Posted by: Green Knight | February 26, 2013

Lead in Aircraft Fuel, Part II

Nearly 3 years ago I did a post on this issue, and still get hits on it from time to time. I looked at it and saw that I was still typing in all lower-case back then. Lazy me!

Anyway, I got curious about it again for some reason, and found a couple more articles on the subject, one a Q & A from Scientific American, and one a Wikipedia listing. The 100LL (“low lead”) aviation fuel, the most commonly used, contains 100 times the lead needed to make it hazardous waste if a dirty batch had to be disposed of. That’s pretty high for “low lead” fuel. The “100” isn’t related to that, though, but rather to the octane rating.

The third article listed below is about military fuel, and doesn’t mention lead at all, but what’s interesting is that what one of my students told me years ago turns out to be true. The most common fuel was JP 4, but JP 5 was developed right before the Resource Conservation & Recovery Act (RCRA) was passed in 1976. To be an ignitable hazardous waste under RCRA, a liquid must have a flash point of less than 140 degrees Fahrenheit (60° Celsius). JP 5 was developed to have a minimum flash point of 140°F (60°C), so a dirty batch wouldn’t have to be considered RCRA hazardous. How about that?

I’m pretty sure that when I inspected the Missouri Air National Guard many years ago, they told me that their jet fuel had lead in it, but I’d have to go look up the file. They don’t tell much to civilians, and not as much as they should to government inspectors. I DO know that aircraft PAINT often has lead and other toxic metals in it, as an anticorrosive and to help it stick to the fuselage better. Not sure if that’s changed in 21 years or not, though.

[“Flash point” is the lowest temperature at which a liquid will catch fire — and keep burning — in the presence of a spark. There’s a specific lab test for it, but you get the idea.]


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