Fuel Systems

A summary of the requirements an ideal fuel should have;

- Easy flow under all operating conditions
- Complete combustion under all operating conditions
- High calorific value
- Non-corrosive
- Low fire hazard
- Good lubrication
- ...

Fuels - Piston Engines

Uses AVGAS (aviation gasoline).The octane rating of the fuel will also be specified with the grade, a higher octane fuel will be used with high performance engines having high compression ratios.

- AVGAS 100 = Green / SG 0.72 / High Lead
- AVGAS 100LL = Blue / SG 0.72 / Low Lead

Fuels - Gas Turbines

Uses kerosene fuels. The main types used are;

- AVTUR (Aviation Turbine fuel)
JET A1 = SG 0.8 at 15°C / -38°C Waxing point
JET A = Similar to A1 but -40°C Waxing point

- AVTAG (Aviation Turbine gasoline)
JET B = Wide cut gasoline & kerosene mix type / SG 0.77 / -60°C Waxing point

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Water in the fuel

Cloudy Fuel = When the fuel gives a cloudy appearance, it usually indicates the presence of water

Measures to minimise water accretion once fuel is transferred to aircraft tanks;

Water drains = Water (heavier) falls to bottom of the tank and can be drained off

Fuel heater = Prevents water in the fuel freezing by passing the fuel through a heat exchanger

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Waxing = The depositing of heavy hydrocarbons from the fuel at low temperatures