EAGLE and Unleaded Avgas

[PaulMillner]

Any comments on John's words?

I cannot speak for the proposed Swift unleaded 100 octane avgas except to say that they use ETBE and current California law prohibits ETBE in any "self-propelled motor vehicle" fuel (per Aviation Consumer magazine, February, 2024).

I've recently communicated with the California Air Resources Board (CARB) about this. It's a twisty tale. CARB's opinion is that the federal government has pre-empted ether, including ETBE, legality, so that CARB is not concerned. California law is twisty.

1) California law defines aircraft as *not* being motor vehicles. That makes sense.

2) California law, however, defines gasoline as including aviation gasoline, and forbids MTBE and ETBE (and other ethers) in gasoline, hence in avgas.

3) But wait! California law defines avgas as gasoline that meets ASTM spec D910. Neither Swift's 94UL, 100R, or GAMI's G100UL meet ASTM spec D910. So under California law, they aren't avgas. And if they're not avgas, then they're not gasoline, per the definition. And since they're not being used in motor vehicles, then ETBE is OK in non-D910 avgas... maybe.

CARB says they're not working the issue... if the federal government issues any necessary waiver (more likely than not I think) for Swift and Lyondell to include ETBE in avgas, it would appear that California law is twisty enough to not interfere, unless CARB or the legislature interferes to prevent ETBE introduction in non-D910 avgas. Given the governor's public position on getting the lead out, it seems unlikely that his administration would interfere with unleaded avgas alternatives coming to market. The good news is that outlawing ETBE avgas would seem to require action; inaction will result in ETBE avgas skirting through the loopholes.

the recent University of North Dakota Flight School incident with exhaust valve seat recession while using this fuel {Swift 94UL}

All we have from UND so far is an observation on valve lash. No data on actual valve seat recession, and no science... they only began monitoring *after* switching to unleaded. So we don't know what these numbers were like on leaded fuel. Haven't heard if they're continuing their monitoring now that they've switched back to leaded; one would hope so. Lycoming's Jennifer Miller indicated at ASTM in New Orleans in December that Lycoming was working with UND to get to the bottom of it. Don't quite know if there's any there there quite yet. However, we do know from work done in the 1990's on the mogas transition to unleaded that valve seat wear can go up from simply reducing the octane of the fuel, which UND obviously did by switching from 100LL to 94UL. More to come.

The auto companies cured the problem by going with a hardened valve seat.

That was part of the response. They also increased sophistication of engine controls substantially to compensate for air/fuel mixture and sense knock and thereby retard timing. Lots of pieces moving at the same time.

Swift filed a patent for an additive of calcium sulfonates to protect against VSR.

Yeah, inside, those engines look like a snow globe exploded, lots of white calcium deposits. This cannot be good thing when it comes to avoiding preignition and other deposit-related woes. But Swift says that deposits are good. Hmmm.

In case VSR is new to you, it involves excessive seat wear due to erosion.

The mainstream view is that reduced octane can cause this erosion by engendering higher intracylinder pressures which push the valve harder into the seat, causing micro-welding to occur. Then, when the valve opens again, those welds break, and the seat erodes over time from welding/breaking cycles.

Soon, you are going to start seeing unleaded 100 octane avgas at airports in California.

I believe that GAMI will succeed with that in 2024.

environmentalists sued the avgas selling FBO's (2011 thru 2014) to force them to post "LEAD" warning signs around airports. ... the FBO's and distributors committed to stop selling leaded gasoline as soon as a suitable unleaded gasoline was commercially available

That's not exactly what they agreed to; they agreed to sell lower lead (including zero lead) avgas when it became commercially available. The definition of commercially available could well be litigated.

in California ... as soon as an affected FBO is able to purchase any unleaded 100 octane avgas, the sale of 100LL will become illegal at that FBO, and that FBO will be subject to a contempt of court citation with a daily fine (likely) for each day that it continues to sell 100LL.

That may well happen.

The biggest problem is the political roadblocks and public deception being promulgated by members of E.A.G.L.E.

I'm not so condemnatory of EAGLE. Folks say EAGLE is wasting taxpayer money continuing to search for an unleaded avgas via PAFI. But that's the FAA's PAFI, not really EAGLE's. In my view, EAGLE is simply a joint FAA/industry communication group, intent on sharing information per their "pillars" identified in their structure with distributors, fuel producers, pilots, FBOs, and others affected by the transition. It's a communication coalition. Sure, some of the players might be evildoers or simply laggards... but I don't think that implicates EAGLE as a whole. Even GAMI and Swift, the decided outsiders here, belong to EAGLE.

{mogas} is not as safe in your airplane as you may think. I am fully aware of the Petersen and EAA STC's. ... there are known real problems caused by vapor lock or fuel instability issues with mogas. As fast as the NTSB is at getting to a crash site, the evidence of vapor lock is always gone before they arrive.

Mogas does reduce the margin of safety. Many have found the remaining margin of safety adequate. John does not agree.

you need to own the STC before you begin your trip.

Maybe. GAMI for one is working with the FAA to enable online purchase of the STC, and allow use of the fuel via electronic filing of that STC. Some paperwork, and verification of placards, may occur at the next annual or other service opportunity. But expediting the process is the intent.
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GAMI has already generated and implemented paperwork that {experimental aircraft owners} can take to {the} local FSDO {to} provide authorization to use GAMI's proprietary FAA Approved documentation to enable use of G100UL in our airplanes.

This would seem to undercut EAA CEO Jack Pelton's primary complaint about GAMI's approval approach. I think Jack is being poorly served by his staff on this issue. Otherwise, Jack would stop complaining.

unleaded avgas ... will benefit us directly in reduced oil change intervals, reduced maintenance costs, longer TBO's and eventually make possible the reintroduction of 100% synthetic oil. Please support the introduction of unleaded avgas.

Well spoken John!

Paul

 

[Dana]

GAMI has already generated and implemented paperwork that {experimental aircraft owners} can take to {the} local FSDO {to} provide authorization to use GAMI's proprietary FAA Approved documentation to enable use of G100UL in our airplanes.

Experimentals don't need any paperwork to use G100UL (or mogas, or any other fuel). It's only standard certificated aircraft that need the STC.

 

[Jeff Oslick]

FYI, ETBE is regulated by the California Water Resources Board as well, as it is a concern in groundwater used for drinking water. Any fueling system with underground storage or piping with ETBE might be an issue.