Is unleaded avgas coming to an airport near you?

By DEAN BILLING.

Perhaps you noticed the announcement that Swift Fuels made at AirVenture 2015, which was also carried by General Aviation News. Swift Fuels has begun distributing 94 MON, unleaded aviation fuel to several airports and has begun a program to distribute it throughout the U.S.

Airports currently carrying the new 94 MON unleaded aviation fuel are KAID, 05C and 7I2 in Indiana and KRMY in Michigan. Each airport replaced a mogas distribution except 05C, which added it as a new fuel service.

I’m not going to delve into the cosmic political and business implications of introducing a “low octane” unleaded avgas while the industry is working diligently on trying to find a 100 octane unleaded “drop-in” replacement for 100LL. Rather, I’m going to try to clarify who can use this fuel at the current time, because it is not everyone you might assume.

Suffice it to say, I think it is a gutsy move after all of these years that we have been told there will “… only be one avgas on our airports, and it will be 100 octane unleaded …” even though 80% of the GA fleet doesn’t need a 100 octane fuel.

I must also admit I’ll be most interested to see the ratio of airports that replace mogas compared to the number of airports that add Swift 94 MON unleaded avgas.

Technical Aspects Of Swift 94 MON Unleaded Avgas

Simply put, Swift claims its new fuel meets ASTM D7592, ASTM D7547 and ASTM D4814. What does all of that acronym gobbledygook mean and why is it important to you?

Let’s take a look at each standard:

ASTM D7592 is the most interesting spec that the new fuel meets because it is an avgas specification for a fuel that is not intended for commercial production. It is essentially 100LL avgas without TEL and has been commonly referred to as 94UL or UL94. If you read the ASTM specification Scope carefully you will notice:

1.4 The current purpose for the fuel specified herein is for certification and testing of an engine and engine components.

1.5 The UL94 standard is to be used for engine calibration and FAA certification.

I published a short thread about 94UL when ASTM approved it back in 2010.

ASTM D7547 is a rather interesting avgas spec with a colorful political history. It resulted from an urgent Department of Defense (DOD) request during the Gulf wars for a 91 MON unleaded avgas for Predator drones. They hoped they could just use the D910 100 octane avgas specification without TEL. ASTM told the Pentagon that wasn’t possible because all D910 avgas is required to have at least a small amount of TEL, but worked with DOD to rush through a new ASTM spec for UL91.

Oddly enough, ASTM was already working on the 94UL specification, which is 100LL without TEL.

Guess which specification emerged first from ASTM: D7547, in record time. Ironically this specification was developed to allow foreign refineries to supply a consistent fuel for Predator drones in the Middle East at about the same time the Rotax-powered Predators were being withdrawn from the theater.

Since that time, Europe has embraced D7547 as a 91 MON unleaded avgas and has manufactured and distributed it for several years, while it isn’t produced for GA use in the US, mainly because we don’t have airport infrastructure for a second aviation fuel that is not FAA approved for any current aircraft without an STC.

It is unknown if it is being produced for the Predators that are now flying over our borders. Nobody is saying. For all I know, they are using 91 AKI mogas, which is approved for the Rotax used in the drone. At least the US makes a very consistent, high quality D4814 fuel, unlike the auto fuel DOD was purchasing in the third world.

The GAfuels blog has covered some of the history of UL91 in a previous thread.

ASTM D4814 is the automotive fuel specification that is the basis for all mogas STCs.

Who Can Put Swift 94 MON Unleaded Avgas In Their Aircraft?

Homebuilt

• If the builder approved fuel meeting ASTM D4814 or D7547, they can use Swift 94 MON unleaded avgas.

Type Certificated Aircraft:

• If your aircraft has a mogas STC from the Experimental Aircraft Association (EAA), you can use Swift 94 MON unleaded avgas since it conforms to ASTM D4814.
• If your aircraft has a Petersen Aviation mogas STC, you can use Swift 94 MON unleaded avgas as Petersen STCs include the ASTM D7547 specification as well as the D4814 specification. If you don’t have an STC yet, but want to use Swift 94 MON unleaded avgas in your aircraft and it is on the Petersen Aviation mogas STC list, buy the STC from Petersen Aviation.
• If your aircraft is not on the Petersen Aviation STC list, but it does have a Lycoming engine that is on the Lycoming SI-1070S list, your engine is approved for Swift 94 MON avgas but you need an STC for your airframe. Check the Swift Avgas STC chart, as airframes like the Cessna 172R and 172S are now approved and more airframes will be added as Petersen Aviation and the FAA sort out the paperwork. You must buy your STC from Swift, but be advised that the STC will only allow you to use Swift 94 MON avgas or any avgas that meets ASTM D7547. However, it is NOT a mogas STC.
• There is no comparable Continental engine list to Lycoming SI-1070S. Therefore, you must have a Petersen mogas STC to use Swift 94 MON avgas in higher power Continental powered aircraft that require 91 AKI mogas.

Light Sport Aircraft

• All LSA which approve the use of ASTM D4814 compliant fuel can use Swift 94 MON avgas.

My website listing airports that provide unleaded aviation fuel, flyunleaded.com, includes the airports that supply Swift 94 MON unleaded avgas. They show up with a 94M* in the AKI field with a note that the fuel is Swift 94 MON unleaded avgas.