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ASA POWERPLANT ORAL EXAM 2026
COMPLETE (135) CURRENT TESTING
QUESTIONS AND CORRECT ANSWERS WITH
DETAILED RATIONALES.
POWERPLANT
Prepare for the ASA Powerplant Oral Exam with this comprehensive study
resource designed to reinforce essential aircraft powerplant systems,
maintenance procedures, troubleshooting, and safety principles. This
document helps you review key topics, strengthen your technical
understanding, and identify areas that may require additional study
before the oral examination. Use it to build confidence and improve your
readiness through focused, organized preparation. An excellent
companion for effective aviation maintenance exam review.
MULTIPLE CHOICE.
SECTION 1: Reciprocating Engine Theory & Construction
(Questions 1–15)
Question 1: What is the main advantage of a horizontally
opposed engine over a radial engine for powering modern
aircraft?
A. Higher power output
B. Much smaller frontal area and easier to streamline
C. Lower fuel consumption
D. Lower maintenance costs
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Correct answer: B. Much smaller frontal area and easier to
streamline
Rationale: The horizontally opposed engine has a much smaller
frontal area and is easier to streamline than a radial engine.
Question 2: How many throws are there in the crankshaft of a
six-cylinder horizontally opposed engine?
A. Three
B. Four
C. Six
D. Twelve
Correct answer: C. Six
Rationale: A six-cylinder horizontally opposed engine has six throws
in the crankshaft.
Question 3: What kind of connecting rod arrangement is used in
a radial engine?
A. Parallel connecting rods
B. Fork-and-blade connecting rods
C. Master rod with link rods
D. Articulated connecting rods
Correct answer: C. Master rod with link rods
Rationale: A master rod connects the single throw of the crankshaft
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with a piston. All of the other pistons are connected to the master
rod with link rods.
Question 4: Of what material are most piston rings made?
A. Aluminum alloy
B. Stainless steel
C. Gray cast iron
D. Bronze
Correct answer: C. Gray cast iron
Rationale: Most piston rings are made of gray cast iron.
Question 5: What is the reason for using hydraulic valve lifters in
an aircraft engine?
A. To increase engine power
B. To reduce engine weight
C. To keep clearance out of the valve operating mechanism and
decrease wear
D. To improve fuel economy
Correct answer: C. To keep clearance out of the valve operating
mechanism and decrease wear
Rationale: Hydraulic valve lifters keep all of the clearance out of the
valve operating mechanism, decreasing the wear of the valve train
components.
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Question 6: At what speed does the camshaft turn, relative to
the crankshaft speed in a horizontally opposed engine?
A. Same speed as the crankshaft
B. Twice the crankshaft speed
C. One-quarter of the crankshaft speed
D. One-half of the crankshaft speed
Correct answer: D. One-half of the crankshaft speed
Rationale: The camshaft turns at one-half of the crankshaft speed.
Question 7: What kind of main bearings are used in a horizontally
opposed engine?
A. Roller bearings
B. Ball bearings
C. Steel-backed, lead-alloy bearing inserts
D. Bronze bushings
Correct answer: C. Steel-backed, lead-alloy bearing inserts
Rationale: Horizontally opposed engines use steel-backed, lead-
alloy bearing inserts for main bearings.
Question 8: On what stroke is the piston of a reciprocating
engine when the intake valve begins to open?
A. Compression stroke
ASA POWERPLANT ORAL EXAM 2026
COMPLETE (135) CURRENT TESTING
QUESTIONS AND CORRECT ANSWERS WITH
DETAILED RATIONALES.
POWERPLANT
Prepare for the ASA Powerplant Oral Exam with this comprehensive study
resource designed to reinforce essential aircraft powerplant systems,
maintenance procedures, troubleshooting, and safety principles. This
document helps you review key topics, strengthen your technical
understanding, and identify areas that may require additional study
before the oral examination. Use it to build confidence and improve your
readiness through focused, organized preparation. An excellent
companion for effective aviation maintenance exam review.
MULTIPLE CHOICE.
SECTION 1: Reciprocating Engine Theory & Construction
(Questions 1–15)
Question 1: What is the main advantage of a horizontally
opposed engine over a radial engine for powering modern
aircraft?
A. Higher power output
B. Much smaller frontal area and easier to streamline
C. Lower fuel consumption
D. Lower maintenance costs
, Page 2 of 67
Correct answer: B. Much smaller frontal area and easier to
streamline
Rationale: The horizontally opposed engine has a much smaller
frontal area and is easier to streamline than a radial engine.
Question 2: How many throws are there in the crankshaft of a
six-cylinder horizontally opposed engine?
A. Three
B. Four
C. Six
D. Twelve
Correct answer: C. Six
Rationale: A six-cylinder horizontally opposed engine has six throws
in the crankshaft.
Question 3: What kind of connecting rod arrangement is used in
a radial engine?
A. Parallel connecting rods
B. Fork-and-blade connecting rods
C. Master rod with link rods
D. Articulated connecting rods
Correct answer: C. Master rod with link rods
Rationale: A master rod connects the single throw of the crankshaft
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with a piston. All of the other pistons are connected to the master
rod with link rods.
Question 4: Of what material are most piston rings made?
A. Aluminum alloy
B. Stainless steel
C. Gray cast iron
D. Bronze
Correct answer: C. Gray cast iron
Rationale: Most piston rings are made of gray cast iron.
Question 5: What is the reason for using hydraulic valve lifters in
an aircraft engine?
A. To increase engine power
B. To reduce engine weight
C. To keep clearance out of the valve operating mechanism and
decrease wear
D. To improve fuel economy
Correct answer: C. To keep clearance out of the valve operating
mechanism and decrease wear
Rationale: Hydraulic valve lifters keep all of the clearance out of the
valve operating mechanism, decreasing the wear of the valve train
components.
, Page 4 of 67
Question 6: At what speed does the camshaft turn, relative to
the crankshaft speed in a horizontally opposed engine?
A. Same speed as the crankshaft
B. Twice the crankshaft speed
C. One-quarter of the crankshaft speed
D. One-half of the crankshaft speed
Correct answer: D. One-half of the crankshaft speed
Rationale: The camshaft turns at one-half of the crankshaft speed.
Question 7: What kind of main bearings are used in a horizontally
opposed engine?
A. Roller bearings
B. Ball bearings
C. Steel-backed, lead-alloy bearing inserts
D. Bronze bushings
Correct answer: C. Steel-backed, lead-alloy bearing inserts
Rationale: Horizontally opposed engines use steel-backed, lead-
alloy bearing inserts for main bearings.
Question 8: On what stroke is the piston of a reciprocating
engine when the intake valve begins to open?
A. Compression stroke
