POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
What is meant by creep of the turbine blades? - Answers___A
condition of permanent elongation of the turbine blades.
Creep is caused by the high temperatures and the high
centrifugal loading imposed on the blades
How is the compressor of a turbine engine cleaned? -
Answers___An emulsion-type cleaner is sprayed through the
engine while it is being motored by the starter or operated at a
low speed. The wash is followed by a clean water rinse. More
vigorous cleaning is done by injecting a mild abrasive, such as
ground-up apricot pits or walnut shells, into the engine while
it is operating at low speed
Where is water injected into a turbine engine for cooling
purposes? - Answers___Into the compressor inlet and into the
engine diffuser case
At what point in a turbine engine is the temperature the
highest? - Answers___At the inlet to the high-pressure turbine
What is the basic difference between a low-tension magneto
and a high-tension magneto? - Answers___The low-tension
ignition system has only one coil in the magneto, and it used a
carbon-brush-type distributor. Low voltage is distributed to
high-tension transformers that are located on the heads of
each cylinder. A high-tension magneto produces high voltage
in the magneto coil, and it is sent to the correct spark plug by
the built-in high voltage distributor
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
What is meant by an All Weather spark plug? - Answers___A
shielded spark plug that has a recess in the shielding in which
a resilient grommet on the ignition lead forms a watertight
seal
What is meant by the reach of a spark plug? - Answers___The
length of the threads on the spark plug that screw into the
cylinder head
What is the difference between a hot spark plug and a cold
spark plug? - Answers___A hot spark plug has a long path for
the heat to travel between the nose core insulator and the
spark plug shell. In a cold spark plug, the heat has a shorter
distance to travel, and the spark plug operates cooler than a
hot spark plug
What is checked when a magneto is internally timed? -
Answers___Internally timing a magneto consists of adjusting
the breaker points so they will open at the instant the rotating
magnet is in its E-gap position, and the distributor rotor is in
the position to direct the high voltage to cylinder number one
What is the purpose of a vernier coupling used on some
aircraft magneto drives? - Answers___Magnetos that are base
mounted must have a vernier coupling between the magneto
drive and the engine. This vernier coupling allows the
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
magneto-to engine timing to be varied in increments of less
than one degree
What is the advantage of fine-wire spark plugs over massive
electrode spark plugs? - Answers___Fine wires spark plugs
have a firing end that is more open that that of a massive
electrode spark plug. The open firing end allows the gases that
contain lead to be purged from the spark plug so they will not
form solid lead contaminates
Why is it important that the spark plugs be kept in numbered
holes in a tray when they are removed from an engine? -
Answers___Spark plugs tell a good deal about the internal
condition of the cylinder from which they were taken. By
knowing the cylinder from which each spark plugs came, the
mechanic can take the proper action when a spark plug
indicates such conditions as detonation or overheating
What is the purpose of staggered timing between the two
magnetos on an aircraft engine? - Answers___Engines in
which the exhaust gas scavenging from the cylinders is
uneven use staggered ignition timing. The spark plug nearest
the exhaust valve, where the fuel-air moisture is diluted, fires
before the spark plug on the intake side. By using staggered
timing, the flame front caused by the two spark plugs will
meet in the center of the piston
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
In what position should the ignition switch be placed when
using a timing light on the magnetos - Answers___In the both
position
Why is it important that a torque wrench always be used when
installing spark plugs in an aircraft engine? - Answers___If
the spark plugs are not put in tight enough, there is the
possibility of a poor seal, and they are put in too tight, there is
a danger of cracking the insulation
Why are pressurized magnetos used on most reciprocating-
engine-powered aircraft that fly at high altitudes? -
Answers___Pressurized air is a better insulator that less dense
air. By pressurizing the distributors, the high voltage is kept
from arcing across to the wrong electrode and causing
vibration and loss of engine power
What type of ignition system is used on most turbine engine?
- Answers___High-intensity, intermittent-duty, capacitor
discharge ignition system
What is meant by the E-gap in magneto timing? -
Answers___The E-gap angle is the position of the rotating
magnet when the primary current flowing in the magneto coil
is the greatest. The breaker points open when the rotating
magnet is in its E-gap position
2024-2026) QUESTIONS AND ANSWERS.
What is meant by creep of the turbine blades? - Answers___A
condition of permanent elongation of the turbine blades.
Creep is caused by the high temperatures and the high
centrifugal loading imposed on the blades
How is the compressor of a turbine engine cleaned? -
Answers___An emulsion-type cleaner is sprayed through the
engine while it is being motored by the starter or operated at a
low speed. The wash is followed by a clean water rinse. More
vigorous cleaning is done by injecting a mild abrasive, such as
ground-up apricot pits or walnut shells, into the engine while
it is operating at low speed
Where is water injected into a turbine engine for cooling
purposes? - Answers___Into the compressor inlet and into the
engine diffuser case
At what point in a turbine engine is the temperature the
highest? - Answers___At the inlet to the high-pressure turbine
What is the basic difference between a low-tension magneto
and a high-tension magneto? - Answers___The low-tension
ignition system has only one coil in the magneto, and it used a
carbon-brush-type distributor. Low voltage is distributed to
high-tension transformers that are located on the heads of
each cylinder. A high-tension magneto produces high voltage
in the magneto coil, and it is sent to the correct spark plug by
the built-in high voltage distributor
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
What is meant by an All Weather spark plug? - Answers___A
shielded spark plug that has a recess in the shielding in which
a resilient grommet on the ignition lead forms a watertight
seal
What is meant by the reach of a spark plug? - Answers___The
length of the threads on the spark plug that screw into the
cylinder head
What is the difference between a hot spark plug and a cold
spark plug? - Answers___A hot spark plug has a long path for
the heat to travel between the nose core insulator and the
spark plug shell. In a cold spark plug, the heat has a shorter
distance to travel, and the spark plug operates cooler than a
hot spark plug
What is checked when a magneto is internally timed? -
Answers___Internally timing a magneto consists of adjusting
the breaker points so they will open at the instant the rotating
magnet is in its E-gap position, and the distributor rotor is in
the position to direct the high voltage to cylinder number one
What is the purpose of a vernier coupling used on some
aircraft magneto drives? - Answers___Magnetos that are base
mounted must have a vernier coupling between the magneto
drive and the engine. This vernier coupling allows the
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
magneto-to engine timing to be varied in increments of less
than one degree
What is the advantage of fine-wire spark plugs over massive
electrode spark plugs? - Answers___Fine wires spark plugs
have a firing end that is more open that that of a massive
electrode spark plug. The open firing end allows the gases that
contain lead to be purged from the spark plug so they will not
form solid lead contaminates
Why is it important that the spark plugs be kept in numbered
holes in a tray when they are removed from an engine? -
Answers___Spark plugs tell a good deal about the internal
condition of the cylinder from which they were taken. By
knowing the cylinder from which each spark plugs came, the
mechanic can take the proper action when a spark plug
indicates such conditions as detonation or overheating
What is the purpose of staggered timing between the two
magnetos on an aircraft engine? - Answers___Engines in
which the exhaust gas scavenging from the cylinders is
uneven use staggered ignition timing. The spark plug nearest
the exhaust valve, where the fuel-air moisture is diluted, fires
before the spark plug on the intake side. By using staggered
timing, the flame front caused by the two spark plugs will
meet in the center of the piston
, POWERPLANT ORAL STUDY GUIDE (ACTUAL
2024-2026) QUESTIONS AND ANSWERS.
In what position should the ignition switch be placed when
using a timing light on the magnetos - Answers___In the both
position
Why is it important that a torque wrench always be used when
installing spark plugs in an aircraft engine? - Answers___If
the spark plugs are not put in tight enough, there is the
possibility of a poor seal, and they are put in too tight, there is
a danger of cracking the insulation
Why are pressurized magnetos used on most reciprocating-
engine-powered aircraft that fly at high altitudes? -
Answers___Pressurized air is a better insulator that less dense
air. By pressurizing the distributors, the high voltage is kept
from arcing across to the wrong electrode and causing
vibration and loss of engine power
What type of ignition system is used on most turbine engine?
- Answers___High-intensity, intermittent-duty, capacitor
discharge ignition system
What is meant by the E-gap in magneto timing? -
Answers___The E-gap angle is the position of the rotating
magnet when the primary current flowing in the magneto coil
is the greatest. The breaker points open when the rotating
magnet is in its E-gap position
