LUBRICANTS AND FUELS Flashcards
(32 cards)
What are the 4 main tasks for engine oil?
- Lubricating
- Cooling
- Cleaning
- Corrosion protection
What generally is lubrication needed for?
Reduce friction metered metal surfaces.
How does the oil cool areas?
Heat is transferred to the oil when in contact with metal surfaces.
How does oil clean?
Clean contaminants (abrasion from gears, bearings or FOD)
Carries particles until caught in oil filter.
What can small contaminants in the oil indicate?
Internal wear.
What engines are mineral oils only used on?
Piston type.
What are the 3 types of synthetic oil?
Type 1- used on older aircraft
Type 2- used in modern gas turbine
Type 3- higher thermal stability and viscosity at high temps than type 2. Used on special aircraft
What are advantages of synthetic oils?
Better viscosity, thermal stability and high pressure resistance.
What is a disadvantage of synthetic oils?
- Higher price.
- Harmful to skin.
- Cannot be mixed with other synthetic oils from other manufacturers, even if same type.
What is the viscosity index of engine oils?
The effect temperature has on the viscosity of oil.
Higher number- least change
What is the viscosity of an oil?
Property of a fluid offering resistance to flow.
What is the pour point of an oil?
Lowest temp that oil will visibly move in a 31.75mm test tube held horizontally for 5 seconds.
What is a flash point of an oil?
Lowest temp oil will give off enough vapour to ‘flash’ when a flame is applied.
What is the fire point of an oil?
Lowest temp oil will ignite and burn continuously for at least 5 seconds.
What is the volatility of an oil?
Ease in which a liquid is converted into a vaporous state.
What is the acidity of an oil?
Measure of corrosion tendencies of the oil.
What is oil foaming?
Measure of resistance of oil to separate from entrapped air.
What is the oxidation and thermal stability of an engine oil?
Ability of oil to resist formation of hard carbon and sludge at high temps.
What is coking of an oil?
Amount of carbon residue remaining in the oil after being subjected to extreme heating.
What can be mixed with oils to impart desirable characteristics?
Chemical additives.
What will a typical fuel be composed of?
84% carbon, 16% hydrogen and small amount of impurities (sulphur, water, nitrogen)
What is a high volatile fuel desirable for?
Engine starts in cold weather and in flight.
What is the Califorc value for?
Measures combustion.
If the ambient pressure decreases, what happens to the vaporising rate of the fuel?
Vaporises easier.
