Engines & Ignition Flashcards
What are the key components of piston engines?
Cylinder, piston, connecting rod, and piston rings.
What is the role of piston rings in an engine?
To create a seal and maintain compression.
What are the four strokes in a four-stroke engine cycle?
Intake, compression, power, and exhaust.
How does the camshaft control valve operations?
By opening and closing valves through push rods and rocker arms.
What is the difference between fixed pitch and constant speed propellers?
Fixed pitch propellers have a set blade angle; constant speed propellers adjust blade angle for efficiency.
What are common methods of engine cooling in piston engines?
Oil cooling and air cooling.
Why is pre-flight inspection critical for aircraft engines?
To check for contamination, damage, engine oil levels, and overall condition.
What is the purpose of the fuselage in an aircraft?
To provide structural integrity and house components like bulkheads, stringers, and skin.
What are the types of undercarriage configurations?
Tricycle and tailwheel configurations.
What is the role of the propeller twist?
To create equal thrust along the blade.
What is the role of magnetos in the ignition system?
To generate electrical current for spark plugs independently of the battery.
What is the purpose of the rocker arms in an engine?
To transfer motion from push rods to open or close engine valves.
What is the compression ratio, and why is it important?
It is the ratio of total volume to clearance volume in an engine cylinder, affecting engine performance and efficiency.
What causes detonation in aircraft engines?
Low octane fuel, high compression, lean mixtures, or overheated engines.
How can detonation in engines be prevented?
Use higher octane fuel, avoid lean mixtures, and monitor engine temperatures.
What is pre-ignition, and what causes it?
Pre-ignition occurs when the fuel-air mixture ignites before the spark plug fires, caused by hot spots or overly lean mixtures.
What is the modified Otto cycle?
A cycle with adjustments to valve timing and ignition to enhance engine power.
What is valve overlap, and why is it important?
A short period when both inlet and exhaust valves are open, improving engine efficiency.
What is volumetric efficiency in engines?
It measures the efficiency of filling the cylinder with the fuel-air mixture; can exceed 100% in turbocharged or supercharged engines.
What happens during the ignition and power stroke in an engine?
The spark plug ignites the fuel-air mixture, driving the piston downward and rotating the crankshaft.
What are the effects of detonation on engine components?
Causes piston damage, increases cylinder head temperature, and reduces engine performance.
What role do spark advance and effective crank angle play in engine operation?
Spark advance maximizes piston momentum, while effective crank angle transmits power to the crankshaft.
What is the difference between detonation and pre-ignition?
Detonation is an uncontrolled explosion after the spark plug fires; pre-ignition occurs when the mixture ignites before the spark plug fires.
What are the advantages of fuel injection systems over carburetors?
More efficient fuel burn, reduced induction icing, consistent power output, and better fuel atomization.
What are the disadvantages of fuel injection systems?
Risk of vapor lock, higher initial cost, and potential for fuel line blockages.
What is vapor lock, and how can it be prevented?
Vapor lock occurs when hot fuel turns into gas, blocking fuel flow. It can be prevented by cooling the engine or using an electric fuel pump.
What are the components of a fuel injection system?
Fuel pump, fuel air control unit, and fuel manifold valve.
How do fuel injection systems prevent carburetor icing?
They eliminate the carburetor, reducing induction icing and providing consistent fuel delivery.
What are the functions of engine oil?
Lubrication, cooling, cleaning, sealing, and corrosion protection.
What are the differences between wet and dry sump systems?
Wet sump systems have the engine in the oil sump; dry sump systems use an external tank with a scavenge pump.
What is the purpose of cow flaps in engine cooling?
To control air intake and exhaust, helping maintain engine temperature and prevent overheating.
What could low oil pressure and high temperature indicate?
Insufficient oil, oil leaks, or engine problems.
What types of engine oil are commonly used in aircraft?
Ashless dispersant oil, straight mineral oil, and synthetic oil.
How does the fuel air control unit function in a fuel injection system?
It meters fuel based on throttle position and sends it to the fuel distributor for precise delivery.
What could high oil pressure and low temperature indicate?
Excessive oil or a blocked oil filter.
At what conditions is carburetor icing most likely to occur?
Below 20°C and relative humidity over 80%, or at temperatures up to 40°C with 50% humidity.
What is the function of carburetor heat?
To warm intake air and prevent carburetor icing by using heat from the exhaust.
What are the symptoms of carburetor icing?
Unexplained drop in RPM, rough running, decreased manifold pressure, and loss of power.
How does carburetor heat affect the fuel-air mixture?
It makes the mixture richer due to less dense air.
What are the advantages and disadvantages of carburetor aircraft?
Advantages: simplicity, cost-effectiveness, reliability. Disadvantages: prone to icing, inefficiency at high performance, not suitable for inverted flight.
What is the effect of a rich fuel-air mixture?
It can cause black exhaust smoke, spark plug fouling, and reduced engine performance.
What is the effect of a lean fuel-air mixture?
It can cause engine overheating, detonation, and potential damage.
Why is mixture control important during taxiing?
To prevent spark plug fouling caused by carbon deposits from a rich mixture.
What do blue and black exhaust smoke indicate?
Blue smoke indicates oil burning; black smoke indicates a rich fuel mixture.
How can spark plug fouling be cleared?
By leaning the mixture and increasing throttle.
What is the purpose of the mixture control in aircraft?
To restrict fuel flow and adjust the fuel-air mixture for optimal engine performance.
What are the risks of running the engine with a too lean mixture?
Detonation and potential engine damage.
What is the role of magnetos in the ignition system?
To provide electric current to spark plugs, allowing the engine to operate even if the battery fails.
Why are dual magnetos important in aircraft engines?
For safety and efficiency, each cylinder has two spark plugs connected to two magnetos.
What is the function of impulse coupling in the ignition system?
To provide a hot, retarded spark for starting the engine, operating on the left magneto only.
What are the potential hazards of a live magneto?
The engine may run even with the keys in the off position, posing safety risks.
What is carburetor icing, and what are its causes?
It occurs when ice forms in the carburetor due to fuel vaporization, throttle icing, or impact icing.
What are the symptoms of carburetor icing?
Rough running, decreased manifold pressure, power loss, and RPM drop.
How can carburetor icing be counteracted?
By applying carburetor heat to burn off the icing.
What is the function of the carburetor enrichment valve?
To provide an additional boost of fuel at high power settings, enriching the mixture.
Why is understanding carburetor icing important for pilots?
To be prepared for icing conditions during VFR and IFR operations and ensure engine performance.
What should pilots do to avoid impact icing?
Decrease altitude and consider icing conditions when flying above freezing levels.
What is a high-density altitude airport?
Airports located at altitudes of 5000-6000 feet or those experiencing high temperatures, resulting in lower air density.
How should the mixture be leaned for best economy?
Lean the mixture to peak exhaust gas temperature (EGT).
How should the mixture be adjusted for best power?
Lean to slightly richer than peak EGT.
What does P, E, G, T stand for?
Peak Exhaust Gas Temperature, used for determining the chemically correct mixture for best economy.
Why is leaning important at high-density altitude airports?
To compensate for lower air density, which can cause engine flooding and inefficient performance.
What is the difference between high-density and low-density altitude airports?
High-density altitude airports are at higher elevations or high temperatures, requiring mixture adjustment; low-density altitude airports do not.
What is the correct mixture setting for best economy?
Peak EGT.
What is the correct mixture setting for best power?
Slightly rich of peak EGT.
Why is peak EGT important for engine performance?
It represents the chemically correct mixture for efficient combustion.
Why is a slightly rich mixture recommended for best power?
It provides a cooling effect and prevents engine overheating.
What are the key components of piston engines?
Cylinder, piston, connecting rod, and piston rings.
What is the role of piston rings in an engine?
To create a seal and maintain compression.
What are the four strokes in a four-stroke engine cycle?
Intake, compression, power, and exhaust.
How does the camshaft control valve operations?
By opening and closing valves through push rods and rocker arms.
What is the difference between fixed pitch and constant speed propellers?
Fixed pitch propellers have a set blade angle; constant speed propellers adjust blade angle for efficiency.
What are common methods of engine cooling in piston engines?
Oil cooling and air cooling.
Why is pre-flight inspection critical for aircraft engines?
To check for contamination, damage, engine oil levels, and overall condition.
What is the purpose of the fuselage in an aircraft?
To provide structural integrity and house components like bulkheads, stringers, and skin.
What are the types of undercarriage configurations?
Tricycle and tailwheel configurations.
What is the role of the propeller twist?
To create equal thrust along the blade.
What is the role of magnetos in the ignition system?
To generate electrical current for spark plugs independently of the battery.
What is the purpose of the rocker arms in an engine?
To transfer motion from push rods to open or close engine valves.
