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Cirrus: G100UL use may void warranties

Materials compatibility tests 'inconclusive'

Cirrus Aircraft may nullify warranties for aircraft that use unleaded General Aviation Modifications Inc. G100UL fuel, the world’s largest piston aircraft manufacturer said in a service advisory published June 19.

Photo by Chris Rose.

The announcement is a setback for GAMI, which has spent years developing an unleaded, high-octane fuel to replace leaded avgas in the worldwide fleet of piston airplanes.

Cirrus has tested G100UL in its SR20, SR22, and SR22T aircraft, and the company said it finds some aspects of the new fuel “encouraging,” but critical safety questions regarding materials compatibility remain “inconclusive.”

“Cirrus does not approve the use of GAMI G100UL fuel in SR Series airplanes,” the company said in its advisory. “Cirrus does not warrant or represent in any way an operator’s use of GAMI G100UL in SR Series airplanes.”

G100UL is made from a different chemical composition than leaded avgas. Any avgas replacement must be compatible with existing aircraft fuel tanks, bladders, lines, and accessories in addition to performing well in engines.

The FAA has approved supplemental type certificates for GAMI G100UL covering the full spectrum of piston aircraft engines. G100UL hasn’t been part of the FAA’s ongoing, multiyear Piston Aviation Fuel Initiative process known as PAFI, however, and it hasn’t been evaluated under American Society of Testing and Materials (ASTM) standards.

About 2,500 Cirrus aircraft are covered by standard three-year and extended five-year warranties. According to the terms of those warranties, they become void if “products . . . not supported or approved by Cirrus are installed on or applied to the aircraft.”

Cirrus SR22, SR22T, and some SR20 models are equipped with Continental engines. Continental warranties exclude damage that results from the use of “non-approved fuel.”

Some SR20s are equipped with Lycoming engines, and Lycoming’s warranty also excludes damage from “non-approved fuels.”

Neither Continental nor Lycoming has specifically approved G100UL.

The aviation industry is seeking to move away from leaded avgas as soon as a safe alternative is certified by the FAA and widely available. The FAA Reauthorization Act of 2024 requires airports that offered avgas in 2022 to continue to do so until 2030 or until an FAA-certified alternative is available.

GAMI, a privately owned firm based in Ada, Oklahoma, has performed extensive fuel tests in its own engine lab and ongoing materials analysis using many types of commonly used fuel tanks, fuel lines, and sealants.

AOPA has logged about 180 flight hours in a Beechcraft Baron using G100UL in the left engine and avgas in the right. The 1966 Baron’s newly overhauled Continental IO-520 engines are being regularly inspected and their data is recorded and closely monitored.

AOPA intends to fly the Baron with other unleaded fuels when they become available.

Cirrus says it’s been collaborating with several unleaded fuel manufacturers including GAMI, Swift, and LyondellBasell to find a safe alternative to leaded avgas.

“Safety is our upmost core value,” the company said. “We will not approve the use of a fuel until we have completed thorough and comprehensive materials and flight testing.”

AOPA Publications staff
AOPA Publications Staff editors are pilots, flight instructors, and aircraft owners with more than 250 years of combined aviation experience.
Topics: Financial, Aircraft Modifications, Supplemental Type Certificate

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