Module 15.9 Lubricants and Fuels Flashcards
What are aviation fuel additives?
Compounds added to the fuel in very small quantities
How are additives measured?
Parts per million (ppm)
Name a fuel anti-ice additive?
Prist®
How is anti-ice additive added to fuel?
To bulk fuel and directly into the fuel tank, usually during refuelling.
What do anti-ice additives also inhibit?
Bacterial growth
What must be kept to a minimum in fuel?
Water
When stored, what should synthetic oils be protected against?
High temperatures
What should be checked before use of synthetic oils?
Shelf life
Why should open containers not be reused?
It will absorb sufficient moisture from the atmosphere to make it unusable.
What are the four main tasks of oil?
Lubricating
Cooling
Cleaning
Corrosion protection
What cleans the system from contamination?
Oil
Why is lubrication needed?
To reduce friction between metal surfaces.
Why is cooling needed?
To remove heat in the lubricating areas caused by the operating engine.
What are the two types of oil?
Synthetic oils
Mineral oils
What are the types of synthetic oil?
Type 1, 2 and 3
Which type of synthetic oil is mostly used on modern gas turbine engines?
Type 2
How does type 3 synthetic oil differ from type 2?
Type 3 oil has higher thermal stability and viscosity at high temperatures.
What is viscosity measured in?
Centistokes
What is the viscosity of type 1 synthetic oil?
3 centistokes
What is the viscosity of type 2 synthetic oil?
5 centistokes
What is viscosity index?
The effect temperature has on the viscosity of the oil.
A higher number indicates a viscosity least affected by a change in temperature.
What is the most important characteristic of engine oil?
Viscosity
What is viscosity?
The internal resistance of a fluid against deformation.
What does the viscosity of the oil depend on?
Temperature
What is the viscosity of oil at high temp and what is it at low temp?
High at low temperatures and low at high temperatures.
What is pour point?
The lowest temperature that oil will visibly move in a 31.75 mm test tube held horizontally for 5 seconds.
What is the pour point of type 2 synthetic oils?
-57 °C
Define flashpoint
The lowest temperature that the oil will give off enough vapour to flash when a flame is applied.
What is the flash-point of type 2 synthetic oils?
Higher than 250 °C.
What is oxidation resistance?
The ability for the oil to resist reacting with oxygen.
What is thermal stability?
The resistance to the decomposition of the oil compounds at high temperatures.
What is oil foaming?
The measure of the resistance of the oil to separate from entrapped air.
What is rubber swelling?
The amount of oil that will cause a particular rubber compound to swell.
What is coking?
The amount of carbon residue remaining in the oil after being subjected to extreme heating.
What kerosene fuels are most commonly used in gas turbine engines?
Jet A1 and Jet A.
Where is Jet A1 most commonly used?
Europe
Where is Jet A most commonly used?
America
What is the flash point of Jet B fuel?
‑20 °C (‑4 °F)
When must type of fuel be recorded?
When refuelling
What two ways can water appear in fuel?
Dissolved and therefore invisible or suspended.
Why must water in fuel be removed periodically?
It encourages ice build-up.
What is another problem with water in fuel, other than ice build-up?
Support microbial growth in the tanks.
How should a fuel leak be dealt with?
First, stop the leakage flow. Then, add a binding agent to the fuel spillage.
