15.9 Lubrications And Fuels Flashcards
What are the issues with mineral based oils?
They suffer from excessive volatility and thermal degradation at high temperature
What are ester based oils also known as?
Third generation oils
What are the benefits of ester based oils?
They were developed with properties suitable for gas turbine engines such as improved thermal stability
What are the main tasks of oils?
Lubrication
Cooling
Corrosion resistance
Cleaning
What are the three types of synthetic oils?
Type 1 older engines
Type 2 modern gas engines
Type 3 special aircraft
What is the largest disadvantage of synthetic oils?
The cost
What is viscosity?
Internal resistance of a fluid against deformation
What is pour point?
The lowest temperature in which oil will visibly move
What is the pour point of type 2 oils?
-57 degrees
What is viscosity in relation to temperature?
Higher at low temperature
Lower at higher temperature
What is flash point?
The lowest temperature the oil will give off enough vapour to flash when a flame is applied
What is the flash point of type 2 oils ?
250 degrees
What is pressure resistance?
Oil film between moving components
What is oxidation resistance?
The reaction between oil and oxygen making it thicker
What is thermal stability?
Oil resistance at high temperature