Fuel System Flashcards
What are the colors of the 5 different types of fuel?
- 80/87 - Red
- 100LL - Blue
- 100/130 (High Lead) - Green
- Jet Fuel - Clear
- MOGAS (for cars) - Yellow
Whatdo the rumbers in a fuel rating mean?
Fuel grades are usually indicated by two numbers: 08/07 or 100/130.
The first number indicates the Octane rating (80%) is at a lean mixture setting
The second number is the octane rating (87%) at a rich mixture
How can 100/130 have a 130% octane value at rich mixture?
Because tons of lead has been added to the fuel which makes it perform like it has 130% octane
How do octane and heptane behave?
Octane burns slow, heptane is explosive
If you do not have access to the type of fuel you need what type should you use?
The next highest octane rating. Do not use a lower one as it will have more heptane (explosive) it could damage your engine.
The higher octane will still lead to spark plug fouling
What does Avgas and Jet Fuel weigh and what happens when it gets colder?
Avgas - 6bls @ 15 degrees
Jet Fuel - 7lbs @ 15 degreees
As it gets colder, the density of the fuel increases and becomes heavier
What is pre-ignition?
A hot spot within a cylinder that begin to act like a third spark plug
What is detonation?
A problem with the fuel/air mixture which causes the fuel to burn explosively. Can also be from using fuel with an octane rating that is too low.
Will result in loss of power, engine overheating (high cylinder head temps are a good indication of detonation), and roughness. Can easily be mistook for pre-ignition.
If left for too long will cause engine damage
What are the 4 major Jet Fuel grades?
Jet A-1
Jet A
Jet B
Prist
What is Jet A-1?
- Kerosine grade of fuel for turbine engined AC
- Flash point of +38 degrees
- Freez point of -47 degrees
- Widely available outside the US
What is Jet A fuel?
- Kerosine grade of fuel for turbine engined AC
- Flash point of +38 degrees
- Freeze point of -40 degrees (lower than Jet A-1)
- Only available in the US
**If you are flying into very cold climates, Prist must be added to the fuel to keep it from freezing. You’d have to ask each FBO if they have Prist.
What is Jet B fuel?
- A distillate comprising naphtha and kerosine
- Can be used as an alt for Jet A-1
- Minimal demand and avilibility for this fuel as it is difficult to handle because it is highly flamable
- The only significant area of use is in very cold climates where better cold performance is important.
- Jet B does not require Prist/FSII
Why do we need Prist/FSII (fuel system ice inhibitor)
It is like antifreeze for your fuel. Becaue fuel often has suspended water molecules, once it gets to colder temps, it will freeze and clog fuel lines or filters. If it gets cold enough the fuel can also just congeal on its own.
Prist/FSII keeps all this from happening. It also supresses bacteria and fungi
Some Jet fuels include Prist and some do not. You have to ask the FBO if theirs does. If your AC does not have fuel heaters, it will be required to have Prist in the fuel, which is good because its expensive at an extra 5 cents per gallon
