Module 15.9 Lubricants and fuels Flashcards
What are the drawbacks of mineral oils?
Lack stability and suffer from excessive volatility and thermal degradation at high temperatures
Ester based synthetic oils are now referred to as what?
Third generation oils
What are the functions of engine oil?
- Lubrication
- Cooling
- Cleaning
- Corrosion protection
What are the types of synthetic oils and uses?
Type 1 - older aircraft
Type 2 - modern GTE
Type 3 - specialised aircraft, jets
What are the advantages of synthetic oils?
- Better viscosity
- Better thermal stability
- High pressure resistance
What is viscosity index?
The effect that temp has on the viscosity
What is viscosity?
Internal resistance of fluid against deformation/flow
What is the pour point?
Lowest temperature oil will visibly move
Type 2 - -57℃
What is the flash point of type 2 oils?
250℃
What is a feature needed for oil when between moving components?
Pressure resistance
What happens to oil when it reacts with oxygen?
It gets thicker
Acidity is a measure of what?
The oil’s corrosive tendencies
What is oil foaming a measure of?
Resistance of oil to separate from entrapped air
Oil can cause rubber to do what?
Swell
What metal is particularly susceptible to oil corrosion?
Copper
What is coking?
Amount of carbon residue in the oil after extreme heating
What are the four types of turbine fuel?
- Jet A
- Jet A1
- Jet B
- JP5 (military application)
What is the flash point and freezing point for JP5?
+65℃ - flash point
-48℃ - freezing point
What is the flash point of jet B?
-20℃
Where is jet A and jet A1 used?
Jet A1 - Europe
Jet A- America
What are the main turbine fuel requirements?
- Low freezing point
- Low flash point for good ignition, but high enough to ensure safe handling
What temp should max viscosity be at?
-20℃
Jet fuels tend to carry what?
Water, dirt and micro-organisms
What are the two conditions water can be carried in, in fuel?
- Disolved
- Suspended
The interface between water and fuel promotes what?
Micro-biological growth
What is the density of Jet A/A1at 15℃?
0.81 kg/Ltr
What are two main reasons additives may be added to fuel?
- Anti-ice
- Anti-microbial
What is a fuel anti-ice additive?
Prist
What are some common additives in use?
- Anti-oxidants
- Static dissipator
- Corrosion inhibitors
- Metal deactivators
Are synthetic oils storage stable?
No
Can open containers of synthetic oil be re-used?
No
Can you mix different brands and types of oil?
No
Fuel leaks are caused by what?
- Refuelling malfunctions
- Aircraft damage
Where do refuelling leaks usually occur?
At vent tank openings
