Class Two - Engines, Electrical Systems, Flight Instruments Flashcards
What are the four parts of a four stroke engine
- Intake stroke (fuel)
- Compression stroke
- Power stroke
- Exhaust stroke
FAA question: What is one purpose for using reciprocating engines?
They are relatively simple and inexpensive to operate.
Why do aircrafts have dual ignition systems (2 spark plugs per cylinder)?
- Efficiency - lighting a fire from multiple sides crease a smoother, more even spreading flame allowing a more “uniform heat distribution”
- Increases safety (these must work at all times)
Magnetos
Spark Generators! A self contained source of electrical energy so if the aircraft lost its electrical power, the engine will continue to run.
How do magnetos work?
They contain spinnable magnets, housed in a metal case, that generate the electrical sparks for the spark plug.
What is a run up test - MAG drops?
Selecting the right or left magneto deactivates the other mag by grounding it to the airframe. Absence of a mag drop can indicate that a mag may not be grounded. Prop safety.
FAA Question: One purpose of the dual ignition system on an aircraft engine is to provide for:
Uniform heat distribution
FAA Question: An electrical system failure (battery and alternator) occurs during flight. In this situation, what would you experience?
Avionics equipment failure (radio).
What does a carburetor do?
To mix a perfect amount of air and fuel together to send to each one of the cylinders
Carburetor Idling System
When the throttle is pulled back all the way, the butterfly valve closes and power is reduced. The engine continues to run at a lower power because the idle mixture screw on the side allows a small amount of fuel to sneak by the throttle (butterfly) valve.
Carburetor’s Accelerator Pump
When throttle is opened quickly (pushed forward and pushes plunger down), the accelerator pump squirts a small jet of fuel into the carburetor’s throat to compensate of the sudden inrush of air into the engine, preventing engine stammer or hesitation.
FAA Question: The operating principle of float-type carburetors is based on what?
The difference in air pressure at the Venturi’s throat and the air inlet.
Carburetor Butterfly Value
As power is added, the butterfly valve opens and closed when power is reduced.
Carburetor Ice
Due to atomization and evaporation of fuel, any moisture present can freeze. CAN happen at any temperature, most likely with outside temperatures between 20-70 degrees F. The temp will drop as much as 70 degree F within a carburetor’s throat.
What are the two form of carburetor ice?
- Throttle ice: forms on the backside and downstream of throttle valve
- Fuel ice: forms along throat of carb and upstream of throttle valve.
Throttle Ice
forms on the rear of throttle valve and mostly likely to occur when the throttle valve is partially closed. Carburetors break up fuel into millions of tiny, atom like droplets and mix them with the air, and this atomization cools the cylinder
Impact Ice
Occurs when visible moisture is present. Moisture can freeze the induction systems air filter and restrict the incoming air, and may also occur during freezing rain.
Carb Heat
Pulling unfiltered air from the heat shroud around the exhaust manifold to prevent or remove impact ice.
How to detect carb ice
- RPM decreasing (you suspect carb ice)
- Apply full carburetor heat (RPM decreases further)
- As ice melts the RMP increases (it rises then stops)
d. Carb heat is then turned off (RMP rises again)
FAA test question: which condition is most favorable to the development of carburetor icing?
Temperature between 20 and 70 degrees F and high humidity
FAA test question: If an aircraft is equipped with a fixed pitch propeller in a float type carburetor, the first indication of carburetor ice would most likely be:
Loss of RPM
Mixture Control - The Red Knob
Allows you to keep your aircraft operating with the proper fuel-air ratio as air density changes with altitude.
1. Pulling it out towards you = leaning
2. Pushing it away from you = rich
How do you accomplish leaning fuel?
Leaning is accomplished by restricting the flow of fuel through the main metering jet (idle cutoff if you pull it all the way out)
Fuel air mixture
Increase in altitude, air becomes thinner and doesn’t weigh as much for a given volume. To maintain the same fuel-air ratio at higher altitudes, we must manually adjust the amount of gas leaving the carburetor.