Induction System Flashcards
What is an induction system
Process of taking outside air and mixing it with fuel
How does air get into the induction system
AIR INTAKE
What is the filter used for
FILTER OUTSIDE AIR
What is the ideal fuel to air ratio
1:12
1 part fuel, 12 parts air
What are the 2 types of mixer used in an induction system
methods of getting fuel and air into the cylinder
- Carburettor
- Injection System
How does a carburettor suck fuel into the mixer
VENTURI EFFECT
Pressure drop occurs
Fuel sucked into airflow from discharge nozzle
Fuel is sucked into the mixer through what component of the engine
DISCHARGE NOZZLE
What is the name given to the space that holds a small reservoir of fuel that is kept at a constant level inside of the engine
FLOAT CHAMBER
At what level is the air pressure in a float chamer normally at
ATMOSPHERIC
What is significant about pressure that allows fuel to be forced from the float chamber to the discharge nozzle
Atmospheric Pressure > Venturi Pressure
Greater pressure in the float chamber pushes fuel down the pipe towards the discharge nozzle
Opening the throttle more results in MORE or LESS RPM
MORE
When the throttle is closed, how is the engine kept running at idle
IDLE JET INLET
aka Slow Running Jet
When a throttle is opened quickly, what device forces fuel into the Venturi to compensate for the sudden increase of airflow
ACCELERATOR PUMP
At high power settings, why is mixture designed to be more fuel rich
EXCESS FUEL ACTS AS COOLANT
Why is mixture contorl important at altitude
LESS DENSE AIR
Less dense air means less efficient burning of mixture
Less dense air means more fuel to air parts
At altitude, the mixture becomes MORE or LESS rich
Why
- MORE
- LESS DENSE AIR = LESS AIR PARTS TO FUEL
At high altitudes, if mixture is left rich, what is the typical ratio
1:8
Above what altitude sjhould mixture control typically be used
3000 ft
when typically should the engine be leaned
CRUISE
When only an RPM gauge available, what are the 4 steps to mixture leaning
- Note RPM
- Lean mixture until RPM peaks then drops
- Enrich mixture until RPM peaks
- Enrich mixture slightly more to maintain rich side peak
When EGT gauge is available, what are the 3 steps to mixture leaning
- Lean mixture until EGT reaches peak and starts to fall
- Richen mixture until EGT peaks
- Richen mixture until EGT falls
What are 5 results of too rich mixture
- Inefficient burn (cooler)
- Reduced RPM
- Engine runs cooler
- Spark Plug Fouling
- Mixture incombustible
What are 5 results of too lean mixture
- Inefficient burn (hotter)
- Reduced RPM
- Engine runs hotter
- Pre-ignition or Detonation
- Engine damage
What is the approximate air temperature drop within the venturi
25℃ to 30℃
What is the dominant factor of carburettor icing
HUMIDITY
What are 4 key symptoms of carb icing
1 answer for fixed prop, 1 for variable
- Decreasing RPM (fixed pitch prop)
- Decreasing Manifold Pressure (CSU prop)
- Rough Running
- Engine Failure
How is warm air introduced into the carburettor to de-ice
CARB HEAT CONTROL
What is the name for;
Icing formed from moist air hitting the cold air intake surface
IMPACT ICING
6 advantages of a fuel injection system
- Reduced Evaporative Icing
- Fuel Flow
- Throttle Response
- Mixture Control
- Fuel Distribution
- Cold Weather Starts
3 disadvantages of a fuel injection system
- Difficult hot engine start
- Vapour Lock
- Difficult engine restart after fuel starvation
2 methods of priming an engine
- Cockpit Primer Control
- Throttle Priming
