Airplane Systems Flashcards
Are there any disadvantages associated with fuel-injected engines? (FAA-H-8083-25)
a. Difficulty in starting a hot engine
b. Vapor locks during ground operations on hot days
c. Problems associated with restarting an engine that quits because of fuel starvation
What is an alternate induction air system and when is it used?
- allow induction airflow to continue should the primary induction air opening become blocked.
- for example impact ice
What is the condition known as vapor lock?
- condition in which AVGAS vaporizes in the fuel line or other components between the fuel tank and the carburetor.
- happens on warm days on aircraft with engine-driven fuel pumps that suck fuel from the tank(s).
- Vapor lock can be caused by excessively hot fuel, low pressure, or excessive turbulence of the fuel traveling through the fuel system.
- In each case, liquid fuel vaporizes prematurely and blocks the flow of liquid fuel to the carburetor.
- Various steps can be taken to prevent vapor lock. The most common is the use of boost pumps located in the fuel tank that force pressurized liquid fuel to the engine
What does the throttle do? (
- control the amount of fuel/air charge entering the cylinders.
- This in turn regulates the engine manifold pressure.
What does the mixture control do?
- Regulates fuel to air ratio with (sometimes) mixture control.
- be controlled by the pilot during flight.
- The purpose of a mixture control is to prevent the mixture from becoming too rich at high altitudes, due to decreasing air density. Leaning the mixture during cross-country flights conserves fuel and provides optimum power.
What are turbochargers?
- Higher performance aircraft at higher altitudes with less air density.
- By compressing the thin air by means of an air compressor, the turbocharged engine will maintain the preset power as altitude is increased.
What are cowl flaps?
- Located on the engine cowling and allow the pilot to control the operating temperature of the engine by regulating the amount of air circulating within the engine compartment.
When are cowl flaps used?
- During starting of the engine
- While taxiing
- During takeoff and high-power climb operation
b. The cowl flaps should be in the “closed” position in the following operations:
- During extended let-downs
- Anytime excessive cooling is a possibility (i.e., approach to landing, engine-out practice, etc.)
What type of propeller does this aircraft have?(AFM/POH) Know your plane
The airplane propeller may be described as
a. All-metal,
b. Two-bladed,
c. Constant-speed, and
d. Governor-regulated.
Discuss fixed-pitch propellers. (FAA-H-8083-25)
- The pitch of this propeller is fixed by the manufacturer and can not be changed by the pilot.
Two types of fixed-pitch propellers are:
- Climb propeller - has a lower pitch, therefore less drag. Results in higher RPM and more horsepower being developed by the engine;
- increases performance during takeoffs and climbs, but decreases performance during cruising flight.
Cruise propeller - has a higher pitch, therefore more drag. Results in lower RPM and less horsepower capability; decreases performance during takeoffs and climbs, but increases efficiency during cruising flight.
Discuss variable-pitch propellers (constant speed)
- constant-speed propeller is capable of continuously adjusting the propeller blade angle to maintain a constant engine speed.
- For example, if engine RPM increases as a result of a decreased load on the engine (descent), the system automatically increases the propeller blade angle (increasing air load) until the RPM has returned to the preset speed.
- The propeller governor can be regulated by the pilot with a control in the cockpit, so that any desired blade angle setting (within its limits) and engine operating RPM can be obtained, thereby increasing the airplane’s efficiency in various flight conditions.
What does the propeller control do?
- The propeller control regulates propeller pitch and engine RPM as desired for a given flight condition.
- The propeller control adjusts a propeller governor which establishes and maintains the propeller speed, which in turn maintains the engine speed.
What would the desired propeller setting be for maximum performance situations such as .takeoff?
- A low pitch, high RPM setting produces maximum power and thrust.
- The low blade angle keeps the angle of attack small and efficient with respect to the relative wind.
- At the same time, it allows the propeller to handle a smaller mass of air per revolution.
- This light load allows the engine to turn at high RPM and to convert the maximum amount of fuel into heat energy in a given time.
- The high RPM also creates maximum thrust because the mass of air handled per revolution is small, the number of revolutions per minute is many, the slipstream velocity is high, and the airplane speed is low.
What is a propeller governor?
- The propeller governor controls the flow of engine oil to or from a piston in the propeller hub.
- When the engine oil, under high pressure from the governor pump, pushes the piston forward , the propeller blades are twisted toward a high pitch/low RPM condition.
- When the engine oil is released from the cylinder, centrifugal force, with the assistance of an internal spring, twists the blades towards a low pitch/high RPM condition.
When operating an airplane with a constant-speed propeller, which condition induces the most stress on the engine?
- Excessive manifold pressure raises the cylinder compression pressure, resulting in high stresses within the engine.
- Excessive pressure also produces high engine temperatures.
- A combination of high manifold pressure and low RPM can induce damaging detonation
