When the EPA began to regulate the use of tetraethyl lead (TEL) in automotive gasoline in the 1980’s, the aviation industry assumed it would only be a matter of time before aviation fuel would be a target even though they had a waiver from the U.S. Environmental Protection Agency (EPA) to keep using it. The Aircraft Owners and Pilots Association (AOPA) lobbied to prevent the EPA from banning the use of unleaded fuel in the early 1990’s and was successful. The aviation industry is the sole user of TEL and as the demand lessens, there will likely be a natural transition away from 100 octane leaded fuel. The industry began to look for alternatives.
In May 2002, Steven W. Ells published an technical article in AOPA Pilot entitled “Lead Is Still King” which outlined the alternatives to leaded fuel that were available or being developed at the time. He states that, “Unfortunately, at the current time there is no transparent solution. In fact, some of the cures appear to be worse than the disease.” Now, fast forward to 2006.
In 2006, a petition was filed by the environmental group Friends of the Earth in which it asked the EPA to regulate general aviation’s lead emissions. This group, which was formed over 40 years ago, is an international environmental group with a network in 77 countries. They have a strong lobbying presence in the U.S. and are still pushing for the removal of lead from aviation fuel.
A second article written by Mr. Ells was published by AOPA in May 2006. It is entitled “Lead Is Still King – Part II” with a subtitle of “Nearly four years later, the story is the same.” Mr. Ells states that “In spite of a two-decade-long search for a replacement, nothing has yet been found to take its place.” Researchers are still looking for a full replacement for 100LL that will work in all types of general aviation aircraft. So far the closest alternative is ASTM standard 91/98 octane unleaded avgas that can be used by 70% of general aviation aircraft now using 100LL. Meanwhile production of TEL continues to decline and in 2006 was only produced by one factory in the United Kingdom. An alternative must be found as the EPA issued an advanced notice of proposed rulemaking (ANPR) in April 2010.