Piston 2 - Week 3A
Why does fuel/air mixture need to be controlled?
Because of changes in altitude and temperature affect fuel density
Because of changes in air temperature and pressure affect engine cooling
Because of changes in air temperature and pressure affect air density
Because of changes in air temperature and pressure affect fuel density
How is an aircraft piston engine shut down?
By turning off the ignition
By turning off the fuel using the fuel selector valve
But turning off the fuel using the mixture control
But turning off the air using the throttle control
What will happen if less air/fuel is allowed to enter an ungoverned engine?
The engine speed will decrease & power will increase
The engine speed & power will decrease
The engine speed & power will increase
The engine speed will increase & power will decrease
Which of the following is the leanest mixture?
10:1
16:1
8:1
14:1
What state does fuel have to be for it to burn?
Plasma or ionized gaseous state
Vapour or gaseous state
Frozen or solid state
Liquid or fluid state
How is the flow of air into an engine controlled?
With a throttle valve in the exhaust system
With a throttle valve in the induction system
With an exhaust valve in the exhaust system
With a fuel metering valve in the induction system
What must be done to maintain the correct mixture into the engine as the aircraft climbs?
The mixture must be leaned
The throttle must be opened
The mixture must be richened
The throttle must be closed
How is fuel vaporized?
Exhaust is mixed with the fuel and then sprayed into exhaust air
Air is mixed with the fuel and then sprayed into induction air
Air is mixed with the fuel and then sprayed into exhaust air
Exhaust is mixed with the fuel and then sprayed into induction air
What will happen if more air/fuel is allowed to enter an ungoverned engine?
The engine speed will increase & power will decrease
The engine speed will decrease & power will increase
The engine speed & power will increase
The engine speed & power will decrease
What is fuel metering?
Adjustment of the amount of air released into the engine depending on the amount of fuel being drawn through the induction system
Adjustment of the amount of fuel released into the engine depending on the speed that the engine is rotating at
Adjustment of the amount of fuel released into the engine depending on the temperatures inside the cylinder
Adjustment of the amount of fuel released into the engine depending on the amount of air being drawn through the induction system
What is mixture ratio referring to?
The ratio of fuel to air going into the engine, by weight
The ratio of air to fuel going into the engine, by weight
The ratio of air to fuel going into the engine, by volume
The ratio of air to fuel going into the engine, in litres
What does an operating engine behave like?
A pump, drawing in spent gasses and forcing out fuel/air
A pump, drawing in fuel/air and forcing out spent gasses
A pump, drawing in air and forcing out spent gasses
A pump, drawing in fuel and forcing out spent gasses
Which of the following is the richest mixture?
14:1
10:1
8:1
16:1
Where is the fuel stored in a float carburetor?
In the venturi
In the float bowl
It is not stored in the carb, it is stored in the fuel tanks
In the accumulator
Where is the discharge nozzle of a carburetor?
Before the venturi
In the venturi
After the venturi, before the throttle valve
After the throttle valve
What does the float do in float carburetor?
It controls the level of fuel storage in the accumulator
It controls the level of fuel storage in the bowl
It controls the level of fuel storage in the venturi
It controls the level of air flow through the venturi
What physical principles does a float carburetor use?
Bernoulli's principle and buoyancy
Charles law and buoyancy
Bernoulli's principle and the general gas laws
Boyles law and gravity
Why was the pressure carburetor developed?
To ensure fuel flow at low altitudes and upright flight maneuvers
To ensure fuel flow at high altitudes and during aerobatic/inverted flight maneuvers
To ensure fuel flow at high altitudes and upright flight maneuvers
To ensure fuel flow at low altitudes and upright flight maneuvers
What is the purpose of a fuel injection system?
To provide higher fuel flow rates to the engine
To eliminate the drawbacks of carburetors
To eliminate the drawbacks of exhaust systems
To eliminate the drawbacks of turbocharging
What is an aircraft fuel injection system also known as?
A sequential fuel injection system
A continuous flow fuel injection system
A GDI fuel injection system
A direct injection fuel injection system
What does a fuel injection system do?
It provides for constant delivery of fuel directly to the intake port of each cylinder
It provides for constant delivery of fuel directly to the carburetor
It provides for constant delivery of air directly to the intake port of each cylinder
It provides for constant delivery of air/fuel directly to the intake port of each cylinder
What will be used to clean & separate the fuel before use in the engine?
An injector
A boost pump
A strainer
A sump
What is the result of using a fuel of high volatility?
Total atomization & more efficient burning
Partial atomization & inefficient burning
Total atomization & inefficient burning
Extreme cooling and potential for ice formation
Where is the fuel strainer located?
In the fuel tank
In the carburetor
At the high point in the fuel system
At the low point in the fuel system
What are the standard avgas ratings?
80, 87, 130, 145
80, 87, 100, 130
80, 100, 100LL
80, 100, 100LL, 130
What colour is 100LL Octane fuel?
Red
Straw or yellow
Green
Blue
What will all fuel strainers have on them?
Clear sides to see any contamination
A valve on the top to skim off water and contaminants
A valve on the bottom to drain water and contaminants
Opaque sides to hide contamination
What is the result of using a fuel of high volatility?
Total atomization & inefficient burning
Total atomization & more efficient burning
Fuel evaporating inside lines creating vapour lock
Partial atomization & inefficient burning
What colour is 80 Octane fuel?
Straw or yellow
Red
Blue
Green
What will happen in the fuel strainer?
Water and sediment will settle to the bottom
Fuel will settle and be taken from the bottom
Water and sediment will settle to the top
Sediment and water will rise to the top
What is the result of using a fuel of low volatility?
Fuel evaporating inside lines creating vapour lock
Total atomization & inefficient burning
Extreme cooling and potential for ice formation
Partial atomization & inefficient burning
What is volatility?
The ability for a material to change from liquid to a vapour
The ability for a material to change from solid to a vapour
The ability for a material to change from plasma to a solid
The ability for a material to change from plasma to a vapour
How can you tell if there has been a fuel leak on your aircraft?
The evaporation of the dye will leave behind the fuel
A wetness can be seen under Infrared light
A glowing wetness can be seen under UV light
The evaporation of the fuel will leave behind the dye used in it
What is detonation?
The uncontrolled explosion of fuel/air in the cylinder due to temperature and pressure
The controlled explosion of fuel/air in the cylinder due to temperature and pressure
The uncontrolled explosion of fuel/air in the cylinder due to temperature and density
The uncontrolled explosion of fuel/air in the cylinder due to density and pressure
What colour is 100 Octane fuel?
Red
Blue
Green
Straw or yellow
What is "lean best power"?
The mixture ratio that provides maximum rpm or manifold pressure
The mixture ratio that provides minimum rpm or manifold pressure
The mixture ratio that uses the least amount of fuel for a power setting
The mixture ratio that provides maximum EGT
How is the mixture controlled on most light aircraft as they climb?
By design
By the passengers
By automatic mixture control
By the pilot
What is the mixture ratio for best economy?
8:1
12:1
16:1
15:1
14:1
Approximately what would be the leanest mixture an engine can operate at?
8:1
16:1
12:1
15:1
14:1
What is the chemically "perfect" or Stoichiometric mixture ratio?
12:1
16:1
14:1
8:1
15:1
When is the mixture leaned on piston aircraft engines?
Right after take odd
Above 110-130tks
Above 30000-40000'
Above 3000-4000'
What is the standard process to lean the engine?
Pull back the mixture to peak EGT and push the mixture forward for a 25 degree drop
Push forward the mixture to peak CHT and pull the mixture back for a 25 degree drop
Push forward the mixture to peak EGT and pull the mixture back for a 25 degree drop
Pull back the mixture to peak CHT and pull the mixture back for a 25 degree drop
What is the process to lean some high performance engines?
Push forward the mixture to peak EGT and pull the mixture back for a 25 degree drop
Pull back the mixture to peak EGT and pull the mixture back for a 25 degree drop
Push forward the mixture to peak CHT and pull the mixture back for a 25 degree drop
Pull back the mixture to peak EGT and push the mixture forward for a 25 degree drop
Approximately what would be the richest mixture an engine can operate at?
16:1
15:1
8:1
12:1
14:1
When the mixture is at idle cut off, what will the valve position be?
Fully closed
1/2 open
1/3 open
Fully open
What instruments will be used on very simple aircraft the lean the mixture?
Fuel pressure or CHT gauges
Fuel flow or CHT gauges
Tachometer or manifold pressure gauges
Mixture gauge or manifold pressure gauge
What is the problem with operating at "best economy"?
It often generates damaging temperatures over short periods of time
It often generates damaging temperatures over longer periods of time
It often generates damaging vibrations over longer periods of time
It often generates damaging airspeeds over short periods of time
What must be done to the air/fuel ratio as the aircraft climbs?
The mixture must be leaned out
The mixture must be moved to ICO
The mixture must be enrichened
The mixture must be moved to full rich
What mixture setting do manufacturers often choose to use to avoid damaging temperatures?
Best economy
Lean best power
Full rich
ICO
When the mixture is full rich, what will the valve position be?
Fully open
Fully closed
1/3 open
1/2 open
What is "rich best power"?
The mixture ratio that provides maximum rpm or manifold pressure
The mixture ratio that uses the least amount of fuel for a power setting
The mixture ratio that provides minimum rpm or manifold pressure
The mixture ratio that provides maximum EGT
What is the mixture ratio for best power?
8:1
15:1
14:1
16:1
12:1
What is "best economy"?
The mixture ratio that provides minimum rpm or manifold pressure
The mixture ratio that uses the least amount of fuel for a power setting
The mixture ratio that provides maximum EGT
The mixture ratio that provides maximum rpm or manifold pressure
What instrument will be used on modern aircraft the lean the mixture?
Manifold pressure gauge
EGT gauges
CHT gauge
Tachometer
What is pre-ignition?
When glow plugs react with the fuel in the cylinder before the desired firing position
When the air/fuel mixture is ignited before reaching the desired firing position
When the air/fuel mixture is ignited after reaching the desired firing position
When glow plugs react with the fuel in the cylinder after the desired firing position
What will minor detonation damage look like when inspecting parts
They will have a heavy carbon build up on them
They will have a light carbon build up on them
They will have a "sand blasted" look
They will have a "polished" look
What will moderate detonation damage look like when inspecting parts?
They will have a "badly hammered" look
They will have a light carbon build up on them
They will have a "lightly hammered" look
They will have a heavy carbon build up on them
What can cause pre-ignition? #1
Red hot pieces of carbon
Red hot spark plugs
Red hot valve edges
All of the above
What can cause pre-ignition? #2
Shutting the engine down at too low an RPM
Clean filters
Too rich mixture settings at shut down
Poor cooling
What will moderate detonation damage look like when inspecting parts?
They will have a light carbon build up on them
They will have a "lightly hammered" look
They will have a heavy carbon build up on them
They will have a "polished" look
What is most likely to cause detonation?
Too low EGT
Too low CHT
Too high octane fuel
Too low octane fuel
What can cause detonation?
Hot spots inside the cylinder
Too low throttle settings & rich mixtures
Too high throttle settings & rich mixtures
Too high temperatures and pressures in the cylinder
What can cause pre-ignition? #3
Dirty filters
Shutting the engine down at too low an RPM
Too rich mixture settings at shut down
Good cooling
What will moderate detonation damage look like when inspecting parts?
They will have a heavy carbon build up on them
They will have a "polished" look
They will have a "sand blasted" look
They will have a light carbon build up on them
What is most likely to cause detonation?
Too high CHT
Too low CHT
Too low EGT
Too high octane fuel
What should be done when a backfire occurs?
Keep cranking the engine and move the mixture to ICO
Stop cranking immediately and move the mixture to ICO
Keep cranking the engine and move the fuel selector to off
Stop cranking immediately and evacuate the aircraft
What is after-fire?
The ignition of fuel in the exhaust system due to a too lean mixture
The ignition of fuel in the induction system due to a too lean mixture
The ignition of fuel in the induction system due to a too rich mixture
The ignition of fuel in the exhaust system due to a too rich mixture
What can an after-fire result in?
Damage to the muffler
The induction air box melting
The air filter catching on fire
The fuel filter catching on fire
What is backfire?
The ignition of fuel in the exhaust system due to a too lean mixture
The ignition of fuel in the exhaust system due to a too rich mixture
The ignition of fuel in the induction system due to a too lean mixture
The ignition of fuel in the induction system due to a too rich mixture
What can a backfire lead to?
A fire in the exhaust manufold
A fire in the induction air box
A fire in the muffler
Fire shooting out of the exhaust pipe
What can a back fire result in?
Damage to the muffler
The fuel filter catching on fire
The air filter catching on fire
The induction air box melting
What is the most common cause of after-fire?
Magneto checks at too low an rpm
Magneto checks with too rich a mixture
Magneto checks at too high an rpm
Magneto checks with too lean a mixture
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