Lycoming Updates The Fight Against 100LL By Environmentalists

By Chris Batcheller

“The clock is ticking” exclaimed Lycoming’s Randy Jenson as he opened the forum on Aviation Fuels. An environmental activist group called the “Friends of the Earth” has petitioned the EPA to ban all leaded fuels in aviation.  He went on to say “The status quo has changed”.  Lycoming fully expects that the EPA will rule against 100LL fuel, forcing the industry to find an alternative in the next 5 to 7 years.  They believe that this ruling will come because of global economic, political and regulatory pressure.

Randy Jenson

The country consumes 9.8 million barrels of mogas (car gas) per day and 4.5 million barrels of road diesel per day. Of the aviation fuels, Jet fuel is consumed the most at 1.8 million barrels per day due to commercial use. In contrast, a mere 20,000 barrels of 100LL is consumed per day. Randy noted that Avgas is considered a “specialty chemical” and that it stopped being a high volume fuel in the 1960’s.

Randy Jenson went on to note that high octane mogas is not a direct suitable replacement for leaded (TEL) fuels.  There are several obstacles to using a mogas or mogas based fuel industry wide as a replacement for 100LL.  While mogas is a high volume fuel and competitively priced, it has lower octane, higher vapor pressures, and is blended many different ways. In addition the aviation community has no voice in setting standards for the fuel. 

Another obstacle is that mogas is currently blended with Ethenol in the United States, which is not compatible with aviation fuel systems.  It is possible to order mogas without ethanol, but it must be purchased in a large enough quantity to make it economically viable.

The first obstacle is the octane, which is sufficient for about 60% of the fleet, but it is not enough for the high performance aircraft. These high performance aircraft consume about 60% of the 100LL that is produced. Then, there is standardization. Aviation fuels are standardized to ensure consistency of important fuel properties all over the world. There is no standard for mogas, and fuels are blended locally based on regional needs. 

As diesel engines continue to gain popularity, Randy also noted that there are fuel-related issues to consider. Road diesel is generally not favorable for aviation use because of the low waxing point. This is the temperature that the full starts to transition from a liquid into a solid. 

While Jet A is an obvious choice for the aviation diesel engine, there are some issues with its use. The largest of those is that cetane is not regulated in the current Jet-A / JP-8 specifications. Cetane controls the ignition timing in a Diesel engine. ExxonMobile recently sent a letter to remind customers that cetane is not tracked and that cetain numbers can vary greatly. They also noted that ExxonMobile can not be responsible if customers use Jet fuel in their Diesel airplanes.

"There is no magic bullet,” Randy said. He noted that the industry's best option for a 100LL replacement is development of a synthetic fuel. For Jet Fuel, the industry needs to determine a minimum cetain number. One way to raise cetane is to inject an additive into the fuel in the vehicle. Either the industry needs to manufacture Jet fuel to a revised standard with a minimum cetane, or Diesel equipped airplanes will need to carry an extra tank for the additive.
 
It is clear that Lycoming expects the EPA to require that 100LL be phased out, probably in the next 5 to 7 years. In this time frame the industry must find a suitable replacement for legacy engines, since newer engines can be designed to run on lower octane fuels. Some additional work also needs to be considered in using Jet fuel in Diesel Engines.

FMI: www.lycoming.com