(ASA) Powerplant Oral Study Guide TEST 2024-2026 ACTUAL
EXAM QUESTIONS AND CORRECT DETAILED ANSWERS
|ALREADY GRADED A+
What is the main advantage of a horizontally opposed engine over a radial engine
for powering modern aircraft? - CORRECT ANSWER The horizontally opposed
engine has a much smaller frontal area and is easier to streamline than a radial
engine
How many throws are there in the crankshaft of a six-cylinder horizontally
opposed engine? - CORRECT ANSWER Six
What kind of connecting rod arrangement is used in a radial engine? - CORRECT
ANSWER A master rod connects the single throw of the crankshaft with a piston.
All of the other pistons are connected to the master rod with link rods
How does metallic sodium in an exhaust valve aid in transferring heat? - CORRECT
ANSWER The sodium melts when the engine is running, and it sloshes up and
down as the valve operates. The sodium picks up heat from the valve head and
carries it into the stem so it can be transferred to the cylinder head and dissipated
into the air
How is the structure around a turbine engine protected from excessive heat from
the engine? - CORRECT ANSWER An insulating blanket protects the structure
from excessive heat
What is the function of blast tubes that are installed in a pressure cooling system
of a reciprocating engine? - CORRECT ANSWER These blast tubes direct cooling
air to the magnetos and the generator
,Of what material is the insulation blanket made that is used to protect the aircraft
structure from the heat produced by a turbine engine? - CORRECT ANSWER
Fiberglass sandwich between sheets of metal foil
Of what material are most recip engine exhaust components made? - CORRECT
ANSWER Corrosion-resistant steel
How is the speed of a turbo controlled? - CORRECT ANSWER By controlling the
amount of exhaust gas that flows through the turbine. This is controlled by the
position of the waste gate that is in the exhaust pipe
What type of actuator is used to control the position of the turbocharger waste
gate? - CORRECT ANSWER A hydraulic actuator that uses engine oil pressure to
move the piston
How does a power recovery turbine increase the power of a recip engine? -
CORRECT ANSWER Exhaust-driven velocity turbines are coupled through a
hydraulic drive to the engine crankshaft. Energy that would normally be lost is
used to drive the turbines, and the turbines assist in turning the crankshaft
how tight should the clamps be tightened that hold sections of a recip engine
exhaust system together? - CORRECT ANSWER They should not be so tight that
they will be damaged when heat expands the exhaust system components
What would be the effect on engine performance of an internal failure of a
muffler? - CORRECT ANSWER This will increase the exhaust back pressure and
cause a loss of engine power
,What effect on turbine engine operation is caused by a change in the area of the
exhaust nozzle? - CORRECT ANSWER Altering the area of the exhaust nozzle
affect the compression ratio, the rpm, the mass airflow through the engine, and
the EGT.
What are two types of thrust reversers that are used with turbojet engines? -
CORRECT ANSWER Mechanical blockage (clamshell) and aerodynamic blockage
(cascade)
How does a noise suppressor reduce the amount of noise produced by a turbojet
engine? - CORRECT ANSWER It breaks up the low-frequency vibrations in the
exhaust stream and converts them into high frequencies. These high frequencies
are dissipated by the air more easily than low frequencies
What is the purpose the ball joints and bellows in the exhaust system of a recip
engine? - CORRECT ANSWER The ball joints and bellows allows the exhaust
system components to change their dimensions without causing any leaks
Why do some supersonic aircraft use a convergent-divergent exhaust duct? -
CORRECT ANSWER A CD exhaust duct controls the gas expansion as it leave the
engine so the gases will produce thrust at supersonic velocities
Why is it important that a lead pencil never be used to mark on an aircraft exhaust
system? - CORRECT ANSWER The graphite in a lead pencil will infuse into the
metal when it gets hot. It makes the metal brittle and likely to crack
What types of damage is normally found in the hot section of a turbine engine? -
CORRECT ANSWER Cracks caused by heat
, What type of device is used on propeller blades to remove ice that has formed on
them? - CORRECT ANSWER Electrically heated deicer boots
What is used to prevent ice forming on a prop blade - CORRECT ANSWER A
mixture of ethylene glycol and isopropyl alcohol slung out along the blades
Should an adjustable-pitch prop be in high pitch or in low pitch for takeoff? -
CORRECT ANSWER In low pitch
What is done to cause a Hydromatic prop to feather? - CORRECT ANSWER High-
pressure engine oil is directed into the prop through the governor
What is done to cause a McCauley prop to feather? - CORRECT ANSWER Oil is
allowed to drain out of the prop
Does centrifugal twisting moment on a prop blade tent to move the blades toward
high pitch or toward low pitch? - CORRECT ANSWER Toward low pitch
Do the counterweights on a prop tend to move the blades toward high pitch or
toward low pitch? - CORRECT ANSWER Toward high pitch
What is the difference between a controllable prop and a constant-speed prop? -
CORRECT ANSWER Basically, it is the control system. A controllable-pitch prop
uses a manually operated oil valve to control the pitch, and a constant-speed prop
uses a governor to control the valve
EXAM QUESTIONS AND CORRECT DETAILED ANSWERS
|ALREADY GRADED A+
What is the main advantage of a horizontally opposed engine over a radial engine
for powering modern aircraft? - CORRECT ANSWER The horizontally opposed
engine has a much smaller frontal area and is easier to streamline than a radial
engine
How many throws are there in the crankshaft of a six-cylinder horizontally
opposed engine? - CORRECT ANSWER Six
What kind of connecting rod arrangement is used in a radial engine? - CORRECT
ANSWER A master rod connects the single throw of the crankshaft with a piston.
All of the other pistons are connected to the master rod with link rods
How does metallic sodium in an exhaust valve aid in transferring heat? - CORRECT
ANSWER The sodium melts when the engine is running, and it sloshes up and
down as the valve operates. The sodium picks up heat from the valve head and
carries it into the stem so it can be transferred to the cylinder head and dissipated
into the air
How is the structure around a turbine engine protected from excessive heat from
the engine? - CORRECT ANSWER An insulating blanket protects the structure
from excessive heat
What is the function of blast tubes that are installed in a pressure cooling system
of a reciprocating engine? - CORRECT ANSWER These blast tubes direct cooling
air to the magnetos and the generator
,Of what material is the insulation blanket made that is used to protect the aircraft
structure from the heat produced by a turbine engine? - CORRECT ANSWER
Fiberglass sandwich between sheets of metal foil
Of what material are most recip engine exhaust components made? - CORRECT
ANSWER Corrosion-resistant steel
How is the speed of a turbo controlled? - CORRECT ANSWER By controlling the
amount of exhaust gas that flows through the turbine. This is controlled by the
position of the waste gate that is in the exhaust pipe
What type of actuator is used to control the position of the turbocharger waste
gate? - CORRECT ANSWER A hydraulic actuator that uses engine oil pressure to
move the piston
How does a power recovery turbine increase the power of a recip engine? -
CORRECT ANSWER Exhaust-driven velocity turbines are coupled through a
hydraulic drive to the engine crankshaft. Energy that would normally be lost is
used to drive the turbines, and the turbines assist in turning the crankshaft
how tight should the clamps be tightened that hold sections of a recip engine
exhaust system together? - CORRECT ANSWER They should not be so tight that
they will be damaged when heat expands the exhaust system components
What would be the effect on engine performance of an internal failure of a
muffler? - CORRECT ANSWER This will increase the exhaust back pressure and
cause a loss of engine power
,What effect on turbine engine operation is caused by a change in the area of the
exhaust nozzle? - CORRECT ANSWER Altering the area of the exhaust nozzle
affect the compression ratio, the rpm, the mass airflow through the engine, and
the EGT.
What are two types of thrust reversers that are used with turbojet engines? -
CORRECT ANSWER Mechanical blockage (clamshell) and aerodynamic blockage
(cascade)
How does a noise suppressor reduce the amount of noise produced by a turbojet
engine? - CORRECT ANSWER It breaks up the low-frequency vibrations in the
exhaust stream and converts them into high frequencies. These high frequencies
are dissipated by the air more easily than low frequencies
What is the purpose the ball joints and bellows in the exhaust system of a recip
engine? - CORRECT ANSWER The ball joints and bellows allows the exhaust
system components to change their dimensions without causing any leaks
Why do some supersonic aircraft use a convergent-divergent exhaust duct? -
CORRECT ANSWER A CD exhaust duct controls the gas expansion as it leave the
engine so the gases will produce thrust at supersonic velocities
Why is it important that a lead pencil never be used to mark on an aircraft exhaust
system? - CORRECT ANSWER The graphite in a lead pencil will infuse into the
metal when it gets hot. It makes the metal brittle and likely to crack
What types of damage is normally found in the hot section of a turbine engine? -
CORRECT ANSWER Cracks caused by heat
, What type of device is used on propeller blades to remove ice that has formed on
them? - CORRECT ANSWER Electrically heated deicer boots
What is used to prevent ice forming on a prop blade - CORRECT ANSWER A
mixture of ethylene glycol and isopropyl alcohol slung out along the blades
Should an adjustable-pitch prop be in high pitch or in low pitch for takeoff? -
CORRECT ANSWER In low pitch
What is done to cause a Hydromatic prop to feather? - CORRECT ANSWER High-
pressure engine oil is directed into the prop through the governor
What is done to cause a McCauley prop to feather? - CORRECT ANSWER Oil is
allowed to drain out of the prop
Does centrifugal twisting moment on a prop blade tent to move the blades toward
high pitch or toward low pitch? - CORRECT ANSWER Toward low pitch
Do the counterweights on a prop tend to move the blades toward high pitch or
toward low pitch? - CORRECT ANSWER Toward high pitch
What is the difference between a controllable prop and a constant-speed prop? -
CORRECT ANSWER Basically, it is the control system. A controllable-pitch prop
uses a manually operated oil valve to control the pitch, and a constant-speed prop
uses a governor to control the valve
