...But You Can’t Just Put Any Old Gas in an Airplane – Even If It Works
Availability of a lead-free aviation fuel for piston-engined aircraft moved a step closer with the arrival at EAA AirVenture of a Piper Archer powered by 93 octane premium unleaded automotive gasoline.
Piper worked with Airworthy AutoGas LLC, of Phoenix, Ariz., to prove the concept in a test flight regime that included flying to Oshkosh from Vero Beach, Florida.
The test Piper Archer is powered by a single 180-hp Lycoming O-360-A4M engine that can burn either 100LL (low lead) fuel or Airworthy AutoGas’s unleaded recipe.
Airworthy AutoGas is a patent pending formulation that meets the requirements of ASTM D4814 and is already approved by Lycoming under under its Engine's Service Instruction 1070S. Unlike traditional automotive gasoline, AutoGas is designed for spark-ignition internal combustion engines used in aircraft applications, including additives that maintain vapor-pressure requirements at altitude.
“As we search for more environmentally friendly fuels than 100LL to power piston aircraft, Piper wanted to take the next step with Lycoming and Airworthy AutoGas to operationally prove the 93UL concept under rigid test conditions from Vero Beach," says Piper president and CEO Simon Caldecott. "Our next operational effort will include cross-country applications, working with Airworthy AutoGas to ensure availability en route."
For now, cross-country flights represent a major problem: all Airworthy Autogas must be trucked specially to wherever the Piper test Archer needs fuel. Indeed, after three or four refueling stops on the way to Oshkosh, the Archer cannot refuel here at AirVenture because lead- and ethanol-free mogas is not available on the field. However, at least 10 airfields within a 50-mile range of Oshkosh already carry the fuel.
Before an aircraft can use AutoGas or an equivalent made by other refiners, it must be powered by an engine whose manufacturer has approved the fuel, and it must obtain a specific supplemental type certificate (STC) for the airframe and its systems. This could be very much like the current STCs available for many aircraft types for the use of regular ethanol-free autogas. But the latter STC has been rendered difficult to comply with by the ban in many states of autogas without ethanol.
Airworthy AutoGas is a petroleum products blender and distributor dedicated to providing the highest quality fuel, promoting general aviation, and making flying more affordable. “We plan to produce and distribute our high-purity, low-vapor-pressure, ethanol-free, 93 octane, premium unleaded AutoGas automotive gasoline beginning in the fall of 2013," says Airworthy's director of business development Mark Ellery. "Bringing Airworthy AutoGas to the marketplace provides an alternative for the majority of general aviation aircraft without compromising airworthiness. Our goal is to get pilots flying more for less."
Piper’s proof-of-concept AutoGas airplane flew here from Florida on Lead-free 93 UL fuel.