M15.9 Lubricants And Fuels Flashcards
Main tasks of engine oil?
Lubrication
Cooling
Cleaning
Corrosion protection
Two types of engine oils?
Synthetic oils
Mineral oils
Three types of synthetic oils?
Type 1- first generation synthetic oil- Old gas turbine engines
Type 2- used on modern gas turbine engines
Type 3- higher thermal stability and viscosity at high temp than type 2. Only used for special aircraft
Advantages and disadvantages of synthetic oil?
Advantages are better viscosity, better thermal stability and high pressure resistance disadvantages are they have a high price, not mixable and cause skin irritation
What is viscosity index?
The effect temperature has on viscosity of the oil
Higher number indicates least affected by a change in temp
What is viscosity?
The internal resistance of a fluid against deformation
Viscosity of oil depends on what?
Temperature
High viscosity at low temp
Low viscosity at high temp
What is the pour point?
Lowest temp that an oil will visibly move in a 31.75mm test tube held horizontally for 5 seconds
Pour point of type two oil?
-57 degrees Celsius
What is a flash point?
The lowest temperature that an oil will give off enough vapour to flash when a flame is applied. Should be as high as possible
Type 2 oil flash point?
250 degrees Celsius
What happens to oil when it reacts with oxygen?
Gets thicker and increase’s viscosity
What types of resistance does oil need?
Pressure resistance
Oxidation resistance
What is thermal stability?
Describes oil resistance to the decomposition of the oil at high temps.
What is volatility?
The measure of the ease with which a liquid is converted to a vaporous state
What is acidity?
A measure of the corrosive tendencies of the oil
What is oil foaming?
The measure of the resistance of the oil to separate from entrapped air
What is rubber swelling?
The amount the oil will cause a particular rubber compound to swell
What is oxidation and thermal stability?
The ability of the oil to resist the formation of hard carbon and sludge at high temperatures
What is coking?
The amount of carbon residue remaining in the oil after being subjected to extreme heating
Four main types of aviation fuel?
Jet A1
Jet A
Jet B
JP 5
What is the most common fuel type for jet engines in Europe?
Jet A1
What is the most common fuel type for jet engines in America?
Jet A
Jet B flash point?
-20 degrees Celsius
Why is JP5 preferred for military aircraft?
Very high flash point of plus 65 degrees Celsius.
Safe to handle
Low freezing point at -48 degrees Celsius
Jet A and Jet A1 densities?
Have the same density of 0.81kg/ltr at a temp of 15 degrees c
Jet A and Jet A1 densities?
Have the same density of 0.81kg/ltr at a temp of 15 degrees c
Two conditions of water being in fuel?
Can be dissolved into fuel (invisible)
Can be suspended in fuel, visible as small droplets or water bubbles
Why is water a hazard in fuel?
Can cause ice build up
Supports corrosion
Can cause flame outs
Microbial growth in fuel tanks
Types of fuel additives?
Anti icing
Anti microbial
Anti oxidants
Static dissipator
Corrosion inhibitor
Metal de activator
What do anti oxidants do?
Prevent formation of gum deposits on fuel system components caused by oxidation of the fuel in storage
What are metal de activators?
Suppress the catalytic effect that some metals, particularly copper have on fuel oxidation
Can open containers be reused of synthetic oil?
No as it will have absorbed moisture
Can synthetic oil brands be mixed?
No as they may not be compatible
How to deal with small and large fuel spills?
If it’s small commercial absorbing agents can be used
If it’s larger then it must be washed away with plenty of water
If fuel is ingested what should you do?
Do not induce vomiting
Drink 250ml of water
Obtain medical attention immediately
How do deal with fuel spilt or leakage?
First stop the leakage flow
Then add a binding agent to fuel spillage
Is refuelling allowed when aircraft engines are running?
No
