2Engine Lubrication And Cooling Principles of Engine LubricationPrimary purpose is to reduce friction between moving parts.Liquid lubricants (oil) are used universally in aircraft.No metal to metal contact occurs.Friction and wear held to a minimum.
3Engine Lubrication And Cooling Principles of Engine LubricationOil film acts as a cushion between metal parts.Crankshaft and connecting rodsShock-loading parts
4Engine Lubrication And Cooling Principles of Engine LubricationAbsorbs heat from the parts.Pistons and cylinder walls.Forms a seal between the piston and the cylinder wall.Reduce abrasive wear.Picks up foreign particles and carries them to the filter.
5Engine Lubrication And Cooling Principles of Engine LubricationReduces frictionCushionsAbsorbs heatCoolingForms a sealReduces abrasive wearCleans
6Engine Lubrication And Cooling Requirements & Characteristics Of LubricantsThe Most important characteristic is its viscosity.The resistance of an oil to flow.High viscosity is oil that flows slow.Low viscosity is oil that flows freely.
7Engine Lubrication And Cooling How does temperature affect the viscosity of oil?
8Engine Lubrication And Cooling Some Grades of oil become practically solid in cold weather.Increases dragMakes circulation difficult.Others become so thin at high temperatures that the oil film is broken.Rapid wear of moving parts.
9Engine Lubrication And Cooling Flash Point And Fire PointFlash Point is the temperature at which a liquid will begin to give off ignitable vapors.Fire Point is the temperature at which there are sufficient vapors to support a flame.
10Engine Lubrication And Cooling Cloud Point, Pour Point And Specific GravityCloud Point is the temperature at which its wax content, normally held in solution, begins to solidify and separate in to tiny crystals.Pour Point is the lowest temperature at which it will flow or can be poured.Specific Gravity is a comparison of the weight of the substance to the weight of an equal volume of distilled water.
11Engine Lubrication And Cooling Aviation oils are classified numerically according to an approximation of their viscosity.Classified under an SAE (Society of Automotive Engineers) system.SAE divides all oils into seven groups according to viscosity at either 130° or 210° F.SAE 10 to 70 (SAE 20W)“W” indicates that the oil is satisfactory oil for winter use in cold climates.
12Engine Lubrication And Cooling Lubricating Oil TypesStraight Mineral OilAshless DispersantSynthetic
13Engine Lubrication And Cooling Straight Mineral oilUsed in engines after overhaul or when new to facilitate wear-in or seating of piston rings.Often forms sludge when exposed to temperatures higher than normal.
14Engine Lubrication And Cooling Ashless Dispersant (AD)Replaces mineral oil after the piston rings have seated.Less tendency to oxidize to carbon, or form ash deposits.Particles don’t clump together, forming sludge.Better lubricating properties than mineral oils.
15Engine Lubrication And Cooling Oil CompatibilityCan different brands and grades of the same oil type be mixed?
16Engine Lubrication And Cooling Oil CompatibilityIf necessary in order to have proper operating oil levels, brands of the same type can be mixed.
17Engine Lubrication And Cooling Internal Lubrication Of Reciprocating EnginesThree Methods usedPressureSplashCombination Splash-And-Pressure
18Engine Lubrication And Cooling Pressure-LubricationA mechanical pump supplies oil under pressure to the bearings throughout the engine.Splash-LubricationUsed in addition to pressure lubrication on aircraft engines.
19Engine Lubrication And Cooling Advantages of pressure lubrication systemPositive introduction of oil to the bearings.Cooling effect caused by the large quantities of oil which can be circulated through a bearing.Satisfactory lubrication in various attitudes of flight.
21Engine Lubrication And Cooling Lubrication SystemsWet-Sump SystemDry-Sump System
22Engine Lubrication And Cooling Wet-SumpSystem consist of a sump or pan, in which the oil supply is contained.The sump or pan is attached to the bottom of the engine case.
23Engine Lubrication And Cooling Wet-SumpWhat are some of the disadvantages and advantages of the wet-sump system?
24Engine Lubrication And Cooling Wet-SumpDisadvantagesOil supply limited by sump.Cooling is difficult.Higher operating temperatures.Not adaptable to inverted flyingAdvantagesRequires no external parts and fittings to complicate installation.No second (scavenge pump) required.Can be operated in much cooler temperatures.
25Engine Lubrication And Cooling Dry-SumpOil supply is carried in a separate tank.Scavenger pumps used to return the oil to the tank.Used in radial engines and engines capable of sustained inverted flight.
28Engine Lubrication And Cooling Engine Cooling SystemsWhy is excessive heat undesirable in internal combustion engines?
29Engine Lubrication And Cooling Affects the behavior of the combustion of the fuel/air charge.It weakens and shortens the life of engine parts.It impairs lubrication.
30Engine Lubrication And Cooling Engine Cooling SystemsAbout one-fourth of the heat released in an engine is changed into useful power.Half of the heat goes out the exhaust, and the other is absorbed by the engine.Oil picks up some heat and transfers it to the airstream.The engine cooling system takes care of the rest.
31Engine Lubrication And Cooling Cooling FinsCooling fins increase the surface of a cylinder.This arrangement increases the heat transfer by radiation (from a jug to a barrel).Cylinders are normally replaced when a specified number of square inches of fins are missing.
32Engine Lubrication And Cooling Cowling and bafflesDesigned to force air over the cylinder cooling fins.Direct the air close around the cylinders and prevent it from forming hot pools.Blast tubes direct jets of cooling air onto the bottom spark plug elbows.
34Engine Lubrication And Cooling Temperature ControlsControls the air circulation over the engine.Keeps the engine from overheating on take off and getting too cold in high-speed low-power letdowns.Cowl Flaps, Augmenters
38Engine Lubrication And Cooling Cylinder Head Temperature Indicating SystemConsists of and indicator, electrical wiring, and a thermocouple.Thermocouple consists of two dissimilar metals connected by wiring to an indicating system. A voltage is produced when the temperature of the junction is different from the temperature where the dissimilar metals are connected.
39Engine Lubrication And Cooling Pilot ResponsibilityCowl Flaps?Power Settings?Airspeed?Fuel Mixture?
40Engine Lubrication And Cooling Thermal ShockOccurs when engine parts that are operating at high temperatures are quickly cooled.Idle power, high airspeed, cool or cold air.Some parts are cooled much more rapidly then others. These parts shrink in size faster then the warmer, surrounding metals.