FAA POWERPLANT WRITTEN EXAM PREP COMPLETE
QUESTIONS WITH 100% CORRECT ANSWERS
QUESTION: 1
What is the purpose of an impulse coupling in a magneto?
A) To increase spark plug firing frequency
B) To reduce magneto noise
C) To produce a high momentary speed of the magneto for starting (Correct
Option)
D) To advance ignition timing during cruise
RATIONALE: The impulse coupling stores energy and releases it to spin the
magneto rapidly, producing a hot spark for engine starting.
QUESTION: 2
What type of connecting rod arrangement is used in a radial engine?
A) Individual connecting rods for each cylinder
B) Fork and blade connecting rods
C) Articulated connecting rods only
D) A master rod connects the single throw of the crankshaft with a piston; all
other pistons connect to the master rod with link rods (Correct Option)
RATIONALE: Radial engines use a master rod system where one rod connects
directly to the crankshaft and all other rods attach to the master rod.
,QUESTION: 3
What is the primary purpose of the freewheeling unit in a helicopter?
A) It allows the engine to be started without driving the main rotor system
(Correct Option)
B) It provides speed reduction between the engine and rotor system
C) It increases rotor speed during autorotation
D) It connects the engine directly to the tail rotor
RATIONALE: The freewheeling unit disengages the engine from the rotor system
during autorotation and allows starting without rotor movement.
QUESTION: 4
What is the approximate position of the rotating magnet in a high tension
magneto when the points first close?
A) E-gap position
B) 90 degrees before neutral
C) Neutral position
D) Full register (Correct Option)
RATIONALE: The rotating magnet is in full register position when the breaker
points first close, beginning the magnetic field buildup.
QUESTION: 5
What is the primary advantage of using propeller reduction gears?
A) To decrease engine weight
B) To reduce fuel consumption
C) To simplify engine design
D) To enable the engine RPM to increase with an accompanying increase in
power while allowing the propeller shaft to remain at lower RPM (Correct
Option)
,RATIONALE: Reduction gears allow engines to operate at higher, more efficient
RPMs while keeping propeller speeds in an efficient range.
QUESTION: 6
What directly regulates the speed of a turbocharger?
A) Throttle position
B) Waste gate (Correct Option)
C) Manifold pressure gauge
D) Fuel control unit
RATIONALE: The waste gate diverts exhaust gases around or through the turbine,
directly controlling turbocharger speed and manifold pressure.
QUESTION: 7
If the turbocharger waste gate is completely closed, what happens?
A) All exhaust gases bypass the turbine
B) The engine loses all power
C) The waste gate controller fails
D) All exhaust gases are directed through the turbine (Correct Option)
RATIONALE: A closed waste gate directs all exhaust gases through the turbine,
producing maximum boost pressure.
QUESTION: 8
What is the function of an exhaust cone assembly on a turbine engine?
A) To increase exhaust gas temperature
B) To reduce exhaust noise
C) To cool exhaust gases
D) To straighten and collect the exhaust gases into a solid exhaust jet (Correct
Option)
, RATIONALE: The exhaust cone straightens gas flow and converts pressure energy
into velocity energy for thrust production.
QUESTION: 9
What is meant by a cam-ground piston?
A) A piston with adjustable cam lobes
B) A piston made from camshaft material
C) A piston with variable compression ratio
D) A piston that is not perfectly round; its dimension parallel with the wrist pin is
less than its dimension perpendicular to the wrist pin (Correct Option)
RATIONALE: Cam-ground pistons are oval-shaped so they become perfectly round
at operating temperature due to thermal expansion.
QUESTION: 10
What is the primary purpose of stator vanes in the compressor of an axial flow
turbine engine?
A) To decrease air pressure
B) To add fuel to the airstream
C) To cool the compressor blades
D) To increase air pressure (Correct Option)
RATIONALE: Stator vanes act as diffusers, converting velocity energy into pressure
energy and directing air to the next rotor stage.
QUESTION: 11
Where on a float-type carburetor is the throttle valve positioned?
A) After the float chamber
B) At the carburetor inlet
C) Before the venturi
QUESTIONS WITH 100% CORRECT ANSWERS
QUESTION: 1
What is the purpose of an impulse coupling in a magneto?
A) To increase spark plug firing frequency
B) To reduce magneto noise
C) To produce a high momentary speed of the magneto for starting (Correct
Option)
D) To advance ignition timing during cruise
RATIONALE: The impulse coupling stores energy and releases it to spin the
magneto rapidly, producing a hot spark for engine starting.
QUESTION: 2
What type of connecting rod arrangement is used in a radial engine?
A) Individual connecting rods for each cylinder
B) Fork and blade connecting rods
C) Articulated connecting rods only
D) A master rod connects the single throw of the crankshaft with a piston; all
other pistons connect to the master rod with link rods (Correct Option)
RATIONALE: Radial engines use a master rod system where one rod connects
directly to the crankshaft and all other rods attach to the master rod.
,QUESTION: 3
What is the primary purpose of the freewheeling unit in a helicopter?
A) It allows the engine to be started without driving the main rotor system
(Correct Option)
B) It provides speed reduction between the engine and rotor system
C) It increases rotor speed during autorotation
D) It connects the engine directly to the tail rotor
RATIONALE: The freewheeling unit disengages the engine from the rotor system
during autorotation and allows starting without rotor movement.
QUESTION: 4
What is the approximate position of the rotating magnet in a high tension
magneto when the points first close?
A) E-gap position
B) 90 degrees before neutral
C) Neutral position
D) Full register (Correct Option)
RATIONALE: The rotating magnet is in full register position when the breaker
points first close, beginning the magnetic field buildup.
QUESTION: 5
What is the primary advantage of using propeller reduction gears?
A) To decrease engine weight
B) To reduce fuel consumption
C) To simplify engine design
D) To enable the engine RPM to increase with an accompanying increase in
power while allowing the propeller shaft to remain at lower RPM (Correct
Option)
,RATIONALE: Reduction gears allow engines to operate at higher, more efficient
RPMs while keeping propeller speeds in an efficient range.
QUESTION: 6
What directly regulates the speed of a turbocharger?
A) Throttle position
B) Waste gate (Correct Option)
C) Manifold pressure gauge
D) Fuel control unit
RATIONALE: The waste gate diverts exhaust gases around or through the turbine,
directly controlling turbocharger speed and manifold pressure.
QUESTION: 7
If the turbocharger waste gate is completely closed, what happens?
A) All exhaust gases bypass the turbine
B) The engine loses all power
C) The waste gate controller fails
D) All exhaust gases are directed through the turbine (Correct Option)
RATIONALE: A closed waste gate directs all exhaust gases through the turbine,
producing maximum boost pressure.
QUESTION: 8
What is the function of an exhaust cone assembly on a turbine engine?
A) To increase exhaust gas temperature
B) To reduce exhaust noise
C) To cool exhaust gases
D) To straighten and collect the exhaust gases into a solid exhaust jet (Correct
Option)
, RATIONALE: The exhaust cone straightens gas flow and converts pressure energy
into velocity energy for thrust production.
QUESTION: 9
What is meant by a cam-ground piston?
A) A piston with adjustable cam lobes
B) A piston made from camshaft material
C) A piston with variable compression ratio
D) A piston that is not perfectly round; its dimension parallel with the wrist pin is
less than its dimension perpendicular to the wrist pin (Correct Option)
RATIONALE: Cam-ground pistons are oval-shaped so they become perfectly round
at operating temperature due to thermal expansion.
QUESTION: 10
What is the primary purpose of stator vanes in the compressor of an axial flow
turbine engine?
A) To decrease air pressure
B) To add fuel to the airstream
C) To cool the compressor blades
D) To increase air pressure (Correct Option)
RATIONALE: Stator vanes act as diffusers, converting velocity energy into pressure
energy and directing air to the next rotor stage.
QUESTION: 11
Where on a float-type carburetor is the throttle valve positioned?
A) After the float chamber
B) At the carburetor inlet
C) Before the venturi
