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STCs for Auto Fuel

By Jack Dueck, Editor – EAA Bits and Pieces, EAA Canadian Council

STCs for Auto Fuel

STCs for Auto Fuel

Yikes! At $1.52 per litre, avgas is getting up there with the price of bottled water! I recently assisted a fellow in obtaining the auto fuel supplemental type certificate (STC) for his Canadian-registered aircraft. I was amazed with how simple the process was and thought I would pass it on to interested readers. There are several holders of auto fuel STCs; EAA is one of them.

EAA began the testing and evaluation of alternate fuels for aircraft piston engines in 1964. These tests included both automobile gasoline and ethanol. In 1982, EAA successfully changed FAA policy to consider the use of automobile gasoline in aircraft. The EAA type certificate program resulted in an FAA STC being issued for the use of automobile gasoline, rather than aviation gasoline, in the Cessna 150 aircraft powered by a Continental O-200 engine. The first pilot to legally fly in an aircraft with automobile gasoline was then FAA Administrator Lynn Helms. Since that time, more than 40,000 STCs have been issued.

So this happened in the United States. What about Canada? I contacted Jim Palmer of Ontario Region, Aircraft Certification, who was most helpful in negotiating the Transport Canada website. He cited CI-513-003 Issue 01, dated 2008-09-15, which says that if the United States is the “state of design” for the aircraft in question (for FAR 23 or CAR 3b only) and the STC is issued by the FAA for that type(s), Transport Canada will accept the STC without any further “design examination” of the STC. To emphasize, this is only true for a U.S. designed and manufactured aircraft.

In order to obtain an auto fuel STC for your aircraft, you need to do four things:

  1. Ensure the aircraft is designed and manufactured in the United States.
  2. Ensure the aircraft and engine are listed below.
  3. Purchase the STC for the specific aircraft.
  4. Enter the STC documents into your appropriate logs (journey and engine as applicable).

Does auto fuel in an aircraft have a downside? I asked an aircraft engine maintenance engineer and here’s what he suggested:  

  1. Mix some avgas with the auto fuel, preferably at a ratio of about 50/50. This will help stabilize the fuel.
  2. Don’t let auto fuel sit in your fuel tank for long periods. Auto fuel tends to destabilize and become gummy with varnish-type deposits. If you’re not going to fly for a period of time exceeding a month or so, drain the fuel from your airplane and use it in your automobile.

You can do a quick cost benefit analysis. The price differential between avgas and mogas is about 40 cents per litre. So if you’re mixing a 50/50 ratio, your fuel saving would be 20 cents per litre. If you’re mixing 25 percent avgas to 75 percent mogas, you’ll be saving about 30 cents per litre. If you’re flying a homebuilt, you don’t need to purchase the STC, and your savings accrue immediately.

EAA offers STCs for automobile fuel for the engine models used in the airframes listed.

Teledyne Continental Engines

A-40, -2, -3, -4, -5


A-50-1, -2, -3, -4, -5, -6, -7, -8, -9


A-65-1, -3, -6, -7, -8, -9, -12, -14 (O-170-3, -5, -7)


A-75-3, -6, -8, -9


C-75-8, -12, -15


C-85-8, -12, -14, -15


C-90-8, -12, -14, -16


C-125-1, -2


E-165-2, -3, -4


E-185-2, -5


E-185-1, -3, -8, -9, -10, -11


C-145-2, -2H, -2HP


O-200-A, -B, -C


GO-300-A, -B, -C, -D, -E


E-225-2, -4, -8, -9


O-470-A, -E, -J


O-470-K, -L, -R, -S


O-470-11, -11B, -15


0-470-4, -13, -13B




Avco Lycoming Engines






O-235-C1, -C2, -E1, -E2




O-290, 0-290-A, -AP, -B, -C, -CP, -D


O-290-D2, -D2A, -D2B, -D2C


O-320-A, -C, -E


O-540-B1A5, -B1B5, -B1D5, -B2A5,
-B2B5, -B2C5, -B4A5, -B4B5


* Engine modification required.
   ● Prices are in U.S. dollars.

Airframe Models Approved

Aero Commander, Inc.

S.L. Industries 100

Aeronca, Inc.

Bellanca, Champion, Trytek, Wagner, B&B Aviation, Citabria, most models, 7 series, 11 series, * 7KCAB

Arctic Aircraft Co., Inc.

Interstate S-1A, * S-1B1, S-1B2

Beechcraft, Inc.

Bonanza 35, A-35, B-35, C-35, D-35, E-35, F-35, G-35, 35R


120, 140, 140A
150, 150A-H, 150J-M, A-150K-M
170, 170A, 170B
172, 172A-E, 172F (T-41A), 172G-H
P172, 172I, K, L, M
175, 175A, B, C
180, 180A-H, 180J
182, 182A-P 305A (O-1A), 305B, 305E (TO-1D, I-1D, O-1F)
305C (O-1E), 305D (O-1G), 305F

Commonwealth, Inc.

Skyranger and Rearwin 175, 180, 185

Ercoupe, Inc.

Airco, Skyranger and Rearwin 415-C, -D, -E, -G, 415-CD, F-1, F-1A, A-2, A-2A, M10



Grumman, Inc.

Gulfstream American AA-1, -1A, -1B, -1C, AA-5, -5A

Luscombe, Inc.

Temco 8 Series, 11A


M-4, most models


M-18C, -18C55, -18L, -18LA


J-3, most models
J-4, most models
J-5, most models
PA-11, most models
PA-12, most models
* PA-15
PA-18, most models
PA-19, most models
PA-20, most models
PA-22, most models
PA-28-140, -150, -151

Porterfield, Inc.

Rankin & Northwest CP-55, CP-65, CS-65


(Univair) * 108 series, HW-75, 10

Superior Aircraft Co., Inc.

LCA, * LFA,Culver, Cadet


A, BC, most models


2000C, 2150, 2150A, 2180

* Airframe approvals only
Revised June 7, 2006

To learn more, visit www.EAA.org/autofuel.


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