ASA POWERPLANT ORAL STUDYGUIDE
EXAM (ACTUAL EXAM) WITH 180+
QUESTIONS WITH VERY ELABORATED
ANSWERS CORRECTRY WELL ORGANIZED
LATEST 2024 – 2025 ALREADY GRADED A+
Why is it important that the spark plugs be kept in numbered holes in a tray when
they are removed from an engine? - ANSWERS-Spark plugs tell a good deal about
the internal condition of the cylinder from which they were taken. By knowing the
cylinder from which each spark plugs came, the mechanic can take the proper
action when a spark plug indicates such conditions as detonation or overheating
What is the purpose of staggered timing between the two magnetos on an
aircraft engine? - ANSWERS-Engines in which the exhaust gas scavenging from the
cylinders is uneven use staggered ignition timing. The spark plug nearest the
exhaust valve, where the fuel-air moisture is diluted, fires before the spark plug
on the intake side. By using staggered timing, the flame front caused by the two
spark plugs will meet in the center of the piston
,In what position should the ignition switch be placed when using a timing light on
the magnetos - ANSWERS-In the both position
Why is it important that a torque wrench always be used when installing spark
plugs in an aircraft engine? - ANSWERS-If the spark plugs are not put in tight
enough, there is the possibility of a poor seal, and they are put in too tight, there
is a danger of cracking the insulation
Of what material are most piston rings made? - ANSWERS-Gray cast iron
What is the reason for using hydraulic valve lifters in an aircraft engine? -
ANSWERS-Hydraulic valve lifters keep all of the clearance out of the valve
operating mechanism. This decreases the wear of the valve train components
At what speed does the camshaft turn, relative to the crankshaft speed in a
horizontally opposed engine? - ANSWERS-The camshaft turns at one half of the
crankshaft speed
What kind of main bearings are used in a horizontally opposed engine? -
ANSWERS-Steel-backed, lead-alloy bearing inserts
What is the main advantage of a horizontally opposed engine over a radial engine
for powering modern aircraft? - ANSWERS-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? - ANSWERS-Six
What kind of connecting rod arrangement is used in a radial engine? - ANSWERS-
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
On what stroke is the piston of a reciprocating engine when the intake valve
begins to open? - ANSWERS-On the exhaust stroke
On what stroke is the piston of a reciprocating engine when the exhaust valve
begins to open? - ANSWERS-On the power stroke
Why are both the hot and cold valve clearances give for most radial engine? -
ANSWERS-The hot clearance is given for valve timing purposes. The timing is
adjusted with the valves in cylinder number one, set with the hot clearance.
When the timing is set, all of the valves are adjusted to their cold clearance.
What is meant by a cam-ground piston? - ANSWERS-A piston that is not perfectly
round. Its dimension parallel with the wrist pin is several thousandths of an inch
less than its dimension perpendicular to the wrist pin. When the piston reaches
operating temperature, the metal in the piston pin boss expands enough that the
piston becomes perfectly round
, Where is the piston in a reciprocating engine when the ignition spark occurs? -
ANSWERS-About 30 degrees of crankshaft rotation before the piston reaches top
center on the compression stroke
What is meant by a full-floating wrist pin? - ANSWERS-A wrist pin that is not
clamped in either the piston or the connecting rod. Full-floating wrist pins are
kept from scoring the cylinder walls by soft metal plugs in their ends
Why do most aircraft reciprocating engines use more than one spring on each
valve? - ANSWERS-By using more than one spring and having the wire diameter
and pitch of the springs different, valve float is minimized. The springs have
different resonant frequencies, so at least one spring will always be exerting a
force on the valve
Would excessive valve clearance cause the valves to open early or late? -
ANSWERS-Excessive clearance will cause the valve to open late and close early
What is the purpose of valve overlap in a reciprocating engine? - ANSWERS-Valve
overlap allows the inertia of the exhaust gases leaving the cylinder to help the
fresh induction charge start flowing into the cylinder
What type of piston rings are installed on the pistons of an aircraft reciprocating
engine? - ANSWERS-Compression rings, oil control rings, and oil wiper rings
Why are some exhaust valves partially filled with metallic sodium? - ANSWERS-
The metallic sodium melts at engine operating temperature and sloshes back and
EXAM (ACTUAL EXAM) WITH 180+
QUESTIONS WITH VERY ELABORATED
ANSWERS CORRECTRY WELL ORGANIZED
LATEST 2024 – 2025 ALREADY GRADED A+
Why is it important that the spark plugs be kept in numbered holes in a tray when
they are removed from an engine? - ANSWERS-Spark plugs tell a good deal about
the internal condition of the cylinder from which they were taken. By knowing the
cylinder from which each spark plugs came, the mechanic can take the proper
action when a spark plug indicates such conditions as detonation or overheating
What is the purpose of staggered timing between the two magnetos on an
aircraft engine? - ANSWERS-Engines in which the exhaust gas scavenging from the
cylinders is uneven use staggered ignition timing. The spark plug nearest the
exhaust valve, where the fuel-air moisture is diluted, fires before the spark plug
on the intake side. By using staggered timing, the flame front caused by the two
spark plugs will meet in the center of the piston
,In what position should the ignition switch be placed when using a timing light on
the magnetos - ANSWERS-In the both position
Why is it important that a torque wrench always be used when installing spark
plugs in an aircraft engine? - ANSWERS-If the spark plugs are not put in tight
enough, there is the possibility of a poor seal, and they are put in too tight, there
is a danger of cracking the insulation
Of what material are most piston rings made? - ANSWERS-Gray cast iron
What is the reason for using hydraulic valve lifters in an aircraft engine? -
ANSWERS-Hydraulic valve lifters keep all of the clearance out of the valve
operating mechanism. This decreases the wear of the valve train components
At what speed does the camshaft turn, relative to the crankshaft speed in a
horizontally opposed engine? - ANSWERS-The camshaft turns at one half of the
crankshaft speed
What kind of main bearings are used in a horizontally opposed engine? -
ANSWERS-Steel-backed, lead-alloy bearing inserts
What is the main advantage of a horizontally opposed engine over a radial engine
for powering modern aircraft? - ANSWERS-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? - ANSWERS-Six
What kind of connecting rod arrangement is used in a radial engine? - ANSWERS-
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
On what stroke is the piston of a reciprocating engine when the intake valve
begins to open? - ANSWERS-On the exhaust stroke
On what stroke is the piston of a reciprocating engine when the exhaust valve
begins to open? - ANSWERS-On the power stroke
Why are both the hot and cold valve clearances give for most radial engine? -
ANSWERS-The hot clearance is given for valve timing purposes. The timing is
adjusted with the valves in cylinder number one, set with the hot clearance.
When the timing is set, all of the valves are adjusted to their cold clearance.
What is meant by a cam-ground piston? - ANSWERS-A piston that is not perfectly
round. Its dimension parallel with the wrist pin is several thousandths of an inch
less than its dimension perpendicular to the wrist pin. When the piston reaches
operating temperature, the metal in the piston pin boss expands enough that the
piston becomes perfectly round
, Where is the piston in a reciprocating engine when the ignition spark occurs? -
ANSWERS-About 30 degrees of crankshaft rotation before the piston reaches top
center on the compression stroke
What is meant by a full-floating wrist pin? - ANSWERS-A wrist pin that is not
clamped in either the piston or the connecting rod. Full-floating wrist pins are
kept from scoring the cylinder walls by soft metal plugs in their ends
Why do most aircraft reciprocating engines use more than one spring on each
valve? - ANSWERS-By using more than one spring and having the wire diameter
and pitch of the springs different, valve float is minimized. The springs have
different resonant frequencies, so at least one spring will always be exerting a
force on the valve
Would excessive valve clearance cause the valves to open early or late? -
ANSWERS-Excessive clearance will cause the valve to open late and close early
What is the purpose of valve overlap in a reciprocating engine? - ANSWERS-Valve
overlap allows the inertia of the exhaust gases leaving the cylinder to help the
fresh induction charge start flowing into the cylinder
What type of piston rings are installed on the pistons of an aircraft reciprocating
engine? - ANSWERS-Compression rings, oil control rings, and oil wiper rings
Why are some exhaust valves partially filled with metallic sodium? - ANSWERS-
The metallic sodium melts at engine operating temperature and sloshes back and
