15:09 Lubricants And Fuels Flashcards
What type of oils were gas turbine engines originally designed to use
Mineral oils
What was developed when mineral oil didn’t provide the necessary operational requirements for gas turbine engines
Synthetic oil
What is the most recent type of oil suitable for gas turbine engines
Ester based synthetic oils
What are the main tasks of oil on modern jet engines
- Lubricating
- Cooling
- Cleaning
- Corrosion protection
What is the purpose of lubrication in engines?
To reduce friction between metal surfaces that move against each other
What are the 2 groups of engine oils
- Mineral
- Synthetic
What type of engines are mineral oils usually used
Piston engines
What are the 3 types of synthetic oils
- Type 1 (older)
- Type 2(modern)
- Type 3 (special)
What is type 1 synthetic oil
A first generation synthetic oil. It is now only used on some older gas turbine engines
What is Type 2 synthetic oil
Mostly used on modern gas turbine engines
What is type 3 synthetic oil
Has a higher thermal stability and viscosity at higher temperatures than those 2 oil. This type of oil is only used on special aircraft for example the Euro fighter
What are the main advantages of synthetic oils
- Better viscosity
- Better thermal stability
- A high pressure resistance
What is the one main disadvantage of synthetic oils
They cannot be mixed with synthetic oils from other manufacturers
They are also harmful to skin and expensive
All lubricants for gas turbine engines must exhibit certain physical and performance properties, and are tested for what?
- Viscosity
- Pour point
- Flash point
- Pressure resistance
- Oxidation resistance
- Thermal stability
- Volatility
- Acidity
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 viscosity
The property of a fluid offering resistance to flow or shear at specific temperature
What is the pour point
The lowest temperature that oil will visibly move in a 31.75mm test tube held horizontally for 5 seconds
What is a flash point
The lowest temperature that the oil will give off enough vapour to flash when a flame is applied
What is the fire point of an oil
Lowest temperature that the oil will ignite and burn continuously for at least 5 seconds
What is the meaning of volatility
The measure of the ease in which a liquid is converted in to a vapourers state
What is the meaning of acidity
A measure of the corrosive tendencies of the oil
What is the meaning of oil foaming
The measure of the resistance of the oil to separate from the entrapped air
What is the meaning of oxidation and thermal stability in oil
The ability of the oil to resist the formation of hard carbon and sludge at high temperatures
What is the meaning of coking
The amount of carbon residue remaining in the oil after being subject to extreme heating
What type of additives are added to oils to improve its characteristics
- Detergents
- Corrosion preventatives
- Dyes
- Antioxidants
- Foam inhibitors
- Viscosity enhancers
- Pour point depressants
What is the most common kerosine type fuel used on modern jet aircraft
Jet A and Jet A1
What are the 4 main types of turbine engine fuels
- Jet A
- Jet A1
- Jet B
- JP5
How much hydrogen and carbon would a typical turbine fuel consist of
- Carbon 84%
- Hydrogen 16%
What is the freeze point and flash point and specific gravity of Jet A1 fuel
+38 and -47
Specific gravity between 0.775 and 0.83
What is the most common turbine fuel in America
Jet A
What is the advantage of Jet B fuel
Better cold weather performance but can be used as an alternative to Jet A1
What is JP5 used for
Military aircraft
Why must the fuel used be recorded when refuelling
Each type of fuel has different handling and operating characteristics
What are the main requirements of turbine engine fuels
A low freezing point and a high flash point low enough to provide good ignition capabilities but as high as possible for safe fuel handling
What should the appearance of turbine fuel be
Clear, bright and visually free from solid matter and undissolved water at normal ambient temperature
What should the composition of turbine fuels be
Limited acidity and limited amounts of aromatics, olefin, sulphur, mercaptan sulphur (which produce pollutants), corrosive gums and odours
What is the density of Jet A and Jet A1 fuel
0.81 kg/ltr at 15 °C
What is the benefit of using anti oxidants as fuel additives
To prevent the formation of gum deposits on fuel system components caused by oxidation of fuel in storage
What are the advantages of using metal deactivators as a fuel additive
These suppress the catalytic effect which some metals, particularly copper have on fuel oxidation
What is the advantage of using Biocide additives in fuel
To combat microbiological growth in fuel
Some de icing additives posses these properties
Fuel handling safety precautions can be divided into what 3 areas
- Fire prevention
- Fire extinguishing
- Personnel safety
What must strictly not be done when refuelling
Changing or topping up oxygen bottles
What should you do if you ingest oil
DO NOT induce vomiting
Drink 250ml/ half a pint of water and obtain medical attention immediately
What conditions could create sparks on aircraft
- Electrical switching
- HF transmission
- Weather radar operation
- Metal parts such as tools being stuck together
- Electric static discharge
To prevent sparks by electric static discharge, what must be done to a refuelling truck
Must be connected to the aircraft by a grounding lead
What type of special tools must be used in fuel tanks
Explosion proof tools
When entering a fuel tank what must the clothing be made from to prevent sparks
Cotton
Why must someone wear tank access socks when working inside a fuel tank
Minimise the danger of damaging internal tank equipment and tank sealers
When is it permitted to enter a tank with out a full face mask
Only when the tank has been deemed health safe
When using gas measuring equipment on tank entry to measure if gas levels are safe, where must you place the measuring equipment
Outside of the safety area as it is not explosion proof
How may people are required for fuel tank maintenance
2 or more
What is a category 1 tank
- Direct access door
- Access by head and shoulders only
What is a category 2 tank
- Direct access door
- Access for complete body
What is a category 3 tank
- No direct access door
- Internal opening
- Wide enough for rescue
What is a category 4 tank
- Not on all aircraft
- Only entered via internal openings which are not wide enough to rescue personnel in emergency
- To get out mechanical cutters must be used
