Final answer:
The minimum octane rating for aircraft fuel varies, but a common aviation fuel, 100LL (low lead), has an octane rating equivalent to pure isooctane and is colored blue. Octane ratings indicate a fuel’s ability to prevent engine knocking or pinging.
Step-by-step explanation:
The octane rating of fuel is important for determining its suitability for use in various types of engines. This rating indicates how well a fuel can resist knocking or pinging during combustion, which are signs of premature combustion. An octane rating of 100 means the fuel is comparable to pure isooctane, which burns very smoothly. Historically, antiknock agents like tetraethyllead were used to improve the octane rating, but due to their toxicity, they have been phased out. Alternative octane enhancers such as ethanol are now used instead. The color of aviation gasoline is often used to indicate its octane rating: for example, 100LL (low lead) aviation fuel is colored blue.