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
What is volatility?
The ease that a liquid becomes vaporous
What is acidity?
Its tendency to be corrosive
What is oil foaming?
Resistance of the oil to separate from entrapped air
What is rubber swelling?
The amount of oil that causes rubber to swell
What is oxidation and thermal stability?
The ability of oil to resist formation of high carbon and sludge
What is corrosiveness?
The effect oil has on metals especially copper
What is pressure?
The ability of oil to carry a load
What is coking?
Carbon residue remaining in the oil after extreme heating
What is JET A1 USA name?
JP1A
What is JET A USA name?
JP1
Jet B flash and freeze point?
Flash = -20 c
Freeze = -48 c
What is the flash and freeze point JP5?
Flash = 65c
Freeze = -48c
What type of fuels are jet fuels?
Kerosene
What are the main requirements for fuels?
-low freezing point
-flash point low enough to give good ignition
-flash point high enough for safe handling
What properties must fuel poses?
-Clear bright and visually free from contaminants
-limited acidity
-max viscosity at -20degrees
-combustion in calorific value
What can water build up in the tank cause?
-microbial growth
-engine power fluctuations and flameout
What is the fuel density of jet A?
0.81 kg per litre at 15 degrees
Also jet a1
How are fuel additives measured?
Parts per million
What anti Ice additives are typically used?
PRIST
What additives can be added to fuel?
Anti ice
Anti microbial
Anti oxidants
Static dissipator
Corrosion inhibitors
Metal de activators
What is important when storing oil?
It cannot be stored open it’s hygroscopic and absorbs moisture
