the pitch is placed in the full fine position.
Explain the need for periodic oil changes.
over time the oil gets dirty which can clog up the system
With the aid of diagrams, distinguish between the indications of the TC and AH under various conditions.
pg 13-20
Describe the pilot checks of oleo-pneumatic undercarriage legs.
pilots should check that the oleo is extended the correct amount. Can lead to nose-wheel shimmy during take-off
Distinguish between detonation and pre-ignition; state the main causes of these conditions, and the reasons for avoiding them.
pre-ignition occurs before the charge was supposed to take place detonation occurs afterwords. Detonation is likely to occur in aircraft when the mixture temperature is at far to high a pressure/temperature. This causes a knock of fuel air mixture igniting after the advancing flame. (Not liklet to be able to hear the knock when flame is. Detonation can cause overheating, it can cause detonation of bearing surfaces, it results in a loss of power. pre-ignition is the condition in which combustion occurs before it was supposed to. this can be caused by over-compressing the charge and causing spontaneous combustion. Can also result form prolonged detonation leading to overheating and local hot-spots. It is more likely to occur on a hot dirty engine caused by carbon deposits. It should be avoided because it can lead to a loss of power and serious engine damage.
pre-ignition
pre-ignition: the ignition of the charge by some means other than the normal spark before the ignition is timed to occur.
Describe the serviceability checks and the accepted indication tolerances of an altimeter system.
prior to flight, check that instrument glass is not broken or cracked and that turning of sub-scale is accompanied by a change in altitude indication. Can be off by +30 or -45
Explain the term RAIM prediction and explain the significance of these predictions.
required for IFR navigation, provides a warning if GPS becomes Inaccurate.
Show the features of a practical alternator, and explain how the AC output is normally rectified to provide DC.
silicon Diodes are fitted to the stator circuits within the alternator. works By attaching diodes to the system
Explain the requirements which the undercarriage system must be able to meet.
support Aircraft on the ground at MAUW Absorb landing loads and provide shock absorption during movement over the ground Withstand side-loads during crosswind take-off and landing. Withstand Side-loads During crosswind take-off and landing. give minimum role friction during take-off have minimum drag when the aircraft is airborne. Provide maximum possible traction for efficient breaking during landing provide protection against inadvertent retraction on the ground have minimum weight for a given strength
With the aid of a diagram, explain the principle of operation of a heading indicator (HI) or direction indicator (DI).
the HI used a Tied Gyro which spins in the vertical plane. It uses jets of air to stabilize it on the horizontal plane
State the common operating limitations and serviceability checks for a DI.
the arrangement of the gyros means that they will tumble if placed in a drift of more than, for certain headings it is possible to do certain manovers if the gyro is in the right place. Needs 3-4 min to spool up after the engine has been started. Check compass while taxing. Mist not precess more than 4 degrees per 15 min
exhaust manifold
the manifold through which exhaust gasses escape into the atmosphere
(d) centre of gravity (CG);
the point where all of the weight is said to act.
(c) moment (including the units used);
the turning effect of any force, depends on size of force and moment arm. usually Expressed in kg-mm
Describe the function and operation of ground retraction protection systems.
there is a safety lock on the cockpit undercarage lever to prevent the gear from being selected in the UP position while on ground
State the advantages of NiCad batteries.
they have a long life and are dependable and have a long life
Describe principle of operation of the common types of wheel brake units.
Expander tube drum breaks-A tube is forced out to the spinning drum hydraulicly or by a Pneumatic system Can also use a pisto operated shoe Disk breaks use a spinning disk and a set of pads that clamp the disk
Demonstrate the use of graphs to: (a) calculate load moment; (b) establish CG position.
17-10
Given appropriate data and using a typical weight and balance work sheet, calculate the CG position at take-off and for landing.
17-14
Given weights and arms, calculate moments and establish a CG position.
17-8
Workable limits of fuel-air ratio for reliable ignition by spark
1:9 to 1:18
Suction Requirements for gyro instruments
3.5-4.5 mm Hg
With the aid of a diagram, describe the principle of operation of a simple generator (a loop conductor rotating inside a magnet).
9-17
With the aid of diagrams, identify the main components of a four-stroke cycle piston engine including: cylinders, pistons, cylinder heads, valves, spark plugs, connecting rods, crankshaft, camshaft and valve operating mechanism.
Cylinders- usually constructed of steel and have a very smooth inner surface. cylinders are Usually air cooled as a weight saving measure and have external cooling fins. Pistons, cast from aluminium alloy and fit closely with the cylinder, There are rings at the top which prevent gasses from escaping. the lower ring is the scraper for oil control. Cylindrical Heads - cylinder heads are fitted on top of each cylinder to enclose the combustion space. They are made of aluminium alloy and have cooling fins. Inlet and exhaust valves-fitted to cover ports or openings in the cylinder heads. Spark Plugs, In aero engines, two electronic operated spark plugs are fitted to each cylinder head. Their function is to ignite the compressed fuel-air mixture at the right time. Connecting rods- attack pistons to crank shafts. Link from piston and connecting rod is made through a gudgeon (or wrist) pin while the link to the camshaft is called a `big and bearing` crank shaft- shaft with cranks or throws for each piston the big end bearings of the connecting rods fit around crank pins on the outer edge of each row. Camshafts- operate the inlet/exhaust valves at the right time. This is done via cam-lobes
Explain the following errors affecting an ASI: (a) density error (IAS/TAS relationship); (b) position (pressure) error; (c) compressibility error.
Density error-ASI cannot account for variations in density. Density depends on temperature and pressure. Position (pressure) error - depends on the accuracy of the pitote and static vents Compressibility error- applicable at higher airspeeds and due to air compressing when it reaches pitote diaphragm.
Distinguish between direct and alternating current, and explain the terms 'Hertz' and 'rectification'.
Direct current only flows from positive to negative terminals in a battery. Alternating current first flows in one direction and then in the other. Hertz is the number of times it changes direction/second. to charge battery electricity must first be rectified.
(e) CG range and limits;
Distanced from the datum which weights must be kept to maintain stable, controlled flight.
Explain the normal symptoms of carburettor ice formation, and the correct use of the carburettor heat control.
Drop in RPM, Engine Rough running. Full Carburettor heat must be applied until the ice melts.
Explain the special precautions which must be taken when fuelling from drum stock, and the avoidance of the use of non-approved plastic containers.
Drums should be filled to the brim with fuel and stored on their sides. Pumping equipment should have an in-line filter which can remove debris and moisture. Do Not use any Unapproved Container.
State the serviceability checks for a VSI and IVSI.
During pre-flight the needle should show neither a climb or a decent. can show +-200 fpm to still be serviceable between -20 to 50 OAT and +-300 when outside these limits. Can be checked in flight by timing a steady climb or steady decent.
Explain the basis of an electrical current, and the direction of the current.
Electrons push away from each other, generally considered to be from positive to negative (but it is actually the opposite).
2 For a fuel system, explain the function, and where appropriate, the correct handling of the following: (a) engine-driven fuel pump; (b) boost (auxiliary) pump(s); (c) engine primers and priming systems.
Engine Driven Fuel Pumps Provide fuel pressure, Electric Fuel pumps act as a backup and are used at critical phases of flight. Engine Primers deliver extra raw fuel into the the intake manifold. The colder the engine, the more priming required. Primer must be locked when engine is running.
For a fuel system, explain the function, and where appropriate, the correct handling of the following: (a) tank filler caps and drains; (b) expansion spaces; (c) tank vents; (d) baffles; (e) sumps and drains; (f) fuel quantity detectors; (g) fuel strainers and filters; (h) tank selector valves; (i) cross feed valves; (j) fuel flow meters.
Expansion Spaces Allow for fuel to expand after it has been put into the tank. Vents: allow air to bee removed from thanks from expansion, and allows air to flow into the tanks for draining. Baffles: Fitted inside tanks to reduce fuel surging and the consequent rapid transfer of weight. Sumps and drains: allows impurities in the fuel to collect so as not to enter the engine, results in sum unusable fuel. Fuel Quantity Detectors: can be electronic or float type, determine the amount of fuel remaining
Describe the management of EFIS system failures.
Failure of one of the line replicable units such as DME ADF or Transponder will be flagged with a warning message. Failure of a sub level computer unit will require a reversion to the back up instruments. Failure of a GDU will result in the other one taking the role of PFD and principle flight display. Redundancy of electrical supply is provided for by the second alternator in twins, or by the battery should all alternators fail. if they both fail, a solid state emergency battery can be used for a very limited time.
Describe the function and operation of a: (a) manual feathering propeller; (b) auto-feather propeller; (c) auto-coarsen propeller.
Feathering props must be done by a feather button or a feather switch, if varies from aircraft to aircraft auto feather automaticly feathers the engine to prevent a loss of control. Auto Course is similar to auto feather but it does not feather completely.
With the aid of a diagram, describe a typical carburettor mixture setting curve and show the operating area where detonation may occur.
Fig 3-2
Explain the precautions which can be taken to avoid fuel contamination with water and other impurities.
Fill fuel tanks to full Overnight.
Firing Interval
Firing Interval: the interval, measured in degrees of crankshaft rotation, between any two cylinders in the ignition sequence. Firing Interval=Number of degrees per cycle/number of cylinders
Firing order
Firing order: the numerical sequence in which the cylinders fire
oil pressure gauges
For direct reading types- the pressure is tapped so that pump pressure is measured. uses a bourdon tube (spring brass hollowed out and anchored at one end) to indicate pressure. Can also use a variable resistance/radiometer. Syncro systems use a magnet which is moved closer to magnetic field depending on pressure.
Fuel Injection systems
Fuel Injection is the introduction of fuel into the air required for combustion, by means of a pressure source other than the pressure differential created by passing that air through that venturi in the carbourater.
fuel pressure gauges
Fuel Pressure indicating systems are smiler to fuel pressure systems, they usually include a diaphragm to prevent fuel loss should a problem occur.
Describe any disadvantages with use of a float-type carburettor in an aeroengine.
Fuel flow can be disturbed by manovers which disrupt the float mechanism. Carburettor Icing
Fuselage Mainplanes Empennage
Fuselage-the body of the aircraft Mainplanes-the wings or major lift producing structures Empennage- made of the finn/rudder and tailplane/elevator
Explain the basic differences between reciprocating (piston) and gas turbine (jet) engines.
Gas flow goes through the same process, however in turbo power is produced continuously, whereas in a reciprocating engine power is produced continuously. turboprops are lighter and have more reciprocating parts. For this reason the turboprop is smaller and lighter.
Explain what is meant by the term gimbal, and list the types of gyroscope.
Gimbals are used to allow the gyro to spin on their axis. Space Gyro=free to move in all 3 planes Earth gyro=free to move in all 3 planes but is kept in place by the force of gravity. (AI) Tied Gyro=free to move in all 3 planes but kept in place by an outside force, (DI) Rate Gyro = freedom of moment in only 1 plane (TC)
(l) zero fuel weight;
Gross Weight of the aircraft Minus the fuel in the tanks
Explain the advantages of an electrically-driven DI versus an air-driven instrument.
Higher RPM and improved Rigidity Greater freedom in Pitch and role before the hi topples, in some cases there are no limits less real drift due to reduced wear and tear from less dust better and faster erection system
Explain the principle of electromagnetic induction.
If a conductor is placed in a magnetic field and then placed so that it cuts the lines of magnetic force, a current will be induced in the conductor
Describe the effect on longitudinal stability and handling with the aeroplane loaded with the CG: (a) forward; (b) outside the forward limit; (c) aft CG; (d) outside the aft limit.
If loaded forward the aircraft will be vary stable longitudinally, Controllability will be poor. If ahead of the forward limit It may prevent you from-raising the nose on take off prevent you from raising the nose during landing not allow sufficient elevator authority to hold a given nose attitude at a given low speed. If the C of G is aft the aircraft will be tail heavy and less stable longitudinally. The elevator stick forces could become so light that control in pitch would become increasingly difficult and the pitch would be difficult further aft of the c of g. There would be a lack of elevator forward authority which could lead to a loss of aircraft control.
Explain the requirements for tyre care and checks.
If the tyre has a inner-tube, check for creeks. Tyres should be properly inflated, should not be bald, or have cuts or creeps. Contamination of the tyre with fuel or rubber should be cleaned away
Explain what a compass swing is and give examples of the occasions on which it is required.
In a compass swing the aircraft is placed at known magnetic headings and the compass deviation noted.
Describe acceleration and turning errors in each hemisphere of a direct-reading compass, and then explain the practical aspects of these errors.
In acceleration, the offset C of G lags behind which causes the magnet to give a false indication of a turn towards the south for positive acceleration. Except when facing north or south. Whe the plane of the magnetic compass becomes tilted, the z component of the magnetic force is free to act on the swivel. This means that when making compass turns
State the principle of operation of the balance ball and, with the aid of diagrams, interpret various TI and TC indications.
In straight and balanced flight the ball will be on centre, the ball will then be off centre if the aircraft is in a skid. In a coordinated turn the ball will be in the centre. Pg 13-9 When the aircraft slips in a turn the ball will have same side indications, when it skids, the ball will have opposite sides.
State the errors which a turn indicator is subject to.
Incorrect rotor speed- if the rate of suction is to high, an excessive rate of turn will be indicated and vice versa.
Outline the operation of: (a) an independent brake system; (b) a boosted brake system; (c) a power brake system.
Independent break systems use a break pad connected to a (usually foot powered) hydraulic system Boost systems are the same as above except they provide some hydraulic assistance from the main hydraulic system. Power breaks - breaks are connected to a break control valve a check valve and actuator will hold pressure in the event of a hydraulics failure.
(a) tachometers;
Indicate the rotational speed of the engine. The Tachometer gives crankshaft RPM, not necessarily propeller RPM. There are 3 main types of tachometers: Mechanical- most light aircraft have mechanical tachometers. Can use flyweights or a drag cup and a permanent magnet. Electrical- Use a generator which is connected to a motor which spins a magnet. Electronic- uses the frequency of the electrical signal of the magneto to time the RPM.
Explain the following errors affecting an altimeter: (a) instrument; (b) position error; (c) lag.
Instrument error is caused by small imperfections arising from the manufacture, installation, maintenance and age of the individual altimeter. position error-if aircraft is flown in a slip or a skid, then the static vent may give a false reading. Instrument lag- the altimeter takes a second or two to respond to pressure changes
Describe the function of common hydraulic system components: (a) reservoirs; (b) pumps; (c) pressure regulators; (d) accumulators; (e) check valves and relief valves; (f) selector valves; (g) actuators; (h) filters.
Resevour- A tank which holds sufficient fluid to ensure that all actuating jacks can be operated at one time if required. Can be pressurized or unpressurised. Hydraulic pumps- Generates pressure within the system and delivers it to the operating lines. Pressure regulator, keep pressure constant by releasing excess fluid, sometimes done by the pump itself. accumulator- provides for a reserve amount of hydraulic fluid to the landing gear. Check Valves- prevent reverse flow within the system. Relief valves- Provide emergency pressure relief Selector valve- provides for the appropriate flow path of the actuator. Actuators- convert hydraulic pressure into mechanical force. Filters- remove contaminants
Explain the following in relation to fuel-air mixture ratios: (a) 'rich' and 'lean'; (b) the 'chemically correct' or stoichiometric ratio.
Rich Fuel Mixture means that there is more air in the mixture. Lean Fuel mixtures Have more air for a given weight of fuel. theoreticaly the best mixture to use is the `chemically correct mixture`which is close to 1:15.most engines run 1:12 for best power and 1:16 for best economy
Describe the angle of dip and components H and Z of the earth's magnetic flux.
Since the magnetic moles will have a magnetic flux into the earth surface. Therefore there is a H component parallel to earth's surface, and a Z component at right angles to earth's surface. Lines which join places of equal dip are called isoclinals.
Distinguish between temporary and permanent magnets, and the properties of 'soft iron' and 'hard iron'.
Soft iron materials loose their magnetism quickly but arrange their particles easily in the presence of a magnetic field. Hard Iron is difficult to magnetize, but one they are magnetized they can retain their properties for a long time.
Force work Power
Something which causes an object to change its speed and/or direction work=force*distance Power is the rate of doing work
Three types of pressure measured in an aircraft
Static Pressure Dynamic Pressure- the pressure of the aircraft from the energy of the relative airflow. =1/2 *roe *V^2 Total pressure (pitote pressure) =static pressure +dynamic pressure
Compare the features of the ashless dispersant (AD) oils used in piston aeroengines with straight mineral oil and detergent oils.
Straight mineral oil is prone to oxidation at high temperatures, and the formation of gummy residues and deposits. Detergent oils have been developed to be less prone to oxidization, and to clean the engine by flushing away any carbon deposits which do form. These oils act by forming metallic ash compounds which can clog oil passages and filters
stroke
Stroke: the distance the piston travels up or down the cylinder can be named as, -Induction (or intake) -down -Compression -up -power (expansion) - down -exhaust -up
Swept Volume
Swept Volume: The volume of the cylinder which is swept by the cylinder between BDC and TDC.
Describe the function and operation of a typical GPWS system.
Takes Inputs from radar altimeter, computer keeps track of altitude and provides an audio warning if the closure rate to the ground and proximity to terrain exceeded certain limits.
Describe the function and operation of a basic FD-AFCS system.
Takes the inputs from sensors and transfers them to directional control, can be one or two axis system. See fig 14-21 for operation controls.
Explain the function(s) of the following in a typical aircraft electrical system: (a) the battery; (b) a ground power source; (c) the alternator or generator; (d) bus bars; (e) over voltage protection.
The battery is simply a container for storing electrical energy in chemical form. Also called an accumulator. provides initial electrical power to start the engine, a supplementary source of power if alternator cant supply enough electricity. An emergency source of electrical power at times should the normal system of the aircraft fail. ground power units are used on planes with engines to big to start by battery. Alternator provides power for lights, radios, and other services . Needs some battery power to start as well. Generators produce DC via a built in commuter. Bus Bars are the main electrical power distributors. Over-voltage regulators remove some of the power produced by the alternator, usually include a voltmeter or over-voltage warning light.
(o) maximum certificated take-off weight (MCTOW)
The maximum certified weight for a take-off run
Describe the importance of correct management of fuel selection.
The pilot is normally the one who faults out the system, the correct tank must be selected
Fuel Metering force
The pressure differential across the jets of a Pressure Injected Carbourater. This Pressure differential is measured by comparing the metered fuel in chamber c with the unmetered fuel in chamber D.
Pressure injected Carburettor
The pressure regulator unit replaces the float by varying the pressure, and therefore the amount of fuel passing through the metering jets into the engine.
Explain the advantages, and the limitations of exhaust driven turbo charging and mechanically driven supercharging.
The principle of supercharging is to increase the density of the air before it reaches the cylinders. All superchargers are limited by the temperature rise caused by compressing the mixture and thus its ability to cause detonation. Mechanically driven superchargers use a engine driven impeller to compress the air after it reaches the carbourater. Exhaust driven superchargers are also known as turbochargers. They run off of a turbine which spins in the stream of the departing exhaust mechanism. If the system is fuel injected the impeller handles air alone and not a fuel air mixture.
erection to a false vertical Pendulosity
acceleration and turning error of the AI
TAWS
aimed a reducing the occurrence of controlled flight into terrain. Includes GPWS
(h) basic empty weight (empty aircraft weight);
airframe engine fixed equipment, unusable fuel, FULL oil and systems fluid
Explain how the constant-speed unit (CSU) acts to change the pitch of the blades and maintain rpm: (a) with changes to power; (b) with changes in airspeed
an increase in power will increase the pitch, if the throttle is closed the CSU will decrease the blade angle. If the airspeed is reduced, propeller torque will increase, the CSU will feather the pitch to maintain the constant speed. If the Aircraft's speed increases, Pitch is made more course.
Distinguish between anti-icing systems and de-icing systems.
anti-icing systems prevent ice formation de-icing systems remove ice which has formed
List the common extinguishing agents and state any precautions when using.
carbon Dioxide: Usually used for baggage compartments, con be used in cabins carefully. Methyl Bromide: very toxic but used for engine fires Dry Powder: used in Galley Kitchens
Explain the serviceability checks for the TI/TC.
check for winding sound and no flags on the gyro, correct indications of both the turn indicator and coordination ball in a turn while taxing the ball should be off centre when aircraft is parked on a slope. In flight a rate 1 turn for 180 degrees should take 1 minute.
