Jeppesen powerplant oral study guide
(Quizzes and solutions) |1st edition 2025
What is the purpose of dynamic dampers on crankshafts? - answer-they reduce engine
vibration
what types of bearings are generally found in reciprocating engines? - answer-Plain,
ball and roller bearings.
Are connecting rods used in each cylinder of a radial engine the same? Explain? -
answer-No. Radial engines use master and articulating rod assemblies
Name the different types of piston rings? - answer-Oil control, compression and oil
scrapper rings.
Where should the piston ring gaps be installed relative to each other and why - answer-
Compression ring gaps should be staggered so that they do not align. This prevents
excessive blow-by.
What could result from incorrectly installed piston rings? - answer-Excessive oil
consumption
What purpose do oil control rings serve? - answer-They regulate the thickness of the oil
film on the cylinder walls
What is used to help prevent valve surge or floating in an aircraft engine? - answer-Two
or more springs are used on each valve
On engines equipped with hydraulic valve lifters, what should the running valve
clearance be? - answer-Zero.
What is the purpose of valve overlap? - answer-It allows better volumetric efficiency and
lowers cylinder head operating temperatures.
What indications are given in the event of a leaking or open primer line while the engine
is running? - answer-The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this
indicate? - answer-No combustion in that cylinder.
When pulling a propeller through, a hissing sound heard, indicating valve blow-by. What
procedure should be performed next? - answer-A compression check should be
performed to identify the faulty cylinder,
,What is the purpose of performing a compression test? - answer-To determine if the
valves, pistons and rings are sealing properly.
When an engine is overhauled, how is total time affected? When an engine is rebuilt,
how is its operating history affected? - answer-Total time on the engine must be
continued and the time since major overhaul is entered into the engine log. If the
manufacture rebuilds the engine, it is granted a zero-time status and is considered to
have no previous operating history.
What inspections should be performed after a propeller strike without sudden stoppage?
- answer-1. Inspect engine mounts, the crankcase and nose section for damage. 2.
Inspect the oil and oil filters/screens for metal particles. 3. Inspect the crankcase or
driveshaft for cracks and misalignment.
Name some precautions that should be preformed prior to engine removal? - answer-
Disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary,
install a tail stand.
When inspecting a piston, where are cracks most likely to be found? - answer-In those
areas that are highly stressed; usually the base of the piston bosses, inside at the
junction of the bore and the walls, and the ring lands.
What does it mean if an engine part is within "serviceable limits"? - answer-It means
that the part is within the manufacturer's limits and can be used in an engine (does not
require replacement).
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness? -
answer-A dial indicator or an inside micrometer is usually used to measure the top of
the cylinder and at the skirt. A telescopic gauge and micrometer can also be used. Two
readings should be taken 90# to each other.
How can a loose stud in an engine crankcase be repaired? - answer-Remove the loose
stud and inspect the hole size and thread condition. It may be necessary to use an
oversized stud or Heli-Coil insert.
What publication is used to check an engine for normal operation? - answer-
Manufacturer's maintenance manual.
A weak cylinder is found during a compression check. What must be inspected? -
answer-The inside of the cylinder.
What purpose does an oil analysis serve? - answer-Metal particles in the oil show
normal and abnormal wear of the engine. This helps in evaluating the engines internal
condition.
, What inspection should be preformed on an engine that has been in storage? - answer-
Perform an inspection to determine if there is any corrosion damage.
Where would a carburetor air temperature bulb be located? - answer-In the ram air
intake duct
What is the fuel pressure range on float type carburetors? - answer-3 to 5 psi.
Name the basic components of a fuel system? - answer-The transmitter and the
indicator.
What unit of measure is generally used to indicate fuel flow? - answer-Gallons or
pounds per hour.
Why is fuel flow monitored? - answer-To determine fuel consumption and engine
performance.
What does the manifold pressure gauge indicate and how is it calibrated? - answer-It
measures the absolute pressure in the engine manifold and is calibrated to inches of
mercury.
What directly controls manifold pressure? - answer-Throttle opening and engine r.p.m.
During engine operation, where should the propeller control be set when checking the
manifold pressure? - answer-Low pitch, high r.p.m.
Is the aircraft electrical system required to power a cylinder head temperature gauge? -
answer-No. A thermocouple is used as the electrical source.
What are the possible indications of an oil pressure transmitter or indicator malfunction?
- answer-A sudden or sever drop in oil pressure while the oil temperature is normal and
the oil supply remains full.
What does the tachometer indicate on a reciprocating engine? - answer-Engine r.p.m.
Where should the thermocouple be installed on a reciprocating engine using a single
probe cylinder head temperature system? - answer-On the hottest cylinder.
Explain the main difference and advantage of a turbofan over a turbojet engines? -
answer-A turbofan engine uses a fan to bypass some air around the engine core and to
provided thrust. The advantage is that this provides additional thrust without increasing
fuel flow.
Name the major components of a gas turbine engine? - answer-Air inlet, compressor
section, combustion section, turbine section, exhaust section, and gearbox and
accessory section.
(Quizzes and solutions) |1st edition 2025
What is the purpose of dynamic dampers on crankshafts? - answer-they reduce engine
vibration
what types of bearings are generally found in reciprocating engines? - answer-Plain,
ball and roller bearings.
Are connecting rods used in each cylinder of a radial engine the same? Explain? -
answer-No. Radial engines use master and articulating rod assemblies
Name the different types of piston rings? - answer-Oil control, compression and oil
scrapper rings.
Where should the piston ring gaps be installed relative to each other and why - answer-
Compression ring gaps should be staggered so that they do not align. This prevents
excessive blow-by.
What could result from incorrectly installed piston rings? - answer-Excessive oil
consumption
What purpose do oil control rings serve? - answer-They regulate the thickness of the oil
film on the cylinder walls
What is used to help prevent valve surge or floating in an aircraft engine? - answer-Two
or more springs are used on each valve
On engines equipped with hydraulic valve lifters, what should the running valve
clearance be? - answer-Zero.
What is the purpose of valve overlap? - answer-It allows better volumetric efficiency and
lowers cylinder head operating temperatures.
What indications are given in the event of a leaking or open primer line while the engine
is running? - answer-The engine will not idle properly.
A cold cylinder is found when troubleshooting a running engine. What does this
indicate? - answer-No combustion in that cylinder.
When pulling a propeller through, a hissing sound heard, indicating valve blow-by. What
procedure should be performed next? - answer-A compression check should be
performed to identify the faulty cylinder,
,What is the purpose of performing a compression test? - answer-To determine if the
valves, pistons and rings are sealing properly.
When an engine is overhauled, how is total time affected? When an engine is rebuilt,
how is its operating history affected? - answer-Total time on the engine must be
continued and the time since major overhaul is entered into the engine log. If the
manufacture rebuilds the engine, it is granted a zero-time status and is considered to
have no previous operating history.
What inspections should be performed after a propeller strike without sudden stoppage?
- answer-1. Inspect engine mounts, the crankcase and nose section for damage. 2.
Inspect the oil and oil filters/screens for metal particles. 3. Inspect the crankcase or
driveshaft for cracks and misalignment.
Name some precautions that should be preformed prior to engine removal? - answer-
Disconnect the battery, turn off the fuel valves, chock the wheels, and if necessary,
install a tail stand.
When inspecting a piston, where are cracks most likely to be found? - answer-In those
areas that are highly stressed; usually the base of the piston bosses, inside at the
junction of the bore and the walls, and the ring lands.
What does it mean if an engine part is within "serviceable limits"? - answer-It means
that the part is within the manufacturer's limits and can be used in an engine (does not
require replacement).
What tools or instruments are used to inspect a cylinder barrel for out-of-roundness? -
answer-A dial indicator or an inside micrometer is usually used to measure the top of
the cylinder and at the skirt. A telescopic gauge and micrometer can also be used. Two
readings should be taken 90# to each other.
How can a loose stud in an engine crankcase be repaired? - answer-Remove the loose
stud and inspect the hole size and thread condition. It may be necessary to use an
oversized stud or Heli-Coil insert.
What publication is used to check an engine for normal operation? - answer-
Manufacturer's maintenance manual.
A weak cylinder is found during a compression check. What must be inspected? -
answer-The inside of the cylinder.
What purpose does an oil analysis serve? - answer-Metal particles in the oil show
normal and abnormal wear of the engine. This helps in evaluating the engines internal
condition.
, What inspection should be preformed on an engine that has been in storage? - answer-
Perform an inspection to determine if there is any corrosion damage.
Where would a carburetor air temperature bulb be located? - answer-In the ram air
intake duct
What is the fuel pressure range on float type carburetors? - answer-3 to 5 psi.
Name the basic components of a fuel system? - answer-The transmitter and the
indicator.
What unit of measure is generally used to indicate fuel flow? - answer-Gallons or
pounds per hour.
Why is fuel flow monitored? - answer-To determine fuel consumption and engine
performance.
What does the manifold pressure gauge indicate and how is it calibrated? - answer-It
measures the absolute pressure in the engine manifold and is calibrated to inches of
mercury.
What directly controls manifold pressure? - answer-Throttle opening and engine r.p.m.
During engine operation, where should the propeller control be set when checking the
manifold pressure? - answer-Low pitch, high r.p.m.
Is the aircraft electrical system required to power a cylinder head temperature gauge? -
answer-No. A thermocouple is used as the electrical source.
What are the possible indications of an oil pressure transmitter or indicator malfunction?
- answer-A sudden or sever drop in oil pressure while the oil temperature is normal and
the oil supply remains full.
What does the tachometer indicate on a reciprocating engine? - answer-Engine r.p.m.
Where should the thermocouple be installed on a reciprocating engine using a single
probe cylinder head temperature system? - answer-On the hottest cylinder.
Explain the main difference and advantage of a turbofan over a turbojet engines? -
answer-A turbofan engine uses a fan to bypass some air around the engine core and to
provided thrust. The advantage is that this provides additional thrust without increasing
fuel flow.
Name the major components of a gas turbine engine? - answer-Air inlet, compressor
section, combustion section, turbine section, exhaust section, and gearbox and
accessory section.
