Question 626 Deck Safety

The correct answer is D) lean to burn. A fuel-air mixture that is below the lower explosive limit is considered too lean to burn. The lower explosive limit (LEL) is the minimum concentration of a flammable vapor or gas in air below which the mixture will not ignite. If the fuel-air mixture is below the LEL, it contains too little fuel to support combustion, making it too lean to burn. The other options are incorrect because: A) A mixture that is too dense would actually be too rich to burn. B) The temperature of the mixture is not the issue - the mixture is simply too lean to ignite. C) A mixture that is too rich would contain too much fuel, not too little.