15.09 Flashcards
(15 cards)
What is a disadvantage of mineral oils
Lack stability from excessive volatility and thermal degradation at high temps.
4 functions of engine oil
Lubrication
Cleaning
Corrosion protection
Cooling.
The three types of synthetic oils
Type 1 - older gas turbines.
Type 2 - most modern gas turbines.
Type 3 - special a/c like fighters.
Pros and cons of synthetic oils.
Pros
- better viscosity.
- thermal stability
- high pressure resistance
Cons
- high price.
Meaning of viscosity index.
Effect of temperature on the viscosity of the oil.
Meaning of viscosity.
Internal resistance of a fluid against deformation.
Low is preferable.
Meaning of pour point
Lowest temp that oil will visibly move
For type 2 oils it is -57 c
What happens when oil reacts with oxygen
The oil gets thicker.
Meaning of coking
Amount of carbon residue in the oil after extreme heating.
Fuel specs for
Jet A
JetA1
Jet B
JP5
A = fl.p. 38 , fr.p. -40
A1 = fl.p. 38, fr.p. -47
B = fl.p. -20, fr.p. -58
JP5 = fl.p. 65, fr.p. -48
Fuel requirements
Low freezing point
Flash point low enough it ignites easily but also allows for safe handling.
Should be clear and free of solid matter.
Max viscosity at -20
Fuel additives
Measured in PPM
Prist - an anti-ice additive added in bulk or directly to tanks.
Antimicrobials
Anti oxidants
Static dissipator additives
Corrosion inhibitors.
Metal deactivators.
Synthetic oil safety precaution
Not storage suitable
Open containers should not be re-used as synthetic oil is hygroscopic (absorbs water).
Safety precautions for oils
Skin irritation
Dizziness or nausea.
Fuel safety precautions
Do not induce vomiting if ingested, drink half pint of water.
Cotton clothes when entering a tank.
