PP Lubrication Systems

What will be the result of operating an engine in extremely high temperatures using a lubricant recommended by the manufacturer for a much lower temperature?

The oil pressure will be higher than normal.
The oil temperature and oil pressure will be higher than normal.
The oil pressure will be lower than normal.

(1) Gas turbine and reciprocating engine oils can be mixed or used interchangeably.

(2) Most gas turbine engine oils are synthetic.

Regarding the above statements,

only 2 is true.
both 1 and 2 are true.
neither 1 nor 2 is true.

An oil separator is generally associated with which of the following?

Engine-driven oil pressure pump.
Engine-driven vacuum pump.
Cuno oil filter.

The time in seconds required for exactly 60 cubic centimeters of oil to flow through an accurately calibrated orifice at a specific temperature is recorded as a measurement of the oil’s

flash point.
specific gravity.
viscosity.

Upon what quality or characteristic of a lubricating oil is its viscosity index based?

Its resistance to flow at a standard temperature as compared to high grade paraffin-base oil at the same temperature.
Its rate of change in viscosity with temperature change.
Its rate of flow through an orifice at a standard temperature.

Lubricating oils with high viscosity index ratings are oils

in which the viscosity does not vary much with temperature change.
in which the viscosity varies considerably with temperature change.
which have high SAE numbers.

Compared to reciprocating engine oils, the types of oils used in turbine engines

are required to carry and dispense a higher level of combustion byproducts.
may permit a somewhat higher level of carbon formation in the engine.
have less tendency to produce lacquer or coke.

The oil used in reciprocating engines has a relatively high viscosity due to

the reduced ability of thin oils to maintain adequate film strength at altitude (reduced atmospheric pressure).
the relatively high rotational speeds.
large clearances and high operating temperatures.

If all other requirements can be met, what type of oil should be used to achieve theoretically perfect engine lubrication?

The thinnest oil that will stay in place and maintain a reasonable film strength.
An oil that combines high viscosity and low demulsibility.
An oil that combines a low viscosity index and a high neutralization number.

Which of these characteristics is desirable in turbine engine oil?

Low flash point.
High flash point.
High volatility.

The viscosity of a liquid is a measure of its

resistance to flow.
rate of change.
weight or density.

What type of oil system is usually found on turbine engines?

Dry sump, pressure, and spray.
Dry sump, dip, and splash.
Wet sump, spray, and splash.

Which of the following helps determine the proper grade of oil to use in a particular engine?

Adequate lubrication in various attitudes of flight.
Positive introduction of oil to the bearings.
Operating speeds of bearings.

Specific gravity is a comparison of the weight of a substance to the weight of an equal volume of

oil at a specific temperature.
distilled water at a specific temperature.
mercury at a specific temperature.

Which of the following has the greatest effect on the viscosity of lubricating oil?

Temperature.
Engine RPM.
Oil pressure.

What advantage do mineral base lubricants have over vegetable oil base lubricants when used in aircraft engines?

Cooling ability.
Chemical stability.
Friction resistance.

The recommended aircraft engine lubricants are

animal, mineral, or synthetic based.
mineral or synthetic based.
vegetable, mineral, or synthetic based.

High tooth pressures and high rubbing velocities, such as occur with spur-type gears, require the use of

an EP lubricant.
straight mineral oil.
metallic ash detergent oil.

Manufacturers normally require turbine engine oil servicing within a short time after engine shutdown primarily to

prevent overservicing.
help dilute and neutralize any contaminants that may already be present in the engine’s oil system.
provide a better indication of any oil leaks in the system.

What type of oil do most engine manufacturers recommend for new reciprocating engine break-in?

Ashless dispersant oil.
Straight mineral oil.
Semi-synthetic oil.

What type of oil do most engine manufacturers recommend after new reciprocating engine break-in?

Metallic-ash detergent oil.
Ashless dispersant oil.
Straight mineral oil.

The type of oil pumps most commonly used on turbine engines are classified as

positive displacement.
variable displacement.
constant speed.

As a general rule, the mixture setting on a reciprocating engine operating at or near takeoff power that provides the best cooling is

FULL RICH.
LEAN.
FULL LEAN.

The engine oil temperature regulator is usually located between which of the following on a dry sump reciprocating engine?

The engine oil supply pump and the internal lubrication system.
The scavenger pump outlet and the oil storage tank.
The oil storage tank and the engine oil supply pump.

What will happen to the return oil if the oil line between the scavenger pump and the oil cooler separate?

Oil will accumulate in the engine.
The return oil will be pumped overboard.
The scavenger return line check valve will close and force the oil to bypass directly to the intake side of the pressure pump.

At cruise RPM, some oil will flow through the relief valve of a gear-type engine oil pump. This is normal as the relief valve is set at pressure which is

lower than the pump inlet pressure.
lower than the pressure pump capabilities.
higher than pressure pump capabilities.

(1) Fuel may be used to cool oil in gas turbine engines.

(2) Ram air may be used to cool oil in gas turbine engines.

Regarding the above statements,

only 1 is true.
only 2 is true.
both 1 and 2 are true.

In a reciprocating engine oil system, the temperature bulb senses oil temperature

at a point after the oil has passed through the oil cooler.
while the oil is in the hottest area of the engine.
immediately before the oil enters the oil cooler.

The oil dampened main bearing utilized in some turbine engines is used to

provide lubrication of bearings from the beginning of starting rotation until normal oil pressure is established.
provide an oil film between the outer race and the bearing housing in order to reduce vibration tendencies in the rotor system, and to allow for slight misalignment.
dampen surges in oil pressure to the bearings.

What is the purpose of the last-chance oil filters?

To prevent damage to the oil spray nozzle.
To filter the oil immediately before it enters the main bearings.
To assure a clean supply of oil to the lubrication system.

In a jet engine which uses a fuel/oil heat exchanger, the oil temperature is controlled by a thermostatic valve that regulates the flow of

fuel through the heat exchanger.
both fuel and oil through the heat exchanger.
oil through the heat exchanger.

What prevents pressure within the lubricating oil tank from rising above or falling below ambient pressure (reciprocating engine)?

Oil tank check valve.
Oil presure relief valve.
Oil tank vent.

In an axial-flow turbine engine, compressor bleed air is sometimes used to aid in cooling the

fuel.
inlet guide vanes.
turbine, vanes, blades, and bearings.

Oil picks up the most heat from which of the following turbine engine components?

Rotor coupling.
Compressor bearing.
Turbine bearing.

Which of the following is a function of the fuel/oil eat exchanger on a turbine engine?

Aerates the fuel.
Emulsifies the oil.
Increases fuel temperature.

According to the Federal Aviation Regulations, oil tank filters on turbine engines must be marked with the word

“oil” and the type and grade of oil specified by the manufacturer.
“oil” and tank capacity.
“oil.”

Oil tank fillers on reciprocating engines are marked with the word

“oil” and tank capacity, in accordance with 14 CFR Part 45.
“oil” type, and grade, in accordance with 14 CFR Part 33.
“oil,” in accordance with 14 CFR Part 25.

After making a welded repair to a pressurized-type turbine engine oil tank, the tank should be pressure checked to

not less than 5 psi plus the maximum operating pressure of the tank.
not less than 5 psi plus the average operating pressure of the tank.
5 psi.

Why are fixed orifice nozzles used in the lubrication system of gas turbine engines?

To provide a relatively constant oil flow to the main bearings at all engine speeds.
To keep back pressure on the oil pump, thus preventing an air lock.
To protect the oil seeds by preventing excessive pressure from entering the bearing cavities.

Possible failure related ferrous-metal particles in turbine engine oil cause an (electrical) indicating type magnetic chip detector to indicate their presence by

disturbing the magnetic lines of flux around the detector tip.
bridging the gap between the detector center (positive) electrode and the ground electrode.
generating a small electric current that is caused by the particles being in contact with the dissimilar metal of the detector tip.

What would be the probable result if the oil system pressure relief valve should stick in the open position on a turbine engine?

Increased oil pressure.
Decreased oil temperature.
Insufficient lubrication.

What is the primary purpose of the fuel/oil heat exchanger?

Cool the fuel.
Cool the oil.
De-aerate the oil.

What unit in an aircraft engine lubrication system is adjusted to maintain the desired system pressure?

Oil pressure relief valve.
Oil viscosity valve.
Oil pump.

Low oil pressure can be detrimental to the internal engine components. However; high oil pressure

should be limited to the engine manufacturer’s recommendations.
has a negligible effect.
will not occur because of pressure losses around the bearings.

What is the primary purpose of the oil breather pressurization system that is used on turbine engines?

Prevents foaming of the oil.
Allows aeration of the oil for better lubrication because of the air/oil mist.
Provides a proper oil spray pattern from the main bearing oil jets.

The purpose of directing bleed air to the outer turbine case on some engines is to

provide optimum turbine blade tip clearance by controlling thermal expansion.
provide up to 100 percent kinetic energy extraction from the flowing gases.
allow operation in a thermal environment 600 to 800 degrees F above the temperature limits of turbine blade and vane alloys.

Some larger reciprocating engines use a compensating oil pressure relief valve to

provide a high engine oil pressure when the oil is cold and automatically lower the oil pressure when the oil warms up.
compensate for changes in atmospheric pressure that accompany altitude changes.
automatically keep oil pressure nearly the same whether the oil is warm or cold.

In order to relieve excessive pump pressure in an engine’s internal oil system, most engines are equipped with a

vent.
bypass valve.
relief valve.

What is the source of most of the heat that is absorbed by the lubricating oil in a reciprocating engine?

Crankshaft main bearings.
Exhaust valves.
Pistons and cylinder walls.

How are the teeth of the gears in the accessory section of an engine normally lubricated?

By splashed or sprayed oil.
By submerging the load-bearing portions in oil.
By surrounding the load-bearing portions with baffles or housings within which oil pressure can be maintained.

What is the purpose of the check valve generally used in a dry sump lubrication system?

To prevent the scavenger pump from losing its prime.
To prevent the oil from the supply tank from seeping into the crankcase during inoperative periods.
To prevent the oil from the pressure pump from entering the scavenger system.

Which of the following factors has the least effect on the oil consumption of a specific engine?

Mechanical efifciency.
Engine RPM.
Lubricant characteristics.

How is the oil collected by the piston oil ring returned to the crankcase?

Down vertical slots cut in the piston wall between the piston oil ring groove and the piston skirt.
Through holes drilled in the piston oil ring groove.
Through holes drilled in the piston pin recess.

Which of the following lubrication system components is never located between the pressure pump and the engine pressure system?

Oil temperature bulb.
Fuel line for oil dilution system.
Check valve.

As an aid to cold-weather starting, the oil dilution system thins the oil with

kerosene.
alcohol.
gasoline.

The basic oil pressure relief valve setting for a newly overhauled engine is made

within the first 30 seconds of engine operation.
when the oil is at a higher than normal temperature to assure high oil pressure at normal oil temperature.
in the overhaul shop.

Where is the oil temperature bulb located on a dry sump reciprocating engine?

Oil inlet line.
Oil cooler.
Oil outlet line.

Cylinder walls are usually lubricated by

splashed or sprayed oil.
a direct pressure system fed through the crankshaft, connecting rods, and the piston pins to the oil control ring groove in the piston.
oil that is picked up by the oil control ring when the piston is at bottom center.

If an oil filter element becomes completely clogged, the

oil flow to the engine will be restricted.
oil will be bypassed back to the oil tank.
bypass valve will open, and the oil pump will supply unfiltered oil.

Oil accumulation in the cylinders of an inverted inline engine and in the lower cylinders of a radial engine is normally reduced or prevented by

reversed oil control rings.
routing the valve-operating mechanism lubricating oil to a separate scavenger pump.
extended cylinder skirts.

What is the primary purpose of changing aircraft engine lubricating oils at predetermined periods?

The oil becomes diluted with gasoline washing past the pistons into the crankcase.
The oil becomes contaminated with moisture, acids, and finely divided suspended solid particles.
Exposure to heat and oxygen causes a decreased ability to maintain a film under load.

What determines the minimum particle size which will be excluded or filtered by a CUNO (stacked disc, edge filtration) filter?

The disc thickness.
The spacer thickness.
Both the number and thickness of the discs in the assembly.

What is the primary purpose of the hopper located in the oil supply tank of some dry sump engine installations?

To reduce the time required to warm the oil to operating temperatures.
To reduce surface aeration of the hot oil and thus reduce oxidation and the formation of sludge and varnish.
To impact a centrifugal motion to the oil entering the tank so that the foreign particles in the oil will separate more readily.

The purpose of the flow control valve in a reciprocating engine oil system is to

direct oil through or around the oil cooler.
deliver cold oil to the hopper tank.
compensate for volumetric increases due to foaming of the oil.

Where are sludge chambers, when used in aircraft engine lubrication systems, usually located?

in the crankshaft throws.
Adjacent to the scavenger pumps.
In the oil storage tank.

Why is an aircraft reciprocating engine oil tank on a dry sump lubrication system equipped with a vent line

To prevent pressure buildup in the reciprocating engine crankcase.
To eliminate foaming in the oil tank.
To prevent pressure buildup in the oil tank.

Excessive oil is prevented from accumulating on the cylinder walls of a reciprocating engine by

the design shape of the piston skirt.
internal engine pressure bleeding past the ring grooves.
oil control rings on the pistons.

(1) Wet sump oil systems are most commonly used in gas turbine engines.

(2) In most turbine engine oil tanks, a slight pressurization of the tank is desired to ensure a positive flow of oil.

Regarding the above statements,

both 1 and 2 are true.
only 2 is true.
neither 1 nor 2 is true.

The pumping capacity of the scavenger pump in a dry sump aircraft engine’s lubrication system

is greater than the capacity of the oil supply pump.
is less than the capacity of the oil supply pump.
is usually equal to the capacity of the oil supply pump in order to maintain constant oiling conditions.

In which of the following situations will the oil cooler automatic bypass valve be open the greatest amount?

Engine oil above normal operating temperature.
Engine oil below normal operating temperature.
Engine stopped with no oil flowing after runup.

In order to maintain a constant oil pressure as the clearances between the moving parts of an engine increase through normal wear, the supply pump output

increases as the resistance offered to the flow of oil increases with more oil being returned to the pump inlet by the relief valve.
remains relatively constant (at a given RPM) with less oil being returned to the pump inlet by the relief valve.
remains relatively constant (at a given RPM) with more oil being returned to the pump inlet by the relief valve.

The valve assembles of opposed reciprocating engines are lubricated by means of a

gravity feed system.
splash and spray system.
pressure system.

What will result if an oil filter becomes completely blocked?

Oil will flow at a reduced rate through the system.
Oil flow to the engine will stop.
Oil will flow at the normal rate through the system.

A turbine engine dry sump lubrication system of the self-contained, high-pressure design

has no heat exchange.
consists of pressure, breather, and scavenger subsystems.
stores oil in the engine crankcase.

Lube system last-chance filters in turbine engines are usually cleaned

during annual inspection.
during 100-hour inspections.
during overhaul.

How are the piston pins of most aircraft engines lubricated?

By pressure oil through a drilled passageway in the heavy web portion of the connecting rod.
By oil which is sprayed or thrown by the master or connecting rods.
By the action of the oil control ring and the series of holes drilled in the ring groove directing oil to the pin and piston pin boss.

The vent line connecting the oil supply tank and the engine in some dry sump engine installations permits

pressurization of the oil supply to prevent cavitation of the oil supply pump.
oil vapors from the engine to be condensed and drained into the oil supply tank.
the oil tank to be vented through the normal engine vent.

An engine lubrication system pressure relief valve is usually located between the

oil cooler and the scavenger pump.
scavenger pump and the external oil system.
pump and the internal oil system.

Where is the oil of a dry sump reciprocating engine exposed to the temperature control valve sensing unit?

Oil cooler inlet.
Engine outlet.
Engine inlet.

Under which of the following conditions is the oil cooler flow control valve open on a reciprocating engine?

When the temperature of the oil returning from the engine is too high.
When the temperature of the oil returning from the engine is too low.
When the scavenger pump output volume exceeds the engine pump input volume.

The purpose of a relief valve installed in the tank venting system of turbine engine oil tank is to

prevent oil pump cavitation by maintaining a constant pressure on the oil pump inlet.
maintain internal tank air pressure at the ambient atmospheric level regardless of altitutde or rate of change in altitude.
maintain a positive internal pressure in the oil tank after shutdown to prevent oil pump cavitation on engine start.

In a reciprocating engine, oil is directed from the pressure relief valve to the inlet side of the

scavenger pump.
oil temperature regulator.
pressure pump.

If the oil in the oil cooler core and annular jacket becomes congealed, what unit prevents damage to the cooler?

Oil pressure relief valve.
Airflow control valve.
Surge protection valve.

The primary source of oil contamination in a normally operating reciprocating engine is

metallic deposits as a result of engine wear.
atmospheric dust and pollution.
combustion deposits due to combustion chamber blow-by and oil migration on the cylinder walls.

A drop in oil pressure may be caused by

the temperature regulator sticking open.
the bypass valve sticking open.
foreign material under the relief valve.

The main oil filters strain the oil at which point in the system?

Immediately after it leaves the scavenger pump.
immediately before it enters the pressure pump.
Just as it leaves the pressure pump.

Which of the following prevents oil from entering the main accessory case when the engine is not turnning?

Pressure valve.
Hydraulic fuse.
Check valve.

An oil tank having a capacity of 5 gallons must have an expansion space of

2 quarts.
4 quarts.
5 quarts.

As a general rule, a small amount of small fuzzy particles or gray metallic paste on a turbine engine magnetic chip deterctor

is considered to be the result of normal wear.
indicates an imminent component failure.
indicates accelerated generalized wear.

Why is expansion space required in an engine oil supply tank?

To eliminate oil foaming.
For oil enlargement and collection of foam.
For proper oil tank ventilation.

The purpose of a dwell chamber in a turbine engine oil tank is to provide

a collection point for sediments.
for a pressurized oil supply to the oil pump inlet.
separation of entrained air from scavenged oil.

Which of the following bearing types must be continuously lubricated by pressure oil?

Ball.
Roller.
Plain.

PP Lubrication Systems

Jon K

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