Powerplant Oral Questions and Answers Graded A+
RECIPROCATING ENGINES - -
RECIPROCATING ENGINES
What types of connecting rods are commonly
found in radial engines? - -Master and
What procedure should be followed when valve articulated rod assemblies.
blow-by is indicated by a hissing sound on a
reciprocating engine when pulling the propeller
through? - -Perform a cylinder What publication is used to check an engine for
compression test to identify the faulty cylinder. normal operation? - -The manufacturer's
maintenance manual.
What is the running valve clearance on engines
equipped with hydraulic valve lifters? - - What are the different types of piston rings? -
Zero. -Compression, oil control, and oil scraper.
When troubleshooting a running engine What is the purpose of oil control rings? - -
malfunction, what does a cold cylinder indicate? - Oil control rings regulate the thickness of the oil
-Lack of combustion in that cylinder. film on the cylinder wall.
What factors about the condition of an engine What types of bearings are in general use in
can be learned by studying the results of a reciprocating engines? - -Plain, ball, and
compression test? - -The results of a roller.
compression test determine if the valves, piston
rings, and pistons are adequately sealing.
Where are cracks most likely to be found in a
piston? - -Highly stressed areas; the base
What should be done to repair a loose stud in an of the pin bosses, inside at the junction of the
engine crankcase? - -Remove the loose head and walls, and the ring lands.
stud, and inspect the hole for size and the
condition of the threads. It may be necessary to
use a suitable oversize stud. How are piston ring gaps installed relative to
each other on a piston, and why? - -
Compression ring gaps should be installed in
How is a cylinder barrel inspected for out of staggered positions (not aligned) around the
roundness? - -A dial indicator (or a piston in order to prevent excessive blow-by.
telescopic gauge and micrometer, or an inside
micrometer) can be used to measure at the top
of the cylinder and also at the skirt. Two readings What is the purpose of valve overlap? - -It
should be taken, 90 degrees to each other. permits better volumetric efficiency and lowers
the cylinder operating temperature.
What is the fuel pressure range on Float-Type
carburators? - -3 to 5 PSI. What is the purpose of crankshaft dynamic
,Powerplant Oral Questions and Answers Graded A+
dampers? - -To reduce engine vibration. operating history and can therefore be issued a
zero-time record.
What is meant when it is said that an engine part
is within "serviceable limits"? - -A part that What is used in an aircraft engine to help prevent
is within "serviceable limits" will not likely wear to valve surge or float from occurring? - -Two
the point of causing engine failure within the next or more springs on each valve.
time between overhaul (TBO) interval.
Is the aircraft electrical system required to power
Name at least one part of an inspection that a cylinder head temperature gauge? - -
should be made after a propeller strike (not NO... A thermocouple is used as the electrical
sudden stoppage). - -(1) Inspect the source.
engine mounts, crankcase, and nose section for
damage.
(2) Inspect the oil and oil screen/filters for metal What are the possible indications of an oil
particles. pressure transmitter or indicator malfunction? -
(3) Inspect the propeller drive shaft or crankshaft -A severe or sudden drop in oil pressure
for misalignment. while the oil temperature remains normal and the
oil supply remains full.
What are some of the precautions to be
observed when preparing an aircraft for engine Standard sea level pressure is - -29.92 in.
removal? - -Disconnect the battery, chock Hg or 14.7 PSI.
the wheels, install a tail stand (if needed), and
turn off the fuel valves.
Standard sea level temperature - -59
degrees Fahrenheit
What is an indication that a primer is leaking or is
open during engine operation? - -The
engine will not idle properly. TURBINE ENGINES - -TURBINE
ENGINES
What may be the result of incorrect installation of
piston rings? - -Excessive oil consumption. What are the major components of a typical gas
turbine engine? - -An air inlet, compressor
section, combustion section, turbine section,
What are some indications of induction system exhaust section, and accessory section.
leakage? - -Low power and uneven
running.
What determines the amount of air passing
through a turbine engine? - -Compressor
When an engine is rebuilt by the manufacturer, speed, forward speed of the aircraft, and air
how is its operating history affected? - -A density.
rebuilt engine is considered to have no previous
, Powerplant Oral Questions and Answers Graded A+
the core engine instead of through it.
What are two principle types of compressors
currently used in turbine engines? - -
Centrifugal and axial flow. What methods are commonly used to accomplish
turbine engine compressor field cleaning? -
-Fluid flush and abrasive grit blast.
How are turbine engine rotor blades attached to
rotor disks? (Name at least two methods.) -
-Bulb, fir-tree, or dovetail type roots. Name an advantage of a turbofan over a turbojet.
- -Additional thrust without increasing fuel
flow.
Name at least three types of combustion
chamber systems. - -Can, annular, can-
annular, and reverse flow annular. What are the functions of axial flow turbine
nozzles? - -They direct the mass airflow to
drive the turbine rotor at a specific angle.
What is the purpose of the interconnect tubes
attached between can-type combustion
chambers? - -For flame propagation during What are some ways of relieving thermal stress
starting. on a turbine disk? - -By directing bleed air
on to the face of the disk, or by grooves being cut
in the disk.
What prevents burning of combustion chambers?
- -Cooling air along the inside of the liner.
What type of compressor blade damage may be
found when inspecting compressor blades? -
What is a unique feature of a split (dual) -Dents, galling, pitting, cracks, scratches,
compressor system? - -Two rotor shafts, burrs, burns, and gouges.
one inside the other.
What is used to mark both hot and cold section
What are carbon seals used for in turbine parts for repair? - -Layout dye, commercial
engines? - -As oil seals for the rotor shaft felt tip marker, or chalk.
bearings.
What is the effect of relative humidity on turbojet
What are the desired effects of turbine engine or turbofan power? - -Negligible effect.
compressor field cleaning? - -Remove
contaminant deposits and improve performance.
What may be the indications if a turbojet engine
is out of trim? - -The engine has high
What is the main operating difference between exhaust gas temperature at the target engine
turbofan and turbojet engines? - -The air pressure ratio for take off power.
that flows through the fan section of a turbofan
engine bypasses, or flows around, the outside of
RECIPROCATING ENGINES - -
RECIPROCATING ENGINES
What types of connecting rods are commonly
found in radial engines? - -Master and
What procedure should be followed when valve articulated rod assemblies.
blow-by is indicated by a hissing sound on a
reciprocating engine when pulling the propeller
through? - -Perform a cylinder What publication is used to check an engine for
compression test to identify the faulty cylinder. normal operation? - -The manufacturer's
maintenance manual.
What is the running valve clearance on engines
equipped with hydraulic valve lifters? - - What are the different types of piston rings? -
Zero. -Compression, oil control, and oil scraper.
When troubleshooting a running engine What is the purpose of oil control rings? - -
malfunction, what does a cold cylinder indicate? - Oil control rings regulate the thickness of the oil
-Lack of combustion in that cylinder. film on the cylinder wall.
What factors about the condition of an engine What types of bearings are in general use in
can be learned by studying the results of a reciprocating engines? - -Plain, ball, and
compression test? - -The results of a roller.
compression test determine if the valves, piston
rings, and pistons are adequately sealing.
Where are cracks most likely to be found in a
piston? - -Highly stressed areas; the base
What should be done to repair a loose stud in an of the pin bosses, inside at the junction of the
engine crankcase? - -Remove the loose head and walls, and the ring lands.
stud, and inspect the hole for size and the
condition of the threads. It may be necessary to
use a suitable oversize stud. How are piston ring gaps installed relative to
each other on a piston, and why? - -
Compression ring gaps should be installed in
How is a cylinder barrel inspected for out of staggered positions (not aligned) around the
roundness? - -A dial indicator (or a piston in order to prevent excessive blow-by.
telescopic gauge and micrometer, or an inside
micrometer) can be used to measure at the top
of the cylinder and also at the skirt. Two readings What is the purpose of valve overlap? - -It
should be taken, 90 degrees to each other. permits better volumetric efficiency and lowers
the cylinder operating temperature.
What is the fuel pressure range on Float-Type
carburators? - -3 to 5 PSI. What is the purpose of crankshaft dynamic
,Powerplant Oral Questions and Answers Graded A+
dampers? - -To reduce engine vibration. operating history and can therefore be issued a
zero-time record.
What is meant when it is said that an engine part
is within "serviceable limits"? - -A part that What is used in an aircraft engine to help prevent
is within "serviceable limits" will not likely wear to valve surge or float from occurring? - -Two
the point of causing engine failure within the next or more springs on each valve.
time between overhaul (TBO) interval.
Is the aircraft electrical system required to power
Name at least one part of an inspection that a cylinder head temperature gauge? - -
should be made after a propeller strike (not NO... A thermocouple is used as the electrical
sudden stoppage). - -(1) Inspect the source.
engine mounts, crankcase, and nose section for
damage.
(2) Inspect the oil and oil screen/filters for metal What are the possible indications of an oil
particles. pressure transmitter or indicator malfunction? -
(3) Inspect the propeller drive shaft or crankshaft -A severe or sudden drop in oil pressure
for misalignment. while the oil temperature remains normal and the
oil supply remains full.
What are some of the precautions to be
observed when preparing an aircraft for engine Standard sea level pressure is - -29.92 in.
removal? - -Disconnect the battery, chock Hg or 14.7 PSI.
the wheels, install a tail stand (if needed), and
turn off the fuel valves.
Standard sea level temperature - -59
degrees Fahrenheit
What is an indication that a primer is leaking or is
open during engine operation? - -The
engine will not idle properly. TURBINE ENGINES - -TURBINE
ENGINES
What may be the result of incorrect installation of
piston rings? - -Excessive oil consumption. What are the major components of a typical gas
turbine engine? - -An air inlet, compressor
section, combustion section, turbine section,
What are some indications of induction system exhaust section, and accessory section.
leakage? - -Low power and uneven
running.
What determines the amount of air passing
through a turbine engine? - -Compressor
When an engine is rebuilt by the manufacturer, speed, forward speed of the aircraft, and air
how is its operating history affected? - -A density.
rebuilt engine is considered to have no previous
, Powerplant Oral Questions and Answers Graded A+
the core engine instead of through it.
What are two principle types of compressors
currently used in turbine engines? - -
Centrifugal and axial flow. What methods are commonly used to accomplish
turbine engine compressor field cleaning? -
-Fluid flush and abrasive grit blast.
How are turbine engine rotor blades attached to
rotor disks? (Name at least two methods.) -
-Bulb, fir-tree, or dovetail type roots. Name an advantage of a turbofan over a turbojet.
- -Additional thrust without increasing fuel
flow.
Name at least three types of combustion
chamber systems. - -Can, annular, can-
annular, and reverse flow annular. What are the functions of axial flow turbine
nozzles? - -They direct the mass airflow to
drive the turbine rotor at a specific angle.
What is the purpose of the interconnect tubes
attached between can-type combustion
chambers? - -For flame propagation during What are some ways of relieving thermal stress
starting. on a turbine disk? - -By directing bleed air
on to the face of the disk, or by grooves being cut
in the disk.
What prevents burning of combustion chambers?
- -Cooling air along the inside of the liner.
What type of compressor blade damage may be
found when inspecting compressor blades? -
What is a unique feature of a split (dual) -Dents, galling, pitting, cracks, scratches,
compressor system? - -Two rotor shafts, burrs, burns, and gouges.
one inside the other.
What is used to mark both hot and cold section
What are carbon seals used for in turbine parts for repair? - -Layout dye, commercial
engines? - -As oil seals for the rotor shaft felt tip marker, or chalk.
bearings.
What is the effect of relative humidity on turbojet
What are the desired effects of turbine engine or turbofan power? - -Negligible effect.
compressor field cleaning? - -Remove
contaminant deposits and improve performance.
What may be the indications if a turbojet engine
is out of trim? - -The engine has high
What is the main operating difference between exhaust gas temperature at the target engine
turbofan and turbojet engines? - -The air pressure ratio for take off power.
that flows through the fan section of a turbofan
engine bypasses, or flows around, the outside of
