Lubrication Systems Flashcards
Important functions of the lubrication system:
1) Reduces friction
2) Removes heat
3) Seals and cushions
4) Protects against corrosion
5) Performs hydraulic action
6) Cleans inside of engine
Contaminants commonly picked up by engine oil:
1) Combustion deposits
2) Sludge
3) Dirt
4) Carbon
5) Particles of metal
Define viscosity:
The resistance of a fluid to flow. The stiffness of the fluid, or its internal friction.
Define viscosity index:
A measure of change in viscosity of an oil as it changes temperature. The higher the viscosity index, the less the viscosity changes.
The “W” in 20W50 stands for ______.
Winter
Define flash point:
The temperature of oil when it gives off enough vapors to ignite and flash, but not continue to burn.
Define fire point:
The temperature to which oil must be heated for the vapors to ignite and burn continuously.
Define cloud point:
The temperature at which the wax in the oil first becomes visible.
Define pour point:
The lowest temperature at which oil will pour without disturbance.
Types of reciprocating engine lubricating oil:
1) Straight mineral
2) Ashless-dispersant
3) Synthetic
4) Semisynthetic
Used for the break-in period of newly overhauled reciprocating engines.
Straight mineral oil.
Type of oil used almost exclusively for turbine engines:
Synthetic oil.
Oil used in applications requiring high film strength:
Extreme pressure (EP) lubricants
Most popular lubricating oil for use in modern aircraft engines:
Ashless dispersant
Oil with high viscosity index changes its viscosity very ______ with changes in temperature.
Little
Advantages of synthetic oil:
1) Superior resistance to oxidation.
2) Low internal friction
Most heat picked up by oil in a reciprocating engine come from the ______ and ______.
Pistons.
Cylinder walls.
When an engine is to remain out of service for an extended period of time, the cylinder walls should be protected with a _______.
Preservative oil.
Recommended breaking in time for new and freshly overhauled engines.
10-50 hours
An ideal lubricating oil has a low ______ and a high ________.
Viscosity.
Film strength.
Recip engine parts that are lubricated by pressure oil.
1) Crankshaft
2) Camshaft
3) Propeller shaft
4) Rocker arm bushings
Explain the thermostatic valve.
Temperature sensitive valve that controls oil temperature. When oil is cold, the valve directs it to the engine. When oil is hot, it redirects it through the cooler.
A valve that controls the temperature of oil in a reciprocating engine.
Thermostatic valve.
Two types of lubricating systems oil storage:
1) Wet sump
2) Dry sump
What returns oil to the tank after lubricating process is complete?
Scavenger pumps
Where is the oil cooler installed?
Between scavenger pump and oil tank
When oil temps are high, the thermostatic valve is ______.
Closed
Types of oil filter arrangements:
1) Full-flow
2) Bypass
Used in large oil tanks to hasten warm up of engine oil:
Hoppers.
Types of oil pumps used in reciprocating engines:
1) Spur gear
2) Gerotor
A constant displacement oil pump requires a _______.
Pressure relief valve
The valve in an oil cooler that prevents high pressure issues caused by congealed oil:
Surge protection valve
Required instruments relating to the engine lubrication system of an aircraft engine:
1) Oil pressure gauge
2) Oil temp gauge
Most popular lubrication system used on modern turbine engines:
Dry sump
Turbine engine oil has a ______ viscosity than reciprocating engine oil.
Lower
Viscosity of turbine engine oil is expressed in _______.
Centistokes.
Component that maintains oil pump pressure at correct value:
Pressure relief valve
In a cold tank dry sump system, the oil cooler is located in the _____.
Scavenger subsystem
In a hot tank dry sump system, the oil cooler is located in the _______.
Pressure subsystem
Types of bearings used to support the turbine shaft:
1) Roller
2) Ball
Different ways that lubrication is applied in an engine:
1) Pressure
2) Splash
3) Spray
Different types of filter elements and their methods:
1) Surface (Wire screen)
2) Edge (Spiral wound/Cuno)
3) Depth (Fibrous mat)
4) Semi-Depth (Pleated Fiber)
T/F
Turbine oil does not contact combustion/airstream.
True
Used to prevent oil from leaving the bearing cavity:
Labyrinth seal
Oils with low pour points will pour _______ (more/less) easily at colder temperatures.
More.
The lower the pour point, the better it pours at colder temperatures
Explain the wet sump lubrication system.
Lubrication system in which the oil supply is carried within the engine itself.
Explain the dry sump lubrication system.
Lubrication system that carries the oil supply in a tank not normally part of the engine.
Types of dry-sump lubrication systems:
1) Hot tank system
2) Cold tank system
Why must turbine shaft bearings be sealed?
To prevent lubricating oil from getting into the engine airstream.
A chamber in an oil tank in which air is allowed to escape from scavenged oil:
Dwell chamber
Commonly used seals in turbine engines:
1) Carbon
2) Labyrinth
Carbon seals are a _______ type seal.
Rubbing
Labyrinth seals are a ______ type seal.
Non-rubbing
A component that removes air from scavenged oil before it is returned to the tank:
Deaerator
The creation of low pressure in an oil pump when the inlet system is not able to supply all the oil the pump requires is called ______.
Cavitation
Oil tanks are required to have an expansion space of ______% of tank capacity.
10%
The air removed from the oil by the deaerator is used to ___________.
Pressurize the oil tank
Types of scavenger pumps:
1) Spur gear
2) Gerotor
3) Vane-type
Oil pumps on turbine engines are what type?
Positive displacement
A device installed in the scavenger system to detect ferrous metal flakes picked up by the circulating oil.
Chip detector
A chip detector that illuminates a warning light on the instrument panel:
Indicating chip detector
Oil level dipsticks will have notations for what two levels?
Max cold.
Max hot.
A test that measures the weight of carbon left in a container when a given weight of oil has evaporated at high temperatures:
Carbon-residue test
A test that measures the weight of residue left after all carbon in a container has evaporated and burned:
Ash test
In a reciprocating engine dry sump system, where is the oil cooler installed?
Between the scavenger pump and the oil tank.
In a reciprocating engine wet sump system, where is the oil cooler installed?
After the oil pump.
Reciprocating engines use what type of oil pumps?
Constant-displacement pump
The _______ prevents oil from seeping past the pump gears and flooding the engine when the aircraft is not in operation for extended periods of time.
Check valve
In the case of a catastrophic oil leak, the ________ ensures there will be enough oil remaining to feather the propeller.
Standpipe
Oil temperature is normally picked up when?
Before the oil enters the engine itself.
Most modern turbine engine oil coolers are what type?
Oil-to-fuel type
