ASA AMT POWERPLANT ORAL AND
PRACTICAL O&P EXAM QUESTIONS
& ANSWERS
RECIPROCATING ENGINES - Correct Answers -RECIPROCATING ENGINES
What are the basic types or configurations of reciprocating engines? - Correct Answers
-Inline, Opposed, V-Type, and Radial
In what position should the crankshaft be when a magneto is being timed to the engine?
- Correct Answers -The piston in cylinder number 1 should be in the correct position for
ignition to occur. This is normally about 30 degrees before top center on the
compression stroke.
What is checked on engine runup to determine the operational condition of the engine?
- Correct Answers -Idling RPM and manifold pressure, engine acceleration, maximum
static RPM and manifold pressure, magneto drop, ignition switch safety check, propeller
pitch change propeller feathering, oil pressure, fuel pressure, and fuel flow.
What is hydraulic lock in an aircraft engine? - Correct Answers -Oil has drained past the
piston rings and filled the combustion chamber of cylinders that are below the center of
the engine. If the crankshaft is turned over with this oil in the cylinder it will lock, and
there is a probability that the piston, cylinder, or connecting rod will be damaged.
How is a hydraulic lock removed from an aircraft engine? - Correct Answers -Remove a
spark plug from the locked cylinder and drain all of the oil out. Clean the sprak plug and
replace it.
What are the strokes of a 4-stroke reciprocating engine? - Correct Answers -Intake,
Compression, Power, and Exhaust
What are the two main causes of a cylinder having low compression? - Correct Answers
-Piston rings not seating or broken, and valves not seating or burned.
What is a low-tension ignition system? - Correct Answers -It is an ignition system using
a magneto with a brush-type distributor and a coil that has no secondary wiring. Low
voltage is directed from the magneto to a transformer mounted on the cylinder head.
Here the low voltage is boosted to a high voltage and is directed through a very short
high-tension lead to a spark plug. There is one transformer for each spark plug.
,What are some advantages of a horizontally opposed engine? - Correct Answers -Low
power-to-weight ratio, ideal for installation on aircraft wings, and low vibration
characteristics.
How can you determine the firing order of an 18-cylinder radial engine? - Correct
Answers -Begin with cylinder 1, and add 11 or subtract 7, whichever will keep the
numbers between 1 and 18. 1-12-5-16-9-2-13-6-17-10-3-14-7-18-11-4-15-8.
What is aa floating cam ring on a large radial engine? - Correct Answers -It is a cam
ring that rides on a shelf-type bearing with a large amount of clearance between the
bearing and the ring. When adjusting the valves on an engine with a floating cam ring,
the pressure of the valve springs on the opposite side of the engine must be removed
so the cam ring will be tight against the bearing for the valves being adjusted.
Why is valve clearance adjusted on radial engines, but not on most horizontally
opposed engines? - Correct Answers -Most horizontally opposed engines have
hydraulic valve lifters that keep all of the clearance out of the valve train. Radial engines
have solid lifters.
Why are both the hot and cold valve clearances given for most radial engines? - Correct
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.
Why is it important to preserve engines that will not be operated for an extended period
of time? - Correct Answers -Moisture will accumulate in the engine, initiating the
corrosion process which can ruin the engine.
Preservation for temporary storage is valid for engines that will be out of service for how
many days? - Correct Answers -30 to 90 days.
What should be done to the cylinders to protect them from rust and corrosion when
preparing the engine for long-time storage? - Correct Answers -Spray a preservative oil
inside the cylinders and replace the spark plugs with desiccant plugs.
What is the formula for calculating indicated horsepower on a 4-stroke engine? - Correct
Answers -Indicated Horsepower = (PLANK)/33,000
Where:
P = Indicated mean effective pressure, in psi
L = Length of stroke, in feet or in fractions of a foot
A = Area of the piston head or cross-sectional area of the cylinder, in square inches
N = Number of power strokes per minute: RPM/2
K = Number of cylinders
What is specific fuel consumption (SFC)? - Correct Answers -SFC is a measure of the
economical use of fuel, which is the fuel weight in pounds per hour per horsepower:
,SFC = (pounds fuel/hour)/horsepower
What must be inspected to determine the airworthiness of an engine installation? -
Correct Answers -The propeller, lubrication system, ignition system, fuel metering
system, cooling system, and the exhaust system.
Where can you find the correct grade of fuel and the amount of engine lubricating oil for
an aircraft engine? - Correct Answers -In the Type Certificate Data Sheets for the
aircraft.
What are the basic steps in troubleshooting an engine installation? - Correct Answers -
a. Know how the system should operate.
b. Observe how the system is operating.
c. Divide the system into smaller parts to find the trouble.
d. Look for the obvious problem first.
Where do you find instructions for removing an engine from an aircraft? - Correct
Answers -In the aircraft maintenance manual
What must normally be done to a nose-wheel airplane before removing an engine? -
Correct Answers -The tail of the airplane must be supported.
What should be used to cover the ends of fuel and oil lines that have been disconnected
from the engine? - Correct Answers -The correct plugs or caps. Never cover the end of
a line with tape.
What is meant by a QEC engine assembly? - Correct Answers -An engine that has
been prepared for a quick engine change. The engine is on its mount and all of the
accessories are installed. A minimum of time is required to change engines. All that is
needed is for the controls, wiring, and fluid lines to be connected to the firewall.
What is meant by rigging the engine controls so they have some "cushion"? - Correct
Answers -The control on the engine component must contact its stop before the control
handle in the flight deck reaches its stop. This causes the control handle to spring back
a slight amount when it is moved to the extent of its travel.
What are two ways of pre-oiling an engine? - Correct Answers -a. Before the spark
plugs are installed and after the oil tank or sump is filled, turn the engine over with the
starter until oil runs out of the fitting to which the oil pressure gage connects.
b. Use a pre-oiler tank. Air pressure forces oil through all of the passages until some of
it flows from the oil pressure gage fitting.
What checks should be made to determine the proper operation of a reciprocating
engine installation? - Correct Answers -Idle RPM and mixture, static RPM, propeller
pitch change operation, magneto check, ignition switch safety check, and carburetor
heat check.
, What is the purpose of a cold cylinder check? - Correct Answers -A cold cylinder check
determines which cylinder is not firing. Run the engine for a few minutes at the speed,
and on the magneto, at which it runs roughest. Shut it down and feel the exhaust stack
near the cylinder head. The cylinder with the stack that is not as hot as the others is the
cylinder that has not been firing.
What are the risks of moving a propeller by hand during aircraft maintenance? - Correct
Answers -If the ignition switch is on, or a magneto ground wire is faulty the engine can
start if the impulse coupling is fired when the propeller is turned. Maintenance personnel
should always verify the magneto switch is off and stay clear of the propeller arc any
time the propeller is moved.
What precautions should be taken prior to and during ground operations of an engine? -
Correct Answers -Improper procedures during ground runs can cause damage to the
aircraft and injury personnel. The maintenance manual and operational checklists
should always be used when operating an engine and aircraft on the ground.
What are the risks associated with incorrect procedures in the event of a reciprocating
engine fire? - Correct Answers -Improper procedures can lead to further damage to the
engine and aircraft. If the engine backfires and causes a fire in the induction system, the
starter motor should continue to run while mixture control is pulled to idle cutoff to
prevent more fuel from entering the engine. If the fire is outside of the engine, pull the
mixture control to idle cutoff and close the fuel firewall shutoff valve to stop the flow of
fuel into the engine compartment. After aircraft maintenance, it is good practice to have
a spotter standing by with a fire extinguisher.
What risks are associated with using procedures other than those developed by the
manufacturer? - Correct Answers -The risks of using other procedures is that important
steps and procedures can be missed, causing damage to the engine, aircraft, or
personnel. The manufacturer's procedures were carefully developed to maintain the
type design configuration and safety of the aircraft.
TURBINE ENGINES - Correct Answers -TURBINE ENGINES
How are the four strokes of a reciprocating engine similar to the sections of a turbine
engine? - Correct Answers -Intake = air inlet section, Compression = compressor
section, Ignition and power = combustion and turbine sections, Exhaust = exhaust
section.
What type of turbojet engine is commonly used in commercial aviation due to lower
noise and better fuel consumption? - Correct Answers -High-bypass turbofan engines.
What four types of gas turbine engines are used in aircraft? - Correct Answers -
Turbofan, turboprop, turboshaft, and turbojet.
PRACTICAL O&P EXAM QUESTIONS
& ANSWERS
RECIPROCATING ENGINES - Correct Answers -RECIPROCATING ENGINES
What are the basic types or configurations of reciprocating engines? - Correct Answers
-Inline, Opposed, V-Type, and Radial
In what position should the crankshaft be when a magneto is being timed to the engine?
- Correct Answers -The piston in cylinder number 1 should be in the correct position for
ignition to occur. This is normally about 30 degrees before top center on the
compression stroke.
What is checked on engine runup to determine the operational condition of the engine?
- Correct Answers -Idling RPM and manifold pressure, engine acceleration, maximum
static RPM and manifold pressure, magneto drop, ignition switch safety check, propeller
pitch change propeller feathering, oil pressure, fuel pressure, and fuel flow.
What is hydraulic lock in an aircraft engine? - Correct Answers -Oil has drained past the
piston rings and filled the combustion chamber of cylinders that are below the center of
the engine. If the crankshaft is turned over with this oil in the cylinder it will lock, and
there is a probability that the piston, cylinder, or connecting rod will be damaged.
How is a hydraulic lock removed from an aircraft engine? - Correct Answers -Remove a
spark plug from the locked cylinder and drain all of the oil out. Clean the sprak plug and
replace it.
What are the strokes of a 4-stroke reciprocating engine? - Correct Answers -Intake,
Compression, Power, and Exhaust
What are the two main causes of a cylinder having low compression? - Correct Answers
-Piston rings not seating or broken, and valves not seating or burned.
What is a low-tension ignition system? - Correct Answers -It is an ignition system using
a magneto with a brush-type distributor and a coil that has no secondary wiring. Low
voltage is directed from the magneto to a transformer mounted on the cylinder head.
Here the low voltage is boosted to a high voltage and is directed through a very short
high-tension lead to a spark plug. There is one transformer for each spark plug.
,What are some advantages of a horizontally opposed engine? - Correct Answers -Low
power-to-weight ratio, ideal for installation on aircraft wings, and low vibration
characteristics.
How can you determine the firing order of an 18-cylinder radial engine? - Correct
Answers -Begin with cylinder 1, and add 11 or subtract 7, whichever will keep the
numbers between 1 and 18. 1-12-5-16-9-2-13-6-17-10-3-14-7-18-11-4-15-8.
What is aa floating cam ring on a large radial engine? - Correct Answers -It is a cam
ring that rides on a shelf-type bearing with a large amount of clearance between the
bearing and the ring. When adjusting the valves on an engine with a floating cam ring,
the pressure of the valve springs on the opposite side of the engine must be removed
so the cam ring will be tight against the bearing for the valves being adjusted.
Why is valve clearance adjusted on radial engines, but not on most horizontally
opposed engines? - Correct Answers -Most horizontally opposed engines have
hydraulic valve lifters that keep all of the clearance out of the valve train. Radial engines
have solid lifters.
Why are both the hot and cold valve clearances given for most radial engines? - Correct
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.
Why is it important to preserve engines that will not be operated for an extended period
of time? - Correct Answers -Moisture will accumulate in the engine, initiating the
corrosion process which can ruin the engine.
Preservation for temporary storage is valid for engines that will be out of service for how
many days? - Correct Answers -30 to 90 days.
What should be done to the cylinders to protect them from rust and corrosion when
preparing the engine for long-time storage? - Correct Answers -Spray a preservative oil
inside the cylinders and replace the spark plugs with desiccant plugs.
What is the formula for calculating indicated horsepower on a 4-stroke engine? - Correct
Answers -Indicated Horsepower = (PLANK)/33,000
Where:
P = Indicated mean effective pressure, in psi
L = Length of stroke, in feet or in fractions of a foot
A = Area of the piston head or cross-sectional area of the cylinder, in square inches
N = Number of power strokes per minute: RPM/2
K = Number of cylinders
What is specific fuel consumption (SFC)? - Correct Answers -SFC is a measure of the
economical use of fuel, which is the fuel weight in pounds per hour per horsepower:
,SFC = (pounds fuel/hour)/horsepower
What must be inspected to determine the airworthiness of an engine installation? -
Correct Answers -The propeller, lubrication system, ignition system, fuel metering
system, cooling system, and the exhaust system.
Where can you find the correct grade of fuel and the amount of engine lubricating oil for
an aircraft engine? - Correct Answers -In the Type Certificate Data Sheets for the
aircraft.
What are the basic steps in troubleshooting an engine installation? - Correct Answers -
a. Know how the system should operate.
b. Observe how the system is operating.
c. Divide the system into smaller parts to find the trouble.
d. Look for the obvious problem first.
Where do you find instructions for removing an engine from an aircraft? - Correct
Answers -In the aircraft maintenance manual
What must normally be done to a nose-wheel airplane before removing an engine? -
Correct Answers -The tail of the airplane must be supported.
What should be used to cover the ends of fuel and oil lines that have been disconnected
from the engine? - Correct Answers -The correct plugs or caps. Never cover the end of
a line with tape.
What is meant by a QEC engine assembly? - Correct Answers -An engine that has
been prepared for a quick engine change. The engine is on its mount and all of the
accessories are installed. A minimum of time is required to change engines. All that is
needed is for the controls, wiring, and fluid lines to be connected to the firewall.
What is meant by rigging the engine controls so they have some "cushion"? - Correct
Answers -The control on the engine component must contact its stop before the control
handle in the flight deck reaches its stop. This causes the control handle to spring back
a slight amount when it is moved to the extent of its travel.
What are two ways of pre-oiling an engine? - Correct Answers -a. Before the spark
plugs are installed and after the oil tank or sump is filled, turn the engine over with the
starter until oil runs out of the fitting to which the oil pressure gage connects.
b. Use a pre-oiler tank. Air pressure forces oil through all of the passages until some of
it flows from the oil pressure gage fitting.
What checks should be made to determine the proper operation of a reciprocating
engine installation? - Correct Answers -Idle RPM and mixture, static RPM, propeller
pitch change operation, magneto check, ignition switch safety check, and carburetor
heat check.
, What is the purpose of a cold cylinder check? - Correct Answers -A cold cylinder check
determines which cylinder is not firing. Run the engine for a few minutes at the speed,
and on the magneto, at which it runs roughest. Shut it down and feel the exhaust stack
near the cylinder head. The cylinder with the stack that is not as hot as the others is the
cylinder that has not been firing.
What are the risks of moving a propeller by hand during aircraft maintenance? - Correct
Answers -If the ignition switch is on, or a magneto ground wire is faulty the engine can
start if the impulse coupling is fired when the propeller is turned. Maintenance personnel
should always verify the magneto switch is off and stay clear of the propeller arc any
time the propeller is moved.
What precautions should be taken prior to and during ground operations of an engine? -
Correct Answers -Improper procedures during ground runs can cause damage to the
aircraft and injury personnel. The maintenance manual and operational checklists
should always be used when operating an engine and aircraft on the ground.
What are the risks associated with incorrect procedures in the event of a reciprocating
engine fire? - Correct Answers -Improper procedures can lead to further damage to the
engine and aircraft. If the engine backfires and causes a fire in the induction system, the
starter motor should continue to run while mixture control is pulled to idle cutoff to
prevent more fuel from entering the engine. If the fire is outside of the engine, pull the
mixture control to idle cutoff and close the fuel firewall shutoff valve to stop the flow of
fuel into the engine compartment. After aircraft maintenance, it is good practice to have
a spotter standing by with a fire extinguisher.
What risks are associated with using procedures other than those developed by the
manufacturer? - Correct Answers -The risks of using other procedures is that important
steps and procedures can be missed, causing damage to the engine, aircraft, or
personnel. The manufacturer's procedures were carefully developed to maintain the
type design configuration and safety of the aircraft.
TURBINE ENGINES - Correct Answers -TURBINE ENGINES
How are the four strokes of a reciprocating engine similar to the sections of a turbine
engine? - Correct Answers -Intake = air inlet section, Compression = compressor
section, Ignition and power = combustion and turbine sections, Exhaust = exhaust
section.
What type of turbojet engine is commonly used in commercial aviation due to lower
noise and better fuel consumption? - Correct Answers -High-bypass turbofan engines.
What four types of gas turbine engines are used in aircraft? - Correct Answers -
Turbofan, turboprop, turboshaft, and turbojet.
