What is the continuous energy-creating process in typical reciprocating airplane engines called?
The four-stroke operating cycle
The four-stroke cycle consists of intake, compression, ignition and expansion, and venting of burned gases.
How is engine speed displayed for aircraft equipped with a fixed-pitch propeller?
In revolutions per minute (RPM) on a tachometer
The tachometer provides a visual representation of the engine’s speed.
What device is used to monitor engine output for a constant-speed propeller?
A manifold pressure gauge
This gauge displays the pressure inside the engine in inches of mercury (Hg).
What is the function of the carburetor in an aircraft engine?
Mixes incoming air with fuel and delivers it to the combustion chamber
The carburetor is essential for the combustion process in engines.
What principle do float-type carburetors operate on?
The difference in pressure at the venturi throat and the air inlet
This principle allows for the proper mixing of air and fuel.
How can the fuel/air mixture be adjusted in some aircraft?
From the cockpit with the mixture control
This allows pilots to optimize engine performance based on conditions.
What causes carburetor ice?
Fuel vaporization and decreasing air pressure in the venturi
These factors lead to a sharp temperature drop in the carburetor.
Under what conditions is carburetor ice more likely to occur?
When temperatures are below 21°C (70°F) and relative humidity is above 80 percent
These environmental factors increase the risk of ice formation.
What system is used to combat carburetor ice in engines with float-type carburetors?
A carburetor heat system
This system routes air across a heat source before it enters the carburetor to eliminate ice.
What is one significant advantage of the fuel injection system in airplanes?
Relative freedom from the formation of induction icing.
Induction icing can negatively affect engine performance.
How can sea-level performance be obtained at high altitudes?
Using either a supercharging or a turbocharging system.
These systems increase the air density entering the engine.
What components make up the ignition system in an airplane?
Magnetos, spark plugs, interconnecting wires, and the ignition switch.
These components work together to ignite the fuel-air mixture.
What occurs during detonation in an airplane engine?
Fuel in the cylinders explodes instead of burning smoothly.
Detonation can cause engine damage and decreased performance.
What is preignition in the context of airplane engines?
Fuel/air mixture being ignited in advance of the normal timed ignition.
Preignition can lead to engine knocking and damage.
What is the purpose of a fuel-pump system in airplanes with fuel injection?
To provide sufficient pressure to the injector nozzles.
This system is also found in low-wing airplanes with carburetors.
What type of fuel system can high-wing airplanes with carburetors have?
Gravity-feed system.
Fuel flows by the force of gravity from the fuel tanks to the engine.
What is a good practice to help prevent moisture buildup in airplane fuel tanks?
Ensure that an airplane’s tanks are refueled following the last flight of the day.
This practice helps mitigate the risk of water contamination.
What does a wet-sump system do?
Uses an oil pump to draw oil from the sump and route it to the engine.
Oil system operation can be monitored by oil pressure and temperature gauges.
How does cooling air enter the engine compartment?
Through an inlet behind the propeller hub.
It is then directed to the hottest part of the engine by baffles.
Where is exhaust normally directed in an airplane?
Out below the engine compartment through a muffler and tailpipe.
Metal shrouds around the muffler capture heat for cabin heating.
What is a fixed-pitch propeller?
Uses a single blade angle selected for the primary function of the airplane.
It does not change blade angle during flight.
What does a constant-speed propeller control allow the pilot to do?
Select a blade angle appropriate for the flight operation being conducted.
It regulates engine RPM and is shown on the tachometer.
What should you avoid with a constant-speed propeller?
Low RPM settings with high manifold pressure.
This can lead to engine stress and potential damage.
What is important to ensure when hand-propping an airplane?
That you have received instruction on the correct procedure and a qualified pilot is at the controls.
Safety is paramount during this operation.
