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ASA POWERPLANT ORAL EXAM 2 NEWEST 2026
ACTUAL VERIFIED EXAM WITH COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS
(100% VERIFIED ANSWERS) |ALREADY GRADED A+|
||NEWEST EXAM!!||
Where is the piston in a reciprocating engine when the
ignition spark occurs? - Answer-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? - Answer-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? - Answer-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 a valve.
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Would excessive valve clearance cause the valves to
open early or late? - Answer-Excessive valve clearance
will cause the valve to open late and close early.
What is the purpose of valve overlap in a reciprocating
engine? - Answer-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? - Answer-Compression
rings, oil control rings, and oil wiper rings.
What is the main advantage of a horizontally opposed
engine over a radial engine for powering modern aircraft?
- 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? - Answer-Six.
What kind of connecting rod arrangement is used in a
radial engine? - Answer-A master rod connects the single
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throw of the crankshaft with a piston. All of the other
pistons are connected to the master rod with link rods.
Of what material are most piston rings made? - Answer-
Gray cast iron.
What is the reason for using hydraulic valve lifters in an
aircraft engine? - Answer-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? -
Answer-The camshaft turns at one half of the crankshaft
speed.
What kind of main bearings are used in a horizontally
opposed engine? - Answer-Steel-backed, lead-alloy
bearing inserts.
On what stroke is the piston of a reciprocating engine
when the intake valve begins to open? - Answer-On the
exhaust stroke.
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On what stroke is the piston of a reciprocating engine
when the exhaust valve begins to open? - Answer-On the
power stroke.
Why are both the hot and cold valve clearances given for
most radial engines? - Answer-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? - Answer-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.
Why are some exhaust valves partially filled with metallic
sodium? - Answer-The metallic sodium melts at engine
operating temperature and sloshes back and forth inside
ASA POWERPLANT ORAL EXAM 2 NEWEST 2026
ACTUAL VERIFIED EXAM WITH COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS
(100% VERIFIED ANSWERS) |ALREADY GRADED A+|
||NEWEST EXAM!!||
Where is the piston in a reciprocating engine when the
ignition spark occurs? - Answer-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? - Answer-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? - Answer-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 a valve.
,2|Page
Would excessive valve clearance cause the valves to
open early or late? - Answer-Excessive valve clearance
will cause the valve to open late and close early.
What is the purpose of valve overlap in a reciprocating
engine? - Answer-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? - Answer-Compression
rings, oil control rings, and oil wiper rings.
What is the main advantage of a horizontally opposed
engine over a radial engine for powering modern aircraft?
- 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? - Answer-Six.
What kind of connecting rod arrangement is used in a
radial engine? - Answer-A master rod connects the single
,3|Page
throw of the crankshaft with a piston. All of the other
pistons are connected to the master rod with link rods.
Of what material are most piston rings made? - Answer-
Gray cast iron.
What is the reason for using hydraulic valve lifters in an
aircraft engine? - Answer-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? -
Answer-The camshaft turns at one half of the crankshaft
speed.
What kind of main bearings are used in a horizontally
opposed engine? - Answer-Steel-backed, lead-alloy
bearing inserts.
On what stroke is the piston of a reciprocating engine
when the intake valve begins to open? - Answer-On the
exhaust stroke.
, 4|Page
On what stroke is the piston of a reciprocating engine
when the exhaust valve begins to open? - Answer-On the
power stroke.
Why are both the hot and cold valve clearances given for
most radial engines? - Answer-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? - Answer-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.
Why are some exhaust valves partially filled with metallic
sodium? - Answer-The metallic sodium melts at engine
operating temperature and sloshes back and forth inside
