The End of 100LL: FAA Sets 2030 Phase-Out Target for Leaded Avgas
The FAA's draft transition plan sets December 31, 2030 as the target end date for 100LL in the continental U.S. Here's where G100UL stands, which aircraft are approved, and what piston pilots need to do before the deadline.
For decades, 100LL — the blue, leaded aviation fuel that powers the majority of piston aircraft in the United States — has been the only practical option at most general aviation airports. That is changing. The FAA's draft unleaded avgas transition plan, released in January 2026, sets a firm target: December 31, 2030 for the continental U.S.
If you fly a piston aircraft, this affects you directly. Here is where the transition stands and what you need to know.
The Phase-Out Timeline
The FAA's draft plan establishes the following deadlines:
| Region | 100LL Phase-Out Target |
|---|---|
| Continental United States | December 31, 2030 |
| Alaska | 2032 |
| U.S. Territories | TBD |
One critical protection is already in place: the FAA Reauthorization Act of 2024 prevents airports from banning 100LL before December 31, 2030 unless a certified replacement is already widely available at that location. In practice, this means pilots will not be stranded overnight — but the clock is running.
G100UL: The Leading Replacement
The furthest along in the transition is G100UL, produced by General Aviation Modifications Inc. (GAMI). Its approval status as of May 2026:
| Detail | Status |
|---|---|
| FAA approval type | Approved Model List (AML) Supplementary Type Certificate (STC) |
| Approval date | September 2022 |
| Aircraft coverage | ~98% of piston-powered aircraft in FAA type certificate database |
| Drop-in compatible | Yes — no engine or airframe modifications required |
| Can be mixed with 100LL | Yes |
The AML-STC means G100UL is approved for essentially every spark-ignition piston engine and airframe in the FAA's records. You do not need a separate STC for your specific aircraft — if your aircraft is in the FAA type certificate database, you are almost certainly covered.
Check your aircraft: Verify your specific make and model at stc.g100ul.com. The database is searchable by manufacturer, model, and engine.
Where It Gets Complicated
G100UL approval does not mean G100UL is available at your airport. Distribution infrastructure is the bottleneck. As of mid-2026, G100UL is available at a limited and growing number of FBOs nationwide — not yet universal.
Additionally, not all manufacturers have added G100UL to their approved fuel lists. Textron Aviation (Cessna, Beechcraft) has requested additional testing before authorizing G100UL fleet-wide. If your aircraft's POH or AFM restricts fuel type, follow the manufacturer's guidance — the AML-STC approval does not override a manufacturer restriction.
Other Fuels in the Pipeline
G100UL is not the only candidate:
- UL100E — ASTM specification granted in January 2026. Still undergoing full-scale evaluation under the FAA's Piston Aircraft Fuel Initiative (PAFI). Testing expected to conclude by late 2026.
- Swift Fuels 100R — Has obtained engine STC for specific Lycoming engines and an airframe STC for Cessna 172 R/S models, with plans to expand coverage.
The FAA's EAGLE initiative (Eliminate Aviation Gasoline Lead Emissions) is the umbrella program coordinating all of this. Progress has been slower than some in the industry hoped, but the 2030 deadline creates a firm backstop.
What This Means for Piston Pilots
Your action items before 2030:1. Check if G100UL is approved for your aircraft at stc.g100ul.com
2. Check your POH/AFM for any manufacturer fuel restrictions
3. Check with your home FBO about their timeline for stocking unleaded alternatives
4. Monitor your aircraft manufacturer's communications — STC and fuel approvals are evolving
The 2030 deadline is four years out. That is enough time to plan, but not enough time to ignore. Pilots who understand the transition now will be in a better position than those who wait for the pump to change.