Powerplant ASA/Baker's School List of
FAA Oral Questions 2023 | 443 Questions
with 100% Correct Answers | Updated &
Verified | Graded A+
What is the main advantage of a horizontally opposed engine over
a radial engine for powering modern aircraft? - -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? - -six
-What kind of connecting rod arrangement is used in a radial
engine? - -A master rod connects the single throw of the
crankshaft with a piston. All other pistons are connected to the
master rod with link rods.
-Of what material are most piston rings made? - -gray cast iron
-What is the reason for using hydraulic valve lifters in an aircraft
engine? - -Hydraulic lifters keep all the clearance out of the valve
operating mechanism. This decreases the wear of the valve train
components.
, -At what speed does the camshaft turn in relation to the
crankshaft? - -one half the speed of the crankshaft
-What kind of main bearings are used in a horizontally opposed
engine? - -steel backed, lead-alloy inserts
-On what stroke is the piston when the intake valve begins to
open? - -exhaust stroke
-On what stroke is the piston when the exhaust valve begins to
close? - -power stroke
-Why are both hot and cold clearances given for radial engines? -
-The hot clearance is given for valve timing purposes. The timing
is adjusted with the valves in the number one piston adjusted with
the hot clearance. When the timing is set, all of the valves are
adjusted to their cold clearance.
-What is meant by "cam-ground" piston? - -A piston that is not
perfectly round. 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 when the ignition spark occurs? - -30
degrees before TDC
, -What is a "full-floating" wrist pin? - -a wrist pin that is not
clamped in either the piston or the connecting rod. soft metal
plugs keep the floating pin from scoring the cylinder wall.
-Why do most engines use more than one spring on each valve? -
-Different springs with different diameter and pitch have different
resonant frequencies which minimize valve float.
-Would excessive valve clearance cause the valves to open early
or late? - -open late and close early
-What is the purpose of valve overlap? (2) - -Exhaust gas inertia
leaving the cylinder helps the fresh induction charge flow into the
cylinder leading to 1) better volumetric efficiency 2) lower
cylinder temperatures.
-What types of piston rings are installed on the pistons? - -
compression rings, oil control rings, oil wiper rings
-Why are some exhaust valves partially filled with metallic
sodium? - -It melts at operating temperature. Sloshing back and
forth, it picks up heat, transfers heat to the valve stem which in
turn transfers it to the cylinder head.
-What causes detonation? - -Excessive heat and pressure in the
cylinder causes the fuel-air mixture to reach its critical pressure
, and temperature which causes an explosion rather than a
controlled burn.
-Why is a compression check important in determining the
condition of an engine? - -The compression check determines the
condition of the seal between the piston rings and the cylinder
walls, and the seal between the valves and their seats.
-What is meant by compression ratio? - -The compression ratio is
the volume of the cylinder with the piston at the bottom of its
stroke to the top of its stroke.
-What cylinder is engine-to magneto-timing based on? - -number
one cylinder
-What are the main causes of the cylinder having low
compression? (4) - -broken rings, rings that do not seat properly,
burnt valves, poorly seating valves
-What should be done to a nosewheel plane before removing the
engine? - -support the tail
-How are conventional reciprocating engines classified? (2) - -
They are classified according to
1) cylinder arrangement: in-line, radial, v-type, opposed
2) method of cooling: liquid, air
FAA Oral Questions 2023 | 443 Questions
with 100% Correct Answers | Updated &
Verified | Graded A+
What is the main advantage of a horizontally opposed engine over
a radial engine for powering modern aircraft? - -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? - -six
-What kind of connecting rod arrangement is used in a radial
engine? - -A master rod connects the single throw of the
crankshaft with a piston. All other pistons are connected to the
master rod with link rods.
-Of what material are most piston rings made? - -gray cast iron
-What is the reason for using hydraulic valve lifters in an aircraft
engine? - -Hydraulic lifters keep all the clearance out of the valve
operating mechanism. This decreases the wear of the valve train
components.
, -At what speed does the camshaft turn in relation to the
crankshaft? - -one half the speed of the crankshaft
-What kind of main bearings are used in a horizontally opposed
engine? - -steel backed, lead-alloy inserts
-On what stroke is the piston when the intake valve begins to
open? - -exhaust stroke
-On what stroke is the piston when the exhaust valve begins to
close? - -power stroke
-Why are both hot and cold clearances given for radial engines? -
-The hot clearance is given for valve timing purposes. The timing
is adjusted with the valves in the number one piston adjusted with
the hot clearance. When the timing is set, all of the valves are
adjusted to their cold clearance.
-What is meant by "cam-ground" piston? - -A piston that is not
perfectly round. 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 when the ignition spark occurs? - -30
degrees before TDC
, -What is a "full-floating" wrist pin? - -a wrist pin that is not
clamped in either the piston or the connecting rod. soft metal
plugs keep the floating pin from scoring the cylinder wall.
-Why do most engines use more than one spring on each valve? -
-Different springs with different diameter and pitch have different
resonant frequencies which minimize valve float.
-Would excessive valve clearance cause the valves to open early
or late? - -open late and close early
-What is the purpose of valve overlap? (2) - -Exhaust gas inertia
leaving the cylinder helps the fresh induction charge flow into the
cylinder leading to 1) better volumetric efficiency 2) lower
cylinder temperatures.
-What types of piston rings are installed on the pistons? - -
compression rings, oil control rings, oil wiper rings
-Why are some exhaust valves partially filled with metallic
sodium? - -It melts at operating temperature. Sloshing back and
forth, it picks up heat, transfers heat to the valve stem which in
turn transfers it to the cylinder head.
-What causes detonation? - -Excessive heat and pressure in the
cylinder causes the fuel-air mixture to reach its critical pressure
, and temperature which causes an explosion rather than a
controlled burn.
-Why is a compression check important in determining the
condition of an engine? - -The compression check determines the
condition of the seal between the piston rings and the cylinder
walls, and the seal between the valves and their seats.
-What is meant by compression ratio? - -The compression ratio is
the volume of the cylinder with the piston at the bottom of its
stroke to the top of its stroke.
-What cylinder is engine-to magneto-timing based on? - -number
one cylinder
-What are the main causes of the cylinder having low
compression? (4) - -broken rings, rings that do not seat properly,
burnt valves, poorly seating valves
-What should be done to a nosewheel plane before removing the
engine? - -support the tail
-How are conventional reciprocating engines classified? (2) - -
They are classified according to
1) cylinder arrangement: in-line, radial, v-type, opposed
2) method of cooling: liquid, air
