1. Engine Intro & Basic Induction
Presented by:
Will Miller

2. Engine Types Turbine Engine Reciprocating Engine
Found in transport Category aircraft
Relatively costly but extremely powerful
Reciprocating Engine
Found in general aviation
Economical, but still very reliable

3. Cessna Engine
Horizontally Opposed
Direct Drive
Air Cooled
4 cylinder

4. Engine Operation
What are the four strokes of an engine?

5. Four Strokes on an Engine

6. Intake When the piston moves away form the cylinder head
Intake valve opens
Fuel/Air mixture is drawn into the combustion chamber

7. Compression Piston moves back toward the cylinder head
Intake valve closes
Fuel/Air Mixture is compressed

8. Power Compression nearly complete Spark plugs fire
Compressed mixture is ignited
Rapidly expanding gases drive the piston, providing the power that rotates the crankshaft

9. Exhaust
Expels the burned gases through the exhaust valve, which opens at the end of the power stroke

10. Induction System
Brings outside air into the engine, mixes it with fuel in the proper proportion and deliver it to the cylinders where combustion occurs.
Throttle
Mixture
Intake Port

11. Throttle Controls Engine Speed
Regulates the amount of fuel/air mixture that flows into the cylinders

12. Mixture
Controls the fuel/air ratio

13. Intake Port Where outside air enters the induction system
Normally contains an air filter to keep out dust and FOD

14. Carburetor
Mixes the incoming air with fuel and delivers it to the combustion chamber

15. Carburetor
Air passes through a venturi, increases velocity and decreases pressure
Fuel enters from a float chamber where it is maintained at a nearly constant level by a float device
Discharge nozzle is located in an area of low pressure created by the venturi
Fuel is forced through the discharge nozzel by the higher atmospheric pressure in the float chamber

16. Overly Rich Mixture What does it mean to have a “Rich” mixture?
As altitude increases, the mixture will get progressively richer due to the decrease in air density.
Can result in engine roughness: excessive carbon buildup on the spark plug will cause them to foul.
High elevation airports, climb or cruise at high elevation

17. Overly Lean Mixture What does it mean to have a “Lean” mixture?
May result in high engine temperatures causing excessive wear or even failure
Enrichen Mixture on descents from high altitudes
Watch engine temperature

18. Carburetor Ice
Occurs due to the effect of fuel vaporization and decreasing pressure in the venturi which causes a sharp temperature drop in the carburetor
If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve
Likely below 21C (70F), humidity above 80%

19. Carburetor Ice

20. Carburetor Ice

21. Carburetor Ice Indications
Why can Carburetor Ice be dangerous?
What are some indications of Carb Ice?
Drop in engine RPM
Engine Roughness
Fuel starvation
What can we do to get rid of carburetor ice or even prevent it from happening in the first place?
Carburetor Heat

22. Carburetor Heat
Carburetor ice is especially dangerous when operating at low power settings, may go unnoticed until power is added
How does carburetor heat work?
Carburetor heat routes air across a heat source before it enters the carburetor
How will carb heat affect engine performance?
Causes a slight decrease in engine power (heated air is less dense)
If ice is present, there will be a decrease followed by a gradual increase in rpm

23. Carburetor Heat