WorksheetsPPL Air Tech - Carburettor
Total questions: 37
Worksheet time: 39mins
What is the fuel air ratio average by weight?
1:8
1:10
1:12
1:14
What is the purpose of the venturi in the carburettor?
to cool down the fuel/air mixture for evaporation
to heat up the fuel/air mixture for evaporation
to draw out the fuel from the nozzle
to accelerate air so the throttle butterfly doesnt flutter
What controls the rate at which air flows through the venturi?
the throttle butterfly
the mixture control
the accelerator pump
the metering jet
Why does a carburettor have an atomisation and diffusion system?
to improve vapourisation of the air
to distribute the mixture to each cylinder
to condense the mixture for smoother flow through the manifold
to improve vapourisation of the fuel
What system ensures there's sufficient fuel for engine operation when the throttle control is closed?
accelerating system
enrichment system
idling system
idle cut-off system
Why is a mixture control required?
To regulate the amount of fuel being metered
To regulate the amount of air being metered
To increase the rate of mixture flow
To increase the rate of fuel flow as throttle is opened
In 'standard' sea level conditions, mixture should be set to...
FULL RICH
FULL LEAN
IDLE CUT OFF
50% LEAN
When should the mixture be leaned?
on a climb
on start up
on descent
on alternator failure
How do you know when the mixture is leaned correctly on a fixed pitch propeller?
the rpm increases to a maximum
the rpm reduces to 2000rpm
the manifold pressure increases to a maximum
the manifold pressure reduces to 18 inches
What will an over-rich mixture most likely create?
detonation due to too much fuel
pre-ignition due to too much fuel
detonation due to not enough fuel
pre-ignition due to not enough fuel
What will an over-lean mixture most likely create?
detonation due to too much fuel
pre-ignition due to too much fuel
detonation due to not enough fuel
pre-ignition due to not enough fuel
Which is worse?
pre-ignition
detonation
Why should the engine be stopped using idle cut-off?
to ensure no fuel is left in the tanks
to ensure no fuel remains in the system
because turning the magentos to OFF could cause damage
because the engine would detonate if the magentos alone were used
What is the following situation called?
The mixture explodes rapidly and produces wildly fluctuating pressures, could cause engine failure if severe.
pre-ignition
detonation
idle cut-off
over rich mixture
A knocking sound accompanied by an excessively high CHT reading would indicate _______
pre ignition
detonation
flooded engine
low oil pressure
What should you do if detonation is experienced? Choose all that apply.
Increase airspeed
Reduce airspeed
Reduce throttle setting
Lean the mixture
Enrich the mixture
What is the following situation?
A mixture combusts before it receives a spark from the spark plug
pre-ignition
detonation
flame front advance
high oil temperature
_____ may occur in the one cylinder whereas _____ normally occurs in all cylinders
pre-ignition, detonation
detonation, pre-ignition
What is the first sign of carburettor ice?
reduction in CHT
reduction in airspeed
reduction in rpm
reduction in EGT
What ice forms immediately downstream of the main metering jet on the venturi?
refrigeration ice
throttle ice
intake ice
impact ice
when do you get refrigeration ice?
when flying in rain
when OAT drops below -15 degrees
when the fuel air mixture temperature drops below 0 degrees
when RH outside the aircraft is >90%
Refrigeration ice can occur with temperatures as high as ____ when RH exceeds _____
15 degrees, 15%
25 degrees, 10%
10 degrees, 50%
25 degrees, 50%
What icing is mainly due to fuel evaporating and therefore cooling plus moist incoming airflow?
throttle icing
refrigerator icing
impact icing
clear ice
What ice is mainly due to the mixture accelerating through the venturi, dropping in pressure and therefore cooling?
throttle icing
refrigerator icing
impact icing
intake icing
What is the required temperature range in the carburettor in order to get throttle or refrigerator icing?
-10 degrees to 0 degrees, visible moisture is required
-10 degrees to 0 degrees, visible moisture is not required
0 degrees to 10 degrees, visible moisture is required
0 degrees to 10 degrees, visible moisture is not required
When is carburettor icing most likely?
at high power settings flying through cirrostratus
at low power setting when carburettor temperature is 3 degrees
at high power settings when carb heat is not on
at low power settings when carb heat is not on
When is impact icing likely? Choose all that apply
When aircraft surfaces are below freezing
When flying into visible moisture >0 degrees
When flying into visible moisture of SCWD
When carb heat is not used
How do you get rid of impact icing?
Carb heat
Climb into warm sector
Descend into warmer air
Increasing throttle setting
What is the dangerous OAT range for refrigerator and throttle icing?
0 to 10 degrees
-10 to 25 degrees
-10 to 20 degrees
-20 to 10 degrees
What could you use as a warning to protect the aircraft from carburettor icing?
EGT gauge
RPM gauge
CHT gauge
CAT gauge
Which statement is incorrect?
Carburettor air is unfiltered
Carb heat should be turned off on final approach
Carb heat should be used on low power descent
If icing is suspected use half carb heat initially
What can you expect after using carb heat for suspected carb icing?
the rpm will increase and then reduce
the rpm will reduce and then increase
the rpm will increase
the rpm will reduce
Direct injection is more complex, heavier and more expensive than indirect fuel injection
true
false
Which statement is correct?
An indirectly fuel injected aircraft must also have a carburettor
A direct fuel injected system has the fuel injected into the combustion chamber
An indirect fuel injected system has the fuel injected into the combustion chamber
Indirect fuel injection is more expensive and complex than direct
What does FCU stand for?
fuel carburettor unit
final carburettor unit
fuel control unit
final control unit
Fill in the blanks for a fuel injected aircraft:
A _____ senses mass of air entering and throttle and mixture positions. The metered fuel passes through the _____ and then to the ____ in the required cylinder.
fuel injection nozzle, fuel control unit, flow divider
fuel injection nozzle, flow divider, fuel control unit
fuel control unit, fuel injection nozzle, flow divider
fuel control unit, flow divider, fuel injection nozzle
Which of the following are advantages of fuel injection system?
no refrigeration ice
less susceptible to contamination
less maintenance
more efficient
no risk of vapour locking
