Cirrus Tells Owners Not To Use Unleaded Fuel

Cirrus says it doesn't approve of the use of G100UL or any other unleaded fuel in its SR series aircraft but G100UL's developer says that position flies in the face of the airframer's own FAA-supervised testing. Cirrus issued a statement on Thursday saying it now believes that G100UL that leaked from an SR22 in California  "resulted in damage to airframe components and could create airworthiness concerns."

George Braly, whose company developed the fuel 15 years ago, said Cirrus submitted a formal engineering report to the FAA over 10 years ago, based on extensive testing of G100UL Avgas which was conducted at Cirrus in Duluth.  That formal engineering report was filed with the FAA and said that exposure of Cirrus’s fiberglass wing structure to G100UL avgas had no adverse impact on the fiberglass and carbon fiber composite material used by Cirrus. 

Cirrus's statement came a few days after staff inspected an SR22 in California that exhibited paint damage in the area around the drain sump. "We are actively engaged with a Cirrus owner who began using GAMI G100UL in November 2024 and has since observed paint degradation, seal degradation, and fuel leakage," the company said.   It acknowledged the positive results of the testing 12 years ago but apparently has done testing since that didn't work out so well. "While some aspects of the initial Cirrus testing of the GAMI G100UL fuel were encouraging, Cirrus has identified specific concerns regarding material compatibility," the company statement said. "Lab testing in coordination with FAA representatives and on-aircraft field observations revealed seal degradation when in contact with GAMI G100UL fuel that has resulted in damage to airframe components and could create airworthiness concerns."

Braly said he, personally inspected the Cirrus with the reported paint damage and is satisfied that “the degradation of the paint was a maintenance-related matter and creates no safety of flight issue.” 

Braly also noted there are dozens of aircraft that have been using G100UL since November that have had no problems.  “That includes a number of  Cirrus aircraft,” he said.  His own TNSR22 has been using G100UL Avgas for 15 years, without any leaks and remains free of any damage to the engine, airframe, or the original paint. 

Cirrus's full statement follows:

"Cirrus is dedicated to advancing personal aviation and proactively addressing the evolving landscape of sustainability regulations, particularly the shift towards unleaded aviation fuels. We continue to actively support industry efforts and the FAA-Industry EAGLE program, including through the PAFI and STC certification program pathways, to develop, evaluate, and advance new fuels while supporting a safe industry transition to a future unleaded fuel environment. 

"As of January 2025, EAGLE is actively evaluating three potentially feasible alternatives/replacements for 100LL: GAMI G100UL, LyondellBasell/VP Racing UL100E, and Swift 100R. GAMI G100UL is the first unleaded, 100-octane aviation fuel to be offered to aircraft owners and operators directly, and the fuel began distribution to aircraft owners in November 2024. It is currently offered at 3 airports: KRHW (Reid-Hillview Airport of Santa Clara County, California), KWVI (Watsonville Municipal Airport, California), and KTUP (Tupelo Regional Airport, Mississippi).

"Cirrus has been engaged in a comprehensive testing and evaluation program of the GAMI G100UL fuel for over a decade, and has been monitoring field experience with GAMI G100UL since November 2024. While some aspects of the initial Cirrus testing of the GAMI G100UL fuel were encouraging, Cirrus has identified specific concerns regarding material compatibility. Lab testing in coordination with FAA representatives and on-aircraft field observations revealed seal degradation when in contact with GAMI G100UL fuel that has resulted in damage to airframe components and could create airworthiness concerns. We are actively engaged with a Cirrus owner who began using GAMI G100UL in November 2024 and has since observed paint degradation, seal degradation, and fuel leakage. Cirrus is working with the FAA and the aircraft owner to conduct further investigation and testing. There have also been reports of non-Cirrus aircraft owners observing similar paint and seal degradation and fuel leaks since using GAMI G100UL which have been posted in various online forums.

"While Cirrus is committed to a safe and timely transition to unleaded aviation fuel, at this time Cirrus does not approve the use of GAMI G100UL fuel, or any unleaded fuel, in any Cirrus SR Series airplanes. Additionally, Cirrus currently does not warrant or represent in any way an operator’s use of the GAMI G100UL fuel in SR Series airplanes. The continued safe operation of all Cirrus aircraft around the world remains our top priority.

"Cirrus is committed to working directly with industry associations and all stakeholders including AOPA, GAMA, the FAA, and the EAGLE program to support the transition to unleaded aviation fuels. Cirrus is dedicated to supporting all major fuel companies in their pursuit to bring alternative high-octane fuels to market with the continued goal to ensure operational safety of both the powerplant and airframe fuel systems. As fuels progress through the development and certification process and be offered to aircraft owners, we are committed to conducting materials compatibility, on-aircraft fuel performance testing, field observation, and testing of real-world usage of these fuels. We look forward to ensuring a safe and smooth transition to unleaded fuel for all Cirrus SR Series owners, and support AOPA’s efforts to gather feedback regarding unleaded aviation fuel usage via their online survey.

"Please refer to Cirrus Service Advisory SA24-14R1 for further information."