The FAA has released a Special Airworthiness Information Bulletin (SAIB) asking aircraft owners, FBOs, repair stations, Flight Standards District Offices (FSDO), and others to report any issues related to the use of unleaded fuel, such as service difficulties or maintenance issues.
Released March 28, 2025, the SAIB notes that the FAA has not identified an unsafe condition that would warrant an airworthiness directive. The bulletin also notes that it is for “information only.”
“Recommendations aren’t mandatory,” FAA officials added.
Background
In 2022, a government-industry initiative, Eliminate Aviation Gasoline Lead Emissions (EAGLE), launched with the goal of transitioning to lead-free aviation fuels for piston-engine aircraft in the United States by 2030 “without adversely impacting the safe and efficient operation of the existing general aviation fleet.”
“The FAA aims to collaborate with aviation stakeholders to collect data and understand any impacts to piston-powered GA aircraft as unleaded fuels are introduced and usage of unleaded fuel increases,” officials said in the bulletin.
“The FAA is also interested in hearing from operators who have transitioned to unleaded fuel without issue,” officials added.
“Several unleaded fuels are currently available and additional fuels are likely to be available soon,” the bulletin explained. “Approval for use of these unleaded fuels can be found in each make/model’s Type Certificate Data Sheet (TCDS), installation manual, service instructions, or Supplemental Type Certificate (STC). As part of providing effective safety oversight, the FAA will need to differentiate between pre-existing fuel issues using 100 octane low lead (100LL) fuel and issues which may arise from using high octane unleaded fuel.”
Several aircraft owners have reported fuel staining after using the new G100UL unleaded fuel developed by General Aviation Modifications Inc. (GAMI).
At the 2025 SUN ’n FUN Aerospace Expo, GAMI officials noted that many of those issues were due to faulty or improperly installed fuel cell bladders or patches inside the bladder, pointing to photos where the staining was blue from 100LL. If G100UL creates a stain, it would be brown, officials said.
SAIB Recommendations
The FAA recommends reporting the following information regarding service difficulties or abnormal maintenance issues using unleaded fuel:
- Aircraft make, model, and year of manufacture
- Manufacturer and type of unleaded fuel used
- Engine make/model and time since new or last overhaul
- Approximate volume (gallons) of unleaded fuel used before issue
- Time from original transition to unleaded fuel until issue observed
- Engine total hours and approximate hours using unleaded fuel
- Any mixing of fuels (unleaded fuel with 100LL fuel, as an example)
- Description and date of issue observed.
In describing your issue, aircraft owners are asked to consider the following:
- Recent aircraft maintenance prior to unleaded fuel use (new hoses, gaskets, fuel sealants, engine maintenance)
- Any related issues observed before transition to unleaded fuel
Issues related to fuel leaks or sealant/gasket breakdown:
- Sealant type and gasket materials used
- Internal inspection/photos of fuel tanks
- Photos of external or substrate damage
- Samples of fuel and/or materials submitted or collected by the local FSDO
Engine related issues:
- Description of any performance degradation
- Details on parts affected or failed parts
- Photos of affected parts/engine condition or any excessive buildup, wear, or degradation
Fuel system issues:
- Excessive wear or degradation of components
- Particulate or foreign object presence
You can submit these reports to [email protected] with “Unleaded Fuel” in the subject line.
Those reporting issues are asked to include their contact information and preferred method of contact, should the FAA have additional questions.
For more information: DRS.FAA.gov
I would imagine you would see Brown fuel stains from this new fuel as that’s the color additive that they add to it. Blue staining is what we commonly see with the 100 LL.